Developing production protocols and connecting producers to consumers of vegetable amaranth

Final report for GNE16-136

Project Type: Graduate Student
Funds awarded in 2016: $14,638.00
Projected End Date: 12/31/2017
Grant Recipient: University of Rhode Island
Region: Northeast
State: Rhode Island
Graduate Student:
Faculty Advisor:
Dr. Rebecca Brown
University of Rhode Island
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Project Information

Summary:

Farmers in the densely populated, ethnically diverse northeastern United States are uniquely positioned to diversify their production landscape and customer base through the addition of ethnic crops. This project focused on amaranth, a traditional leaf vegetable in many of the fastest-growing cultural communities in the northeastern United States. Amaranth is understudied for intensive production, especially in temperate climates. Because amaranth is a heat-loving C4 plant, preliminary production investigations in 2016 included assessing 10 varieties for suitability to the northeastern temperate climate, and using two varieties to investigate the benefit of microclimate modification through plasticulture production systems. Three production systems were selected for further research: 1) 0.8-mil clear slitted low tunnel over 1-mil embossed black plastic mulch, 2) 1-mil embossed black plastic mulch (with no crop cover), and 3) bare soil. Four varieties of A. tricolor (‘Green Pointed Leaf,’ ‘Miriah,’ ‘Red Callaloo,’ and ‘White Leaf’) that were strong performers and represented a range of appearances and growth habits were assessed in these three systems in 2017. Each variety was treated with targeted production and harvesting strategies, based on observed agronomic traits. Low tunnel yields were highest and bare soil yields lowest for all varieties, but the magnitude of production system effect varied between the varieties. These results demonstrate the value of variety-level information for growers making production decisions for unfamiliar crops.

In surveys of farmers’ market shoppers in Providence, RI, these same varieties were used to determine familiarity with and preference for visually disparate amaranth varieties among diverse customer groups. Over 75% of respondents were familiar with at least one variety, and preference was significantly associated with demographic response. The Broad Street Farmers’ Market was ideal for engaging with diverse customers who regularly purchase ethnic produce. However, extrapolation of these findings to a market with a different cultural composition is likely not appropriate. Because so many respondents were already familiar with amaranth, these results also provided little insight to preferences of customers who do not have pre-existing cultural associations with different types of amaranth. However, these findings indicate that identification of a target market should be foundational in amaranth variety selection.

Introduction:

Diversified cropping systems allow growers to reduce economic risk and environmental impact, which is especially important for small and beginning farms. By incorporating alternative crops, growers may also benefit from expansion into new markets (Fritz and Meyers, 2004). The market for traditional ethnic crops presents one such opportunity and is receiving increased attention as the United States population increases in cultural diversity (Ballenger and Blaylock, 2003). In 2015, recent immigrants and their U.S.-born family members comprised 27% of the U.S. population (U.S. Census Bureau, 2015). These shifting demographics represent an expanding market of consumers seeking their traditional produce and engender an expansion of the American “food repertoire,” which broadens the customer base for traditional ethnic foods (Ballenger and Blaylock, 2003).

Amaranth is a traditional leaf vegetable in over 50 countries, and this wide familiarity to regular buyers of ethnic produce could aid growers in connecting to new markets. Amaranth leaves are high in nutritional value, so consumers seeking increased variety of nutritious produce may present a secondary market. Although intensive production research is lacking, amaranth is regarded as easy to grow and resilient; if supported by regional production research, amaranth could also offer a low-maintenance addition to small farms seeking sustainability through diversified production.

Amaranth Marketing Potential

Ethnic crop marketing surveys in the northeastern United States have found that ethnic produce consumers are eager to buy more of their traditional produce locally. Respondents who were regular purchasers of ethnic produce tended to spend 40% – 80% more on produce overall than those who purchased traditional American produce. Ethnic produce consumers were also characterized by regularly purchasing produce at multiple types of markets and citing freshness and availability as important reasons for their shopping choices (Govindasamy et al., 2006). Amaranth leaves are featured in a range of traditional Asian, Latino, and African cuisines, and competition from imports is minimal. Post-harvest sensitivities to temperature and relative humidity make long-distance shipping challenging (Wheeler et al., 2015), and amaranth leaves are a strong candidate for fresh, direct to consumer sale.

In New England, the percentage of farms that engage in direct to consumer sales, and the proportional contribution of these sales to the total agriculture market, are roughly five times that of the United States as a whole (NASS, 2012). Customers in direct sale systems tend to value both variety and high nutritional value (Bond et al., 2009). Amaranth leaves are high in protein and essential micronutrient content (Achigan-Dako et al., 2014), and they have been rated comparably to spinach in sensory evaluations (Abbott and Campbell, 1982). These traits could be valuable in marketing amaranth to health-conscious consumers interested in novel substitutes for more common produce.

A clearly identified path to market influences the decision of farmers to incorporate crop diversification strategies (Lin, 2011) and holds special importance in consideration of ethnic crop production where crop and/or customer may be unfamiliar to growers (Govindasamy et al., 2006; Govindasamy et al., 2007). Amaranth’s wide use around the world is advantageous for farmers interested in connecting to the market for traditional ethnic crops. However, amaranth production and cooking methods can vary substantially with socio-cultural background (Achigan-Dako et al., 2014). Vegetable amaranth varieties comprise a wide range of appearances, and information is lacking on the cross-over appeal of vegetable amaranth varieties to different ethnic vegetable consumer groups. Target customer and intended use may even influence what are deemed desirable agronomic traits for amaranth (Achigan-Dako et al., 2014).

