For Review OnlyGrowth and vegetable yield of Amaranthus hybridus L. as impacted by harvest methods in southern Ontario, Canada

Journal: Canadian Journal of Plant Science

Manuscript ID CJPS-2019-0106.R2

Manuscript Type: Article

Date Submitted by the Author: 15-Nov-2019

Complete List of Authors: Farintosh, Geoff; University of Guelph, Plant AgricultureRiddle, Rachel; University of Guelph Simcoe Station, Plant Agriculture; University of GuelphVan Acker, Rene; University of Guelph, Plant Agriculture

Keywords: Edible amaranth, callaloo

Is the invited manuscript for consideration in a Special

Issue?:Not applicable (regular submission)

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Growth and vegetable yield of Amaranthus hybridus L. as impacted by harvest

methods in southern Ontario, Canada

Geoff Farintosh1, Rachel Riddle2 and Rene Van Acker1

1University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1

2University of Guelph, Simcoe Research Station, 1283 Blueline Rd, Simcoe, ON, Canada N3Y

4N5

Amaranthus hybridus L. is a nutritious leafy vegetable amaranth species grown primarily in

tropical regions. Weedy amaranth species thriving in southern Ontario suggest the edible biotype

could also grow efficiently as a crop. Field trials in Guelph, Simcoe, and Stouffville, Ontario

examined yield in response to three harvest frequencies (weekly, every two weeks, and every

three weeks) cut at 15 cm above ground level, two traditional harvest practices (Afro-Caribbean

and European) cut every two weeks, and a control which was not cut until the final harvest. The

highest marketable yields and quality measures were observed in plants cut every two weeks,

every three weeks, and using the Afro-Caribbean cutting technique which selects and harvests

thicker stems while leaving new shoots for later harvests. The difference in growth among sites

suggests plants prefer warm, well-drained soil. Marketable yield was as high as 4.02±0.340 kg m-

2 in Simcoe with an average yield across all three sites of 2.37±0.229 kg m-2. This demonstrates

that A. hybridus has the potential to be grown as a vegetable crop in southern Ontario and that

marketable yield can be optimized by method of harvest.

Key words: Edible amaranth, callaloo

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Introduction

Amaranthus hybridus L. is a leafy vegetable amaranth that can be found on every

continent with the exception of Antarctica (Sauer 1967). A. hybridus is generally considered a

weed in North America, commonly known as smooth amaranth, but the leaves and stems are

consumed as a staple food in other areas of the world such as Africa, Asia, the Caribbean and

part of Europe (Abbasi et al. 2013; Schwerzel 1986). With an increasing immigrant population in

Canada, the demand for A. hybridus has grown (Filson and Adekulne 2017). This demand,

coupled with the ability of A. hybridus to grow quickly and its high nutrient content (Akubugwo

et al. 2007), make it a strong candidate for a new crop in southern Ontario (Filson and Adekulne

2017).

Edible vegetable amaranth is harvested differently in different parts of the world based on

climate or customer cultural preferences. In southern Ontario there has yet to be a comparison of

different cutting methods and their impact on marketable yield. Harvesting too frequently may

hinder the plant from re-growing, while waiting for a prolonged period might affect quality if the

harvested product is too tough or stringy for consumers (Materechera et al. 2006). In addition to

harvest timing, the height of the cut is also likely to impact marketable yield. While some

consumers may value the tender growing tips, only cutting them will probably limit yield, while

cutting the entire stem may boost yield but be less desirable to the consumer.

The primary objective of this study was to evaluate which harvest techniques are the most

effective at optimizing both yield and quality of A. hybridus in southern Ontario. These results

may increase the potential to grow more vegetable amaranth in southern Ontario, and be used in

further studies on this crop.

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Materials and Methods

Field experiments were conducted in 2017 at three different field sites: the Guelph Centre

for Urban Organic Farming (Guelph) located at the University of Guelph, in Guelph, Canada

(43° 32’N, 80° 13’W), the Simcoe Research Station (Simcoe) in Simcoe, Canada (42° 51’N, 80°

16’W) and at Farintosh Farms (Stouffville) in Stouffville, Canada (43° 56’N, 79° 21’W). Soil

samples were taken from all three sites using a metal soil corer to a depth of 8 cm. The plot at

Guelph was a loam soil classified as a Luvisol had a pH of 7.6 and had organic matter of 5.2%,

the sample from Simcoe was a very fine sandy loam (VFSL) known as Watford and had a pH of

7.4 and 2.0% organic matter, while Stouffville was a Bookton sandy loam with a pH of 6.3 and

2.7% organic matter (Table 1).

