Progress 03/01/24 to 02/28/25
Outputs Target Audience:The target audience for this initiative includes chile (Capsicum annuum) farmers and processors. The shift towards mechanical harvesting is crucial for sustaining New Mexico pod-type green chile production and green chiles. However, two significant challenges arise: effectively removing stems during mechanical harvesting and cultivating transplants with growth patterns conducive to mechanical harvesting. The research pursued two primary goals: facilitating easy destemming in New Mexico pod-type green chile and other chiles (e.g. jalapenos) and discovering transplant techniques that promote deep root growth and upright plant habits, thereby enhancing the efficiency of mechanical harvesting. Access to destemming germplasm and advanced transplant techniques will allow growers to transition from manual to mechanical harvesting methods, leading to reduced production costs and increased revenue. This shift will contribute to the sustainability of production. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?There has been significant training opportunities in this grant. In NM and UC Davis. This project is the basis for a Masters student thesis and research associate was trained. In CA, 3 interns were trained in plant breeding and molecular biology as well as a senior research associate in mechanical harvesting. How have the results been disseminated to communities of interest?At a basic level, we have communicated the results and goals to K-12 and teachers and consumers through the New Mexico Pepper Institute. Results were communicated the International Pepper and Solanaceae Genomincs meetings, as well as Seed industry conferences and field days; reaching growers , seed industry and academic audiences. These are our targeted audiences. What do you plan to do during the next reporting period to accomplish the goals?To confirm previous findings, we will repeat the harvesting and Q-plug study in 2025 with the goal of publishing the results. Additionally, we have expanded our data collection capabilities by acquiring a LI-COR porometer/fluorometer, which will allow us to measure stomatal conductance and chlorophyll fluorescence. These metrics will provide critical insights into plant stress responses and further clarify how different transplant methods affect plant vigor and physiological performance. At UC Davis, we will run a final mechanical harvest trial on most advanced lines in our program including the checks previously used, repeating commercial checks and new F1 hybrids developed by a private collaborator using our materials to evaluate its performance in their genetic backgrounds including capturing video online to refine inline quality data capture. We will also evaluate imaging of plants at the flowering stage to capture architecture traits and see if that correlates with plant architecture traits at harvest. We will plant 5 populations segregating near the Chr10 QTL to genetically fine map the loci.
Impacts What was accomplished under these goals?
The long-term goal of this project is to develop pepper varieties that are amenable to mechanical harvesting. The critical need is to ensure the long-term sustainability of the US chile pepper industry by reducing dependence on the increasingly inadequate supply of manual labor for harvest, as well as mitigating labor's high costs compared to other producing countries. Our supporting objectives formulate a systems approach combining genomics, plant breeding, physiology, horticulture, and mechanization. They include: 1. Develop breeding lines of green jalapeno and New Mexico chile pepper that combine destemming, plant architecture and uniformity. 2. Characterize genotype x environment x management (GxExM) interactions of plant architecture on yield with mechanical harvesting. 3. Determine the genetic basis of plant architecture and determinacy (uniformity of ripening) in pepper. 4. Fine-map key loci and determine physiological interactions of destemming in pepper. This proposal leverages and complements, (but does not duplicate) resources being developed by PDs for a USDA grant# 2021-67013-33942 ending 01/2024 and several other non-USDA sources of funding that combine essential traits for pepper production. Objective 1 We used plants from destemming selections (MUC14) x jalapeno crosses and backcrosses (F4 to F5 and BC2S4 from 2 destem donors) that were selected in the field for destemming and fruit quality to cross with architecture x destemming in CA selections, (F4 to F5 from 3 destem donors and 5 elite jalapenos). The architecture traits are coming from GUC1046 lines (3 donors) selected for low branch angle, lowest fruits above the ground (> 12 inches), the fasciculate ("determinate") phenotype, and fruit size and shape. We have shown selection on these architecture traits