Amaranth Production

Existing amaranth production literature is relatively sparse and includes a wide range of varieties, belonging to at least seven distinct species, studied in varied climates. Recent regional studies include vegetable amaranth variety trials by Maynard (2013) in Connecticut, and field trials by Sciarappa et al. (2016) comparing amaranth yields in Florida, New Jersey and Massachusetts. Interestingly, Sciarappa et al. (2016) reported that yields from Florida and Massachusetts were not significantly different, while yields from New Jersey were significantly greater than both other locations.

Although amaranth species inhabit a wide range of latitudes, variety-level research is sparse on suitability for intensive production in temperate climates. Studies suggest that variety sensitivities to temperature, moisture, and photoperiod are varied (Campbell and Abbott, 1982; Wu et al., 2002), making regionally-focused production research particularly important. Furthermore, amaranth varieties are less developed than more common vegetables, so replication of regionally-focused research will also be beneficial.

Amaranth is a heat-loving C4 crop, and its culture will differ significantly from common spring and fall greens in the northeastern United States. Popular vegetable amaranth species thrive in temperatures up to 40 ºC (104 ºF), do not tolerate temperature below 15 ºC (59 ºF), and have substantially higher light saturation points than familiar greens like lettuce and spinach (Ebert et al., 2011). Regional ethnic crop production studies have found that many tropical and sub-tropical crops are easily produced in the northeastern temperate climate, and the advantages of engagement with a favorable market can outweigh production challenges (Mangan et al., 2008; Sciarappa et al., 2016).

Plasticulture systems, including plastic mulches, drip irrigation, and plastic crop covers, are often used to enhance the yields of warm-weather crops in temperate climates. Given amaranth’s affinity for high heat, it is likely that plasticulture production would be of some benefit in the northeastern temperate climate. Studies have reported successful amaranth production with black plastic mulch and drip irrigation, but production system comparison was not the focus of these studies (Meyers et al., 2001; Sciarappa, 2016). The use of crop covers has not been investigated.

There is substantial room for variation in plasticulture system design. Target crops, production area, and markets should be the deciding factors in plasticulture design decisions (Wells and Loy, 1993). Because alternative crops like amaranth may have unfamiliar or unestablished environmental requirements and marketing chains, the trade-offs associated with various production systems warrant special consideration.

Each structural and material combination results in varying levels of protection, microclimate effect, permanence, accessibility, and cost. For crop covers, low tunnels (row covers) and high tunnels represent the spectrum of these considerations. The evolution of low tunnel technologies includes early designs that provided maximum night-time frost protection but required daily manual ventilation. With the development of breathable cover materials that could be left on throughout the day, labor costs associated with manual ventilation were reduced. However, these materials also reduced light transmission (Wells and Loy, 1985a; Wells and Loy, 1985b; Wells and Loy, 1993). Because amaranth has a high light saturation point, reduced light transmission would limit amaranth’s photosynthetic capacity. Clear slitted plastic combines high light transmission and self-ventilation. Although these covers provide minimal night-time frost protection, they may be left in place throughout the day, providing accelerated accumulation of heat units over time. Heat unit accumulation, often measured in cumulative growing degree days (GDD), is directly linked to growth for many warm-weather crops. Low tunnels perform this function so effectively that excessively high temperatures within tunnels becomes a concern for many crops in high ambient temperatures (Wells and Loy, 1985a; Wells and Loy, 1985b; Wells and Loy, 1993). However, given its temperature requirements, this is likely not a concern for amaranth in temperate climates like southern New England.

The required low tunnel materials are relatively inexpensive, but it is difficult to reuse plastic without compromising light transmission or structural integrity. Any crop maintenance beyond irrigation and fertigation requires removal of low tunnel plastic, which interrupts heat unit accumulation. A low initial investment is tempered over time by repeated material cost, as well as the corresponding labor cost of tunnel construction and removal (Waterer, 2003). Amaranth’s relatively short time to harvest would magnify these labor costs.

High tunnels, in contrast, typically use 4- to 6-mil plastic that can be used for multiple seasons. Although high tunnel designs vary, most allow effortless access to crops for maintenance or harvest. Although high tunnels require a greater initial investment, expenditures can be reliably recovered when growing high value crops (Carey et al., 2009; Lamont, Jr., 2009). The NRCS Environmental Quality Incentives Program (EQIP) also provides financial support for the implementation of conservation practices, including high tunnels (NRCS, 2017). Regardless of financial assistance, however, high tunnels are valuable resources that should be used to maximum effectiveness. High tunnels are often used strategically to take advantage of early- and late-season pricing for high value crops (Carey et al., 2009); this is not currently feasible with vegetable amaranth because neither market chains nor pricing are well established.

Formation of Objectives

The goal of this project was to support growers interested in vegetable amaranth production with regionally-focused, variety-specific information on production and marketing of vegetable amaranth. We began investigating varieties and production systems in 2016. We evaluated yield stability and agronomic traits of 10 varieties throughout the season. In these trials, low planting densities and long growth periods allowed extended investigation of variety potential. Production and harvesting strategies were standardized for ease of comparison. In reality, however, varieties with disparate traits would benefit from targeted production strategies.

