EFFECT OF MID-SEASON DROUGHT AND RECOVERY ON PHYSIOLOGICAL TRAITS AND ROOT SYSTEM IN PEANUT GENOTYPES (Arachis hypogaea L.)

Physiological traits are useful as representative characters for drought tolerance in peanut. The information on the responses of diverse peanut genotypes for physiological characters under mid-season drought is rather limited. The aim of this study was to examine the physiological traits for drought tolerance in diverse peanut genotypes responses under mid-season drought. The experiment was conducted from November 2011 to March 2012 and from November 2012 to March 2013. The experimental design was a split plot in randomized complete block. Two water regimes were assigned as the main plot (field capacity and mid-season drought). Five peanut genotypes were assigned in sub plot. Data were recorded for percent of root length density, relative water content (RWC) and stomatal conductance at 30, 45, 60, 75 and 90 days after planting. Shoot growth and pod growth rate were calculated. Drought significantly decreased RWC and stomatal conductance, but it increased root length density. High genotypic variation for root and physiological traits were observed at mid-season drought and after recovery. Associated of physiological traits and biomass and pod yield were higher at mid-season drought and after recovery than at the initiation of drought. Genotypes KKU 60, ICGV 98305 and Tifton 8 increase high water uptake by root system except for Tainan 9 and KS 2. Selection for physiological traits using RWC and stomatal conductance might be effective improving peanut for drought tolerance. The knowledge of this study will be useful for breeding of peanut for mid-season drought condition.