Optimization of Controlled Water and Nitrogen Fertigation...

Research ArticleOptimization of Controlled Water and Nitrogen Fertigation onGreenhouse Culture of Capsicum annuum

Youzhen Xiang12 Haiyang Zou1 Fucang Zhang 12 YouWu1 Shicheng Yan1

Xinyan Zhang1 Jianke Tian1 Shengcai Qiang1 HaidongWang1 and Hanmi Zhou3

1College of Water Resources and Architectural Engineering Northwest AampF University Yangling 712100 China2Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas of Ministry of EducationNorthwest AampF University Yangling 712100 China3College of Agricultural Engineering Henan University of Science and Technology Luoyang 471003 China

Correspondence should be addressed to Fucang Zhang zhangfcnwsuafeducn

Received 6 November 2017 Accepted 18 February 2018 Published 15 April 2018

Academic Editor Zhenli He

Copyright copy 2018 Youzhen Xiang et alThis is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

This study investigated the effects of different combinations of irrigation and nitrogen levels on the growth of greenhouse sweetpeppers assessing yield quality water use efficiency (WUE) and partial factor productivity from applied N (PFPN) By usingcontrolled drip irrigation the optimal conditions for efficient large-scale high-yield and high quality production of sweet peppersin Northwest China were determined Using the local conventional irrigation and nitrogen regime as a control (105 ET0 N300 kgsdothmminus2) three alternative irrigation levels were also tested at 90 75 and 60 ET0 These were combined with nitrogenlevels at 100 as the control and 75 50 and 25 resulting in 16 combination treatmentsThe results show that different suppliesof water and nitrogen nutrition had a significant impact on the growth yield WUE PFPN and quality of fruit The treatments ofW090N075 W090N050 W075N075 andW075N050 can better maintain the ldquosource-sinkrdquo relationship of peppersThey increased theeconomic yield WUE and PFPN A principal component analysis was performed to evaluate indicators of fruit quality revealingthat the treatment of W075N050 resulted in the best fruit quality For greenhouse sweet peppers produced in Northwest Chinathe combination of W090N075 resulted in the highest economic yield of 3485 kgsdothmminus2 The combination of W075N075 had thehighest WUE of 1650 kgsdotmminus3 TheW075N050 combination treatment had the highest fruit quality score For sustainable ecologicaldevelopment and in view of limited water resources in the area we recommend the W075N050 combination treatment since itcould obtain the optimal fruit quality while its economic yield and WUE were 9 and 4 less than the maximum respectivelyThis study provides a theoretical basis for the optimal management of water and nitrogen during production of greenhouse sweetpeppers in Northwest China

1 Introduction

The ever-increasing imbalance between supply and demandof agricultural water has forced adjustments of modernagricultural irrigation practices [1] Crop yields generallybenefit from short growth cycles and the selection of high-yield varieties that undergo rapid development strategies thathave effectively increased the income of farmers However inorder to maximize yield excessive irrigation and fertilizationare often required resulting in overuse and serious runoffof fertilizer Other negative effects are more frequent plantdiseases and pests [2] a reduction of product quality less

efficient water and fertilizer utilization [3] and damage tolocal soil and water environments [4]

Water and nitrogen are critical factors determining cropyield and quality [5] Appropriate irrigation technologies andnitrogen application strategies can lead to high yields andgrowth efficiencies of crops Compared to conventional fur-row irrigation fertigation (the injection of fertilizer solutioninto the soil) effectively reduces surface runoff evaporationbetween plants and deep percolation [6] At the same timethe drip irrigation technology with small flow can lowerthe downward migration rate of nitrogen into the soil andreduce nutrient loss [7] As a result a suitable nutrient

Hindawie Scientific World JournalVolume 2018 Article ID 9207181 11 pageshttpsdoiorg10115520189207181

2 The Scientific World Journal

microenvironment in the crop root zone can be achievedpromoting absorption of nutrients into the crops

C annuum (L var grossum) amember of the Solanaceaeproduces fruits with a high nutritional value Its effectiveculture is strongly dependent on the environment [8] as theplant requires a constant supply of water and nutrients [9]The availability of nitrogen is an important determinant ofcrop yield and quality by directly affecting photosynthesisand the accumulation transfer and distribution of biomass[10] Previously the studies of water-fertilizer managementmainly focused on irrigation methods [11] irrigation amountand frequency [12] and various types of fertilizers [13ndash15]

Lately an improved fertigation technique was developedthat applies nutrients with water to the crops Comparedto classical fertigation this new technique significantlyincreases yield water use efficiency (WUE) and nutrient useefficiency [16ndash22] For instance compared to conventionalfurrow irrigation properly controlled fertigation increasesthe yield of C annuum and enhances WUE [11 23] It wasexperimentally shown that carefully determined fertilizerquantities could ensure high yield of C annuum at thesame time reducing production costs [13] Another studyreported that compared to conventional furrow irrigation anoptimized fertigation strategy could increase the WUE of Cannuum by 95 saving water by 34 and fertilizer by 20[15]

Few studies have investigated the comprehensive influ-ence of a water-nitrogen coupling effect on the growth yieldand quality of C annuum and a quantitative index remainsto be determined Particularly fruit quality as a function ofthe water-nitrogen ratio has rarely been reported Thereforethe experiments presented here aimed at enhancing theutilization of water and nitrogen as well as promoting yieldand quality of C annuum crops Using an automaticallycontrolled irrigation and fertilization system plot tests wereperformed in a sunlight greenhouse to optimize water andnitrogen management and make full use of water-nitrogensynergistic effects This work provides technical support forapplication of automatic water and nitrogen managementsystems inC annuum cultivation under protected conditionsand offers a scientific basis for reference of high quality highefficiency and large-scale production

2 Materials and Methods

21 Experimental Materials

211 Experimental Plots The experiments were conductedin a test area with the Guanzhong plain China located at108∘041015840E and 34∘201015840N The work was performed betweenApril and July 2014 in a sunlight greenhouse belonging tothe Key Laboratory of the Ministry of Education for Agri-cultural Water and Soil Engineering in Arid Area NorthwestAgriculture and Forestry University China The greenhousewindows face south and north with vents at the top andsouthern-facing bottom of the greenhouse The test facilityhas an altitude of 521m and warm temperature due to a localsemihumid climate The annual average temperature is 13∘Cwith annual average precipitation from 550 to 600mm The

greenhouse measures 76m in length 75m in width and28m in height Heavy soil (1 sand 72 silt and 27 clay)was used with details on its physical and chemical propertiesshown in Table 1 The soil bulk density was measured by dryweight Soil samples were collected from a depth between 0and 80 cm (every 20 cm) with a ring knife (diameter 5 cmheight 5 cm) A small weather station (HOBO Event LoggerOnset Computer Corporation USA) was set up inside thegreenhouse The atmospheric pressure temperature photosynthetically active radiation (PAR) relative humidity andmeteorological factors such as solar radiation were recordedevery 10minutesThe obtainedmeasurements confirmed thatthese parameters were comparable for all plots

212 Fertigation Equipment An online irrigation fertilizerapplicator (NETAJET 3G INLINE NETAFIM Israel) wasemployed for fertigation which can precisely apply andcontrol fertilization based on the amount of irrigation waterThe flow rate supported by this system is from 05 to20m3sdothminus1 Venturi-type applicators were used equippedwithan optical fertilizer meter with a flow rate capacity from 30 to300 Lsdothminus1 Both fertilizer and acid solutions can be used Inaddition the system includes electrical conductivity (EC) andpH measurement and control modules Drip irrigation pipe(inner diameter 8mm)was employed using drip laterals withinline emitter distanced at 30 cm between emitter providinga flow rate of 2 Lsdothminus1 for each emitter and pipe workingpressure of 03MPa

213 C annuum Type and Fertilizer Used American Cannuum ldquoMarcordquo (Capsicum annuum L var grossum Mar-comi F1) was used as this type is particularly suitable forgreenhouse production The long lantern shaped fruit isgreen when young and turns red when ripe The fertilizerused in the experiment contains urea calcium superphos-phate (Ca(H2PO4)2sdot2H2O) and potassium chloride (KCl)

