Specialty Pumpkin: Laying the Groundwork for an Emerging Crop and Lucrative Products

Progress report for LS21-360

Project Type: Research and Education
Funds awarded in 2021: $399,999.00
Projected End Date: 03/31/2023
Grant Recipients: University of Florida; University of Puerto Rico ; University of Georgia
Region: Southern
State: Florida
Principal Investigator:
Dr. Geoffrey Meru
University of Florida
Co-Investigators:
Dr. Carlene Chase
University of Florida
Dr. Andre da Silva
University of Georgia
Dr. Andrew MacIntosh
University of Florida
Dr. Angela Ramírez
University of Puerto Rico
Dr. Jorge Ruiz-Menjivar
University of Florida
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Project Information

Abstract:

Specialty pumpkins such as the tropical pumpkin or calabaza (Cucurbita moschata) fulfill lucrative emerging markets for the crop in the U.S. The desirable characteristics of the fruit include high soluble solids for the brewing industry; deep orange/non-stringy flesh for canning/ novel food-ingredient; and a favorable combination of flavor, fruit size, flesh texture/color for the fresh-cut market. Additionally, quality seeds are required by the snack food industry, and for pumpkin seed butter, which are non-allergenic and nutritious alternatives to nuts and nut butters. Organically grown produce is a priority for many restaurants, community supported agriculture, and for baby food. Optimized organic and conventional cropping systems will be needed to maximize profitability for growers supporting these industries. We propose a two-year, multi-institutional, transdisciplinary, regional project with University of Florida as the lead institution, in collaboration with University of Puerto Rico and University of Georgia. Our systematic approach includes Social Science research that will engage growers, industry stakeholders, and consumers to assess potential risks and benefits of specialty pumpkin production, as well as barriers to acceptance. Our breeders will provide germplasm that will be evaluated in Florida, Georgia, and Puerto Rico to select those most suitable for release as cultivars for organic and conventional systems. The suitability of the germplasm for food applications will be addressed by our food scientists who will also examine the functional attributes of the fruit and processed products. Additionally, our horticulturists will assess germplasm suitability for a conservation tillage, organic system based on summer cowpea and winter rye cover crops grown in sequence. This system will offer a sustainable, no plastic mulch approach that has the potential to suppress weeds and plant-pathogenic nematodes while improving soil health and soil fertility. We will monitor for pest and beneficial arthropods in all cropping systems to garner information that allows for the development of cultural and biological control tactics for arthropod pest management. We will conduct a thorough study of the potential acceptance of specialty pumpkin with key players in the production system from farm to consumer. This will include interviews with farmers and operators of sales points conducted through video conferencing. We will also conduct a nationwide consumer acceptance study. These three components will allow us to identify and address barriers to acceptance and take advantage of opportunities to build demand. Farmer engagement throughout the project is an important component of this project. We will work with growers to conduct on-farm trials based on treatments of their choice, grower assessments of on-station research, and an industry advisory panel that provides oversight of the overall progress of the project and makes recommendations to improve outcomes. The development of specialty pumpkin cultivars will improve environmental sustainability with a resilient, adapted crop in which pests, pathogens, and weeds will be managed with an integrated suite of physical, cultural, and biological methods. Farmer economic sustainability is also expected to improve since our systems approach will yield results that will overcome barriers to crop adoption and will identify lucrative products that are desired by consumers. 

Project Objectives:
  1. Assess potential risks/benefits of specialty pumpkin production and barriers to acceptance.
  2. Evaluate pumpkin germplasm lines and cultivars for use as flesh, seeds, and as product ingredients.
  3. Determine yield, fruit quality and disease resistance of tropical pumpkin cultivars in the Southeastern U.S. and Puerto Rico in organic and conventional cropping systems and determine phenotypic relationships among nutrition, flavor and fruit size traits in select germplasm.
  4. Develop cropping systems for sustainable organic and conventional specialty pumpkin production.
  5. Monitor arthropod pests and beneficial insects in specialty pumpkin to design cultural and biological control tactics for organic and conventional systems.