In a separate trial, two of the 10 varieties were evaluated in the following production systems: 1) A gothic-style high tunnel represented the greatest initial investment. Acknowledging that amaranth monoculture is not the most profitable use of these structures, amaranth was grown alongside tomatoes, which are one of the most common high tunnel crops (Carey et al., 2009). The temperature requirements of tomatoes, rather than amaranth, guided ventilation of the high tunnel. This treatment was designed to evaluate amaranth as a realistic addition to existing high tunnel production. 2) Low tunnel in combination with black plastic mulch was selected as a treatment to provide maximum heat. 3) Black plastic mulch (with no crop cover) was chosen to represent the most basic plasticulture production system. 4) Bare soil production was also evaluated.

Results of the production system comparison clearly indicated that low tunnels with black plastic mulch would produce the greatest yields. However, the difference in yields between the production systems decreased as ambient temperatures rose throughout the season. The benefit of low tunnels plateaued as yields from the three other production systems increased throughout the season. The cost-benefit analysis of these systems will depend on timing and climate, existing supplies and production strategies, and the market price for amaranth. Furthermore, the range of growth habits and yield responses we observed in the variety trials indicated that the magnitude of response to these production systems could vary substantially for different amaranth varieties.

This SARE project was designed to expand on these preliminary projects and address their limitations. The results of this project will aid growers in developing an amaranth production and marketing plan that considers existing production strategies, production timing and climate, and target customer base.

 

Project Objectives:

The objectives of this project were:

  1. Perform study on demand for vegetable amaranth at Rhode Island farmers’ market; investigate appeal of varieties with varied appearances, both overall and for particular customer groups.
  2. Develop intensive production protocols for vegetable amaranth in the northeastern temperate climate, using promising varieties and production systems from preliminary research.
  3. Share new information with farmers that will allow them to make informed amaranth variety selection and production decisions, based on desired production strategies and target markets.

Cooperators

Click linked name(s) to expand
  • Dr. Rebecca Brown

Research

Materials and methods:

Two projects were completed in 2016 that informed the materials and methods for this project:

Preliminary Project #1 – Variety Trials:

Over seven plantings, 10 vegetable amaranth varieties were evaluated for suitability in the northeastern temperate climate. Eight of the varieties were A. tricolor, the most popular and widely available vegetable amaranth species. A. tricolor varieties were ‘Asia Red,’ ‘Green Pointed Leaf,’ ‘Red Stripe Leaf,’ ‘Southern Red,’ (Evergreen Seeds, Anaheim, CA), ‘Red Garnet,’ ‘White Leaf’ (Kitazawa Seed Co., Oakland, CA), ‘Miriah,’ and ‘Red Callaloo’ (Baker Creek Heirloom Seed Co., Mansfield, MO). ‘Green Callaloo’ (Baker Creek Heirloom Seed Co., Mansfield, MO) is a variety of A. viridis. ‘Mchicha’ is a variety of A. hybrids provided by members of the African Alliance of Rhode Island (AARI). Varieties were selected to represent a range of growth habits and visual traits.

All plant material was started from seed in the greenhouse and transplanted to raised beds covered with black plastic mulch under 0.8-mil clear slitted low tunnels. Beds were fertilized with organic 5N-1.3P-3.3K fertilizer (Pro-Gro 5-3-4; North Country Organics, Bradford, VT) at 50 lb/acre of N at the time of bed preparation and drip-irrigated as needed.

Each experimental plot contained 10 plants in two rows, with 12-inch spacing between and within rows. Plots were arranged in a randomized complete block design with four replications. Plants were harvested by cutting directly above the soil surface; harvest readiness was defined by flower bud formation, similar to methods used in vegetable amaranth varieties by Campbell and Abbott (1982). Air temperatures within low tunnels were recorded every 4 hours by temperature sensors (iButton; ThermoChron, Lawrenceburg, KY) at 25 cm above the soil surface.

Yield per plot, biomass leaf to stem ratio, and coefficients of variation (CV) for yield were recorded. The ANOVA functions in R (version 3.2.3; R Core Team, Vienna Austria) were used to determine the effects and interactions of variety and planting date on both yield and leaf to stem ratio. Tukey’s HSD test was used for means separation. All tests were performed at the P < 0.05 significance level.

Preliminary Project #2: Production Methods Investigation

Two varieties of A. tricolor, ‘Green Pointed Leaf’ and ‘Red Stripe Leaf’ (Evergreen Seeds, Anaheim, CA), were used throughout the experiment, which included three plantings over the 2016 growing season. Response was evaluated in four production systems:

  • High tunnel: The gothic-style high tunnel was covered in a double, inflated layer of 6-mil 4-year Tufflite IV greenhouse plastic (Berry Plastics Corp., Evansville, IN). Following ventilation procedures for tomatoes, which were also growing in the high tunnel, an automated vent at the top of the tunnel (Nolt’s Produce Supplies, Leola, PA) was set to open at 90 ºF; ventilation was also provided by rolling up the sides of the high tunnels to the sidewall height of 4 ft.
  • Low tunnel: Raised beds were covered in 1-mil embossed black plastic mulch; low tunnels were constructed immediately after transplant, using clear slitted 0.8-mil plastic and galvanized metal hoops.
  • Black plastic mulch (no crop cover): Raised beds were covered in 1-mil embossed black plastic mulch.
  • Bare soil: Plants were transplanted directly into tilled soil.