22 Experimental Design Two experimental variables werestudied the amount of irrigation water and the amount ofnitrogen fertilizer Based on the reference crop evapotranspi-ration (ET0) four irrigation levels were tested at 105 ET0(W105) 90 ET0 (W090) 75 ET0 (W075) and 60 ET0(W060) Based on the locally recommended nitrogen appli-cation amount of 300 kgsdothmminus2 (300 kgsdothmminus2 N100) threealternative regimes were tested with 75 N (225 kgsdothmminus2N075) 50 (150 kgsdothmminus2 N050) and 25 (75 kgsdothmminus2 N025)The test was designed to assess all 16 possible combinations ofthese variables with three identical plots for each situationreaching a total of 48 plots Cultivation in furrows coveredwith film was adopted which is typically used by localfarmers Each ridge had a height of 25 cm and width of75 cm The top of the ridge was flat with spacing of 50 cmbetween ridges plants were spaced at 45 cm and rows wereseparated by 30 cm Individual planting was used with aplanting density of 31000 plants per hm2 Each plot consistsof one ridge with two plant rows A drip lateral pipe wasinstalled in the middle of two plant rows so that one pipecontrolled two rows Each plot was 670 times 125m with a

The Scientific World Journal 3

Table 1 Physical and chemical properties of the experimental field soil

Soil depth(cm)

Soil bulkdensity(gsdotcmminus3)

Fieldcapacity()

Wiltingpoint()

Saturatedmoisture

()pH value

Organicmattercontent()

Total Ncontent()

Total Pcontent()

Total Kcontent()

0ndash20 146 244 152 453 803 145 008 006 01720ndash40 157 238 182 420 815 157 008 005 01440ndash60 148 247 176 490 820 143 006 004 01460ndash80 145 252 160 352 820 140 005 002 012

total area of 840m2 To prevent the interaction of water andfertilizer between neighboring plots the plots were separatedby embedding plastic foil 1m deep into the soil

23 Irrigation and Fertilization On January 6 2014 seedswere soaked in water for 12 hours followed by incubationin 1 copper sulfate solution for 5min and subsequentlywashed with water The seeds were then placed into athermostat for germination from 25 to 30∘C for ten daysThe budding seeds were sowed in a hotbed Five weeks laterthe greenhouse was disinfected as follows For each cubicmeter of soil 5 g sulfur 01 g 80 insecticide (dichlorvos 22-dichlorovinyl dimethyl phosphate) and 10 g saw dust weremixed uniformly and ignited After sealing the greenhouseovernight the greenhouse was vented and sealed again Theelevated temperature of the greenhouse was continued for48 hours On April 1 and 2 the soil was prepared andbasic fertilizer (phosphate) was applied The seedlings with1 heart and from 8 to 12 leaves were planted on the nextday and uprooted on July 23 To ensure a proper seedlingsurvival rate 40mm planting water was applied Beginningfrom April 19 irrigation was conducted every five daysDuring the whole growth period the total irrigation amountsfor W105 W090 W075 and W060 were 2631 2312 1994and 1678mm respectively After transplanting the seedlingsnitrogen was applied seven times at day 20 40 55 65 7585 and 95 with amounts of 133 133 133 20 20 133and 67 of the total nitrogen amount applied to the wholegrowth period After cultivation for 40 days phosphate andpotassium fertilizer was applied every 15 days for a totalof five times with application of 85 kgsdothmminus2 of phosphatefertilizer and 25 kgsdothmminus2 of potassium fertilizer each timeDuring the whole growth period plant management such assupport pruning and thinning was performed according tolocal custom

24 Measurements and Methods

241 Dry Matter Content (DM) During the experimentthree C annuum plants were randomly selected from eachplot on 33 54 66 81 and 112 days after transplanting (DAT)and the DM content of the plants (including stems leavesfruit and roots)was determinedTheplantmaterial was driedby incubation at 105∘C for 30min followed by drying at 75∘Cuntil the weight was constant The samples were then cooledin a dryer and weighed using a precision electronic scale For

each plot the plant dry weight was expressed as the averageof three plants and the total biomass (tsdothmminus2) was calculatedby multiplying the dry weight with the planting density

242 Chlorophyll Content At the same time points thatdry weight was determined 01 g leaves were picked fromrandomly chosen plants for each plotThe third new leaf fromthe heart was selected which grows rapidly The amount ofchlorophyll comprised of chlorophyll a and chlorophyll bwas measured by a UV-Vis spectrophotometer (EV300PCThermo Fisher USA) using an extraction method previouslydescribed [24]

243 Fruit Yield During the ripening stage red fruits in eachtest plot were picked every 10 days and weighed The yieldsfrom each pick were added together to obtain the economicyield and this was converted to tsdothmminus2 Three plants fromeach plot were marked and weighed and the average yieldper plant was calculated

244 Fruit Quality Ripe fruits with similar developmentcharacteristics were picked in each plot The content of solu-ble solids in the fruits was measured as previously described[25] using an RHBO-90 hand refractometer (LINK Co LtdTaiwan China) The capsaicin content was measured by highperformance liquid chromatography and the vitamin C con-tent was obtained by spectrometry using the molybdenumblue colorimetric method [24]The soluble sugar content wasmeasured by sulfuric acid anthrone colorimetry and nitratecontent was obtained using aUV-Vis spectrophotometer [19]

245 Water Use Efficiency The water content in the soil wasdetermined with a TDR moisture meter [26] and calibratedby traditional drying method Two days before and after thetest the water content in the soil was measured every 10 cmup to a depth of 80 cm

The evapotranspiration (ET mm) of the plants at variousstages was calculated by a water balance based on thereference [26]There was no precipitation in greenhouseThedeep percolation and runoffwere considered negligible sincethe amount of water each time was less (the maximum valuewas about 241mm) The equation used to calculate ET is

ET = 119868 minus Δ119882 (1)

where 119868 is the irrigation amount (mm) and Δ119882 is the watervariation (mm) in the initial and final soil


The irrigation amount 119868 can be calculated as follows

119868 = 119870119888 sdot ET0 (2)

where 119870119888 is the crop coefficient which was based on FAO56[27] and 119870119888ini 119870119888mid and 119870119888end were 060 105 and 090respectively

In the greenhouse evaporation and heat transfer stilloccur even in the absence of wind since the air boundarylayer is a nonneutral stable layer ET0 was calculated accord-ing to themodifiedPenmanndashMonteith equation for a sunlightgreenhouse as published previously [28] Meteorologicaldata for calculating ET0 were taken from the weather stationinside the greenhouse

ET0 (119875 minus119872)

=0408Δ (119877119899 minus 119866) + 120574 (1713 (119890119886 minus 119890119889) (119879 + 273))

Δ + 164120574(3)

where ET0 is the referenced crop evapotranspiration(mmsdotdminus1) 119877119899 is the surface net radiation (MJsdotmminus2sdotdminus1) 119866is the soil heat flux (MJsdotmminus2sdotdminus1) 119890119886 is the saturated vaporpressure (kPa) 119890119889 is the actual vapor pressure (kPa) Δ isthe slope of saturated vapor pressure curve (kPasdot∘Cminus1) 120574is the dry wet constant (kPasdot∘Cminus1) and 119879 is the averagetemperature at 2m (∘C)

The water use efficiency WUE is calculated as follows[29]

WUE = 119884

(ET lowast 10) (4)

where 119884 is the yield in kgsdothmminus2

246 Partial Factor Productivity from Applied Nitrogen Thepartial factor productivity from applied nitrogen (PFPN) canbe calculated as follows [30]

PFPN = 119884119865 (5)

where 119865 is the total mass of applied nitrogen (kgsdothmminus2)

25 Data Analysis Statistical analysis software includingExcel 2010 and SPSS Statistics 180 was used to analyze theexperimental data Duncanrsquos new multiple range test methodwas employed for multiple comparisons If a significant dif-ferencewas observed (119875 lt 005) TukeyHSD comparisonwasadopted All figures were plotted using Origin 80 software

3 Results

31 Influence of Water-Nitrogen Regimes on Dry MatterContent of C annuum Growth of C annuum plants wasfollowed during the course of the experiment by determiningdry matter content (DM) at various time points as shownin Figure 1 The DM initially increased rapidly followed by aslower increase at later stages Fifty-four days after plantingDM starts to show increasing differences between the tested

conditions As expected DM is affected by the amount of Nsupplied to the plants According to the slopes of the curves(Figure 1) under the same irrigation regime the increase ofDM is more rapid at N075 and N050 than at N100 while N025produced the slowest increase in dry weight

The average DM at the highest irrigation level applied(W105) varies from 173 to 1250 tsdothmminus2 at 54ndash112 days ForW090 this variation is 096ndash115 times that ofW105 forW075 itis 091ndash105 times that of W105 and at W060 (least irrigation)the variation of average DM is only 078ndash076 times that ofW105 Thus compared to W105 irrigation levels W090 andW075 resulted in a more rapid DM increase in the middleand end growth stage while W060 suppressed DM increaseduring the complete growth periodThis indicates that underlimited water stress (irrigation levels W090 and W075) cropyield is promoted resulting in a DM increase during themiddle and end growth stage