Cooperators

Click linked name(s) to expand/collapse or show everyone's info
  • Keith Anderson - Producer
  • Dr. Alex Bolques (Researcher)
  • Dr. Oscar Liburd (Researcher)
  • Dr. Gabriel Maltais-Landry (Researcher)
  • Margie Pikarsky - Producer
  • Dr. Amy Simonne (Researcher)
  • Dr. Marilyn Swisher (Researcher)
  • Dr. Chris Worden - Producer

Research

Materials and methods:

Objective 1: Assess potential risks/benefits of specialty pumpkin production and barriers to acceptance.

Team: Jorge Ruiz-Menjivar and Marilyn Swisher

Activity 1: Consumer survey to understand consumer perceptions, preferences and willingness to pay for specialty pumpkin based on country of origin, certification labels other food product attributes.

Institutional RevIew Board approval. We obtained IRB approval to collect data with 450 American consumers via Qualtrics (IRB202000525)

Survey Development.

  • Informed by the extant literature on food preference for new food products, native foods, and consumer demand for fresh produce. ​
  • Conceptual model guided by the Theory of Planned Behavior-TPB (Attitude, Subjective norm, Perceived behavioral control, and Behavioral intention)​
  • Design of Discrete Choice Experiments (DCE) with five attributes.
      • Nationally representative panel accessed via Qualtrics XM (Predetermined quotas: Gender (F: 52%; M:48%), Age (18-34: 30%; 35-54: 32%; 55+: 38%), Race (White: 75%; Non-White: 25%), and Ethnicity (Hispanic/Latino: at least 30%). ​Inclusion criteria: U.S. Adults 18+ and must have consumed/ purchased fresh pumpkins or butternutsquash for cooking purposes within the last two months.​
      • Example of choice set presented to respondents

         

        • Structure: (a) Informed consent and inclusion criteria Q's; (b) cooking Q's, food neophobiascale, consumer trust scales, TPB Q's; (c) Importance of Calabaza attributes and (d) Discrete Choice (DC) experiment. 

        We used scales such as the Food Neophobia Scale (Rabadán, & Bernabéu, 2021), validated instruments measuring Food Agency, Skills and Confidence (Wolfson et al., 2020), and Trust (farmer, retailer, and government and supply food system).

        Rabadán, A., & Bernabéu, R. (2021). A systematic review of studies using the Food Neophobia Scale: Conclusions from thirty years of studies. Food Quality and Preference, 93, 104241.

        Wolfson, J. A., Lahne, J., Raj, M., Insolera, N., Lavelle, F., & Dean, M. (2020). Food agency in the United States: associations with cooking behavior and dietary intake. Nutrients, 12(3), 877.

        Data collection. We collected data from 450 American consumers in February 2022.

        Sample: 450 American consumers​

      • Compensation: $9.26 per respondent.​

    • Analysis.  Descriptive statistics and Partial Least Squares Structural Equation Modeling (PLS-SEM).

  • Cross-check questions (Birth year and Age) and Survey completions under 5 minutes were not deemed valid.
  • Activity 2: Interviews with actors in the distribution system and sales points ranging from farmers’ markets to traditional commercial outlets, to identify key bottlenecks and opportunities to market in a variety of venues. ​

     

    Main goals​

    • Understand the barriers to carrying calabaza in different venues ​
    • Identify opportunities to address those barriers through breeding​

    Target Populations​

    • General managers, produce managers and others who participate in decisionsabout the produce stocked in a given venue​
    • Covers a range of venues beyond the standard chain supermarket​
    • Includes a focus on points of sale in venues serving Latinx, Afro-Americanand Afro-Caribbean and other clientele groups who have a food culture heritage of consuming calabaza​
    • Conducted in Spanish when appropriate

     

    Activity 2.1: Accommodation to Consumer Preferences – This information is currently being collected from results forthcoming after completion of point-of-sale interviews.

