JKAU: .S"i.. vol. 6, pp. 29-36(1-11-1 A.H./199-1 A.D.

Changes in Sugar Quality and Mineral Elements DuringFruit Development in Five Date Palm Cultivars in

AI-Madinah AI-Munawwarah

ABDUL AZIZ A. GASIM

Dept. of Natura.! Sciences, Faculty of Education,King Abdulaziz University, AI-Madinah AI-Munawarrah, Saudi Arabia

ABSTRACT. The reducing and non-reducing sugars and nine nutrient weredetermined in fruits of Ajwa. Beid. Burni, Rabeia and Safawi Date Palmcultivars. grown at AI-Madinah AI-Munawwarah, during four stages offruit development. Results showed that most of the studied characters

(physical and chemica! composition) at four stages of fruit maturity differedfrom one cultivar to another. Higher values of fruit and seed weight as wellas length and diameter were found during the early stages of developmentand minimum in the Tamre stage. Sugars contents accumulated gradually

during fruit development in all cultivars were also found to vary among thefive cultivars. Nitrogen and potassium contents were higher as compared tothe minerals in the different cultivars. Also in the micro-elements. iron waspresent in higher concentration than zinc and copper. The change fromKimri to the Tamre stage was accompanied with a reduction in the amountsof all minerals for all the cultivars.

Introduction

Date Palm (Phoenix dactylifera L.) is considered as one of the most important fruittrees in the Arab countries, particularly Saudi Arabia. However, earlier study ofphysical and chemical composition of the fruits of different date palm cultivars hasbeen reported at different countries by several workers (Haas[I], Furr & Cook[2],Hussein etal.[3], Hussein & EI-Zeid'-I', Minessy etal.15], Sawaya et al. [609], and Saad etal.IIO]). AI-Madinah AI-Munawwarah is number one producer of dates in SaudiArabia (Asifetal.IIII).

29

30 Gasim

The main aim of this study is to evaluate the fruit growth and changes in sugars andnutrient element content of five date palm cultivars Ajwa, Beid, Burni, Rabeia andSafawi growth at AI-Madinah AI-Munawwarah region at four different developmentstages (Kimri, Khalal, Rutab and Tamre).

Material and Methods

Five date palm (Phoenix dactylifera L.) cultivars grown at an orchard in Quba areain Al-Madinah Al-Munawwarah, were used in this investigation. Five date palm var-ieties were included; Ajwa, Beid, Burni, Rabeia, and Safawi. The trees were about17 -year-old. Three palm trees of similar vigour were selected from each cultivar. Or-chard was fertilized and irrigated according to the requirement of the field. All treeswere pollinated by hand on April 15, 1989. Fruit samples were collected on July 2, 12weeks after pollination, and continued at 15 days interval upto September 1. Fruitsamples were collected at four different stages of fruit development. These stageswere as follows: (1) Kimri, (2) Khalal, (3) Rutab, and (4) Tamre. Three sampleswere taken from each cultivar at the fourth stage of fruit development. Each sample,consisting of 120 dates, was collected from each of the three trees of the five cultivars.Physical characteristics of the fruits (fruit length and diameter, fruit and seed weight,pulp weight) were determined. Vernier caliper was used for measuring length anddiameter of fruits.

Total sugars, reducing and non-reducing sugars, were estimated according to theA.O.A.C. methods[12]. Mineral content of the flesh were carried out. Oven-driedand ground for chemical analysis, nitrogen was determined by microkjeldahl method(A.O.A.C.)112] and P, K, Na, Ca, Mg, Fe, Zn and Cu, were determined by AA-775series, atomic absorption spectrophotometry (A.O.A.C.)l121.

Results and Discussion

Morphological Changes

The data on the morphological changes occurring during the development of fruitsof Ajwa, Beid, Burni, Rabeia and Safawi are presented in Table 1. The averagelength and diameter of the fruit, in the five cultivars increased as the dates reachedthe KhalaJ stage and then decreased in the Tamre stage. The fruits of Safawi cultivarwere largest in size followed by Burni and Rabeia cultivars while Beid and Ajwa wereabout the same measurements in both stages (Rutab and Tamre). The weight of fruitand seed in the five cultivars increased at the Rutab stage and then decreased in theTamre stage. Also data showed that the Pulp percentage was higher during develop-mental stages. Similar results were obtained by Sawaya et al. [6J in Khudari, Selej andSifri date palm cultivars grown in Riyadh.