All plots were fertilized with organic 5N-1.3P-3.3K fertilizer (Pro-Gro 5-3-4; North Country Organics, Bradford, VT) at 50 lb/acre of N at the time of bed preparation and drip-irrigated as needed. The production systems were main plot factors in a split-plot design with four replications. Full randomization of the production systems was not possible because pre-constructed high tunnels were used. The varieties were subplot factors and were randomized within each main plot. Each experimental plot contained 10 plants. Air and soil temperature data were logged every 4 hours using temperature sensors (iButton; Thermochron, Lawrenceburg, KY) placed 25 cm (9.8 inches) above the soil surface and 10 cm (3.9 inches) below the soil surface.  

Plants were harvested 25-26 days after transplanting, by cutting the stem directly above the soil surface. Yield per plot and biomass leaf to stem ratio were recorded. stems and leaves of a random two-plant subsample were separated and dried to calculate a biomass leaf to stem ratio, which we expressed as leaf-percentage of total dry weight. The ANOVA functions in R (version 3.2.3; R Core Team, Vienna Austria) were used to determine the effects and interactions of production system and variety on both yield and leaf to stem ratio. Fisher’s LSD test was used for means separation. All tests were performed at the P < 0.05 significance level. Pearson’s test of correlation was used to examine the following relationships: yield and leaf to stem ratio; yield and cumulative air GDD; yield and cumulative soil GDD.

Varieties

Four varieties from the 10 previously tested were included in continued production research, as well as farmers’ market surveys. In addition to yield performance in 2016, varieties were selected to represent the range of appearances, growth habits, and agronomic traits observed in the 10 varieties previously tested.

  • ‘Miriah’ (Baker Creek Heirloom Seed Co., Mansfield, MO) was the highest yielding variety overall in 2016 and produced stable yields throughout the growing season (CV = 22%). ‘Miriah’ is a moderately branched variety with variegated red and green leaves (Image 1).
  • ‘Green Pointed Leaf’ (Evergreen Seeds, Anaheim, CA) was the second highest yielding variety overall in variety trials conducted in 2016. Yield CV of 30% indicated less stable yields, though this calculation was affected by notably high yields in early- and late-season plantings; yields were not significantly different from top yielding varieties in any 2016 planting. ‘Green Pointed Leaf’ is a moderately branched variety with slender, green leaves (Image 2).
  • ‘Red Callaloo’ (Baker Creek Heirloom Seed Co., Mansfield, MO) produced the second-lowest yields in the 2016 variety trials, but yields were not significantly different from highest yielding varieties in the second, third, and fourth planting. ‘Red Callaloo’ is a tall variety and a vigorous early grower, compared to most other varieties tested. This variety exhibited minimal branching in 2016. In addition to representing visually similar varieties in the farmers’ market study, this variety was selected to investigate whether targeted production and harvesting strategies could positively affect leaf to stem ratio and branching (Image 3).
  • ‘White Leaf’ (Kitazawa Seed Co., Oakland, CA) is a dwarf variety that produced very stable yields in 2016. Although ‘White Leaf’ yields were third lowest overall, CV for yield was the lowest of all varieties tested (21%) and leaf to stem ratio was the highest of all varieties tested (82%). ‘White Leaf’ is not a vigorous early grower and has light green, rounded leaves and a dense, bushy growth habit (Image 4).

         

Farmers Market Study

Surveys were conducted at the Broad Street Farmers’ Market (807 S. Broad St.) in Providence, RI in July and August 2017. These methods were adjusted from the originally proposed methods for achieving Objective #1, which included conducting surveys at multiple farmers’ markets around Rhode Island. The number of survey locations was reduced to decrease statistical noise and increase the likelihood of obtaining useful results with a realistic number of survey respondents. The complexity and length of surveys was also reduced in an attempt to minimize language barriers and time commitments for customers at the diverse, bustling market. 

At the market, the four vegetable amaranth varieties were displayed and referenced by letters A through D. Survey respondents were asked to indicate:

  • Which, if any, of these varieties they were familiar with (i.e., had eaten, purchased, or seen for sale).
    • If familiarity was indicated, by what name they knew any or all of the varieties.
  • Which variety they preferred (i.e., would be most likely to purchase).
  • How frequently they bought produce at farmers’ markets (in season).
  • Their cultural or geographic origin or identity; respondents were given an opportunity to provide additional or clarifying information if desired.

A chi-square test for independence was performed in R (version 3.2.3; R Core Team, Vienna Austria) to determine the likelihood of a relationship between variety preference and demographic response. U.S. Census Tract data was used to examine whether survey respondents were representative of the community surrounding the market. Broad Street Farmers’ Market (marked in map below) lies near the border of four Census Tracts from which data was pooled to estimate community demographics (U.S. Census Bureau, 2010).

Production Research Site

The production research funded by Northeast SARE was conducted during the 2017 growing season at the University of Rhode Island Greene H. Gardener Agricultural Experiment Station in Kingston, RI (lat. 41º28’50’N). The soil type is Bridgehampton silt loam with a 0% to 3% slope. Average daily temperatures in Kingston from June to September range from 64 ºF to 72 ºF; average minimum temperatures are 52 ºF to 60 ºF; and average maximum temperatures are 76 ºF to 83 ºF. In 2017, the average temperatures for June, July, and August were within 1ºF of historical averages; the average temperature in September was 2.8 ºF above the historical average. These months received 12.2 inches of precipitation in 2017, compared to the historical average of 16.5 inches.