    Activity 2.1: Identify traits of calabaza that both consumers and grocers want that can be generated through breeding​

    • Procedures: Present key findings regarding traits that are critical forconsumers (based on our survey) to the point-of-sale decision-makers​
    • Ascertain degree to which the point-of-sale can or will accommodatethe consumer preferences identified​
    • Example: Consumer preference for chopped calabaza adds cost at the point-of-sale for labor, chilling, and possibly traying – will this be a major barrier tocarrying calabaza?

     

    Activity 2.2: Identify other traits of potential importance to grocers as barriers or as incentives – This activity is currently in progress with results forthcoming after completion of point-of-sale interviews.

    • Seasonal availability​
    • Size of the squash​
    • Color of the squash rind and flesh​
    • In-store perishability​
    • Size of standard shipping units (e.g., bin vs. 50lb box)​
    • Value of the Fresh from Florida identity for calabaza​
    • Value of country-of-origin labelling​
    • Information about how to prepare the squash, including recipes

     

    Activity 2.3: Differences among clientele groups – This activity is currently in progress with results forthcoming after completion of point-of-sale interviews to include different cultural groups.

     

    • Understand the incentives for and barriers to carrying calabaza in the sales points that are frequented by different cultural groups ​
    • Both consumer and vendor preferences may vary based on different foodways

     

    Next Steps for Activity 2:

    • Conduct cognitive test of proposed interview protocol with at least three point-of-sale representatives and make revisions as needed​ IRB approved grocer interview #IRB202000525. First cognitive test resulted in a need to revise the instrument.  It showed that grocers could not answer some of the questions and revealed that further clarifying information needed to be included.  Additional input was obtained from two UF colleagues, Gene McAvoy and Dr. Rose Koenig, both with extensive experience in marketing fresh produce.  McAvoy is the Associate Director for Stakeholder Relations at the Southwest Florida Research and Education Center.  He has over fifty years’ experience with temperate and tropical environments including fourteen years’ experience living and working in Africa and the Caribbean.  Dr. Koenig is the interim director for the Global office for the University of Florida Institute of Food and Agricultural Sciences and a lecturer at the University of Florida. She previously worked with the Rodale Institute in Africa, operates a 17-acre organic farm with one of the state’s first Community Supported Agriculture programs, and has helped establish two farmers’ markets.

    Second cognitive test resulted in an answerable instrument.

    • Secure IRB approval for human subject research, including both Spanish-languageand English-language versions of the research instruments and statement of informed consent​.  Revised IRB has been translated to Spanish and Chinese.  These versions are awaiting IRB approval.
    • Complete 10 interviews and conduct qualitative analysis of the data​. Data collection is still in progress. Thus far, three interviews have been conducted from contact with 41 points of sales in venues serving Latinx, Afro-American, Afro-Caribbean, Asian, and other clientele groups. During the interviews, the instrument was successful. The difficulty is the availability of produce managers at the various venues.  These managers report being extremely busy especially due to a labor shortage.  They seem willing, but they just do not have the time.
    • Prepare grower interview protocol​. Grower interview protocol is being prepared with expectations of commencement in early summer.

     

    Activity 3: Interviews with farmers to identify key barriers, opportunities and research priorities for specialty pumpkin production. 

     

    Main Goals:

    • Assess grower interest in producing calabaza among non-producers​
    • Assess existing grower interest in increase calabaza production ​
    • Both consumer and vendor preferences may vary based on different foodways,necessitating different accommodations to their needs​

    Next Steps​

    • Conduct tests of current interview protocol andmake adjustments as needed​
    • Include key findings of consumer and grocer studies to clarify their needs togrowers​
    • Target populations: current and potential producers with an emphasis onLatinx, Afro-Caribbean and Afro-American growers

 

Objective 2: Evaluate pumpkin germplasm lines and cultivars for use as flesh, seeds, and as product ingredients.

Team: Andrew MacIntosh and Amy Simonne

Activity 1: Pilot study to examine utility of calabaza for ale fermentation

Materials and methods:

After receiving 4 bulk plastic containers of tropic pumpkins from The University of Florida Horticulture, a full analysis was conducted. The majority of the pumpkins were cut, roasted, and delivered to First Magnitude, a local brewery that is a commercial partner to create a pumpkin beer. The final product First Magnitude created turned out quite well as the product sold at a much faster rate than anticipated.