The Simcoe site was planted to rye (Secale cereale L.) in the fall of 2016 and glyphosate

(Roundup Transorb (isopropylamine salt), 360 g a.e. L-1) was applied at 720 g a.e. ha-1 on 9 May

2017. The field was then cultivated on 31 May and 700 kg ha-1 of 15.7-7.2-11.4 (NPK) fertilizer

was applied. Prior to planting the land was worked again to incorporate the fertilizer and bury

emerging weeds. The Stouffville site was planted with edible amaranth in 2016 and ploughed in

the fall, 550 kg ha-1 of 6-24-24 was applied and the soil was cultivated three times before

planting. The Guelph site was covered primarily in orchard grass (Dactylis glomerata L.) before

it was rototilled and raked by hand before planting.

There were six treatments in total and four blocks (replicates) at each site with the

exception of Guelph where there was only room for three blocks (replicates). Three harvest

treatments were cut to 15 cm above ground at three different timing intervals: weekly, every two

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weeks, and every three weeks. In addition to these three treatments, two harvest treatments were

included to mimic the two most common consumer self-harvesting approaches (pick your own).

First, Afro-Caribbean consumers tend to desire the plants to be cut low, where the side shoots

meet the main stem, selecting thicker, more mature stalks. Other consumers, including those of

European descent, prefer to take the very tips of each stalk. Both of these “consumer” treatments

were applied every two weeks. Finally, a control treatment was included where the plants were

not harvested until the final harvest date. Field plots were arranged in a randomized complete

block design.

Seeds were planted into 128 cell trays in Stouffville on 26 April 2017 and placed in a

greenhouse to encourage seed germination and the establishment of seedlings. Approximately

eight seeds were planted into each 28.6 mm2 cell. As the seeds emerged and the seedlings grew,

they were thinned to five seedlings per cell. Once the seedlings were approximately 10 cm in

height they were transplanted into the field sites. The A. hybridus seedlings were transplanted at

the Simcoe, Guelph, and Stouffville sites on 9, 12 and 13 June 2017 respectively. At the Simcoe

and Stouffville sites each transplant was planted with roughly 250 mL of 8.5g L-1 20-20-20

(NPK) synthetic liquid fertilizer while at Guelph the transplants were planted with 250 mL of

water due to the organic certification of the site. Transplants were planted with 45 cm spacing in

the row, with the rows 1 m apart. In early July, 85 kg ha-1 of 46-0-0 fertilizer was applied at the

Simcoe and Stouffville sites whereas the Guelph site received no fertilizer. Once the plants were

roughly 30 cm tall, all six treatments were cut to a height of 15 cm in early July to encourage

adventitious growth. When plants grew back to 30 cm tall the initial harvest began. The plants at

the Guelph site grew much slower, likely due to no fertilizer application, so the harvest began

three weeks after Simcoe and Stouffville, when the plants were only 20 cm in height. Each plot

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comprised of three rows with five plants in each row, for a total of 15 plants per plot. For harvest

measurements and analyses, only the three middle plants from the center row were sampled.

Plants were harvested by cutting perpendicular to stems using a sharp knife. Cuttings

from the middle three plants in each plot were pooled for a given plot. Fresh weights were

immediately measured on site using an ADAM®CPW plus -15 scale (Adam Equipment Inc.,

Fox Hollow Road, Oxford, CT, USA, 06478) with a precision of 5 g and a max weight of 15 kg.

Once fresh weights were measured, samples were put in a paper bag, labeled, and moved to a

dryer. The dryer maintained a temperature of 48.9 °C. After two weeks in the dryer, the dry

weight was measured using the same scale. Weight measurements were converted to kg m-2.

Statistical analysis software (SAS) version 9.4 (SAS Institute, Cary, NC) was used for all

statistical data analysis. An analysis of variance (ANOVA) for mixed models was carried out

using PROC GLIMMIX. The different harvest treatments were the fixed effects, while block was

the random effect. There was a significant interaction between site location and harvest treatment

thus data for each location was analyzed separately. The data was tested for normality using the

Shapiro-Wilk test and Q-Q plots generated by PROC UNIVARIATE. The PDMIX800 macro on

SAS was used in combination with Tukey’s test to convert Fisher's LSD means separation into

letter groupings. All analyses were considered significant at α=0.05.

