Screening Rice (Oryza Sativa L.) Genotypes for Drought Tolerance Under Field Conditions

We evaluated the root pulling resistance (RPR) technique developed at the International Rice Research Institute (IRRI) for transplanted rice (Oryza sativa L.) to determine its applicability for assessing the drought tolerance of direct seeded rice. Experiments were conducted in 1988 and 1989 at the University of Arkansas at Pine Bluff Agricultural Research Farm. Fifty genotypes from four countries were grown with and without irrigation. The genotypes identified as drought tolerant germplasm by the RPR method in both years were significantly correlated. In both 1988 and 1 989, RPR was directly related to maximum root length, root number, and root dry weight. Root dry weight (RWT) had the highest correlation with RPR in both 1988 (r= 0.82 ** ) and 1989 (r=0.46 * * ). Cultivars with the greatest root lengths and root dry weights had the highest root pulling resistances