Keeping the nitrogen supply constant the DM exhibitsfirst an increase and then a decreasewith increasing irrigationlevels At harvest time the DM of N075 N050 and N025 is112 103 and 084 times that of N100 suggesting that theapplied nitrogen amounts in N075 and N050 are favorable forhigher DMThus for both irrigation and nitrogen levels theDM first increases followed by a decrease At harvest timesamples withDMabove 130 tsdothmminus2 include the combinationsW105N075 W105N050 W090N075 W090N050 W075N075and W075N050 These conditions resulted in an increase ofDM of 777 261 982 637 722 and 303 respectivelycompared to the control (W105N100 DM of 1287 tsdothmminus2)which represents local conventional irrigation and nitrogenapplication

32 Influence of Water-Nitrogen Regimes on ChlorophyllContent Chlorophyll content in the leaves was determinedto provide a measure of the growth status of the plantsChlorophyll is required for photosynthesis to produce sugarsthat enable growth but a high chlorophyll content in theleaves can be disadvantageous for fruit production when theplants favor growth of parts other than fruit

During growth the overall chlorophyll content in theleaves first increased followed by a decrease (Figure 2) Com-paring conditions with the same irrigation level (individualcurves within a panel) showed that the chlorophyll contentincreased with nitrogen levels However when the nitrogenlevel was kept constant (comparing curves with the samecolor) an increase in irrigation resulted first in an increaseand then in a decrease of the chlorophyll content in leavesAccording to the slope of the curve obtainedW090 andW075had the largest influence on chlorophyll content compared toW105 Particularly between days 54 and 61 a rapid increasewas observed This phase corresponds to the floweringfruiting and reproductive stages of the plant The productsof photosynthesis are mainly reserved for growth of stemsleaves and fruits and these plant parts may compete witheach other Under various irrigation levels control fertilizerlevel N100 resulted in a high leave chlorophyll content duringthe entire fruiting stage (Figure 2) Under this nitrogen supplylevel a large number of small fruits developed which after


15

12

9

3

6

0

N100

N075

N050

N025

30 60 90 120

Days aer transplanting (d)

Dry

mat

ter c

onte

nt (t

middothＧ

minus2)

(a) W105 treatment

15

12

9

3

6

0

N100

N075

N050

N025

30 60 90 120


Dry

mat

ter c

onte

nt (t

middothＧ

minus2)

(b) W090 treatment

15

12

9

3

6

0

N100

N075

N050

N025

30 60 90 120


Dry

mat

ter c

onte

nt (t

middothＧ

minus2)

(c) W075 treatment

15

12

9

3

6

0

N100

N075

N050

N025

30 60 90 120


Dry

mat

ter c

onte

nt (t

middothＧ

minus2)

(d) W060 treatment

Figure 1 Effects of different water and nitrogen levels on dry matter content of greenhouse sweet pepper Panel (a) shows treatment W105corresponding to an irrigation of 105 of the reference crop evapotranspiration ET0 panel (b) shows treatment W090 panel (c) showsW075and panel (d) shows treatmentW060 (60ET0)The black curves represent treatmentN100 (100 of recommendedN fertilizer 300 kgsdothmminus2)red curves show N075 blue shows N050 and light green shows N025 (5 of recommended N fertilizer)

thinning resulted in fewer nutrients being distributed tothe fruits allowing the stem and leaves to grow vigorouslyIn contrast the condition W060N025 produced fewer fruitssuggesting that lowwater and nitrogen supplies resulted in animbalance of resources accelerating leaf aging and resultingin low chlorophyll content As can be seen in Figures 2(b) and2(c) under conditions W090N075 W090N050 W075N075and W075N050 the chlorophyll content increased fastest togive maximum levels at day 54 indicating that limited waterstress and nitrogen application can promote the allocation ofnutrients to the fruits and this can accelerate fruit growth

Towards the end of the fruiting stage the chlorophyllcontent of leaves was shown to increase independent of the

fertigation regime (Figure 2) This is because the perennialplant quickly develops to the next growth period after ripefruit has been picked

33 Influence of Water-Nitrogen Regimes on Fruit Yield andWater Usage The influence of various irrigation and nitro-gen supply combinations on economic yield WUE andPFPN is shown in Table 2 As can be seen water and nitrogenlevels have a significant (119875 lt 001) impact on fruit yieldWUE and PFPN

Under the same irrigation condition an increase ofnitrogen level resulted in an initial increase in the economicyield andWUE followed by decrease while PFPN decreased


Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(a) W105 treatment

Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(b) W090 treatment

Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(c) W075 treatment

Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(d) W060 treatment

Figure 2 Effects of different water and nitrogen levels on chlorophyll content of greenhouse sweet pepper The codes for treatment and color useare as described for Figure 1

(Table 2) Compared to the control water supply W105 theeconomic yield ofW090 increased by 964 and that ofW075by 253 while for these conditionsWUE increased by 2304and 3344 respectively In contrast the economic yield ofW060 decreased by 3423 with WUE increasing by 528Compared to W105 the PFPN of W090 increased by 722whereas forW060 it decreased by 3589 (W075 showed littledifference to the control) Under the same nitrogen leveland an increase of irrigation the economic yield WUE andPFPN initially increased followed by a decrease Comparedto nitrogen level N100 under conditions N075 and N050 theeconomic yield increased by 3768 and 3554 respectivelywhile WUE increased by 3574 and 3367 respectively Incontrast N025 only resulted in marginal increases of theseparameters Compared to N100 the PFPN of N075 and N050

increased by 8046 and 16652 For N025 this increase wasas high as 30194

In combination these results indicate that moderatewater supply (W090 and W075) and limited nitrogen appli-cation (N075 and N050) promote the forming of the fruitresulting in higher yields while improvingWUEOverly highlevels of water (W105) and nitrogen (N100) supply can pro-mote plant growth to a certain extent but excessive growthresults in reduced economic yields Strong water stress(W060) and nitrogen stress (N025) are insufficient for optimalplant growth leading to lowDM (Figure 1) and low economicyieldsThus compared to the control W105N075 W105N050W090N075 W090N050 W075N075 andW075N050 resulted inimproved economic yields with an increase of 1239 6472016 1438 1713 and 1522 respectively In terms of WUE


Table 2 Effects of different water and nitrogen levels on sweet pepper marketable yield and WUE

Irrigation treatment Nitrogen treatment Market yield (tsdothmminus2) WUE (kgsdotmminus3) PFPN (kgsdotkgminus1)

W105

N100 2219de 897f 7396d

N075 3028c 1148de 12616c

N050 3151bc 1195de 19696c

N025 2411de 914f 30132d

W090

N100 2550d 1100e 7969c

N075 3485a 1503b 14519ab

N050 3248ab 1401c 20300b

N025 2568d 1107e 32095c

W075

N100 2303e 1152de 7195c

N075 3299ab 1650a 13745a

N050 3163bc 1582ab 19767a

N025 2317e 1159de 28957c

W050

N100 1520g 905f 4751d

N075 2018f 1202de 8408c

N050 2084f 1241d 13026c

N025 1487g 886f 18590d

Significance level (119865 value)Irrigation 22077lowastlowast 22077lowastlowast 260lowast

Nitrogen 10334lowastlowast 10334lowast 288lowast

Irrigation times nitrogen 12629lowastlowast 12629lowastlowast 1093lowast

Statistical significance is shown as superscripts with different superscripts indicating significant (119875 lt 005) differences within a parameter under constantirrigation At the bottom of the table significance 119865 values are indicated with lowastlowast119875 value 0001 and lowast119875 value 005

W090N075 W090N050 W075N075 andW075N050 resulted inan increase of 3672 3015 5459 and 5206 respectivelyFinally again compared to the control the PFPN increasedby 6021 12876 5618 and 13043 respectively OverallW075N075 treatment provided the optimal combination forenhanced economic yield and improved WUE and PFPNsimultaneously Similar economic yields were obtained withW090N075 W090N050 and W075N050 though the otherparameters were suboptimal Likewise water use was alsoefficient in W075N050 and PFPN of W090N050 was similarto the optimal condition W075N075

34 Influence of Water-Nitrogen Regimes on the Quality ofthe Produce The influence of water and nitrogen on thecontent of soluble sugar capsaicin vitamin C (Vc) nitratesand soluble solids in the fruits is shown in Table 3 The testedregimes had a strong impact on the quality indexes (119875 lt001) and Vc content was also significantly affected (119875 lt005) Comparing increasing nitrogen levels with a constantwater supply the content of soluble sugars Vc and solublesolids first increased and then decreased while capsaicin andnitrates contents both increased Under the same nitrogenlevel an increase of irrigation resulted in a decrease in solublesugar and nitrates content while Vc content first increasedand then decreased and capsaicin and soluble solids contentsboth increased