Production Systems

All plant material was started from seed in the greenhouse. No supplemental light was used, and greenhouse set points were 70 ºF (night) and 74 ºF (day). The greenhouse was cooled passively by ventilation, and high temperatures were regularly above the set point. Seeds were planted into 50-cell trays (cell volume 6.77 inch3) using a soilless growing medium (Metro-Mix 830; Sun Gro, Agawam, MA) covered with a thin layer of vermiculite. Varieties were seeded every three weeks for a total of three plantings over the growing season.

Three production systems were selected from the four previously tested: low tunnel with black plastic mulch, black plastic mulch with no crop cover, and bare soil. In 2016, high tunnel yields (requiring the greatest initial investment) were most similar to bare soil yields (requiring the least initial investment). Given these results, high tunnels were not included in this study.

Low tunnels were constructed over raised beds covered in 1-mil embossed black plastic mulch. Galvanized metal hoops with a center height of 3 ft were placed 5 ft apart and covered with 0.8-mil clear slitted plastic. Plastic was laid over hoops and staked down at the ends and along the sides of each tunnel, and a second set of hoops was driven into the ground over the plastic. Black plastic mulch plots were raised beds covered in 1-mil embossed black plastic mulch. In bare soil plots, plants were transplanted directly into tilled soil.

All plots were irrigated as needed, using drip tape with 12-inch emitter spacing (Aqua Traxx, Bloomingston, MN). Based on soil test results and findings that amaranth responds well to organic forms of N (AdeOluwa et al., 2009; Edomwonyi and Opeyemi, 2009; Makinde, 2015), plots were fertilized with organic 5N-1.3P-3.3K fertilizer (Pro-Gro 5-3-4; North Country Organics, Bradford, VT) at 50 lb/acre of N at the time of bed preparation. After first harvest, plots were side-dressed using 15N-0P-0K fertilizer (Jack’s Professional 15-0-0; J.R. Peters, Inc., Allentown, PA) at a rate of 25 lb/acre of N. Vegetable amaranth fertility studies have reported a positive yield response to N application rates up to 135 kg·ha-1 (120.4 lb/acre) (Singh and Whitehead, 1996), but Onyango et al. (2012) found the positive response began to plateau at 20 kg·ha-1 (17.8 lb/acre) of N. The conservative rate of N application used for this study reflects a desire to minimize nitrate accumulation and leaching losses. 

In all treatments, two rows of plants were spaced 10 inches apart in 30-inch-wide, north-south oriented beds. Each plot contained five plants; plots were arranged in a randomized complete block design with five replications. Within rows, ‘Miriah’ and ‘Green Pointed Leaf’ plants were spaced 12 inches; ‘Red Callaloo’ plants were spaced 10 inches; and ‘White Leaf’ plants were spaced 8 inches.

Harvest

In our preliminary production methods study, harvest was based on calendar days. Our results indicated that yield was closely linked to cumulative GDD, and this method highlighted the effects of the production systems. However, it did little to illuminate the trade-offs to consider with each system. In this study, harvest dates were based on standardizing cumulative GDD calculated from recorded air temperatures across the three production systems (i.e., low tunnel plots were harvested first and cumulative air GDD calculated; black plastic and bare soil plots were harvested when a similar number of air GDD had accumulated). Information gleaned from this system can begin to address the practical questions involved in making production decisions for amaranth. For instance, this system can be used to estimate the amount of time required to produce similar yields in each production system (and how that changes throughout the growing season), or to determine the effect of increased soil temperatures if air temperature remains constant.

Based on traits observed in preliminary research, we developed a schedule for a first and second harvest for each variety, based on cumulative air GDD (Table 1). When black plastic and bare soil plots were harvested for the second time, low tunnel plots were harvested a third time to compare cumulative yields for the same number of calendar days. The target air GDD for each variety, and the actual air GDD and soil GDD (average of three plantings) for each production system and variety at final harvest shown in Table 1. Production dates are shown in Table 2. A summary of harvest methods used for each variety is listed in Table 3.

Table 1. Target cumulative GDD (Tbase = 50 ºF) for four vegetable amaranth varieties and average of actual cumulative GDD at final harvest of three plantings in 2017. *When black plastic and bare soil plots were harvested for the second time, low tunnel plots were harvested a third time.

  Variety   Target GDD (air) Avg. recorded GDD at final harvest
Low tunnel* Black plastic Bare soil
First harvest Second harvest Air Soil Air Soil Air Soil
Green Pointed Leaf 600 225 1,012 997 842 872 823 779
Miriah 600 225 1,012 997 842 872 823 779
Red Callaloo 500 500 1,158 1,168 993 1,046 974 926
White Leaf 675 300 1,149 1,132 958 1,011 941 896

 

Table 2. Production dates for vegetable amaranth varieties based on target air GDD.

 

Action

 

Planting No.

