ASHS 2024 Conference

The significance of Carolina Gold specialty rice in South Carolina's (SC) agricultural history is deeply rooted, dating back to colonial times. Its unique flavor and texture have made it a prized variety among chefs and food enthusiasts. Currently, saltwater intrusion and weed infestation threaten this specialty rice production in SC. Understanding salt tolerance and weed interactions is crucial for ensuring the continued production and quality of this specialty rice. Preliminary experiments assessed the impact of different concentrations of ocean water and native weed pressure on rice plant vigor when cultivated organically under controlled environmental conditions. In brief, we screened rice germplasm under various seawater concentrations (0, 0.375, 0.75, 1.5%, and 3%) in both weed-free and weed competition conditions. In our preliminary greenhouse studies, we observed weed competition reduced the rice plant biomass by 2-3 times and yield up to 5 times at a 3% seawater concentration. M202 and Doble Carolina exhibited the highest salt tolerance and higher photosynthesis rate when compared to local genotypes, Carolina Gold and Santee Gold. The cultivars demonstrating superior performance under these conditions were subsequently subjected to further testing in organic research plots, incorporating supplemental irrigation with tidal ocean water. A field experiment was designed to evaluate and validate the salinity tolerance of six rice genotypes (Carolina Gold, Santee Gold, Doble Carolina, M202, Jupiter, and JN100) under different seawater concentrations (0%, 1.5%, 3%, 6%, and 12%), both in weed-free and weed-competition scenarios. Using a gasoline pump, we collect brackish water from the adjacent marsh in a 4000-gallon-capacity reservoir/pool. The calculated volumes are then pumped into the field plots based on each plot's fresh and seawater volumes. The salinity level of treated plots is monitored by measuring the EC values. The results indicated that M202, Doble Carolina and JN100 showed the highest salt tolerance. Weed competition reduced the rice plant height, number of tillers, panicles, dry root, and shoot weight across the entire salinity gradient. Weed competition led to an approximately 50% reduction in both the aboveground (shoot) and belowground (root) weights of rice plants, as compared to weed-free plots, across the tested salinity levels. Weed biomass, weeding time and regrowth of weeds declined significantly above 3 % seawater concentration when compared to control. Eventually, the most promising cultivars identified are being incorporated into a breeding program to integrate salt-tolerant genes into the Carolina Gold specialty rice.

Cucumber (Cucumis sativus L.) fruit has characteristic taste and aroma, the important organoleptic qualities influencing consumer preference and marketability. Profiling of metabolites conferring bitterness and aroma is required to improve cucumber fruit quality and produce preferred fruit. In this study, we profiled cucurbitacins responsible for bitterness and volatile compounds using fruit of 69 cucumber genotypes with different fruit shape, color, and origin and provided qualitative and quantitative information of metabolites involved in the organoleptic quality. Among six types of cucurbitacis (CuA-E, I), only CuC was detected in six inbreds while most genotypes didn’t contain them. It means bitterness has been lost in modern cucumber cultivars with domestication process. The 69 genotypes were classified into four clusters according to the profiles of cucurbitacins and volatile compounds. Clusters 2 and 3 accumulated the highest and lowest volatile contents, respectively. Clusters 1 and 4 were discriminated by minor volatiles rather than major ones, suggesting they have distinct background flavor. Clusters 1 and 4 also showed different phenotypes such as length and color, implying a relationship between fruit phenotype and background flavor. However, the clustering was inconsistent with cultivar types or origins. It suggests independent domestication for bitterness and flavor has been conducted for cultivars in different origins. We further examined hybridization effect on metabolite compositions using 15 F1 hybrids from selected inbreds. Total volatile compound (TVC) content was reduced in the F1 hybrids, especially due to decrease in total alcohol content affecting increase in ratio of aldehyde to TVC. These findings will contribute to improvements of cucumber organoleptic qualities and will provide useful information for selecting cucumber materials to produce preferred fruit.

In the Southeastern U.S., cucurbit production is vulnerable to the sweetpotato whitefly Bemisia tabaci and the viruses it transmits. There are limited control methods for the whitefly pest, including mulches, row covers, and spray programs. Unfortunately, none of these practices reduce the whitefly populations to zero, leaving whiteflies behind to transmit viruses. Therefore, host resistance is the best management practice, and the identification of resistant genotypes to whitefly transmitted viruses is a top priority. To aid watermelon breeding for resistance, 21 Citrullus genotypes were evaluated over two field seasons in Tifton, GA in 2022 and 2023. The traits evaluated were viral disease severity (AUDPC), Cucurbit leaf crumple virus (CuLCrV), Cucurbit yellow stunting disorder virus (CYSDV), and Cucurbit chlorotic yellows virus (CCYV) viral loads and in 2022 only, whitefly counts were collected to evaluate whitefly preference. Leaf tissue was collected 5 weeks after transplanting (WAT) in 2022 and 7 WAT in 2023. Total nucleic acids were extracted, and qPCR was performed to determine viral loads. Grif 16444 was the only genotype that had lower adult whitefly counts, indicating non-preference of this genotype. Over the two years there were three consistent genotypes with the statistically lowest AUDPC, two C. mucosospermus (PI 595203 and PI 494528) and one C. ecirrhosus (Grif 16444). In 2022, these three genotypes had significantly lower CuLCrV viral loads than the cultivar checks, however, in 2023 due to low CuLCrV presence there were no significant differences. For CYSDV and CCYV, there were no genotypes with significantly lower viral loads than the cultivar checks in both years. These wild crop relatives provide sources of resistance that can be used by breeders to improve cultivated watermelon.