The contents of soluble sugars capsaicin Vc and solublesolids provide important indexes of fruit quality as theydetermine the nutritional value and flavor A lower nitrate

content of vegetables is generally preferred whereas green-house cultures have a higher nitrogen content than open-air cultures (Liao et al 2011) Five indexes were calculatedto assess the nutritional value of the produced fruit solublesugar (1198831) capsaicin (1198832) Vc (1198833) nitrates (1198834) andsoluble solids (1198835) using SPSS 18 software The calculatedcontribution ratio for each index is as follows soluble sugar42851 capsaicin 28923 Vc 20569 nitrates 5779and soluble solids 1879 The former three indexes con-tribute 92342 of the total index Thus these three maincontents were used and the corresponding characterizationvalues produced were 1205821 = 2143 1205822 = 1446 and 1205823 = 1028respectively

By calculation the main content can be expressed asfollows

First main content 1198651 = 06831198831 minus 02881198832 +02981198833 + 01051198834 minus 03931198835Second main content 1198652 = minus03511198831 + 08321198832 +03681198833 + 00461198834 + 05791198835Third main content 1198653 = 04311198831 + 04361198832 +09861198833 minus 00841198834 + 00381198835

Using the ratio of each characterization value to the sum ofthe values as a weighing factor a comprehensive evaluationfunction was established that calculated the quality of theproduced fruits given as 119865 = 04641198651 + 03131198652 + 02231198653Higher scores calculated with this function indicate betterfruit quality


Table 3 Effects of different water and nitrogen levels on fruit quality

Irrigationtreatment

NitrogenTreatment Soluble sugarpermil Capsaicinpermil Vcpermil Nitratepermil Soluble solidspermil

W105

N100 2355h 023a 2588de 042cd 785ab

N075 2644gh 022ab 2988cd 035def 740bcdef

N050 3056def 022abc 3294bc 031efg 760abc

N025 2613gh 019cdf 2605de 023g 750abcde

W090

N100 272hi 020abcd 2781cde 045c 795a

N075 3234d 021abc 3031cd 035def 755abcd

N050 3587c 021abc 4224a 033def 705defg

N025 2796efg 019cdf 2547de 021g 735bcdef

W075

N100 2951defg 021abc 2845cde 067a 725cdef

N075 3719bc 020bcd 3638b 047c 720defg

N050 3927bc 021abc 4653a 035def 704defg

N025 3113de 017f 2539de 025fg 680h

W060

N100 3080def 019cdf 2367e 070a 695fgh

N075 4010b 018df 2679de 057b 700efgh

N050 4467a 016f 3055cd 040cde 685gh

N025 3193d 015f 1891f 031efg 620i

Significance level (119865 value)Irrigation 5786lowast 1596lowastlowast 2481lowastlowast 2678lowastlowast 273lowastlowast

Nitrogen 5977lowastlowast 912lowastlowast 6132lowastlowast 7181lowastlowast 91lowastlowast

Irrigation times nitrogen 253lowast 08 367lowastlowast 327lowast 209Significance is indicated as for Table 2

The results (Table 4) show that under the same nitrogenlevel W075 resulted in the highest average score followedby W090 and W105 while W060 produced the lowest scoreUnder the same irrigation condition N050 gave the highestscore followed by N075 and N100 (N025 was the lowest)These results again indicate that moderate irrigation (W090andW075) and nitrogen (N075 and N050) levels are favorablefor nutrients absorption into the fruits Particularly thesoluble sugar and Vc content in the fruit can be increasedusing these regimes

The conditions were ranked for the obtained scoreswhich placed the control at the 11th position The topsix scores were obtained with W075N050 (score value164) W090N050 (122) W075N075 (079) W060N050 (040)W105N050 (035) and W090N075 (022) The lowest scoreobserved (minus116) was obtained with W060N025 This oncemore shows that W075N050 W090N050 and W075N075represent favorable conditions for greenhouse culture of Cannuum here assessed for parameters determined by theabsorption of nutrients into the fruits

4 Discussion

Adjustment of water and fertilizer supplies is the basis ofoptimizing agricultural practices and facility managementProper water management and nitrogen control can improvecrop growth significantly resulting in increased economicyields more efficient water use and higher quality produce

with lower investment costs and higher output Converselypoormanagement ofwater and fertilizer can lead to increasedcosts wasted use of water and nitrogen resources andnegative effects on the leaf area index of crops as well as finalyields [31] Nitrogen is of particular importance as it directlyaffects vegetable growth and fruit development Properwater-nitrogenmanagement can improve the photosynthetic assim-ilation of the plants and the quality of the produce [10] Thefertigation technique can provide crops with optimal suppliesof water and nutrients [17 19ndash21 32] Based on previousresearch we assessed in detail the influence of water andnitrogen supplies on the growth photosynthesis economicyield WUE PFPN and quality of C annuum fruit in orderto define the optimal conditions for greenhouse culture of thiseconomically important produce

The results have identified that conditions of water levelsW090 and W075 (90 and 75 ET0 resp) in combinationwith nitrogen levels N075 and N050 (225 and 150 kgsdothmminus2resp) provide an optimal window A moderate water stressand limited nitrogen supplies promote the growth anddevelopment of fruit and result in a favorable increase ofchlorophyll in the leaves which in turn is responsible foran increase in DM These results are in accordance withpreviously recorded observations [11 23 33] Under thetest conditions the optimized water and nitrogen levelsavoid excessive water and fertilizer use while supportingproper growth and development In contrast to our findingsAyodele and colleagues concluded that the DM content of


Table 4 Evaluation of fruit quality under different water and nitrogen levels by multiple component analysis

Irrigationtreatment Nitrogen treatment Principal component Comprehensive

evaluation RankingFirst Second Third

W105

N100 minus2256 2670 minus0330 minus028 11N075 minus1254 1693 0249 000 8N050 minus0744 1590 0886 035 5N025 minus1145 0205 minus0959 minus068 15

W090

N100 minus1380 1471 minus0435 minus028 10N075 minus0484 1060 0513 022 6N050 0840 0905 2462 122 2N025 minus0784 minus0255 minus0960 minus066 14

W075

N10 minus0333 0669 minus0265 000 9N075 1102 minus0075 1369 079 3N050 1640 0543 3199 164 1N025 0277 minus1621 minus1027 minus061 13

W060

N100 0187 minus0811 minus1271 minus045 12N075 1447 minus1630 minus0268 010 7N050 2349 minus2498 0413 040 4N025 0926 minus3434 minus2287 minus116 16

C annuum positively correlates with nitrogen level supplies[34] However these authors tested much lower suboptimalnitrogen levels (between 0sim75 kgsdothmminus2) so that any increasewill be positive This has also been observed by others [35]Here we compared nitrogen levels from 150 to 225 kgsdothmminus2which covered the complete range from suboptimal to over-fertilization Candido et al compared four nitrogen levels (0100 200 and 300 kgsdothmminus2) under 100 ET119888 water level andshowed that the aboveground biomass individual fruit massand fruit thickness increased first and then decreased with anincrease of nitrogen level [36]Their study resulted in optimalfruit indexes at a nitrogen level of 200 kgsdothmminus2 which iscomparable to our findings though our results indicate anoptimal window instead of absolute values which is of morepractical use for farmers The optimal water supply hasalso been studied by Gupta and coworkers who compared100 ET 80 ET and 60 ET in combination with threeNPK levels (150 90 60 kgsdothmminus2 at 100 80 and 60) Theirresults indicated that under the same water level the DMof C annuum increased with nitrogen level while 80 ETwater level was favorable for fruit growth giving an optimalcombination of 80 ET and 80 NPK to maximize DM[33] Our results corroborate these findings and also show thebeneficial effects of a limited water stress For sunflowers itwas shown that severe drought can greatly reduce the DMbut under proper water levels the crop growth rate can beincreased by higher nitrogen levels [37] However for thatcrop the consumption of nitrogen did not change the relativegrowth rate and net absorption rate consistent with findingswe report here Likewise in previous studies concerningwatermelon and muskmelon [21 38] it was concluded thatmoderate water and nutrient conditions are best for vegetablegrowth