While data were collected for a total of eight weeks (initial harvest, six weeks of harvest

with treatments applied, and a final harvest where plants were cut to ground level) to best display

results, the data were placed into three groupings to make relevant comparisons. These groupings

were:

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A. Regrowth: Contains only harvest data from the six weeks after the initial harvest. These

data are most representative of the treatments as they do not contain the initial harvest

before the treatments were implemented and because the treatments that were harvested

weekly, every other week, and every three weeks all fall naturally on the sixth week

without harvesting any trial prematurely.

B. Marketable yield: Contains the harvest data from the six weeks in addition to the initial

harvest. The final harvest was not included in this group as the plants were cut down to

ground level and much of the biomass would not be close to the quality expected by

consumers. This grouping provides the most accurate estimate of marketable yield from a

seven week period.

C. Total Biomass: Contains initial harvest, the six week treatments where applied and the

final harvest where plants were cut down to ground level. With so much focus on what is

being harvested it is important to also have a final harvest to account for all plant growth

during the experiment period. By combining all the harvest data together it is easier to

understand how the treatments affected the biomass production of this species under

these conditions.

Results and Discussion

These groups were presented individually for each site as there were significant

differences between the three sites (P =

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was certified organic and thus no synthetic fertilizer could be used which could have an effect on

plant growth. Another reason that the Guelph site may have been behind in plant growth was due

to a wet start to the growing season. There were 244 mm of rain in June and July in Guelph,

when Stouffville and Simcoe had only 136 mm and 102 mm, respectively, during the same

period (Table 2). There was no supplemental irrigation at any of the sites. Guelph was also not as

warm as the other two sites throughout the course of the experiment (Table 2). The differences in

yield between Guelph and Stouffville are harder to assign to monthly temperature and

precipitation differences or differences in soil fertility. Rather, the timing of rainfall may have

been a factor, especially in June in which Stouffville received heavy rain early in the month. In

Simcoe rainfall was more even throughout the month of June. These differences in weather

seemed to have affected yield greatly over the course of the experiment. While the first harvest

was done at the same time across all three sites, the plants were already very different in size

between sites and may have responded differently to treatments that did not account for plant

size at time of application.

Regrowth

Analysis of plants harvested at the Stouffville site showed significant fresh weight

differences among all five harvest treatments (Table 3). From highest to lowest yield, the

treatments ranked as; the customer method of selecting for large stems and cutting low, then

triweekly, biweekly, weekly, and lastly harvesting only the tips. Dry weight measurements

followed the same treatment order, with significant differences between some treatments with

respect to dry weights (Table 3). Like fresh weight, for dry weight, the customer treatment was

significantly higher than other treatments, while the tips only treatment was not significantly

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different from the weekly harvest treatment. The ratio of fresh to dry weight was greatest for the

triweekly treatment, closely followed by the customer treatment. These two treatments both

allowed the plant to grow longer and achieve thicker stems, suggesting that the stems may be

able to contain more water as a percent than the leaves.

At Simcoe the results followed a similar pattern to the Stouffville site, with customer and

triweekly treatments providing the greatest fresh and dry weights (Table 3). The results at the

Simcoe site for the tip only treatment also mirrored the results Stouffville with significantly

lower fresh and dry weight versus the other treatments. Only the fresh to dry weight ratio of the

customer treatment was significantly higher than the tip only treatment. For the Simcoe site, the

ratios were higher in general compared to the Stouffville site. This was surprising considering

Stouffville received 62 mm more rain in July and August than did Simcoe. Neither site was

irrigated but the Simcoe site received rainfall more regularly, while the Stouffville site had only a

few high-rainfall events (Table 2).

The Guelph site had very few significant differences among treatments. The dry weight

of the weekly treatment was significantly higher than the tips only treatment, the biweekly and

the triweekly treatments. The ratio of the tips only treatment was significantly higher than the

weekly cutting treatment (Table 3). The fresh and dry weights from this site were low compared

to the other sites and there was greater variation around the means. This meant that even in cases

where the means between treatments were numerically great (e.g. fresh weight for the customer

treatment was more than triple the other treatments) the differences were not statistically

significant. In addition, the mean separation power was lower for this site than the other two sites

because there were only three and not four replicates. As well, the site environment was not

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consistent in multiple directions with a large greenhouse to the south and a waterway to the

north. The low yields for this site were likely due to multiple factors but the key factor may have

been the lack of soil nitrogen because the site was certified organic and thus no synthetic

fertilizer was applied. Ideally, a comparable organic fertilizer would have been used to help

remove some variability from the results.