Researching the fermentability of each pumpkin line was conducted in the Food Processing and Engineering lab at the University of Florida. This process began by taking a representative sample from each line of pumpkin. The flesh from 3 different pumpkins per line (except for P57) was added to a blender to be homogenized.  Creating this puree consisted of adding 0.6 kg of pumpkin with 0.5kg of water to create enough pumpkin juice to run a fermentability experiment.

After individually blending each line with those approximate weights, the scientists allowed the pumpkin puree to sit in the fridge for 24 hours to allow all of the fermentable sugars to dissolve into the liquid. Each puree was separately centrifuged to separate the solids from the liquid. After spinning the pumpkin puree at 7000rpm for 10 minutes, the juice was decanted.

The pumpkin juice was then analyzed using a density meter analysis 35 (DMA 35) from Anton Paar to preliminary access the sugar level. Using the line of pumpkin juice with the lowest Plato, each other sample was diluted to the baseline sugar level. Having the same sugar level for each line of pumpkins is crucial to be able to compare how fermentable each line of pumpkins is. Using an American Society of Brewing Chemists (ASBC) standard method for accessing fermentable sugars, 250mL of pumpkin juice was added to duplicate flasks. The Standard method called for 1g of yeast per flask and post fermentation data has collect and analyzed. 

Samples of the pumpkin juice pre and post fermentation were assessed with using an Alcohol Extract Meter 500 (ALEX 500) from Anton Paar and a spectrophotometer from Shimadzu. The ALEX 500 is used to give data about the density, alcohol, and sugar content of the juices to correlate changes before and after fermentation. The spectrophotometer is used to correlate the color of the juice to a visible light wavelength and how intensely the light is absorbance by the sample. 

Another method to assess the pumpkin lines was a texture analysis test. Using Stable Micro Systems TA.XTplusC Texture Analyser to assess parameters of the flesh and the hardness of the skin. Using a standard program for each sample with a standard size of 3cm cubes to accurately determine the differences.

Activity 2: Pilot study to examine rind thickness and flesh hardness

Materials and methods:

Texture analysis test was conducted to assess the pumpkin lines rind thickness. A Stable Micro Systems TA.XTplusC Texture Analyser was used to assess parameters of the flesh and the hardness of the skin. Using a standard program for each sample with a standard size of 3cm cubes to accurately determine the differences.

 

Objective 3: Determine yield, fruit quality and disease resistance of tropical pumpkin cultivars in the Southeastern U.S. and Puerto Rico in organic and conventional cropping systems and determine phenotypic relationships among nutrition, flavor and fruit size traits in select germplasm.

Team: Geoffrey Meru, Angela Ramírez, Andre da Silva, and Carlene Chase

Activity 1: Conventional trial in Florida

Materials and methods

Initial conventional field trials were conducted for ten cultivars in Homestead FL and Live Oak FL. Seedlings were transplanted at 3 weeks in plastic mulch. Plant management (nutrient and pest management) followed UF/IFAS guidelines for pumpkin production in Florida.  The germplasm will be evaluated using a randomized complete block design consisting of three plots, each plot with 5 plants. In-row spacing will be 3 ft, while 6ft between-row spacing will be applied. Data was collected on growth habit (bush or vining), flowering time (days to male or female flowering), fruit size, fruit shape, plant vigor, vine length, disease/ insect tolerance, and yield (fruit and seed). At harvest, representative fruits per plot per cultivar will be processed to determine fruit quality attributes including, flesh color, flesh thickness, seed-cavity size, and degree brix. Data was analyzed using the GLM procedure of SAS (SAS Institute Inc., Cary, NC).