Our results show that nitrogen fertilizer correspondingwith 150ndash225 kgsdothmminus2N in combination with irrigation con-ditions representing from 75 to 90 ET0 results in highindividual plant and economic yields while outside this rangetoo much or too little water and nitrogen result in negativeeffects This conclusion is consistent with previous works[10 14 39]When zooming in on the partial factor productiv-ity from applied nitrogen (PFPN) under the samewater levelthis factor decreases with an increase of nitrogen Converselyunder the same nitrogen level the PFPN increases first andthen decreases with water supply consistent with conclusionsobtained by others [39] Economic yields ofC annuum undertest conditions have been reported as 2729sim6569 tsdothmminus2 withaWUEof 1472sim3290 kgsdotmminus3 and as 2972sim4654 tsdothmminus2 withaWUEof 776sim1071 kgsdotmminus3 [40] Yields as 2101sim3530 tsdothmminus2with a WUE of 47sim79 kgsdotmminus3 [23] or economic yieldsof 146sim503 tsdothmminus2 [37] WUE of 78sim123 kgsdotmminus3 [41] or41sim67 kgsdotmminus3 [42] have also been reported Compared tothese published results the economic yield under optimalconditions as determined here (3163sim3485 tsdothmminus2 with aWUE of 1503sim1650 kgsdotmminus3) had greatly improved In partthis may be due to the type of C annuum used while the factthat experiments were conducted in a protected environmentmay also have helped However the positive effect of theonline intelligent irrigation fertilizer applicator cannot beignored which when set correctly increases the utilizationefficiency of both water and fertilizer

After comprehensive consideration of economic yieldwater-nitrogen use efficiency and fruit quality it was con-cluded thatW090N075 resulted in the highest economic yieldwith slightly reduced water-nitrogen use efficiency and qual-ity Although W075N075 resulted in the highest WUE witheconomic yield comparable to W090N075 its nitrogen use


efficiency was poor W075N050 resulted in lower economicyields Compared to locally applied treatment W105N100 ouroptimal condition could increase yields by 1522 withWUEimproved by 5206 At the same time fruits produced underW075N050 had excellent scores for contents of capsaicin Vcand soluble solids while the nitrates mass fraction was lowerthan the standard limit In addition the soluble sugar massfraction was high ensuing tasteful fruit

In this study principal component analysis was used toanalyze the main factors affecting fruit quality The results(Table 4) show that conditions W090 W075 N075 and N050resulted in fruit of good quality W075N050 W090N050 andW075N075 produce the top 3 rankings while W060N025ranks last W075N075 has the best water-nitrogen couplingeffect and W060N025 confines the absorption of nutrientsinto the fruits resulting in poor fruit quality Other studieshave also shown that proper water-nitrogen supply cannotonly promote plant growth and fruit development [19] butalso enhances fruit quality with no apparent reduction inyield [21 43 44] These results are consistent with ourwork Thus it is plausible to improve the mass fractionof nutrients in C annuum by adjusting water-nitrogenapplication Moreover an intelligent irrigation fertilizer canprecisely apply and control fertilization based on the amountof irrigation water providing accurate technical parametersfor water and fertilizer integrated large-scale cultivation ofC annuum

5 Conclusions

Experimental culture of C annuum with precisely dosedwater and nitrogen supplies in a greenhouse located in thenorthwest of China identified an optimal window between75 and 90 ET0 and between 50 and 75 of conven-tionally used nitrogen fertilizer resulting in an increase ofeconomic yields of over 20 with a simultaneous increase inDM PPFN and fruit quality and an improved WUE Theseinsights are extremely valuable for farming practices

Conflicts of Interest

The authors declare that they have no conflicts of interest

Authorsrsquo Contributions

Youzhen Xiang and Haiyang Zou contributed equally to themanuscript

Acknowledgments

This study was jointly supported by the NationalKey Research and Development Program of China(2017YFC0403303) the National High-Tech RampD Pro-gram China 863 Program (2011AA100504) the NationalKey Research and Development Program of China(2016YFC0400202) and the National Natural ScienceFoundation of China (51579211)

References

[1] D Jackson-Smith Toward Sustainable Agricultural Systems inthe 21st Century 2010

[2] R BThompson CMartınez-GaitanM Gallardo C Gimenezand M D Fernandez ldquoIdentification of irrigation and Nmanagement practices that contribute to nitrate leaching lossfrom an intensive vegetable production system by use of acomprehensive surveyrdquo Agricultural Water Management vol89 no 3 pp 261ndash274 2007

[3] J Pretty ldquoAgricultural sustainability Concepts principles andevidencerdquo Philosophical Transactions of the Royal Society BBiological Sciences vol 363 no 1491 pp 447ndash465 2008

[4] M Romic and D Romic ldquoHeavymetals distribution in agricul-tural topsoils in urban areardquo Environmental Geology vol 43 no7 pp 795ndash805 2003

[5] K Roma and A Kaushal ldquoDrip Fertigation in Sweet Pepper AReviewrdquo Journalof Engineering Research and Applications vol 8pp 144ndash149 2014

[6] J H Cai C G Shao and Z H Zhang ldquoWater demand andirrigation scheduling of drip irrigation for cotton under plasticmulchrdquo Journal of Hydraulic Engineering vol 33 no 11 pp 119ndash123 2002

[7] A Silber M Bruner E Kenig et al ldquoHigh fertigation frequencyand phosphorus level Effects on summer-grown bell peppergrowth and blossom-end rot incidencerdquo Plant and Soil vol 270no 1 pp 135ndash146 2005

[8] M Cui F Wang and H Xu ldquoResponse of Physiological-biochemical Characters of Sweet Pepper Seedlingsrdquo ChineseAgricultural Science Bulletin vol 21 no 5 p 225 2005

[9] L M Reyes D C Sanders and W G Buhler ldquoEvaluation ofslow-release fertilizers on bell pepperrdquo HortTechnology vol 18no 3 pp 393ndash396 2008

[10] M K Xian B Y Wang and Y W Yuan ldquoResearch progress ofnitrogen in vegetable crops (bell pepper)rdquo Modern agriculturalscience and technology vol 7 pp 6ndash9 2006

[11] A S Lodhi A Kaushal and K G Singh ldquoImpact of irrigationregimes on growth yield and water use efficiency of sweetpepperrdquo Indian Journal of Science and Technology vol 7 no 6pp 790ndash794 2014

[12] S M Sezen A Yazar and S Eker ldquoEffect of drip irrigationregimes on yield and quality of field grown bell pepperrdquoAgricultural Water Management vol 81 no 1-2 pp 115ndash1312006

[13] FM delAmor ldquoYield and fruit quality response of sweet pepperto organic andmineral fertilizationrdquo Renewable Agriculture andFood Systems vol 22 no 3 pp 233ndash238 2007

[14] T R Abu-Zahra ldquoVegetative flowering and yield of sweetpepper as influencedby agricultural practicesrdquo Middle EastJournal of Scientific Research vol 11 no 9 pp 1220ndash1225 2012

[15] R Kumari A Kaushal and K G Singh ldquoWater use efficiencyof drip fertigated sweet pepper under the influence of differentkinds and levels of fertilizersrdquo Indian Journal of Science andTechnology vol 7 no 10 pp 1538ndash1543 2014

[16] T B S Rajput and N Patel ldquoWater and nitrate movementin drip-irrigated onion under fertigation and irrigation treat-mentsrdquo Agricultural Water Management vol 79 no 3 pp 293ndash311 2006

[17] T M Darwish T W Atallah S Hajhasan and A HaidarldquoNitrogen and water use efficiency of fertigated processingpotatordquoAgriculturalWaterManagement vol 85 no 1-2 pp 95ndash104 2006


[18] M Sturm N Kacjan-Marsic V Zupanc B Bracic-ZeleznikS Lojen and M Pintar ldquoEffect of different fertilisation andirrigation practices on yield nitrogen uptake and fertiliser useefficiency of white cabbage (Brassica oleracea var capitata L)rdquoScientia Horticulturae vol 125 no 2 pp 103ndash109 2010

[19] Y Xing C F Zhang and F L Wu ldquoDetermination of appropri-ate drip fertigated system based on tomato yield quality waterand fertilizer use efficiencyrdquo Transactions of the Chinese Societyof Agricultural Engineering (Transactions of the CSAE) vol 31Supp 1 pp 110ndash121 2015

[20] D-P Fang F-C Zhang J Li H-D Wang Y-Z Xiang andY Zhang ldquoEffects of irrigation amount and various fertigationmethods on yield and quality of cucumber in greenhouserdquoChinese Journal of Applied Ecology vol 26 no 6 pp 1735ndash17422015

[21] X Yang X Zhang J Ma et al ldquoEffects of drip fertigation ongrowth yield and quality of watermelon in plastic greenhouserdquoNongye Gongcheng Xuebao vol 30 no 7 pp 109ndash118 2014

[22] H-M Zhou F-C Zhang K Roger et al ldquoPeach yield and fruitquality is maintained under mild deficit irrigation in semi-aridChinardquo Journal of Integrative Agriculture vol 16 no 5 pp 1173ndash1183 2017

[23] S M Sezen A Yazar Y Dasgan et al ldquoEvaluation of cropwater stress index (CWSI) for red pepper with drip and furrowirrigation under varying irrigation regimesrdquo Agricultural WaterManagement vol 143 pp 59ndash70 2014

