Location: Crop Genetics and Breeding ResearchTitle: Genetic and seed treatment effects in organic peanut Author
Submitted to: Peanut Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2012
Publication Date: 3/1/2012
Citation: Cantonwine, C.G., Holbrook Jr, C.C., Culbreath, A.K., Tubbs, R.S., Boudreau, M.A. 2012. Genetic and seed treatment effects in organic peanut. Peanut Science. 38:115-121. Interpretive Summary: Soil borne diseases can reduce seedling emergence and plant stand establishment in organic peanut production in the Southeastern United States. We conducted field experiments for two years to evaluated the potential of genotype selection, shelling procedure, and an organically approved seed treatment to improve seedling emergence and stand establishment. Although significant differences were observed among the genotypes, no levels of resistance high enough to solve this problem in organic peanut production were observed. The organically approved seed treatment also did not supply a level of protection that could be used to alleviate this problem. Hand shelling did improve seedling emergence and stand establishment in comparison to mechanical shelling. This was probably due to more seed damage with mechanical shelling, and illustrates the need to use seed from well-sorted seed lots where damaged seed are removed. Additional research is needed to evaluate alternative seed treatments and to enhance cultivar traits involved in seedling establishment and growth.
Technical Abstract: Stand establishment has been a challenge for organic peanut production in the Southeastern United States. Field experiments were conducted in 2007 and 2009 in research plots certified for organic production to evaluate the potential of genotype selection, shelling procedure, and seed treatment with Bacillus subtilis to improve stand establishment and seeding emergence rates, reduce incidence of Aspergillus crown rot, and increase seedling biomass. Seed of 15 peanut genotypes were mechanically shelled or hand-shelled, and treated with B. subtilis or untreated prior to planting in early June. Percent stand was estimated for each plot 17-21 days after planting (DAP), and percent seedlings affected by Aspergillus crown rot and plant biomass were estimated 21-24 DAP. Seed treatment significantly affected stand establishment for three genotypes each year, Georgia-01R both years, C-99R and Tifguard in 2007, and C34-24-69 and C724-19-25 in 2009. In all of these cases, the hand-shelled plots had significantly greater stands than the mechanically shelled plots for untreated and/or B. subtilis treated seed. B. subtilis treatment improved stands for two of the mechanically shelled treatments that significantly responded to hand shelling. Despite low incidence, there was a significant reduction of crown rot in the hand-shelled plots compared to the mechanically shelled plots across years and genotypes. The cultivar Georganic, which has been planted in organic peanut systems in Georgia in recent years, was among the genotypes with the lowest seedling establishment rates and biomass. Based on these results, it is recommended that sorting thresholds for damaged seed be higher for seed destined for organic production, and that breeding efforts that include assessment of factors involved in seedling establishment and growth be prioritized.