Activity 2: Organic and conventional trial in Puerto Rico

Materials and methods

Seed distribution was performed early in 2022 for evaluation of UPRM materials in Florida. To accomplish objective 1, one undergraduate student was hired for field and pumpkin processing work. Two trials were performed under the UPRM AES facilities at the Organic Research Farm and Conventional site at the UPRM Lajas Substation.  The Lajas substation is located at 18◦030 0000 N, 67◦0303400 W at 9 m above the sea level. Lajas has soils belonging to the Mollisol and Vertisol orders, and has temperatures between 19 to 33 ◦C, an annual precipitation of 1143 mm, and an average relative humidity of 80%. Genotypes were seeded in a greenhouse in Lajas on 6 December 2021 in a commercial planting mix (ProMix®; Premier Tech Horticulture, Quakertown, Pennsylvania). Seedlings were watered daily. Seedlings were kept in a greenhouse (14 days) until being transplanted to the field. that were moved outside for hardening. Fourteen -old seedlings were transplanted to the field and arranged in a randomized complete block design with three replications at each production system. Seedlings were planted on raised beds [1.83 m center-to-center] with drip irrigation (perforations 12 inches apart) no plastic mulch was used. The experimental unit was 4.6 m with a planting distance of 0.91m for a total of 5 plants per experimental unit.

 

Objective 4: Develop cropping systems for sustainable organic and conventional specialty pumpkin production.

Activity 1: Organic system trial and nutrient cycling study in North Florida

Team: Carlene Chase and Gabriel Maltais-Landry

Materials and methods 

In 2021, ten pumpkin lines were evaluated in a reduced tillage system with roller-crimped rye used as mulch on certified organic land at two field sites, the Plant Science Research and Extension Unit, Citra, FL (29.4103°N, 82.1448°W) and North Florida Research and Education Center – Suwannee Valley (30.3020°N, 82.8978°W). The pumpkin germplasm lines were UFTP8, UFTP22, UFTP24, UFTP38, UFTP42, UFTP45, UFTP46 (‘La Estrella’), UFTP47, UFTP57, UFTP58 (‘Kakai’). Two additional tilled treatments included ‘La Estrella’ evaluated with the rye incorporated and either left without mulch or with raised beds covered with black plastic mulch.

The reduced tillage system was initiated with the planting of a cowpea (US-1136) cover crop in summer 2020 and ‘Wrens Abruzzi’ rye was planted after roller-crimping cowpeas in late fall 2020. The rye was roller-crimped in spring 2021. Two-week-old pumpkin seedlings were transplanted two weeks after rye termination (04/22/2021 at Citra; 04/29/2021 at Live Oak). Dates of first male and female flowers were recorded. Pumpkin fruits were harvested approximately 100 days after transplanting. The data collected included fruit number and weight, fruit flesh thickness, diameter, and flesh color.

Soils were sampled in both Citra and Live Oak 1) at rye cover crop termination, 2) after fertilization and pumpkin transplant, and 3) at pumpkin harvest. For these soils, inorganic N were quantified at sampling and N release using incubations, in addition to carbon soil health indicators (permanganate oxidizable carbon [POXC], loss on ignition [LOI]). Soil sampling focused on the three systems used for cultivar UFTP46: mulched rye, rye incorporated without plastic mulch and rye incorporated under plastic mulch. Nutrient concentrations were also quantified in harvested pumpkins for cultivar UFTP46 under the three rye management systems, in addition to three germplasm lines (UFTP38, UFTP42, UFTP57) that showed promising yield in organic conditions.

The trials are being repeated for the 2022 season for which cowpea and rye were planted in summer and late fall 2021, respectively. Cowpea cover crop biomass was sampled at cowpea termination and prepared for nutrient analyses. Soils were sampled at cowpea termination to quantify soil N and conducted incubations to quantify N release from cover crop mineralization. Soils have been pre-processed for soil health indicator quantification. The rye will be terminated in spring 2022 followed by pumpkin transplanting. Rye biomass will be sampled for nutrient concentrations. Following rye termination, we will repeat plant/soil sampling and measurements conducted during the 2021 pumpkin growing season.

Research results and discussion:

Objective 1: Assess potential risks/benefits of specialty pumpkin production and barriers to acceptance.