combined with low destemming force can translate to good mechanical harvest. Markers at the major QTL for destemming on chr10 were used to select plants carrying the destemming allele for all crosses and backcrosses, the destemming/jalapeno x destemming/architecture F1s were crossed and backcrosses with 5 jalapeño inbred lines. The F1/BC parents for all of these families have been backcrossed to jalapeno inbreds 2 additional times in greenhouse during 2023 and 2024. In addition, the 2024 field trial at Davis also included 8 - BC3S1 and 2 - BC4S1 destemming x jalapeno populations representing 6 unique pedigrees were evaluated. Objective 2 Preliminary findings from the transplant techniques research show that ihort Q plug plants, while not growing as tall as direct-seeded plants, demonstrated equivalent mechanical harvest efficiency and similar root length. These results suggest promise for developing a transplant-based method to enhance harvest efficiency now tested in 3 environements. This is particularly valuable for high-cost hybrid seeds, which are typically transplanted rather than direct-seeded. Similar, In Davis, we now have shown that over 2 years the Q-plugs that by seeding in Q-plugs and transplanting at 4-weeks rather 6-8 weeks dramatically improves plant architecture, resulting in a a few primary roots and dominant primary stem with limited basal branching. This method of management avoids breaking of both apical and radicle dominance (mainatining a primary root) caused by restricting root growth to a root ball when transplants are delayed to 6-8 weeks. It also results in a healthier more deep rooted plant accessing deeper root zones, minerals and water. The vast majority of peppers are hybrid and thus transplanted in California making these results particularly important for mechanical harvesting. In 2024 in Davis, we conducted a mechanical harvest trial including 15 entries, 10 of our most advanced selections from our destemming (MUC14) donor crossed with jalapeno (BC1S2 to BC1S6). We also included a commercial hybrid (Ciclon) that was described as "fruit destems very easily" and 3 additional hybrids from a seed company. Our best mechanical harvesting MUC14 selection was included as a check. We use a randomized complete block design with 3 reps. After 3 years of testing advanced lines for mechanical harvesting at Davis, we have shown that our original selection, MC-200 consistently performs well with low torque force and 35-50 % of marketable fruit harvested and destemmed, although MC-200 does not have acceptable fruit shape and size. We also have shown that in 2023 and 2024, we are able to transfer this trait with similar proportion of marketable fruit destemmed, but with increased yield and fruit quality. We have improved architecture both with management as above and through selection. In 2024 we explored capturing video "inline' on the harvester to capture fruit quality including destemming using a GoPro camera. We are working with Heather Manching (NCSU) and Amanda Hulse-Kemp (USDA/ARS) to refine this. We are also capturing fruit quality for nursery trials with photographs incorporated with Field Book app, also developed by USDA/ARS. Objective 3 We have evaluated populations derived from combining Jalapeno/destem/architecture from objective 1 in 2023 and 2024 field trials. In order to better understand the genetics of plant architecture in this material, 16 - F2/S1 families representing 9 unique pedigrees having destemming/jalapeno combined with destemming/architecture and crossed again with jalapeno inbreds were evaluated during 2024 field trial in Davis, CA. Four of these populations were segregating for architecture traits and seed for a total of 192 F3 (or BCS2) families was collected. The following traits are collected for nursery and replicated trials: plants succumbed to Tomato Spotted Wilt Virus, distance from ground to bifurcation (cm), fruit bearing basal branches, total basal branches, lowest fruit height (cm), destem force, destem rate. Objective 4 Plants for 18 populations (BC1 or BC2 S3 or S4) having a recombination event near the left or right of the chr10 qtl were grown. More than 1100 individuals from 12 populations were genotyped to identify close recombinants. At least 12 different crossover events within the chr10 QTL were identified. Individuals that were heterozygous between the two crossover events were genotyped (about 1445 individuals) and evaluated in the field in 2024 (2 reps of 8 plants per plot for each family and genotype -Allele 1, 2 or Het. All the parents for the fine mapping populations grown in the GH were stained at mature green stage and a score was given to them based on the staining pattern to detect abscission zones. Fruits collected from the field from the genotyped families were also stained at the mature green stage.