Specialty pumpkins, such as the tropical pumpkin or “calabaza” (Cucurbita moschata Duchesne), are widely grown and consumed in Puerto Rico, ranking second among the most important vegetables on the island. This crop is also increasingly becoming a lucrative emerging market in the United States, particularly in communities with a high density of households of Latino/Hispanic and Caribbean heritage. Yield, fruit quality, and disease resistance of 21 genotypes were evaluated under conventional and certified organic management conditions in Puerto Rico at the University of Puerto Rico Lajas Research Station from January to May 2022, and from November 2022 to March 2023. The genotypes were evaluated using a randomized complete block design with three replications. The number of marketable fruits, total fruits per plot, yield (kg ha-1), and incidence of whiteflies, among other variables, were recorded. Overall, the number of fruits per plot and marketable fruits ranged from 2 and 12, while the yield reached 9,229 kg ha-1 to 65,707 kg ha-1. Under organic certified management, the highest yield was obtained by UFTP42 with 46,567 kg ha-1, while UFTP4 obtained the lowest yield with 5,110 kg ha-1. Under conventional conditions, the UFTP34, UFTP80, and ‘Soler’ lines obtained the highest performance, with 66,677; 63,974, and 75,971 kg ha-1, respectively. On the other hand, the genotypes UFTP4, UFTP10, UFTP22, and UFTP46 obtained lower yields with 9,229; 10,881; 17,635, and 15,408 kg ha-1, respectively. Verde Luz, showed the lowest incidence of whiteflies (< 10%), under both management conditions, while the remaining genotypes showed no significantdifferences between them. In summary, UFTP34, UFTP44, UFTP45, and UFTP80 could be released as prospective cultivars for the southern area of Puerto Rico and could be used as parents for breeding purposes under organic and conventional cropping systems.

Anisogramma anomala, causal agent of Eastern Filbert Blight (EFB), is endemic to eastern North America and was accidentally introduced to the Pacific Northwest hazelnut (Corylus avellana) growing regions around 1960. A single gene conferring resistance was identified in the pollinizer ‘Gasaway’ by the OSU Hazelnut Breeding Program, and deployed across the Willamette Valley in the majority of cultivars released since 2008. In preparation for a mutation or second accidental new introduction, research has focused on discovering, mapping, and developing useful molecular markers for new sources of resistance. In October 2023, a new isolate of A. anomala was detected in a grower’s orchard in Woodburn, OR, growing on the previously resistant ‘Jefferson’. The results of this study focus on linkage group 2 resistance (LG2), conveyed by ‘Georgian OSU 759.010’. Using two populations from a cross between ‘OSU 1477.047’ with Georgian resistance and ‘Sacajawea’ with quantitative resistance, n=272 recombinant offspring were identified using existing SSR markers. Marker development resulted in 40 new SSR markers covering an 8.5Mbp region, and a linkage map of the resistance region was constructed. Characterization of the 40 new SSR markers is in progress.

Wild plum, Prunus maritima, has a native habitat that ranges from coastal Virginia to Nova Scotia and is well known to be associated with beach communities with sandy soils. Recent trials by Rutgers, New Jersey Agricultural Experiment Station suggests beach plum has the potential to be grown throughout the state where higher clay content, fertile soils contribute to increased vegetative growth leading to a dense bush habit. Crop potential is abundant due to high natural bloom density. However fruit set has been challenging under traditional commercial growing systems, partly due to self-incompatibility. BP1-1 Jersey Jems cultivar was bred and selected by the Rutgers University Plant Breeding program for its high yield, large size and superior flavor in costal locations where there are diverse beach plum pollen clouds. In order to establish clonal orchards of this cultivar, a pollen parent must be identified. In this study, a total of 7 controlled test crosses were made in triplicate on BP 1-1. Fruit yields were collected from BP1-1 and top yielding crosses were noted. The purpose of this study is to find compatible pollen parents, ensuring quality and uniform yield to base future pollen parent recommendations in New Jersey commercial tree fruit orchards.

Vermicompost, derived from the processing of organic waste by earthworms, is a beneficial soil amendment known to improve plant and soil health due to the presence of beneficial microorganisms. Vermicompost microbiome can vary radically depending on the starting substrate, environmental conditions, and earthworm species, making it important to characterize the microbial community over time under a variety of vermicomposting conditions. To characterize the microbial community of vermicompost produced from rabbit manure, four samples were collected from vermicomposting bins (Avery Islands, LA) for Nanopore long-read sequencing: one unprocessed manure samples, and samples which had been composting for 1-, 6-, and 12-months. About 135Gb of sequence data with a median quality of Q19 was produced. Relative taxonomic abundance of the microbial community was assessed using Kraken2 and Braken. Manure samples differed in microbiome composition, but were both much less diverse than vermicomposted samples, which had much greater bacterial diversity and were rich in nitrogen-fixing bacteria such as Mesorhizobium and Bradyrhizobium. 1-month old vermicompost more closely resembled 12-month old vermicompost than unprocessed manure, suggesting that a majority of the benefits of vermicomposting are realized within a relatively short period of time.