Transplant

Final harvest

(Third low tunnel  harvest; second black plastic and bare soil harvest)

Variety

1

14 June

20 July

Green Pointed Leaf

 

 

20 July

Miriah

 

 

29 July

Red Callaloo

 

 

27 July

White Leaf

2

5 July

11 Aug

Green Pointed Leaf

 

 

11 Aug

Miriah

 

 

18 Aug

Red Callaloo

 

 

16 Aug

White Leaf

3

26 July

6 Sep

Green Pointed Leaf

 

 

6 Sep

Miriah

 

 

8 Sep

Red Callaloo

 

 

12 Sep

White Leaf

 

Table 3.Harvest methods used for vegetable amaranth varieties.
Variety  Method
First harvest Second and third harvest
Green Pointed Leaf Cut central stem 6-7 inches from soil surface. Cut axillary shoots 5-6 inches from central stem.
Miriah Cut central stem 6-7 inches from soil surface. Cut axillary shoots 5-6 inches from central stem.
Red Callaloo

* Pinch tops early (~1 week after transplant) to encourage axillary growth (Figure 4).

“Top” central stem, leaving no less than 3 developing axillary shoots.

Cut axillary shoots and regrowth, leaving no less than 3 leaf nodes on each.
White Leaf Cut central stem 5-6 inches from soil surface. Cut axillary shoots 4-5 inches from central stem.

Production Data Collection and Analysis

Air and soil temperatures were recorded every 4 hours by waterproof temperature sensors (RC-51; Elitech Technology, Logan, UT). Air temperature sensors were located 25 cm (9.8 inches) above the soil surface, approximating mature canopy height; soil temperature sensors were located 10 cm (3.9 inches) below the soil surface. Yield per plot was recorded by weighing all plants from a plot at each harvest, and cumulative yields were calculated. Stems and leaves of a random two-plant sub-sample were separated and dried at 110 ºF until they reached a constant weight. Dried leaf and stem weights were used to calculate a biomass leaf to stem ratio, which we expressed as the leaf-percentage of total dry weight. Leaf to stem ratio was not recorded for the third harvest of low tunnel plots.

For each variety, the analysis of variance functions (ANOVA) in R (version 3.2.3; R Core Team, Vienna Austria) were used to test for effects and interactions of production system and planting date on both yield and leaf to stem ratio. Fisher’s least significant difference (LSD) test was used for means separation. All tests were performed at P < 0.05 significance level.

Research results and discussion:

Farmers’ Market Study

Consumer Preferences

The relationship between demographic response and vegetable amaranth variety preference was significant (χ2,N = 78, P < 0.001) (Table 4). It is important to note that respondents were asked which variety they preferred or would be most likely to purchase. Although respondents could indicate they were not likely to purchase any of the varieties, predictive modeling of demand would depend on other factors, such as pricing, that respondents were not asked to consider here. Nonetheless, a significant association of demographic response and preference is a useful starting point for further investigation.

The assumption that familiarity would be related to preference is inherent in the hypothesis that consumer preference would be linked to cultural background. Many respondents were familiar with more than one variety. However, 69% of respondents indicated preference for a variety with which they were already familiar; respondents who indicated they were not familiar with, nor likely to purchase any of the varieties are included in this calculation. The remaining 31%, those who indicated preference for a variety with which they were not familiar, include 16 respondents who were not previously familiar with any variety. Excluding those 16 respondents, only eight respondents (10%) were previously familiar with at least one variety and indicated preference for a previously unfamiliar variety.

The very low stated preference for ‘White Leaf’ is notable. However, ‘White Leaf’ was also the variety with which respondents were the least familiar overall (Table 5). Of those that indicated no familiarity with any variety, six respondents each indicated a preference for ‘Miriah’ and ‘Red Callaloo;’ four preferred ‘Green Pointed Leaf;’ one preferred ‘White Leaf;’ and two respondents indicated they were not likely to buy any of the varieties. Because over 75% of respondents were familiar with at least one variety, conclusions about customers who are brand new to amaranth cannot be drawn from the small pool of remaining respondents.

Table 4. Responses to preferred variety (i.e., which would you be most likely to purchase) by demographic response.

 

 

No. Respondents indicating each variety as preferred

 

Regional/cultural response

Green Pointed Leaf

Miriah

Red Callaloo

White Leaf 

None 

Total

Africa

13

13

2

0

28

Asia

12

3

6

0

3

24

Latin America

2

7

8

0

17

United States

1

2

3

2

9

 Total

 28

 25

 19

 2

 4

78

 

Table 5. Responses to familiarity with varieties (i.e., had purchased, eaten, or seen for sale before). Because respondents could indicate familiarity with more than one variety, total responses exceed the actual number of respondents.

 

Green Pointed Leaf

Miriah

Red Callaloo

White Leaf

None

Africa

26

25

12

7

0

Asia

16

15

13

3

5

Latin America

6

9

4

0

8

United States

3

2

2

1

6

Total

51

51

31

11

19

Demographics

Although more categories were originally considered for demographic response, the responses we received fit neatly into the regions listed in Table 4 (categories with zero responses are not shown). Almost all survey respondents provided clarifying information for their demographic response, which are listed by region in Table 6. These detailed responses were highly useful in this study, but they are not the same categories for ethnicity and race used in Census Tract data, making direct comparison to community demographics challenging (Table 7). When asked how frequently they bought produce at farmers’ markets (in season), 53% responded at least once per week; another 41% indicated two to three times per month. So, it is possible that respondents reflect a subset of the community with which growers would be most likely to engage.