Sugar Analysis

Total sugar content of the fruits in the five cultiyars reached its maximum in theTamre stage (Table 2). At the Kimri stage, the content ranged from 42.5-54.3% andthen increased rapidly in the Khalal stage. Thereafter, the total sugar content in-

Changes in Sugar Quality and Mineral Elements.

Morphological characteristics of Ajwa, Beid, Burni, Rabeia and Safawi date cultivars.ILE

Stage of development

Cultivar Kimr Khalal

F.lengthcm

F. diametercm

Wt/fruit

gWI/seed Pulp

g %diameter

cmWt/frult

g

WI/seed PulpI F,length

g % cm

AjwaBeidBurniRabeiaSafawi

1.22:!:O.06 O.79:!:O.08 4.67:!:O.96 1.21:!:O.21 791.34:!:O.O2 1.18:!:O.06 5.12:!:O.72 1.13:!:O.11 821.67:!:O.15 O.56:!:O.O2 4.96:!:O.95 1.11:!:O.O5 771.19:!:O.17 O.51:!:O.04 3.92:!:O.21 1.11:!:O.1O 821.52xO.18 O.85:!:O.O5 5.21:!:O.19 1.~:!:O.08 78

3.34:!:O.18 2.39:!:O.09 8.75:!:1.76 1.32:!:O.31 873.52:!:O.22 2.97:!:O.13 8.92:!:1.33 1.25:!:O.20 884.49:!:O.29 2.31:!:O.35 9.21:!:1.19 1.25:!:O.11 823.99:!:O.35 2.34:!:O.25 6.25:!:O.39 1.34:!:O.24 874.49:!:O.41 2.62:!:O.29 10.91:!:O.12 1.35:!:O.12 82

Rutab Tamre

Wt/fruit

g

WI/seed PulpI F.length

g % cm

WI/fruit

~

WI/seed Pulp1\ %

F,length F,diametercrn cm

F. diametercm

3.07:!:O.06 2.21:!:O.OI 8.24:!:O.32 O.97:!:O.O3 892.99:!:O.06 2.44:!:O.O3 7.14:!:O.28 O.80:!:O.O3 903.95:!:O.O5 2.II:!:O.04 8.15:!:O.32 O.75:!:O.O2 893.28:!:O.IO 2.13:!:O.O5 7.88:!:O.33 O.95:!:O.06 914.07:!:O.O7 2.45:!:O.04 9.46:!:O.43 I.OO:!:O.O5 89

AjwaBeidBumiRabeiaSafawi

3.19:!:O.25 2.25:!:O.18 11.2 :!:1.21 1.20:!:O.22 903.11:!:O.26 2.45:!:O.31 13.2 :!:1.15 1.42:!:O.11 914.22:!:O.19 2.25:!:O.29 15.13:!:1.93 1.10:!:O.06 893.77:!:O.24 2.24:!:O.18 11.21:!:O.79 1.49:!:O.74 914.52:!:O.25 2.44:!:O.19 13.82:!:O.78 1.55:!:O.22 88

S.D.

creased slightly upto Tamre stage and were 84.2, 75.5, 81.5 and 75.2 for Ajwa, Beid,Burni, Rabeia and Safawi cultivars, respectively. These results are in harmony withthose reported by Ragab et al.[13], Mawlood(14J, Hussein et al.[3], and Sawaya et al.[6.7]on different date-palm cultivars.

Table 2 also represented the development changes in reducing sugars content infruits of the cultivars under study. The preparation of glucose to fructose changedwith development of fruits, from 1.4-1.7: 1 at the early stages of the development to1: 1 in Tamre stages. In general, the reducing sugars in the five date cultivars showeda trend similar to that of total sugars. At Kimri stage, Safawi fruits were highest in re-ducing sugars (54.3%), while Ajwa fruits recorded the lowest values 42.5. After-wards, the fruits continued to gain more reducing sugars during all developmentalstages to reach a maximum at Tamre stage.