[24] H S Li Principles and techniques of plant physiology andbiochemistry experiment 2000

[25] X Chen Y F Ma and G Z Fang ldquoPreliminary study on theinfluence of soil moisture on yield and quality of processedtomatordquoWater Saving Irrigation vol 4 pp 1ndash4 2006

[26] H Feng X Liu Y Zuo and K Yu ldquoEffect of gravel mulchingdegree on farmland moisture and water consumption featuresof cropsrdquo Nongye Jixie XuebaoTransactions of the ChineseSociety for Agricultural Machinery vol 47 no 5 pp 155ndash1632016

[27] R Allen G L Pereira S D Raes andM SmithCrop Evapotran-spiration Guidelines or Computing Crop Water Requirementsvol 56 FAO Irrigation and Drainage Rome 1998

[28] M X Chen J H Cai and X H Li ldquoCalculation of crop evap-otranspiration in greenhouserdquo The Journal of Applied Ecologyvol 18 no 2 pp 317ndash321 2007

[29] L Wu F Zhang H Zhou et al ldquoEffect of drip irrigation andfertilizer application on water use efficiency and cotton yield inNorth of Xinjiangrdquo Nongye Gongcheng Xuebao vol 30 no 20pp 137ndash146 2014

[30] A IernaG Pandino S Lombardo andGMauromicale ldquoTuberyield water and fertilizer productivity in early potato as affectedby a combination of irrigation and fertilizationrdquo AgriculturalWater Management vol 101 no 1 pp 35ndash41 2011

[31] C A Norwood ldquoWater use and yield of limited-irrigated anddryland cornrdquo Soil Science Society of America Journal vol 64no 1 pp 365ndash370 2000

[32] A J Gupta M F Ahmad and F N Bhat ldquoStudies on yieldquality water and fertilizer use efficiency of capsicum underdrip irrigation and fertigationrdquo Indian Journal of Horticulturevol 67 no 2 pp 213ndash218 2010

[33] T Gadissa and D Chemeda ldquoEffects of drip irrigation levelsand planting methods on yield and yield components of greenpepper (Capsicum annuum L) in Bako Ethiopiardquo AgriculturalWater Management vol 96 no 11 pp 1673ndash1678 2009

[34] J O Ayodele O E Alabi and M Aluko ldquoNitrogen FertilizerEffects on Growth Yield and Chemical Composition of HotPepper (Rodo)rdquo International Journal of Agriculture and CropSciences vol 8 no 5 p 666 2015

[35] S I M Khan S Roy and K K Pall ldquoNitrogen and phosphorusefficiency on the growth and yield attributes of CapsicumrdquoAcademic Journal of Plant Sciences vol 3 no 2 pp 71ndash78 2010

[36] V Candido VMiccolis andA R Rivelli ldquoYield traits andwaterand nitrogen use efficiencies of bell pepper grown in plastic-greenhouserdquo Italian Journal of Agronomy vol 4 no 3 pp 91ndash100 2009

[37] M Mojaddam S Lack and A Shokuhfar ldquoEffects of waterstress and different levels of nitrogen on yield yield componentsandWUEof sunflower hybrid iroflorrdquoAdvances in Environmen-tal Biology vol 5 no 10 pp 3410ndash3417 2011

[38] W Yue F Zhang Z Li H Zou and Y Gao ldquoEffects of waterand nitrogen coupling on nitrogen uptake of muskmelon andnitrate accumulation in soilrdquo Transactions of the Chinese Societyfor Agricultural Machinery vol 46 no 2 pp 88ndash119 2015

[39] A W Xu ldquoHigh yield fertilizer technology of Pepperrdquo Hebeiagricultural science and technology vol 6 no 010 2002

[40] Q Kong G Li Y Wang and H Huo ldquoBell pepper response tosurface and subsurface drip irrigation under different fertiga-tion levelsrdquo Irrigation Science vol 30 no 3 pp 233ndash245 2012

[41] L Dalla Costa and G Gianquinto ldquoWater stress and watertabledepth influence yield water use efficiency and nitrogen recov-ery in bell pepper Lysimeter studiesrdquo Australian Journal ofAgricultural Research vol 53 no 2 pp 201ndash210 2002

[42] N Dagdelen E Yilmaz F Sezgin et al ldquoEffects of Water Stressat Different Growth Stages on Processing Pepperrdquo PakistanJournal of Biological Sciences vol 7 no 12 pp 2167ndash2172 2004

[43] J Z Li J Li and C F Zhang ldquoEffects of water and nitrogensupply on yield and quality of greenhouse cucumber under fer-tigationrdquo Journal of northwest agriculture and forestry universityof science and technology (natural science edition) vol 12 no022 2015

[44] S C Lu L J Wang and G Yu ldquoEffects of nitrogen fertilizer onpepper fruit quality and yieldrdquo Journal of Northeast AgriculturalUniversity vol 36 no 4 pp 448ndash450 2005

Nutrition and Metabolism

Journal of

Hindawiwwwhindawicom Volume 2018


Food ScienceInternational Journal of


International Journal of

Microbiology

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Hindawiwwwhindawicom

Applied ampEnvironmentalSoil Science

Volume 2018

AgricultureAdvances in


PsycheHindawiwwwhindawicom Volume 2018

BiodiversityInternational Journal of


ScienticaHindawiwwwhindawicom Volume 2018

GenomicsInternational Journal of


Plant GenomicsInternational Journal of


Biotechnology Research International


Forestry ResearchInternational Journal of


BotanyJournal of


EcologyInternational Journal of


Veterinary Medicine International


Cell BiologyInternational Journal of



BioMed Research International

Agronomy



Submit your manuscripts atwwwhindawicom


microenvironment in the crop root zone can be achievedpromoting absorption of nutrients into the crops

C annuum (L var grossum) amember of the Solanaceaeproduces fruits with a high nutritional value Its effectiveculture is strongly dependent on the environment [8] as theplant requires a constant supply of water and nutrients [9]The availability of nitrogen is an important determinant ofcrop yield and quality by directly affecting photosynthesisand the accumulation transfer and distribution of biomass[10] Previously the studies of water-fertilizer managementmainly focused on irrigation methods [11] irrigation amountand frequency [12] and various types of fertilizers [13ndash15]

Lately an improved fertigation technique was developedthat applies nutrients with water to the crops Comparedto classical fertigation this new technique significantlyincreases yield water use efficiency (WUE) and nutrient useefficiency [16ndash22] For instance compared to conventionalfurrow irrigation properly controlled fertigation increasesthe yield of C annuum and enhances WUE [11 23] It wasexperimentally shown that carefully determined fertilizerquantities could ensure high yield of C annuum at thesame time reducing production costs [13] Another studyreported that compared to conventional furrow irrigation anoptimized fertigation strategy could increase the WUE of Cannuum by 95 saving water by 34 and fertilizer by 20[15]

Few studies have investigated the comprehensive influ-ence of a water-nitrogen coupling effect on the growth yieldand quality of C annuum and a quantitative index remainsto be determined Particularly fruit quality as a function ofthe water-nitrogen ratio has rarely been reported Thereforethe experiments presented here aimed at enhancing theutilization of water and nitrogen as well as promoting yieldand quality of C annuum crops Using an automaticallycontrolled irrigation and fertilization system plot tests wereperformed in a sunlight greenhouse to optimize water andnitrogen management and make full use of water-nitrogensynergistic effects This work provides technical support forapplication of automatic water and nitrogen managementsystems inC annuum cultivation under protected conditionsand offers a scientific basis for reference of high quality highefficiency and large-scale production

2 Materials and Methods

21 Experimental Materials

211 Experimental Plots The experiments were conductedin a test area with the Guanzhong plain China located at108∘041015840E and 34∘201015840N The work was performed betweenApril and July 2014 in a sunlight greenhouse belonging tothe Key Laboratory of the Ministry of Education for Agri-cultural Water and Soil Engineering in Arid Area NorthwestAgriculture and Forestry University China The greenhousewindows face south and north with vents at the top andsouthern-facing bottom of the greenhouse The test facilityhas an altitude of 521m and warm temperature due to a localsemihumid climate The annual average temperature is 13∘Cwith annual average precipitation from 550 to 600mm The

greenhouse measures 76m in length 75m in width and28m in height Heavy soil (1 sand 72 silt and 27 clay)was used with details on its physical and chemical propertiesshown in Table 1 The soil bulk density was measured by dryweight Soil samples were collected from a depth between 0and 80 cm (every 20 cm) with a ring knife (diameter 5 cmheight 5 cm) A small weather station (HOBO Event LoggerOnset Computer Corporation USA) was set up inside thegreenhouse The atmospheric pressure temperature photosynthetically active radiation (PAR) relative humidity andmeteorological factors such as solar radiation were recordedevery 10minutesThe obtainedmeasurements confirmed thatthese parameters were comparable for all plots