Team: Jorge Ruiz-Menjivar and Marilyn Swisher

Activity 1: Consumer survey to understand consumer perceptions, preferences and willingness to pay for specialty pumpkin based on country of origin, certification labels other food product attributes.

Results and discussion:

  • Taste, price, flesh color, size of calabaza, ease of preparation for cooking, and availability in nearby stores are all important factors reported by American consumers who had purchased calabaza and pumpkin varieties within the last two months.
  • Variety of calabaza, organic label, and packaging were not significant factors that appeared to influence consumers’ decision to purchase calabaza.
  • Based on our conceptual model informed by the Theory of Planned Behavior and using PL-SEM, we found that consumers trust (specifically, trust in food actors and confidence in the food safety system) were strong predictors of purchase intention for calabaza. Cooking habits and skills (as measured by food agency, skills, and confidence) were significantly related to purchase intention. Our results did not support a significant relationship between certification labels (i.e., organic products) and purchase intention.

 

Objective 2: Evaluate pumpkin germplasm lines and cultivars for use as flesh, seeds, and as product ingredients.

Team: Andrew MacIntosh and Amy Simonne

Activity 1: Pilot study to examine utility of calabaza for ale fermentation

Results and discussion:

After running each through the ALEX 500 the data was tabulated in table 1. The raw juice extract has variability between lines that should be noted as P24 had the highest Brix at 4.84 and P38 had the lowest Brix at 4.24. All of the lines (excluding P38) prior to pitching yeast were diluted down to achieve a unanimous sugar content.

After the fermentation, the resulting sugar converted into alcohol.

 Table 1. ALEX 500 data from each line of pumpkin before and after fermentation

 

P24

P38

P46

P57

Raw

Average

Average

Average

Average

Alcohol (%w/w)

-0.09

-0.25

0.08

N/A*

Density (g/cm3)

1.0172

1.0148

1.0414

1.0160

Extract Apparent (%w/w)

4.84

4.24

4.72

4.56

Extract Total (g/L)

48.75

41.85

48.40

N/A*

Brix (°)

4.84

4.24

4.72

4.56

After Fermentation

 

 

 

 

Alcohol (%w/w)

1.43

1.64

1.58

1.48

Density (g/cm3)

1.0025

1.0004

1.0036

1.0019

Extract Apparent (%w/w)

1.11

0.57

0.71

0.97

Extract Total (g/L)

18.20

13.67

14.83

16.97

Brix (°)

1.11

0.57

0.71

0.97

Plato (°)

0.99

0.53

0.70

0.95

Original Extract (°Plato)

4.64

4.60

4.61

4.59

Extract Real (%w/w)

1.69

1.32

1.46

1.57

 

*Due to limited number of samples we were unable to collect extract and brix measurements.

Each pumpkin line showed a slightly different level of absorbance which correlates to how much the sample scatters, skews, and absorb the light being shot through the sample. A common wavelength where absorbance peaked was at 447nanometers (nm) (Graph 1). This wavelength correlates to the orange color that each sample had to varying degrees. Water is used to zero the machine and read an absorbance of 0 as all of the light passed through the cuvette. The P24 line had the highest absorbance at 1.67 AU at 447nm. The P38 line had the lowest absorbance at 0.55 AU at 447nm. The P46 line had an absorbance at 0.57 AU at 447nm. Lastly, the P57 line had an absorbance at 0.93 AU at 447nm.

After fermentation, the absorbance of each line of pumpkins decreased as showed in graph 2. The brutal conditions that the pumpkin juice underwent during the fermentation caused many of the compounds that gave the raw pumpkin juice it’s bright and vibrant color to degrade. This color change was fully expected as color degradation is common in fermentations.

graph 1
Graph 1. Absorbance at Different Wavelengths for Raw Pumpkin Juice for each pumpkin line 
graph 2
Graph 2. Absorbance at different wavelengths for post-fermentation pumpkin juice for each pumpkin line

Activity 2: Pilot study to examine rind thickness and flesh hardness

Results and discussion:

Two tests were ran using the texture analysis equipment. The first test investigated the hardness of the skin by using a standard method with a puncture probe. The lowest was force required to puncture the skin was 53N for the P57 line of pumpkins. There was a statistically significant difference between P24 an P57 as indicated in graph 3.