Across all three sites, the customer harvest treatment tended to provide the highest fresh

weight yield, closely followed by the triweekly treatment. This result is valuable not just because

it highlights how to maximize yield through harvest approach but also because two very different

harvest approaches provided similar results. The customer method is very time consuming as

each stem has to be evaluated and cut individually based on thickness, while the triweekly

cutting method is very time efficient with just a single swipe of the knife required for harvesting

plants every three weeks. The tips only treatment tended to provide the lowest fresh weight yield.

One of the more obvious reasons for this is that such a small part of the plant is being harvested.

The fresh weight yield from the weekly treatment tended to be close to the tips only treatment,

suggesting that two weeks was too long of a harvest interval for the tips only treatment or that

the weekly cuttings allowed the plants to sprout more adventitious growth. A study by Mager et

al. (2006) aimed at reducing plant weight via physical removal of the apical shoot highlighted the

ability of amaranth to produce adventitious growth efficiently. The results showed that when

common waterhemp, Amaranthus tuberculatus L., shoots were removed at a plant height of 10

or 20 cm tall, there was no reduction in weight compared to control plants six weeks after

removal (Mager et al. 2006).

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Marketable Yield

The marketable yield results were very similar to the regrowth results given that the only

difference between these groups was the addition of the initial harvest. Before the initial harvest

approximately the same amount of biomass was present on each plant. By adding the somewhat

constant initial harvest to each treatment the differences were greatly reduced compared to the

regrowth results. Notable from the marketable yield results was how much the initial harvest

differed between sites. The Simcoe site had the largest initial harvest, averaging 1.97 kg m-2,

Guelph had the smallest with 0.28 kg m-2, and Stouffville was in the middle with 0.89 kg m-2. It

is important to highlight these initial harvest weights given that plant size at initial harvest

impacts the extent to which the plant is able to branch and regrow (Harper 1977). For example,

at the Simcoe and Stouffville sites, the initial harvest 15 cm above ground level was relatively

low in relation to the height of the plant, falling just above the first break in the stem. This could

promote growth of new shoots and higher yield. This was not the case at the Guelph site,

however, given that the plants were quite small at first harvest and the cut at 15 cm was near the

top of most plants. At this site, therefore, this initial harvest would have been similar to a tips

only treatment which does not necessarily promote as much branching. It may have been better

to make the initial cut timing based on a physiological stage, and the cut height at a percent of

the plant’s total height to avoid the site differences compounding other variables.

Generally, the results for marketable yield were similar to the results for regrowth, with

the customer and triweekly treatments generating the greatest fresh weights at all three sites,

however, this difference among treatments was only significant for the Stouffville site (Table 4).

The tips only treatment also generally produced the lowest fresh and dry weights but in the case

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of marketable yield versus regrowth, the differences from other treatments were smaller. There

were less significant differences between treatments for the ratios as well, with most significant

differences coming from a lower ratio for the tips only treatment at the Stouffville and Simcoe

sites. By adding the first harvest the effect of the treatments on the ratio between fresh and dry

weight becomes less significant.

The marketable yield and regrowth results provided yield measures from only a relatively

short seven-week harvest season. These results did not include the final harvest which

represented further harvest potential in an open fall season.

Total Biomass

The total biomass results were very different compared to the regrowth and marketable

yield results. The control treatment produced significantly more fresh weight than any of the

other treatments in Stouffville, but this was not the case at the other two sites where none of the

six treatments were significantly different from one another (Table 5). The tips only treatment

was no longer the lowest yielding treatment but one of the highest yielding because while the

small growing tips were being harvested regularly the plant continued to grow thicker, longer

stems and produce reproductive structures. When it comes to edible amaranth though, yield is

only valuable if quality is acceptable for the consumer, and for the total biomass results, the

control and tips only treatments contained very little quality yield (tender leaves and stems) as a

proportion of the total biomass harvested (personal observation). However, the measure of total

biomass allowed us to explore whether the ratio between fresh and dry weight was an effective

measure of quality. This was highlighted when applying the ratio to extreme examples, such as

the control treatment where the plant material was far too tough to be acceptable to consumers.