Publications
- Type:
Peer Reviewed Journal Articles
Status:
Accepted
Year Published:
2024
Citation:
Joukhadar, I., Ortega, F., Velasco-Cruz, C., Barchenger, D., Hill, T., Van Deynze, A., Walker, S. (2024) Correlations among New Mexico pod-type green chile (Capsicum annuum) fruit morphology characteristics with destemming force. Crop Science 64: Pages 2698-2708.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2025
Citation:
Joukhadar, I, Coon, D, and Walker, S. (2025) Assessing Different NM Type Green Chile Transplant Methods for Mechanical Harvest. Abstract American Society of Horticultural Science. 60: 841-851.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2024
Citation:
Breeding peppers for climate change. 2024. Van Deynze, Seed central. UC Davis, Davis, CA. Sept 12 2024.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2024
Citation:
Coon, D, Joukhadar, I., and Walker, S. (2024) Assessing Different Transplant Methods with Chile Pepper to Mimic Direct Seeding. Abstract International Chile Pepper Conference. Ithaca, NY.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2025
Citation:
Coon, D, Afroze, J, and Walker, S. (2025) Assessing Different Transplant Methods with Chile Pepper to Mimic Direct Seeding. Abstract New Mexico Chile Pepper Conference. Las Cruces, NM.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Genetics of destemming in pepper: A step towards mechanical harvesting. 2023. Theresa Hill , Vincenzo Cassibba , Israel Joukhadar , Charles Havlik, Franchesca Ortega , Armando Garcia-Llanos, Stephanie Walker, Allen Van Deynze. UC Davis Plant Breeding Retreat. Bodega Bat, CA, Dec 15, 2023.
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Progress 03/01/23 to 02/29/24
Outputs Target Audience:The target audience for this research project is chile farmers and processors and recruitment of K-12 students. The shift towards mechanical harvesting is crucial for sustaining chile production in US, concentrated in New Mexico and California. However, two significant challenges arise: effectively removing stems during mechanical harvesting and cultivating transplants with growth patterns conducive to mechanical harvesting. The research pursued 3 primary goals: facilitating easy destemming in green chile, breeding for desired plant architecture, and discovering transplant techniques that promote deep root growth and upright plant habits, thereby enhancing the efficiency of mechanical harvesting green chile. Access to destemming germplasm and advanced transplant techniques will allow growers to transition from manual to mechanical harvesting methods, leading to reduced production costs and increased revenue. This shift will contribute to the sustainability of production. Secondly, K-12 children and teachers in Northern California went thru experiential learning modules developed by the UC Davis Student program that trains and employs undergraduates to both create and implement learning modules using pepper diversity as a base. Changes/Problems:We had anticipated the completion of our publications by now, yet the revision phase is proving to be more time-consuming than initially projected. Our aim is to have all publications finalized by July 2024. Despite the delay, we are dedicated to ensuring that our work meets the highest standards of quality and accuracy. In addition, due to high disease pressure in our southern NM research plots in 2023, we have moved our research to the Los Lunas Agricultural Science Center for 2024. No major changes for Davis program. What opportunities for training and professional development has the project provided?There has been significant training opportunities in this grant. In NM, this project is the basis for a Masters student thesis and research associate was trained. IN CA, 2 interns were trained in plant breeding and molecular biology as well as a senior research associate in mechanical harvesting. Over 600 K-6 students were enticed in plant sciences by completing hands on modules learning about pepper diversity and plant breeding (every student took a plant home), as well as undergraduate students were trained in plant breeding and pedogy to implement the K-12 modules. How have the results been disseminated to communities of interest?At a basic level, we have communicated the results and goals to K-12 and teachers and consumers through the New Mexico Pepper Institute. Results were communicated the International Pepper and Solanaceae Genomincs meetings, as well as Seed industry conferences and field days; reaching growers , seed industry and academic audiences. These are our targeted audiences. What do you plan to do during the next reporting period to accomplish the goals?In 2024 we plant to evaluate segregating populations for Fruit quality, plant architecture, determinacy and destemming in both New Mexico and jalapeno types. These will lay the foundation for Obj 3 and 4. We also will run advanced breeding lines and commercial checks in a mechanical trial in Davis focusing on same traits. We will also continue outreach as described for K-12, growers and processors.
Impacts What was accomplished under these goals?