The double compression test was used to compare the hardness of the flesh of each pumpkin. Although, the double compression test can look at many different parameters such as springiness, cohesiveness, chewiness, etc. For preliminary purposes, the hardness of the pumpkin flesh was the main focus for analysis. P38 emerged as the winner in terms of flesh hardness (graph 3).

graph 3
Graph 3. Rind and flesh hardness analysis

 

Objective 3: Determine yield, fruit quality and disease resistance of tropical pumpkin cultivars in the Southeastern U.S. and Puerto Rico in organic and conventional cropping systems and determine phenotypic relationships among nutrition, flavor and fruit size traits in select germplasm.

Team: Geoffrey Meru, Angela Ramírez, Andre da Silva, and Carlene Chase

Activity 1: Conventional trial in Florida

Results and discussion:

Earliness: Setting of the first female flower at both locations (Homestead FL and Live Oak FL) was earliest in UFTP58, UFTP24 and UFTP46 breeding lines (Table 1). Similar patterns were observed for male flowering.

Table 1A
Table 1A: Flowering patterns and vine length in Live Oak FL

Table 1B
Table 1B: Flowering patterns in Homestead FL

Most of the cultivars had short to medium vine length, with UFTP45 (Soler) exhibiting the longest vine length.

Flesh quality: UFTP38 had the best rating for flesh color (deep orange), while UFTP58 was the least (Fig 1).

FiG 1
Fig 1: Range of flesh quality observed among the breeding lines

Brix values were highest for UFTP24, followed by UFTP42 and UFTP8.

Fruit size: UFTP8, UFTP22 and UFTP24 had the smallest fruits (4.4 – 5.3 lb) while UFTP38, UFTP42, UFTP45 and UFTP57 had the largest fruits (6-12 lb) (Fig 2)

FiG 2
Fig 2: Variation in fruit size observed among the breeding lines

Further analysis is ongoing for yield-related traits. Second round trials underway in south Florida, Spring 2022.

Activity 2: Organic and conventional trial in Puerto Rico

Results and discussion:

All traits (silverleaf evaluation, vigor, vine length, flowering male, and female) were statistically significant. Means separation was performed using Tuckey (a= 0.05). Data on disease evaluation demonstrate that lines UFTP58 (Figure 1) and Verde Luz were the only ones to show <10% of leaves symptoms for silverleaf. 

Figure 1
Figure 1. Genotype UFTP58 under organic production showing no symptoms of silverleaf.

Most lines under the conventional trial had silverleaf on >50-80% of the leaves (scores of 3.5 to 4). Genotypes Fortuna and Soler had higher (5) scores for silverleaf symptoms under the conventional trial. While under the organic trial genotypes UFTP58, Fortuna and Verde Luz had scores of 1. Overall, the other genotypes have scores over 3.5 (>50% of leaves with symptoms) (Figure 2 and 3).  

Figure 2
Figure 2. A genotype with a score of 5 for silverleaf.
Figure 3
Figure 3. General view of genotypes with silverleaf symptoms.

Regarding powdery mildew (PM) evaluation, the only genotype showing PM symptoms was UFTP58 under both cropping systems (Figure 4).

Figure 4
Figure 4. PM on genotype UFTP58.

Under the horticultural evaluation lines UFTP34 and UFTP81 had excellent vigor (score of 5) under the conventional cropping system. However, those genotypes did not have the same vigor under the organic trial. Genotypes UFTP38 and UFTP32 had the poorest vigor under the organic, while under the conventional those genotypes had scores of 4.6 and 4, respectively. Genotype UPFTP58 had the poorest vigor the conventional trial.