212 Fertigation Equipment An online irrigation fertilizerapplicator (NETAJET 3G INLINE NETAFIM Israel) wasemployed for fertigation which can precisely apply andcontrol fertilization based on the amount of irrigation waterThe flow rate supported by this system is from 05 to20m3sdothminus1 Venturi-type applicators were used equippedwithan optical fertilizer meter with a flow rate capacity from 30 to300 Lsdothminus1 Both fertilizer and acid solutions can be used Inaddition the system includes electrical conductivity (EC) andpH measurement and control modules Drip irrigation pipe(inner diameter 8mm)was employed using drip laterals withinline emitter distanced at 30 cm between emitter providinga flow rate of 2 Lsdothminus1 for each emitter and pipe workingpressure of 03MPa

213 C annuum Type and Fertilizer Used American Cannuum ldquoMarcordquo (Capsicum annuum L var grossum Mar-comi F1) was used as this type is particularly suitable forgreenhouse production The long lantern shaped fruit isgreen when young and turns red when ripe The fertilizerused in the experiment contains urea calcium superphos-phate (Ca(H2PO4)2sdot2H2O) and potassium chloride (KCl)

22 Experimental Design Two experimental variables werestudied the amount of irrigation water and the amount ofnitrogen fertilizer Based on the reference crop evapotranspi-ration (ET0) four irrigation levels were tested at 105 ET0(W105) 90 ET0 (W090) 75 ET0 (W075) and 60 ET0(W060) Based on the locally recommended nitrogen appli-cation amount of 300 kgsdothmminus2 (300 kgsdothmminus2 N100) threealternative regimes were tested with 75 N (225 kgsdothmminus2N075) 50 (150 kgsdothmminus2 N050) and 25 (75 kgsdothmminus2 N025)The test was designed to assess all 16 possible combinations ofthese variables with three identical plots for each situationreaching a total of 48 plots Cultivation in furrows coveredwith film was adopted which is typically used by localfarmers Each ridge had a height of 25 cm and width of75 cm The top of the ridge was flat with spacing of 50 cmbetween ridges plants were spaced at 45 cm and rows wereseparated by 30 cm Individual planting was used with aplanting density of 31000 plants per hm2 Each plot consistsof one ridge with two plant rows A drip lateral pipe wasinstalled in the middle of two plant rows so that one pipecontrolled two rows Each plot was 670 times 125m with a



Soil depth(cm)


Fieldcapacity()

Wiltingpoint()

Saturatedmoisture

()pH value


Total Ncontent()

Total Pcontent()

Total Kcontent()












ET = 119868 minus Δ119882 (1)




119868 = 119870119888 sdot ET0 (2)



ET0 (119875 minus119872)

=0408Δ (119877119899 minus 119866) + 120574 (1713 (119890119886 minus 119890119889) (119879 + 273))

Δ + 164120574(3)



WUE = 119884

(ET lowast 10) (4)



PFPN = 119884119865 (5)



3 Results








15

12

9

3

6

0

N100

N075

N050

N025

30 60 90 120


Dry

mat

ter c

onte

nt (t

middothＧ

minus2)

(a) W105 treatment

15

12

9

3

6

0

N100

N075

N050

N025

30 60 90 120


Dry

mat

ter c

onte

nt (t

middothＧ

minus2)

(b) W090 treatment

15

12

9

3

6

0

N100

N075

N050

N025

30 60 90 120


Dry

mat

ter c

onte

nt (t

middothＧ

minus2)

(c) W075 treatment

15

12

9

3

6

0

N100

N075

N050

N025

30 60 90 120


Dry

mat

ter c

onte

nt (t

middothＧ

minus2)

(d) W060 treatment








Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(a) W105 treatment

Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(b) W090 treatment

Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(c) W075 treatment

Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(d) W060 treatment








W105

N100 2219de 897f 7396d

N075 3028c 1148de 12616c

N050 3151bc 1195de 19696c

N025 2411de 914f 30132d

W090

N100 2550d 1100e 7969c

N075 3485a 1503b 14519ab

N050 3248ab 1401c 20300b

N025 2568d 1107e 32095c

W075

N100 2303e 1152de 7195c

N075 3299ab 1650a 13745a

N050 3163bc 1582ab 19767a

N025 2317e 1159de 28957c

W050

N100 1520g 905f 4751d

N075 2018f 1202de 8408c

N050 2084f 1241d 13026c

N025 1487g 886f 18590d














Irrigationtreatment


W105

N100 2355h 023a 2588de 042cd 785ab



N025 2613gh 019cdf 2605de 023g 750abcde

W090

N100 272hi 020abcd 2781cde 045c 795a

N075 3234d 021abc 3031cd 035def 755abcd

N050 3587c 021abc 4224a 033def 705defg


W075


N075 3719bc 020bcd 3638b 047c 720defg

N050 3927bc 021abc 4653a 035def 704defg

N025 3113de 017f 2539de 025fg 680h

W060

N100 3080def 019cdf 2367e 070a 695fgh

N075 4010b 018df 2679de 057b 700efgh

N050 4467a 016f 3055cd 040cde 685gh

N025 3193d 015f 1891f 031efg 620i






4 Discussion








W105


W090


W075


W060








5 Conclusions






Acknowledgments


References















































Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy






Soil depth(cm)


Fieldcapacity()

Wiltingpoint()

Saturatedmoisture

()pH value


Total Ncontent()

Total Pcontent()

Total Kcontent()












ET = 119868 minus Δ119882 (1)




119868 = 119870119888 sdot ET0 (2)



ET0 (119875 minus119872)

=0408Δ (119877119899 minus 119866) + 120574 (1713 (119890119886 minus 119890119889) (119879 + 273))

Δ + 164120574(3)



WUE = 119884

(ET lowast 10) (4)



PFPN = 119884119865 (5)



3 Results








15

12

9

3

6

0

N100

N075

N050

N025

30 60 90 120


Dry

mat

ter c

onte

nt (t

middothＧ

minus2)

(a) W105 treatment

15

12

9

3

6

0

N100

N075

N050

N025

30 60 90 120


Dry

mat

ter c

onte

nt (t

middothＧ

minus2)

(b) W090 treatment

15

12

9

3

6

0

N100

N075

N050

N025

30 60 90 120


Dry

mat

ter c

onte

nt (t

middothＧ

minus2)

(c) W075 treatment

15

12

9

3

6

0

N100

N075

N050

N025

30 60 90 120


Dry

mat

ter c

onte

nt (t

middothＧ

minus2)

(d) W060 treatment








Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(a) W105 treatment

Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(b) W090 treatment

Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(c) W075 treatment

Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(d) W060 treatment








W105

N100 2219de 897f 7396d

N075 3028c 1148de 12616c

N050 3151bc 1195de 19696c

N025 2411de 914f 30132d

W090

N100 2550d 1100e 7969c

N075 3485a 1503b 14519ab

N050 3248ab 1401c 20300b

N025 2568d 1107e 32095c

W075

N100 2303e 1152de 7195c

N075 3299ab 1650a 13745a

N050 3163bc 1582ab 19767a

N025 2317e 1159de 28957c

W050

N100 1520g 905f 4751d

N075 2018f 1202de 8408c

N050 2084f 1241d 13026c

N025 1487g 886f 18590d














Irrigationtreatment


W105

N100 2355h 023a 2588de 042cd 785ab



N025 2613gh 019cdf 2605de 023g 750abcde

W090

N100 272hi 020abcd 2781cde 045c 795a

N075 3234d 021abc 3031cd 035def 755abcd

N050 3587c 021abc 4224a 033def 705defg


W075


N075 3719bc 020bcd 3638b 047c 720defg

N050 3927bc 021abc 4653a 035def 704defg

N025 3113de 017f 2539de 025fg 680h

W060

N100 3080def 019cdf 2367e 070a 695fgh

N075 4010b 018df 2679de 057b 700efgh

N050 4467a 016f 3055cd 040cde 685gh

N025 3193d 015f 1891f 031efg 620i






4 Discussion








W105


W090


W075


W060








5 Conclusions






Acknowledgments


References















































Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy






119868 = 119870119888 sdot ET0 (2)



ET0 (119875 minus119872)

=0408Δ (119877119899 minus 119866) + 120574 (1713 (119890119886 minus 119890119889) (119879 + 273))

Δ + 164120574(3)



WUE = 119884

(ET lowast 10) (4)



PFPN = 119884119865 (5)



3 Results








15

12

9

3

6

0

N100

N075

N050

N025

30 60 90 120


Dry

mat

ter c

onte

nt (t

middothＧ

minus2)

