Effect of Gypsum Application Rate On Seed Quality of Medium and Large Seed-Sized Runner Peanut Cultivars.

The most common limiting nutrient in peanut (Arachis hypogaea L.) production in the Southeastern United States is Calcium (Ca). Lack of proper calcium levels in the soil can negatively affect pod yield and seed quality. Previous research has shown the amount of calcium needed to obtain optimum germination rates is dependent on seed size. The University of Georgia Cooperative Extension recommends a soil Ca level of 560 kg ha^-1 or greater for commercial peanut production. If peanuts are to be grown for seed, 1120 kg ha^-1 Gypsum (CaSO₄) is recommended to be applied regardless of soil calcium level. Recently, large-seeded cultivars have become popular with peanut producers in Georgia. To help determine if calcium recommendations for peanut production are applicable to these new large-seeded cultivars, field experiments were conducted during the 2012 growing season. Experiments were conducted in a randomized split block design with 4 replications with gypsum (CaSO4) application rate as the main factor. Gypsum was applied at four rates (0, 560, 1120, 1650 kg/ ha). A large (Georgia-06G) and medium-seeded (Georgia Greener) runner-type cultivar were used. After harvest, peanuts were shelled and sorted according to standard industry procedures. Standard germination tests were performed along with seed calcium content analysis to determine correlation of gypsum application rate to germination rate and seed calcium content and to determine if a differential response exists between the two cultivars. Gypsum application and cultivar had no effect on percent standard germination (<97%). Gypsum rate had a significant effect on seed calcium content, but there was no difference between the two cultivars. Calcium content of the seed was 663, 721, 821, and 802 mg/kg for the 0, 560, 1120, and 1680 kg/ ha gypsum rates, respectively. The response of the 1120 and 1680 kg/ha rates were significantly different from the untreated control (0 kg/ha) and 560 kg/ha gypsum rate.