In general, female flowering begun 38 (UFTP58) after transplanted, and the latest genotypes to had females flower was at 61 (Fortuna) days after transplanted under the conventional, while in the organic, genotype UPFT58 (34 d) was the earliest and UFPT10 and Soler was the latest (54 days). Considering male flowering under the organic started at 22 days (UFTP34) and the latest at 56 days (Fortuna). Under the conventional the earliest to had male flower was UFTP58 at 22 days after transplanting and UFPT22, UFPT26 and Fortuna (51 days) the latest. Average male flowering regardless the cropping system was at 44 days after transplanting. In general most genotypes tended, under both cropping system, to have small to medium vine length.

Regarding yield and fruit quality, UPRM has started to initiate the harvest and fruit processing, data will be reported at this time (Fig 5).

Figure 5
Figure 5: Fruits harvested from the organic and conventional trials in Puerto Rico. Further analysis is underway.

A second trial will be performed in September 2022.

 

Objective 4: Develop cropping systems for sustainable organic and conventional specialty pumpkin production.

Activity 1: Organic system trial and nutrient cycling study in North Florida

Team: Carlene Chase and Gabriel Maltais-Landry

Results and discussion:

In Citra, FL in 2021, UFTP38 and UFTP42 performed very well with high numbers of marketable fruit per plant (1.4) and high marketable yields (22,113 and 26,614 kg/ha, respectively). UFTP45, UFTP47, and UFTP58 performed poorly (<10,000 kg/ha). Fruit diameter and flesh thickness ranged from 11.4 to 22.8 cm and 1.9 to 6.7 cm, respectively. In Live Oak, UFTP24, UFTP38, UFTP57 were among the best performing lines with 0.9 to 1.1 marketable fruits per plant and marketable yields of 9,129 to 10,874 kg/ha, whereas poor performing lines included UFTP45, UFTP47, and UFTP58. Fruit diameter and flesh thickness ranged from 11.2 to 19.0 cm and 1.7 to 4.9 cm, respectively at Live Oak, FL. At both locations, yields with ‘La Estrella’ (UFTP46) were unremarkable with the roller-crimped rye. However, its yields doubled with plastic mulch, but this response was significant only in Live Oak.


There was no consistent difference among cultivars for nutrient concentrations in pumpkin fruits. However, UFTP46 had N and K concentrations that were 20-25% higher in the plastic vs. rye-mulched system, and fruit N and K concentrations were 45-65% higher at the Citra vs. the Live Oak site. Soil N release following rye was similar among sites and unsurprisingly increased after fertilization. However, there was a greater N release when rye was incorporated in the soil as opposed to mulched at the surface. Soil health C indicators (SOM and POXC) were higher after rye was incorporated in the soil as opposed to mulched at the surface.

Summer 2021 onwards (cowpea cover crop): Laboratory analyses for plant and soil samples collected are ongoing.

Participation Summary

Education

Educational approach:

To be accomplished later this year-2022

Educational & Outreach Activities

2 Consultations
1 Curricula, factsheets or educational tools
2 Online trainings
10 Tours
2 Webinars / talks / presentations

Participation Summary:

Education/outreach description:

Education and outreach 

Carlene lab

  • Results were presented at the Southern Weed Science Society meeting and the TriScocieties meeting in 2021.

Meru lab

  • Grower education efforts through lectures (n = 2) in Miami-Dade county and Hernando County
  • Online resource PowerPoint June 4, 2021 (126 views so far): This video provides information on growing calabaza pumpkin for home gardeners. https://www.youtube.com/watch?v=WNZ0EZRQNEk
  • UF/IFAS Southeast Extension District (SEED): Feb & Oct 2021

Learning Outcomes

2 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation

Project Outcomes

Project outcomes:

Growers have demonstrated interest in growing calabaza as evidenced by seed requests to our program. To-date more than 75 seed packets of calabaza have been distributed to growers.  Two local growers in south Florida have tested a few of the breeding lines at their farms at small scale and have sold their produce profitably (no empirical data available at this point). On-farm trials with grower cooperators later this year (2022) will provide a better understanding of the viability of calabaza production under both conventional and organic systems.

Information Products

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.