The significant relationship between demographic response and variety preference is a useful finding that can be employed in targeted production and marketing strategies by growers. However, it also means that the overall preferences at this market cannot necessarily be generalized to a population with a different cultural composition. These results reveal the importance of identifying and understanding a target market for amaranth. If grown for a particular community or ethnic group, the preferences of that group should be the first factor considered in variety selection, which will then influence production strategies.

Table 6. Clarifying information provided by respondents, organized by regions used in analysis.

Region

Response

No. respondents

Africa

Burundi

4

 

Congo

7

 

Liberia

11

 

Nigeria

4

 

 

 

Asia

Cambodia

3

 

Hmong

2

 

India

3

 

Laos

9

 

Nepal

7

 

 

 

Latin America

Dominican Republic

4

 

El Salvador

2

 

Guatemala

6

 

Mexico

4

 

 

 

United States

African American

2

 

New York

1

 

Providence

6

 

Table 7. Combined race and ethnicity data from the four Census Tracts surrounding Broad Street Farmers’ Market (Image 5).

Race reported in Census Tracts

Portion of population

White

19%

African American       

22%

Asian  

5%

American Indian or Alaskan Native   

2%

Native Hawaiian or Pacific Islander  

10%

Some other race

26%

Two or more races    

16%

 

 

Ethnicity reported in Census Tracts   

 

Hispanic or Latino

74%

Not Hispanic or Latino

26%

Production Systems

‘Green Pointed Leaf’ and ‘Miriah’

There was a significant interaction of planting date and production system for ‘Green Pointed Leaf’ yield (P = 0.003) and ‘Miriah’ yield (P = 0.007). Consequently, production systems were analyzed separately for each planting date. The rankings of production system yields remained constant for both varieties, but the magnitude of effect changed throughout the season (Figure 1; Figure 2).

Recommendations:

In our previous studies and trials conducted by Maynard (2013), these and closely-related varieties have been high-yielding in both bare soil and plasticulture systems. Varying harvest methodologies have also been used with success. The production and harvesting guidelines listed in Table 1 and Table 2 can be used as a guide, but these varieties appear to be versatile, strong performers. If these moderately branched varieties are harvested at the central stem, axillary shoots will provide long-lasting growth sufficient for multiple additional harvests. Delayed harvesting of axillary shoots leads to stem elongation and a decreased leaf to stem ratio.

Figure 1. ‘Green Pointed Leaf’ yields from three plantings.
Figure 2. ‘Miriah’ yields from three plantings.

‘Red Callaloo’

There was no significant interaction of production system and planting date for ‘Red Callaloo’ yield, so yields from three plantings were pooled for analyses. Low tunnel and black plastic yields were not significantly different. Due to variations in harvest methodology, we are unable to compare leaf to stem ratios to those from 2016. However, our observations indicate that the methods used here, including an early first harvest to encourage low branching from the central stem (Table 1; Table 2), will be highly beneficial.

Based on our knowledge of ‘Red Callaloo’ from 2016, we predicted that early and repeated harvest would improve ‘Red Callaloo’ performance; this season’s methods were developed through testing in a small side plot, where we compared branch and leaf number for plants that had been pinched one week after transplant to those that had not. The results demonstrate the predicted response pattern (Figure 4).

Recommendations:

Low tunnels are not recommended for ‘Red Callaloo.’ Regardless of differentials in physiological response to increased temperatures, the earlier low tunnels are removed for harvest, the less benefit they will provide. While this is certainly a factor in these results, adaptation of the harvest schedule for ‘Red Callaloo’ provided substantial benefits from a product quality perspective. In 2016, ‘Red Callaloo’ yields were often negatively affected by central stems breaking in high winds; this issue was also reduced.

The average difference between bare soil and black plastic yields was 0.40 lb/plot (five plants/plot). If grown at a large scale, these yield differences could be felt by farmers. However, amaranth is not typically grown at a large scale, currently, and the value of these yield differentials will depend upon material costs and amaranth pricing. Stand establishment is an issue for many types of amaranth, but ‘Red Callaloo’ is one of the most vigorous early growers. If existing production strategies prohibit the use of black plastic mulch, ‘Red Callaloo’ is the most appropriate choice of the varieties presented here for bare soil production.

Figure 3. Pooled ‘Red Callaloo’ yields from three plantings.
Figure 4. Effect of pinching one week after transplant on branch and leaf number of ‘Red Callaloo’ plants.

‘White Leaf’

There was no significant interaction of production system and planting date for ‘White Leaf’ yield. Yields from three plantings were pooled for analyses, and yields from all three production systems were significantly different. 

Recommendations:

‘White Leaf’ is one of the least vigorous early growers, and the differences in yield for a plot of 5 plants would produce a substantial economic impact (Figure 5). Some form of microclimate modification is recommended for growing ‘White Leaf’ in the northeastern temperate climate. If low tunnels are a viable option, given existing production strategies, ‘White Leaf’ is a good candidate from a production perspective for multiple reasons. ‘White Leaf’ requires the longest initial growth period (Table 1), so low tunnels can be left in place longer, increasing their effect and reducing the frequency of labor input. Because ‘White Leaf’ is a dwarf variety, it also will not outgrow low tunnels.

