Genetic and Protein Engineering

Plant root is one of the major organs for water and nutrient uptake from soil. Root development and amount of water absorption from the soil are closely related. Under drought condition, the success of crop plants oft en depends on growth of roots. In the present study, gravimetric experiment was conducted to evaluate the yield potential of released and pre-released groundnut genotypes. Root growth parameters such as root length, shoot length, shoot weight, leaf length, root volume and dry root weight were recorded in fi ve genotypes viz., KCG-2, TMV-2, GKVK-5, GKVK-3 and GKVK-13 under controlled and water stress conditions in pot experiment at University of Agricultural Sciences, Bangalore, India. Stress was imposed for

20 days during fl owering stage by balancing the amount of water applied to make it 50% stress. Analysis of variance revealed highly signifi cant diff erences for the traits observed indicating the existence of variability in the material selected. In controlled condition all the root traits exhibited higher mean values over stress condition in the genotypes studied except in GKVK-5

for root dry weight. In stress treatment GKVK-5, GKVK-3 and GKVK-13 genotypes exhibited higher mean values for root volume, root dry weight and root length. Genotypes GKVK-5, TMV-2 and KCG-2 recorded higher mean for shoot weight and leaf length. Among all genotypes GKVK-5 was identifi ed as high yielding with 2.8 to 3.0 t/ ha, with low to moderate Δ13C (17.53) and high δ18O (31.24) and low specifi c leaf area (107.76 cm2/g) and was found to have higher water use effi ciency or to be drought tolerant genotype indicating effective partitioning of the accumulated biomass towards root and shoot, while diverting relatively lesser towards shoot biomass. Hence, breeding for root development proved to be eff ective in increasing crop water use effi ciency and drought tolerance.