Department of Plant Science and Agricultural Resources, Faculty of Agriculture, Khon Kaen University, Khon Kaen 40002, Thailand.
The root is an important plant part contributing to peanut productivity under water-limited conditions. Root volume, root surface area and root diameter may be characters responding to pre-flowering drought (PFD) in peanut. The objectives of this study were to investigate the responses to PFD for root surface area, root volume and root diameter and to determine the inter-relationships among the response of rooting traits and the response of yield. The experiment was conducted under field conditions in the dry season 2007 and 2009. A split-plot experiment in a 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, root diameter and root surface were measured by auger method at 25 days after emergence (DAE), first seed (R5) and physiological maturity (R7). Total dry weight and pod yield were measured at harvest. Root surface area of ICGV 98305 with increase in pod yield was greater in deeper soil layers under PFD compared to FC treatment at both stress and recovery periods. Under PFD conditions, the correlations between drought tolerance index (DTI) for root surface area at deeper soil layer and DTI for pod yield in both seasons were positive and significant at stress and recovery periods, but the correlations were not significant for root diameter and root volume. The response of peanut for root surface area at deeper soil layer contributed to pod yield. This finding could be useful for peanut production in these drought conditions. Keywords: Early season drought; Drought tolerance index; Root volume; Root diameter; Root surface area.