Figure 5. Effect of production system on pooled ‘White Leaf’ yields from three plantings.
Research conclusions:

Amaranth is a promising alternative crop for growers in the northeastern region. However, the results of these studies indicate that individualized production and marketing strategies, which are lacking in existing literature, are warranted for different types of amaranth. All vegetable amaranths will have some traits in common. Broadly, it is true that all the varieties tested in 2016 and 2017 produced increased yields under low tunnels. However, this season’s results showed that the magnitude of the benefit is not the same for all varieties. Because our findings indicate that consumer preference for amaranth varieties is not universal, we recommend identifying a target market before developing production strategies. The effect of production system was also variable throughout the season for some varieties, which should not be overlooked. For ‘Green Pointed Leaf,’ black plastic yields from the second planting were similar to low tunnel yields from the first planting. Once a target market is established, growers can assess the value of earlier yields (or the cost of delayed yields) for that market in evaluating a production system. Beyond the yield responses shown in these studies, the fitness of an amaranth production system will depend on existing supplies and production strategies for each grower. The focused production and marketing information from these studies will support the economic sustainability of northeastern growers by aiding in accurate assessment of production systems and efficient connection to markets. The wide familiarity indicated by diverse survey respondents is promising for marketing amaranth to traditional ethnic produce consumers. However, the question of marketability to customers who are yet unfamiliar with amaranth remains unclear.

 

Participation Summary

Education & Outreach Activities and Participation Summary

3 Consultations
1 Online trainings
1 Published press articles, newsletters
3 Webinars / talks / presentations
1 Workshop field days

Participation Summary

2 Farmers
20 Number of agricultural educator or service providers reached through education and outreach activities
Education/outreach description:

Completed Outreach activities

The numbers above are based on estimates of attendance at talks and other in-person contacts. Estimates of interaction with online/published materials are given below.

Consultations:

  1. Based on findings from research in 2016, I provided guidance around amaranth variety selection and plant spacings to one URI Cooperative Extension Agent, who was including amaranth in a season extension-focused research project for multiple ethnic crops. I provided similar information for one URI faculty member in the Department of Plant Sciences and Entomology, who was including amaranth in research trials focused on intensive polyculture production of ethnic crops in urban settings.
  2. While conducting farmers’ market research, I consulted with 2 residents of Providence, RI, originally from Nigeria, who were interested in growing amaranth or a similar green, celosia, in an urban community plot; I visited the plot and discussed challenges and strategies for growing their native crops in southern New England (August 2017).

Online Training/Field Day:

  1. Produced Virtual Field Day Video, recorded from the RI Agricultural Experiment Station that was shared with URI faculty and Cooperative Extension personnel (summer 2017); video is currently on URI Cooperative Extension YouTube channel. The URI Youtube channel has over 2,600 followers.

Virtual Field Day – URI Cooperative Extension YouTube

Published

  1. Abstract from oral presentation at ASHS Annual Conference published as supplement to HortScience Volume 52(9). “A Taste of Home: Growing Amaranth in New England” (September 2017).

Webinars, Talks, Oral Presentations

  1. Oral presentation of research to students and faculty in seminar attended by ~20 students and faculty from the Sustainable Agriculture and Food Systems interdisciplinary specialization at URI (Spring 2017).
  2. Thesis defense oral presentation at URI, attended by 4 URI faculty and 5 students (July 2017).
  3. Open access publication of master’s thesis (August 2017). http://digitalcommons.uri.edu/cgi/viewcontent.cgi?article=2073&context=theses    Downloaded 55 times by readers in nine countries; majority of downloads from educational institutions.
  4. Oral presentation at American Society for Horticulture Science annual conference in Waikoloa, HI; “A Taste of Home: Growing Amaranth in New England;” ~20 attendees (September 2017).

Outreach activities in progress:

  1. Manuscript conditionally accepted to HortTechnologyVegetable amaranths for summer greens production in the northeastern United States” (November 2017).
  2. A second manuscript based on production and marketing for amaranth is being prepared for submission to HortTechnology.

Project Outcomes

1 Grant applied for that built upon this project
1 Grant received that built upon this project
$500.00 Dollar amount of grant received that built upon this project
Project outcomes:

By nature, the production and marketing of alternative crops cannot be taken for granted, so focused research is important to the success of growers. The potential benefits of incorporating new crops include increased diversity and niche market access, both of which contribute to resilience and mitigate risk. This project, specifically, involves connecting to the market for traditional ethnic crops. This market has been characterized as underserved and promising for growers in the northeastern region (Govindasamy et al., 2006; Mangan et al., 2008). Engaging with diverse communities is also beneficial from a social perspective, and these communities may have valuable insights on crop production and marketing.

No additional research grants have been received as a result of this project. The grant indicated above was for travel to the American Society for Horticultural Science conference to share the results of this project. While farmer adoption of the techniques and recommendations provided by this project was not measured, farmers can access the results of this project in a variety of forms (listed in Education and Outreach). I worked closely with both URI Cooperative Extension and faculty throughout this project; both groups have ongoing projects focused on traditional ethnic crops, which will increase the impact of this project.

Knowledge Gained:

The goal of assessing production systems was a beneficial and challenging exercise in identifying the numerous factors involved in decision-making for growers. Through this exercise, I developed a solutions-based understanding of sustainability, in which the balance of environmental, social, and economic considerations may vary by farm, community, region, or season. While this relativity complicates decision-making, I think this attitude is necessary for producing responsive, flexible progress in sustainable agriculture and food systems. My professional goals reflect this attitude; by working in Cooperative Extension, I hope to apply research-based information in developing local solutions to farming and food systems challenges.

Assessment of Project Approach and Areas of Further Study:

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Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.