The long-term goal of this project is to develop pepper varieties that are amenable to mechanical harvesting. The critical need is to ensure the long-term sustainability of the US chile pepper industry by reducing dependence on the increasingly inadequate supply of manual labor for harvest, as well as mitigating labor's high costs compared to other producing countries. Our supporting objectives formulate a systems approach combining genomics, plant breeding, physiology, horticulture, and mechanization. They include: 1. Develop breeding lines of green jalapeno and New Mexico chile pepper that combine destemming, plant architecture and uniformity. 2. Characterize genotype x environment x management (GxExM) interactions of plant architecture on yield with mechanical harvesting. 3. Determine the genetic basis of plant architecture and determinacy (uniformity of ripening) in pepper. 4. Fine-map key loci and determine physiological interactions of destemming in pepper. This proposal leverages and complements, (but does not duplicate) resources being developed by PDs for a USDA grant# 2021-67013-33942 ending 01/2024 and several other non-USDA sources of funding that combine essential traits for pepper production. For Objective 1. We have created several populations in both jalapeno and New Mexico pod-type chiles. These were evalaued in nurseries and selections made on plant architecture, destemming force and fruit quality. F3 to F6 and BC2S2 advanced lines were then evaluated with controls in replicated trials over 3 years in NM an d CA. Our findings are detailed in an extensive publication (Hill et al 2023), Joukhadar et al. 2024,and Ortega et al. 2024. For New Mexico type peppers we have successfully conducted backcrossing on the top three breeding lines (385W21, 398W21, and 345W21) which were identified for their larger fruit size while preserving the easy destemming trait. The parentage of 385W21 includes MUC14 and NuMex Joe E. Parker, while 398W21 and 345W21 originate from MUC14 and Odyssey. Consequently, 385W21 underwent backcrossing with NuMex Joe E. Parker, while 398W21 and 345W21 were backcrossed with Odyssey. BC1F1 seeds will be harvested from these crosses and subsequently multiplied in the greenhouse for planting in the 2025 season. Similarly, we have multiple populations segregating for Plant architecture, detsemming and determinacy in jalapenos with BC2S2s or F3s between BC2s and crossed for different combination of traits. We evaluated and selected these in the field at Davis in 2023in 2 reps on single row plots. Each family was rated for each traits with destemming measured with a torque meter for both frequency and force as per Hill et al. (2023). Our analysis of the correlations between fruit morphology characteristics and destemming force suggests a significant relationship between the fruit length and pericarp thickness and their impact on destemming force. Typically, thicker walled and longer fruit tend to have higher destemming forces, although we have observed variations in this correlation in specific crosses. This discovery inspires optimism that intensified future breeding efforts could ultimately result in the development of cultivars that not only meet the demands of the processing industry, but also reduce labor costs and address labor shortages effectively. These populations serve as teh basis for obj. 2-4. Objective 2. We have made signifcant advancements to understand , G x E x M, specifically for transplants specifically with transplants in Jalapeno types. We tested initiating plants with Q-plugs, paperpots and transplanting at 4 weeks vs 6-8 weeks as traditionally in replicated trials.Q-plugs transplanted at 4 weeks dramatcially changed architecture to a plant with with a primary stem followed by bifercation into several secondary branches. Importantly, this also resulted in a deeper more apical dominant tap root system giving strong support to the plant for mechanical harvesting using a "stripper" header type harvester that we are breeding for, i.e. the Etgar series 1000. Mechanical harvest of our best selections resulted in 90% of fruit being harvested with 50% of that fruit being destemmed directly from harvest. These are 2 year averages. Obje 3 and 4 will be addressed in Year 2.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2024
Citation:
Joukhadar, I. (2024) New Mexico Green Chile Mechanization: Current Developments and Innovations. New Mexico Chile Pepper Conference Presentation. Las Cruces, NM.
- Type:
Journal Articles
Status:
Accepted
Year Published:
2024
Citation:
Joukhadar, I., Ortega, F., Velasco-Cruz, C., Barchenger, D., Hill, T., Van Deynze, A., Walker, S. (2024) Correlations among New Mexico pod-type green chile (Capsicum annuum) fruit morphology characteristics with destemming force. Submitted for publishing in Crop Science.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Genetics of destemming in pepper: A step towards mechanical harvesting. 2023. Theresa Hill , Vincenzo Cassibba , Israel Joukhadar , Charles Havlik, Franchesca Ortega , Armando Garcia-Llanos, Stephanie Walker, Allen Van Deynze. Solanaceae Genomics Conference, Montreal, Canada. 14-18, 2023
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Franchesca Ortega , Armando Garcia-Llanos, Stephanie Walker, Allen Van Deynze. UC Davis Plant Breeding Retreat. Bodega Bat, CA, Dec 15, 2023
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Seed Biotechnology Center Update. 2023. Van Deynze, A. California Seed Association. Monterey, CA. September 28, 2023.
- Type:
Journal Articles
Status:
Accepted
Year Published:
2024
Citation:
Identification of QTLs involved in easy destemming for New Mexico pod-type green chile. 2024.Franchesca Ortega, Theresa Hill, Allen Van Deynze, Armando Garcia-Llanos, Stephanie Walker. Frontiers in Plant Sciences. In Review
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