Table 3 presents the accumulation of total sugars in fruits of the cultivars understudy at Tamre stage. Statistical analysis indicated that no significant differencesamong Beid, Rabeia and Safawi with regard to their contents of total sugars, andthey had the lowest values, while Burni was in between. On the other hand, Ajwahad the highest total sugar values that significantly excelled the other cultivars. Simi-lar results were obtained by Sawaya et al.[7].

With respect to non-reducing sugars, (which consisted of sucrose only), datashowed that it increased from low level in the Kimri stage (1.3-2.4%) to relativelyhigher level in the Rutab stage (11.2-24.5%). However, at Tamre stage, Safawi fruits

32

A.A. A. Gas;.

TABLE 2. Sugar contents of Ajwa, Beid. Burni, Rabeia and Safawi date cultivars at different stage of de-velopment (% of dry weight).

Glucose%ofR.S.

Stageofdevelop-

ment

Reducingsugar(R.S.)

Fructose% ofR.S.

RatioG/F

Total

sugar

Sucrosenon-R.S

AJwa1323.524.7

3.1

61.256.351.551.2

38.843.748.548.7

1.51.21.1

KimriKhalalRutabTamre

42.565.870.084.2

41.242.545.381.1

Beid2.0

12.314.73.3

Burni1.8

12.513.83.0

36.839.744.647.3

1.71.51.21.1

45.764.567.875.5

43.752.253.172.2

63.260.355.452.7

KimriKhalalRutabTamre

50.553.056.678.5

59.757.556.054.2

40.342.544.045.8

1.41.31.31.2

KimriKhalalRutabTamre

52.365.570.481.5

Rabeia1.5

13.314.24.8

Safawi2A

3.811.25.0

43.357.572.677.7

63.261.559.251.3

36.838.540.848.2

1.71.61.41.1

KimriKhalalRutabTamre

41.844.258.472.9

58.956.554.251.7

41.1

43.545.848.1

1.41.31.21.0

KimriKhalalRutabTamre

54.357.869.975.2

51.954.058.770.2

TABLE 3. Comparison of sugar contents of fruits between the date cultivars l1t Tamre stage.

FructoseRed Suc GlucoseCultivars Tot

3.1 b3.3b3.0b4.8a4.8a

5t.2b52.7b54.235t.3b5t.7b

48.7b47.3b45.8a48.2b48.3b

84.2a'75.5b81.5 ab77.7b75.2b

81.1 a72.2b78.5a7~.9b70.4b

AjwaBeidBurniRabeiaSafawi

'Means.

within a column followed by the same Ictter do not differ significantly of the 5"/0 Icvel of probability according to

Duncan's Multiple Rangc Test.

were highest in sucrose (5.0%), while Ajwa fruits recorded the lowest values (1.3%).These results are in agreement with those reported by Sawaya et al.ln] in three Riyadhdate palm cultivars. The data indicated that reducing sugars were the dominant forsugars during all developmental stages as compared with in a decrease in non-reduc-

33Changes in Sugar Quality and Mineral Elements

ing sugars. Haas and Bliss[15], working on different date palm cultivars, pointed outthat at the early stage of development, the sugars' content was largely in the form ofreducing sugars. Cook and Furr[!6] found that soft date cultivars contained littleamounts of sucrose. Hussein[!?] suggested that fruits of soft date cultivars containedlittle or no sucrose, while those of dry cultivars contained a relatively high proportionof sucrose to reducing sugars. The present data on sugar status of the fruits indicatethat all the five cultivars, Ajwa, Beid, Burni, Rabeia and Safawi belong to the soft-date group.