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While the control treatment had one of the lowest ratios at the Simcoe and Guelph sites, it had

the highest ratio in Stouffville. This difference between sites showed that the ratio was

determined not just by the treatment but also by site factors such as rainfall and soil fertility. The

best measure of quality was a simple visual inspection, making sure leaves were not wilting and

that stems were tender rather than tough.

The total biomass results are important across all three sites because they show that A.

hybridus will produce just as much or more biomass when left untouched or when just the

growing tips are harvested compared to the treatments that have outperformed the others in the

other two groupings (regrowth and marketable yield). This means that when applying cutting

treatments, total yield will not increase in most scenarios, but rather decrease compared to

leaving the plants to grow untouched. The only advantage to cutting treatments compared to a

control is the quality of the yield, as it is unlikely for a consumer to value a plant which was left

to grow fibrous and tough. These results are especially pertinent to the treatment where just the

growing tips were taken, as the treatment went from the lowest yielding to one of the highest

when you consider total biomass. This suggests that there are still improvements to be made for

this treatment, as the plant is still producing a lot of biomass in the stems rather than producing

more growing tips as in the weekly treatment. By cutting more frequently than every two weeks

the plant would likely produce more tips rather than the thick stems which lead to such high total

biomass.

This research showed that longer time periods between cuttings will produce more yield

but lower quality and less marketability. The stems and leaves harvested from the control were

far from market quality indicating that it is unlikely the plants could go for much longer than

three weeks between cuttings and continue to maintain quality. Cutting frequency also appears to

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be connected to the harvest method. If only the leaves or growing tips are being harvested, a

shorter cutting period of one to two weeks may increase yield and quality, while if the plants are

cut lower and the stems are harvested, the period can be extended to three weeks or possibly

more to maximize yield without sacrificing quality.

Conclusions

Personal communication with Ontario farmers led to the idea that the “customer”

treatment based on the typical method of cutting the larger stems low to the ground would

encourage adventitious shoot growth and outperform the other treatments. While this treatment

did stimulate new growth and resulted in the highest yields, cutting straight across the entire

plant at a set height of 15 cm above ground level every three weeks yielded an amount which

was not significantly different. This finding has promising real world implications for larger

operations as the same amount can be harvested with far less labour (and perhaps even

automated) while maintaining quality.

There are certain customers that prefer just the growing tips of edible amaranth but the

harvest treatment we explored, of only selecting these tips every two weeks stunted marketable

yields compared to the other treatments. A significantly better approach to harvesting what

appears to be the same portion of the plant was the weekly harvest treatment. By cutting more

frequently the plants appeared to create far more growing tips to be harvested instead of

investing in fewer. While the yield is still low compared to other treatments it is important if the

amaranth is being grown specifically for a consumer base that favours the tender growing tip.

The cutting treatments could be optimized by harvesting based around weather and other

factors rather than being held to a set interval. We chose a set interval so that we could

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standardize treatments and to fit scientific methodology. Regardless, the amount harvested in the

field trials is already more than promising and this research showed that edible amaranth has the

potential to be a viable crop for farmers in southern Ontario.

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References

Abbasi, A. M., Khan, M. A., Shah, M. H., Shah, M. M., Pervez, A., and Ahmad, M. 2013. Ethnobotanical appraisal and cultural values of medicinally important wild edible vegetables of Lesser Himalayas-Pakistan. Journal of Ethnobiology and Ethnomedicine, 9: 66.

Akubugwo, I. E., Obasi, N. A., Chinyere, G. C., and Ugbogu, A. E. 2007. Nutritional and chemical value of Amaranthus hybridus L. leaves from Afikpo, Nigeria. African Journal of Biotechnology, 6: 2833-2839.

Filson, G. C. and Adekunle, B. 2017. Greater Toronto area preferences for ethnocultural vegetables. Pages 33-54 in S. McMenemy, ed. Eat Local, Taste Global: How Ethnocultural Food Reaches Our Tables. Wilfrid Laurier University Press, Waterloo, Canada.

Harper, J.L. 1977. The influence of density on form and reproduction. Pages 195-228. Population Biology of Plants. London: Academic Press, London, UK.

Mager, H. J., Young, B. G., and Preece, J. E. 2006. Characterization of compensatory weed growth. Weed Science, 54: 274-281.

