Calcium Nutrition of Peanut Grown in Solution Culture. II. Pod-zone and Tissue Calcium Requirements for Fruiting of a Virginia and a Spanish Peanut

Abstract

ABSTRACT Virginia peanut types need more calcium (Ca) in the soil than Spanish types for high pod yield, but their actual soil solution and fruit tissue Ca requirements have not been well defined. A split root and pod solution culture technique was used to examine the effects of Ca concentration on fruiting of one Virginia cv. ‘Virginia Bunch 1’ and one Spanish peanut cv. ‘TMV-2’. Plants were grown in complete nutrient solution (root zone) containing 100 μM Ca, and six treatments imposed in which the pod zone solution Ca was controlled at 0 to 2500 μM. ‘TMV-2’ produced some mature seeds with no Ca added to the pod zone solution and 81% of maximum seed dry matter at 5 μM Ca, a concentration at which its pod dry matter production was close to maximum. In contrast, ‘Virginia Bunch 1’ produced no pods with no Ca added to the pod zone and only 28% of maximum pod dry matter at 5 μM Ca. ‘TMV-2’ required 6 and 21 μM Ca in the pod zone solution for 95% of maximum pod and seed production, respectively. The corresponding solution concentrations for ‘Virginia Bunch 1’ were 35 and 50 μM Ca. The seed dry matter production of ‘Virginia Bunch 1’ decreased with ≥112 μM Ca in the pod zone solution due to a decrease in individual seed mass, but there was no depression in the case of ‘TMV-2’ up to the highest pod zone solution concentration of 2500 μM Ca studied. The Ca concentration in pod walls and seeds of both cultivars increased with increase in Ca up to 500 μM in the pod zone, the effect being greater in ‘TMV-2’. However, the seed production of both cultivars was maximized at approximately the same seed Ca concentration of 0.04%. The results of this study have shown that the Spanish peanut cv. ‘TMV-2’ and the Virginia peanut cv. ‘Virginia Bunch 1’ have a similar tissue Ca requirement for seed growth despite the higher pod zone Ca requirement of ‘Virginia Bunch 1’.