Mineral Content

Mineral composition of date palm fruits is presented in Table 2. Data showed thatthe level of concentration in the five cultivars ranged for N 0.72-1.23%, P 0.120-0.161%, K 0.185-1.51%, Ca 0.25-0.50%, Mg 0.25-0.37%, Na 0.19-32%, Fe 205.1-251.5 ppm, Cu 4.95-6.25 ppm and Zn 27.5-72.70 ppm. The data clearly showed thatK is the predominant macro-element in the flesh of the five date palm cultivars,whereas phosphorus was found in smaller quantities than the other macro-elements.With respect to micro-elements, data also showed that Fe is the predominant micro-element, while Cu was found in small quantities (Table 4).

TAB~E 4. Mineral composition of Ajwa, Beid, Burni, Rabeia and Safawi date cultivars of various stagesof maturity.

Stage ofdevelop

mentCa%

Mg%

Na%

Feppm

Cuppm

Znpprn

Cultivars N%

P"/0

K

"/0

KimriKhalalRutabTamre

1.231.030.930.82

0.2100.1800.1500.090

1.301.050.850.65

0.320.200.190.18

0.270.250.210.20

0.190.210.180.25

205.1192.5180.3172.0

6.254.274.003.75

72.727.525.724.5

Ajwa

0.390.290.250.19

0.250.190.150.11

0.250.190.170.18

212.2195.7174.5170.3

5.243.152.242.80

42.539.439.230.5

KimriKhalalRutabTamre

0.720.520.440.40

0.1210.0950.0720.065

1.511.121.111.09

Beid

0.220.200.180.19

225.2190.5180.4175.5

4.654.123.753.63

50.845.240:534.2

KimriKhalalRutabTamre

0.940.820.650.45

0.1610.1220.0850.050

1.320.940.650.70

0.500.320.250.22

0.290.190.150.14

Burni

0.320.290.250.26

251.5200.2177.5174.9

5.244.502.752.72

27.522.920.020.5

KimriKhalalRutabTamre

1.551.120.790.62

0.1440.0950.0540.044

1.221.351.110.95

0.460.300.330.27

0.370:2240.1450.120

Rabeia

233.5197.3188.5180.3

4.952.942.502.22

44.231.129.520.9

KimriKhalalRutabTamre

0.990;620.590.47

0.1270.0950.0520.045

0.1851.220.990.80

0.250.110.120.18

0.270.200.120.13

0.220.250.190.20

Safawi

34 A.A. A. Gasim

There were significant differences in the dates' mineral contents of the whole sea-son of the five date cultivars, when the averages of all trees were compared (Table 5).Date mineral contents ranged for N 0.520-1.020%, P 0.079-0.157%, K 0.853-1.215%, Ca 0.165-0.280%, Mg 0.175-0.214%, Na 0.197-0.280%, Fe 175.3-201.0ppm, Cu 2.776-4.037 and Zn 22.723-42.67 ppm. The results were in parallel withthose reported by Haas!!], Minessy et al.!5], Sawaya et al.[8], and Saad et al.[IO] formany date palms cultivars grown in Saudi Arabia.

TABLE 5. Average of the whole season mineral composition of Ajwa, Beid, Burni, Rabeia and Safawidate cultivars. /

P%

K%

Ca%

N%

Mg%

Na%

Fe

ppm

Zn

ppm

Cu

ppmCultivars

1.0033'0.520b0.715b1.023O.668b

0.157a0.088 bO.l04abO.084b0.079b

0.963b1.208a0.905b0.853 b1.215a

0.230 b0.280b0.32330.3423O.l65b

0.213aO.l75bO.l93b0.214aO.ISOb

0.208 b0.197b0.198b0.280a0.215b

175.3c187.2ab183.4b192.9a2O1.0a

AjawaBeidBumiRabeiaSafawi

4567 a

2.776 b

4.037 a

3.852ab

3.152b

27.612c36.9ab42.67b22.723c31.425a

"Means, within a column followed by the same letter do not differ significantly of the 5% level of probability according toDuncan's Multiple Range Test.

