Responses of rooting traits in peanut genotypes under pre-flowering drought stress

The root is an important plant part contributing to peanut productivity underwater-limited conditions. Root volume, root surface area and root diameter may becharacters responding to pre-flowering drought (PFD) in peanut. The objectives ofthis study were to investigate the responses to PFD for root surface area, rootvolume and root diameter and to determine the inter-relationships among theresponse of rooting traits and the response of yield. The experiment was conductedunder field conditions in the dry season 2007 and 2009. A split-plot experiment ina randomized complete block design was used. The main plots were field capacity(FC) and PFD and six peanut genotypes as the sub-plots. Root volume, rootdiameter and root surface were measured by auger method at 25 days afteremergence (DAE), first seed (R5) and physiological maturity (R7). Total dryweight and pod yield were measured at harvest. Root surface area of ICGV 98305with increase in pod yield was greater in deeper soil layers under PFD compared toFC treatment at both stress and recovery periods. Under PFD conditions, thecorrelations between drought tolerance index (DTI) for root surface area at deepersoil layer and DTI for pod yield in both seasons were positive and significant atstress and recovery periods, but the correlations were not significant for rootdiameter and root volume. The response of peanut for root surface area at deepersoil layer contributed to pod yield. This finding could be useful for peanutproduction in these drought conditions.Keywords: Early season drought; Drought tolerance index; Root volume; Rootdiameter; Root surface area.