Materechera, S. A. and Medupe, M. L. 2006. Effects of cutting frequency and nitrogen from fertilizer and cattle manure on growth and yield of leaf amaranth (Amaranthus hybridus) in a South African semi-arid environment. Biological Agriculture & Horticulture, 23: 251-262.

Sauer J.D., 1967. The grain amaranths and their relatives: A revised taxonomic and geographic survey. Annals of the Missouri Botanic Garden, 54: 103-137.

Schwerzel, P.J. 1986. Amaranth: a nutritious crop for the developing world. Farming World, 12: 3-9.

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Table 1. Soil test results from samples taken in 2017 from Guelph Centre for Urban Organic Farming in Guelph, Farintosh Farms in Stouffville, and the Simcoe Research Station in Simcoe, Ontario, CanadaSoil Properties Guelph Stouffville SimcoepH 7.6 6.3 7.4Organic Matter (%) 5.2 2.7 2.0Phosphorus (ppm) 20 137 55Potassium (ppm) 87 111 135Magnesium (ppm) 304 71 175Calcium (ppm) 2832 1420 720Cation Exchange (MEQ/100 g) 18.1 9.2 5.5

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Table 2. Monthly precipitation and mean air temperature for 2017 at Guelph, Stouffville, and Simcoe, Ontario, Canada. Data were collected from the nearest Environment Canada meteorological station to each of the three sites.

Precipitation (mm) Mean air temperature (°C)Month Guelph Stouffville Simcoe Guelph Stouffville SimcoeJan 111 70 81 -3.6 -1.6 -1.9Feb 103 58 86 -1.8 -0.2 0.2Mar 61 68 111 -2.0 -0.5 -0.4Apr 117 111 107 8.1 9.4 9.7May 136 143 142 10.1 12.6 12.7Jun 176 98 84 17.4 19.4 19.6Jul 68 38 18 19.1 21.8 20.7Aug 48 75 33 17.3 20.1 18.9Sep 54 30 29 16.3 18.8 17.5Oct 90 58 105 11.0 13.3 12.6Nov 92 60 103 1.7 3.7 3.2Dec 55 40 60 -6.8 -5.2 -5.4

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Table 3. Mean (plus or minus standard error) regrowth weight of A.hybridus L. as affected by harvest approaches over six weeks at Farintosh Farms in Stouffville, Simcoe Research Station in Simcoe, and the Guelph Centre for Urban Organic Farming in Guelph, Ontario, Canada in 2017.Site Harvest approach Fresh weight

(kg m-2)Dry weight(kg m-2)

Ratio(fresh kg m-2/dry kg m-2)

Stouffville Weeklya 0.59±0.024d 0.18±0.042bc 3.74±0.694bBiweekly 0.78±0.052c 0.16±0.012b 4.97±0.399bTriweekly 1.26±0.053b 0.18±0.009b 6.89±0.383aCustomerb 1.89±0.117a 0.35±0.021a 5.46±0.453abTipsc 0.30±0.026e 0.07±0.008c 4.28±0.242b

Simcoe Weekly 0.96±0.044b 0.15±0.007b 6.35±0.277abBiweekly 1.24±0.083ab 0.18±0.008a 6.82±0.400abTriweekly 1.45±0.164ab 0.23±0.013a 6.34±0.391abCustomer 1.48±0.140a 0.22±0.022ab 6.78±0.181aTips 0.33±0.019c 0.06±0.003c 5.74±0.214b

Guelph Weekly 0.12±0.033a 0.05±0.006a 2.99±1.222bBiweekly 0.10±0.014a 0.02±0.001b 5.14±0.415abTriweekly 0.10±0.027a 0.02±0.003b 5.05±0.625abCustomer 0.34±0.126a 0.08±0.031ab 4.71±0.301abTips 0.08±0.014a 0.01±0.003b 6.12±0.699a

Note: Means followed by the same lowercased italic letter within a site and column are not significantly different according to a Tukey’s multiple range test (α=0.05).a Weekly, Biweekly and Triweekly treatments were cut at 15 cm above ground level. b Customer treatment mimicked Afro-Caribbean preference by cutting larger stems near the base every other week.c Tips treatment mimicked European preference by cutting just the below the growing tip every other week.