References

[I] Haas, A.R.C., Inorganic composition of date fruits, Date Grower's Inst. Rep. 12: 6-8 (1935).[2] Furr, J.R. and Cook, J.A., Nitrogen content of pinnae, fruit and seed of Deglet Noor and Khadrawy

date palms as related to nitrogen fertilization, Date Grower's Inst. Rep. 29: 13-14 (1952).[3] Hussein, F., Mustafa, S., AI-Kahtani, M.S., EI-Shamiraea, F. and AI-Zeid, A., Studies on physical

and chemical characteristics of eighteen date cultivars grown in Saudi Arabia, Coil. Agric. Res. Bull.,King Saud Univ., Riyadh 2: 187-203 (1974).

[4] Hussein, F. and EI-Zeid, A.A., Chemical composition of Khalas dates grown in Saudi Arabia. EgyptJ. Hort. 2: 209-214 (1975).

[5] Minessy, F.A., Bacha, M.A. and EI-Azab, E.M., Changes in sugars, and nutrient elements content infruits of four soft date varieties in Egypt, Alex. J. Agric. Res. 23: 301-306 (1975).

[6] Sawaya, W.N., Khalil, J.K. and Saft, W.M., Fruit growth and composition of Khudari, Sellej andSifri date cultivars grown in Saudi Arabia, Proc. 1st Symp. Date Palm. March 23-25. King FtiisalUniv., AI-Hassa, Saudi Arabia, pp. 202-209 (1982).

[7] Sawaya, W.N., Khalil, J.K., Khatchadourian, H.A., Saft, W.M. and Mashadi, A.S., Sugars, tanninsand some vitamins contents of twenty date cultivars grown in Saudi Arabia at the Khalal (Maturecolor) and Tamre (Ripe) stages, Proc. 1st Symp. Date Palm, King Faisal Univ., AI-Hassa, SaudiArabia, pp. 468-478 (1982).

[8] Sawaya, W.N., Saft, W.M., Khalil, J.K. and Mashadi, A.S., Physical measurements, prominateanalysis and nutrient elements content at twenty-five date cultivars grown in Saudi Arabia at theKhalal (Mature color) and Tamre (Ripe) stages. Proc. 1st Symp. Date Palm, King Faisal Univ., AI-Hassa, Saudi Arabia, pp. 454-466 (1982).

[9] Sawaya, W.N., Khalil, J.K. and Saft, W.M., Chemical composition and nutritional quality of dateseeds,J. FoodSci. 49:617-:619(1984).

[10] Saad, F .A., Shaheen, M.A. and Bacha, M.A., Chemical analysis of fruits of some Saudi grown datepalm cultivars with emphasis on their mineral content, Proc. Saudi Bioi. Soc. 9: 22-23 (1986).

[II] Asif, I., AI-Tahir, O.A. and AI-Kahtani, M.S., Inter-Regional and Inter-Cultivar variations in datesgrown in the Kingdom of Saudi Arabia, Proc. 1st Symp. Date Palm, King Faisal Univ., AI-Hassa,Saudi Arabia, pp. 234-248 (1982).

35Changes in Sugar Quality and Mineral Elements.

[12] A.O.A.C., Official Methods of Analysis, 12th ed., Association of Official Analytical Chemists.Washington, D.C. (1975).

[13] Ragab, M.H.H., EI-TobeyShehata, A.M. and Sedky,A., Studies on the Egyptian dates. 2. Chemicalchanges during development and ripening of six varieties, Food Tech. 10: 407-410 (1956).

[14] Mawlood, E.A., Physiological studies on fruits development of Sam many and Zaghloul date palm cul-tivars. Ph.D. Thesis, Hort. Dept., Fac. Agric., Cairo Univ. (1980).

[15] Haas, A.R.C. and Bliss, D.E., Growth and composition of Deglet Noor dates in relation to water in-jury. Hilgardia 9: 295-344 (1935).

[16] Cook, J.A. and Furr,J.R., Kinds and relative amounts of sugars and their relation to texture in someAmerican grown date varieties, Proc. Amer. Soc. Hort. Sci. 61: 286-292 (1953).

[17] Hussein, F., Kinds and relative amounts of sugars in some Egyptian date cultivars. Beitr. Trop. &Subtrop. Landwist and Tropenveterina armedizin 10(2): 159-162 (1972); (Hort. Abst. 44(6): 4295).

I

36 A.A. A. Gasim

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