Variability for Drought Related Traits of Virginia-Type Peanut Cultivars and Advanced Breeding Lines

Water deficit is increasingly becoming a limiting factor for peanut production in the Virginia–Carolina (VC) peanut growing region. Even though extensive research efforts have been made worldwide to improve drought tolerance in peanut, performance of genotypes largely depends on the environment in which they grow and no such information is available for the VC area. The objective of this study was to determine the variability for CO2 assimilation rate (A), stomatal conductance (gs), transpiration efficiency (A:gs), specific leaf area (SLA), chlorophyll content estimate (soil plant analysis development [SPAD] meter readings), stomata number per square centimeter and per leaf, and canopy temperature depression (CTD) of 18 peanut (Arachis hypogaea L.) virginia-type cultivars and breeding lines grown in rain-fed plots in southeastern Virginia. The relationship between physiological and agronomic traits was then analyzed. Genotype had a significant effect on all physiological traits. Excepting CTD, year also had a significant effect on all physiological characteristics. The genotype × year interaction was not significant for A, gs, A:gs, SPAD, and SLA suggesting dominant controlling factors for these traits. Under water stress in both years, pod yield was consistently associated with A (higher A results in higher yield) and SPAD (greener leaves results in higher yield). These results suggest that development of cultivars with greener leaves and higher A when gs is low may ensure better yields under rain-fed conditions in the VC region.