(a) W105 treatment

15

12

9

3

6

0

N100

N075

N050

N025

30 60 90 120


Dry

mat

ter c

onte

nt (t

middothＧ

minus2)

(b) W090 treatment

15

12

9

3

6

0

N100

N075

N050

N025

30 60 90 120


Dry

mat

ter c

onte

nt (t

middothＧ

minus2)

(c) W075 treatment

15

12

9

3

6

0

N100

N075

N050

N025

30 60 90 120


Dry

mat

ter c

onte

nt (t

middothＧ

minus2)

(d) W060 treatment








Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(a) W105 treatment

Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(b) W090 treatment

Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(c) W075 treatment

Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(d) W060 treatment








W105

N100 2219de 897f 7396d

N075 3028c 1148de 12616c

N050 3151bc 1195de 19696c

N025 2411de 914f 30132d

W090

N100 2550d 1100e 7969c

N075 3485a 1503b 14519ab

N050 3248ab 1401c 20300b

N025 2568d 1107e 32095c

W075

N100 2303e 1152de 7195c

N075 3299ab 1650a 13745a

N050 3163bc 1582ab 19767a

N025 2317e 1159de 28957c

W050

N100 1520g 905f 4751d

N075 2018f 1202de 8408c

N050 2084f 1241d 13026c

N025 1487g 886f 18590d














Irrigationtreatment


W105

N100 2355h 023a 2588de 042cd 785ab



N025 2613gh 019cdf 2605de 023g 750abcde

W090

N100 272hi 020abcd 2781cde 045c 795a

N075 3234d 021abc 3031cd 035def 755abcd

N050 3587c 021abc 4224a 033def 705defg


W075


N075 3719bc 020bcd 3638b 047c 720defg

N050 3927bc 021abc 4653a 035def 704defg

N025 3113de 017f 2539de 025fg 680h

W060

N100 3080def 019cdf 2367e 070a 695fgh

N075 4010b 018df 2679de 057b 700efgh

N050 4467a 016f 3055cd 040cde 685gh

N025 3193d 015f 1891f 031efg 620i






4 Discussion








W105


W090


W075


W060








5 Conclusions






Acknowledgments


References















































Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy





15

12

9

3

6

0

N100

N075

N050

N025

30 60 90 120


Dry

mat

ter c

onte

nt (t

middothＧ

minus2)

(a) W105 treatment

15

12

9

3

6

0

N100

N075

N050

N025

30 60 90 120


Dry

mat

ter c

onte

nt (t

middothＧ

minus2)

(b) W090 treatment

15

12

9

3

6

0

N100

N075

N050

N025

30 60 90 120


Dry

mat

ter c

onte

nt (t

middothＧ

minus2)

(c) W075 treatment

15

12

9

3

6

0

N100

N075

N050

N025

30 60 90 120


Dry

mat

ter c

onte

nt (t

middothＧ

minus2)

(d) W060 treatment








Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(a) W105 treatment

Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(b) W090 treatment

Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(c) W075 treatment

Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(d) W060 treatment








W105

N100 2219de 897f 7396d

N075 3028c 1148de 12616c

N050 3151bc 1195de 19696c

N025 2411de 914f 30132d

W090

N100 2550d 1100e 7969c

N075 3485a 1503b 14519ab

N050 3248ab 1401c 20300b

N025 2568d 1107e 32095c

W075

N100 2303e 1152de 7195c

N075 3299ab 1650a 13745a

N050 3163bc 1582ab 19767a

N025 2317e 1159de 28957c

W050

N100 1520g 905f 4751d

N075 2018f 1202de 8408c

N050 2084f 1241d 13026c

N025 1487g 886f 18590d














Irrigationtreatment


W105

N100 2355h 023a 2588de 042cd 785ab



N025 2613gh 019cdf 2605de 023g 750abcde

W090

N100 272hi 020abcd 2781cde 045c 795a

N075 3234d 021abc 3031cd 035def 755abcd

N050 3587c 021abc 4224a 033def 705defg


W075


N075 3719bc 020bcd 3638b 047c 720defg

N050 3927bc 021abc 4653a 035def 704defg

N025 3113de 017f 2539de 025fg 680h

W060

N100 3080def 019cdf 2367e 070a 695fgh

N075 4010b 018df 2679de 057b 700efgh

N050 4467a 016f 3055cd 040cde 685gh

N025 3193d 015f 1891f 031efg 620i






4 Discussion








W105


W090


W075


W060








5 Conclusions






Acknowledgments


References















































Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy





Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(a) W105 treatment

Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(b) W090 treatment

Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(c) W075 treatment

Chlo

roph

yll c

onte

nt (m

gmiddotminus1)

20

16

12

8

4

N100

N075

N050

N025

30 60 90 120


(d) W060 treatment








W105

N100 2219de 897f 7396d

N075 3028c 1148de 12616c

N050 3151bc 1195de 19696c

N025 2411de 914f 30132d

W090

N100 2550d 1100e 7969c

N075 3485a 1503b 14519ab

N050 3248ab 1401c 20300b

N025 2568d 1107e 32095c

W075

N100 2303e 1152de 7195c

N075 3299ab 1650a 13745a

N050 3163bc 1582ab 19767a

N025 2317e 1159de 28957c

W050

N100 1520g 905f 4751d

N075 2018f 1202de 8408c

N050 2084f 1241d 13026c

N025 1487g 886f 18590d














Irrigationtreatment


W105

N100 2355h 023a 2588de 042cd 785ab



N025 2613gh 019cdf 2605de 023g 750abcde

W090

N100 272hi 020abcd 2781cde 045c 795a

N075 3234d 021abc 3031cd 035def 755abcd

N050 3587c 021abc 4224a 033def 705defg


W075


N075 3719bc 020bcd 3638b 047c 720defg

N050 3927bc 021abc 4653a 035def 704defg

N025 3113de 017f 2539de 025fg 680h

W060

N100 3080def 019cdf 2367e 070a 695fgh

N075 4010b 018df 2679de 057b 700efgh

N050 4467a 016f 3055cd 040cde 685gh

N025 3193d 015f 1891f 031efg 620i






4 Discussion








W105


W090


W075


W060








5 Conclusions






Acknowledgments


References















































Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy







W105

N100 2219de 897f 7396d

N075 3028c 1148de 12616c

N050 3151bc 1195de 19696c

N025 2411de 914f 30132d

W090

N100 2550d 1100e 7969c

N075 3485a 1503b 14519ab

N050 3248ab 1401c 20300b

N025 2568d 1107e 32095c

W075

N100 2303e 1152de 7195c

N075 3299ab 1650a 13745a

N050 3163bc 1582ab 19767a

N025 2317e 1159de 28957c

W050

N100 1520g 905f 4751d

N075 2018f 1202de 8408c

N050 2084f 1241d 13026c

N025 1487g 886f 18590d














Irrigationtreatment


W105

N100 2355h 023a 2588de 042cd 785ab



N025 2613gh 019cdf 2605de 023g 750abcde

W090

N100 272hi 020abcd 2781cde 045c 795a

N075 3234d 021abc 3031cd 035def 755abcd

N050 3587c 021abc 4224a 033def 705defg


W075


N075 3719bc 020bcd 3638b 047c 720defg

N050 3927bc 021abc 4653a 035def 704defg

N025 3113de 017f 2539de 025fg 680h

W060

N100 3080def 019cdf 2367e 070a 695fgh

N075 4010b 018df 2679de 057b 700efgh

N050 4467a 016f 3055cd 040cde 685gh

N025 3193d 015f 1891f 031efg 620i






4 Discussion








W105


W090


W075


W060








5 Conclusions






Acknowledgments


References















































Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy






Irrigationtreatment


W105

N100 2355h 023a 2588de 042cd 785ab



N025 2613gh 019cdf 2605de 023g 750abcde

W090

N100 272hi 020abcd 2781cde 045c 795a

N075 3234d 021abc 3031cd 035def 755abcd

N050 3587c 021abc 4224a 033def 705defg


W075


N075 3719bc 020bcd 3638b 047c 720defg

N050 3927bc 021abc 4653a 035def 704defg

N025 3113de 017f 2539de 025fg 680h

W060

N100 3080def 019cdf 2367e 070a 695fgh

N075 4010b 018df 2679de 057b 700efgh

N050 4467a 016f 3055cd 040cde 685gh

N025 3193d 015f 1891f 031efg 620i






4 Discussion








W105


W090


W075


W060








5 Conclusions






Acknowledgments


References















































Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy








W105


W090


W075


W060








5 Conclusions






Acknowledgments


References















































Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy







5 Conclusions






Acknowledgments


References















































Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy

































Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy




Optimization of Controlled Water and Nitrogen Fertigation...

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Transcript of Optimization of Controlled Water and Nitrogen Fertigation...