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Table 4. Mean (plus or minus standard error) marketable vegetable yield of A. hybridus L. as affected by harvest approaches over seven weeks at Farintosh Farms in Stouffville, Simcoe Research Station in Simcoe, and the Guelph Centre for Urban Organic Farming in Guelph, Ontario, Canada in 2017.Site Harvest approach Fresh weight

(kg m-2)Dry weight(kg m-2)

Ratio(fresh kg m-2/dry kg m-2)

Stouffville Weeklya 1.75±0.102b 0.30±0.042ab 6.07±0.876ab

Biweekly 1.85±0.114b 0.36±0.092abc 5.94±1.043ab

Triweekly 2.60±0.131a 0.33±0.010b 7.96±0.253a

Customerb 2.56±0.143a 0.42±0.030a 6.05±0.398b

Tipsc 0.50±0.019c 0.10±0.009c 5.36±0.308bSimcoe Weekly 3.46±0.242a 0.40±0.042a 8.74±0.811a

Biweekly 3.60±0.379a 0.45±0.058a 8.08±0.269aTriweekly 4.02±0.340a 0.50±0.030a 8.01±0.679aCustomer 3.77±0.265a 0.47±0.032a 8.08±0.107aTips 0.48±0.009b 0.08±0.002b 5.91±0.0417b

Guelph Weekly 0.36±0.117ab 0.08±0.009a 3.74±0.694bBiweekly 0.41±0.059a 0.07±0.015ab 4.97±0.399bTriweekly 0.50±0.216ab 0.09±0.044ab 6.89±0.383aCustomer 0.74±0.267ab 0.14±0.048ab 5.46±0.453abTips 0.15±0.010b 0.02±0.004b 4.28±0.242b

Note: Means followed by the same lowercased italic letter within a site and column are not significantly different according to a Tukey’s multiple range test (α=0.05).a Weekly, Biweekly and Triweekly treatments were cut at 15 cm above ground level. b Customer treatment mimicked Afro-Caribbean preference by cutting larger stems near the base every other week.c Tips treatment mimicked European preference by cutting just the below the growing tip every other week.

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Table 5. Mean (plus or minus standard error) total vegetative biomass yield of A. hybridus L as affected by harvest approaches at Farintosh Farms in Stouffville, Simcoe Research Station in Simcoe, and the Guelph Centre for Urban Organic Farming in Guelph, Ontario, Canada in 2017.Site Harvest approach Fresh weight

(kg m-2)Dry weight(kg m-2)

Ratio(fresh kg m-2/dry kg m-2)

Stouffville Weeklya 2.74±0.181c 0.59±0.0280d 4.65±0.348abBiweekly 2.91±0.104c 0.67±0.090bcd 4.50±0.491abTriweekly 3.94±0.201b 0.77±0.031c 5.10±0.107bCustomerb 3.64±0.454bc 0.77±0.103abcd 4.78±0.1.91bTipsc 4.61±0.224b 0.94±0.033ab 4.89±0.137bControld 5.60±0.147a 0.99±0.021a 5.64±0.084a

Simcoe Weekly 4.78±0.246a 0.58±0.042b 8.35±0.479aBiweekly 5.03±0.313a 0.62±0.066b 8.10±0.2079aTriweekly 5.48±0.507a 0.69±0.015b 7.91±0.469abCustomer 5.66±0.602a 0.74±0.040b 7.71±0.164aTips 5.48±0.433a 0.89±0.100ab 6.15±0.095cControl 5.58±0.361a 0.86±0.019a 6.50±0.297bc

Guelph Weekly 0.61±0.203a 0.14±0.043a 3.98±0.729abcBiweekly 0.64±0.068a 0.13±0.011a 4.83±0.313aTriweekly 0.92±0.384a 0.23±0.167a 4.14±0.244abCustomer 1.47±0.514a 0.42±0.274a 3.66±0.198bcTips 0.80±0.114a 0.24±0.085a 3.39±0.492abcControl 1.00±0.244a 0.39±0.265a 2.81±0.378c

Note: Means followed by the same lowercased italic letter within a site and column are not significantly different according to a Tukey’s multiple range test (α=0.05).a Weekly, Biweekly and Triweekly treatments were cut at 15 cm above ground level. b Customer treatment mimicked Afro-Caribbean preference by cutting larger stems near the base every other week.c Tips treatment mimicked European preference by cutting just the below the growing tip every other week.d Control treatment plants were not harvested until the final harvest date.

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