Effect of Cultivar, Irrigation, and Soil Calcium on Runner Peanut Response to Gypsum

Calcium is oft en limiting to peanut (Arachis hypogaea L.) yield, grade, and germination in the southeastern United States. The response of large-seeded (Georgia-06G) and small-seeded (Georgia Green) runner peanuts to gypsum applications was evaluated in 14 tests in southern Alabama and Georgia. Experiments were conducted in a randomized complete block design with four replications of gypsum applications as main treatments (0, 560, 1120, and 1680 kg ha(-1)) in soils with a range of soil Ca (178-498 mg kg(-1)) in both irrigated and non-irrigated tests. Increases in yield, grade, seed Ca, and germination were significant with increased gypsum application for non-irrigated tests when data were combined. In the non-irrigated tests, yield increases ranged from 500 to 1000 kg ha(-1) and grade indicated by sound mature kernels (SMK) increased 3.4 to 5%. Critical pegging zone soil Ca values of 150 and 250 mg kg(-1) were evaluated and found appropriate for irrigated and non-irrigated peanuts, respectively. Georgia-06G had lower seed Ca concentrations and slightly lower germination than Georgia Green. More than 95% germination of Georgia-06G and Georgia Green was observed when seed Ca concentrations were > 600 mg kg(-1). Analysis of Ca concentrations in nearly mature seeds pre-harvest may provide an indication of seed germination quality as seed Ca concentration increased at approximately the same rate as seed size from immature white to mature black peanut maturity classes using the hull-scrape method.