Proline, catalase and root traits as indices of drought resistance in bold grained rice (Oryza sativa) genotypes
AbstractThe present experiment was carried out with 39 bold grained rice genotypes to study the genetic variability of the traits conferring drought resistance and to screen the drought tolerant rice genotypes
with a view to formulate an efficient breeding programme for time bound genetic enhancement. The field experiment was grown during Sali season of 2007 to estimate the genetic variability of eight quantitative traits; root weight (g), number of primary roots, number of tillers/plant, root length (cm),shoot weight (g), root:shoot ratio by length and root:shoot ratio by weight. The data for the quantitative traits were recorded after 60 days of transplanting. The analysis of variance of eight quantitative traits
revealed that there was significant genetic variation among the genotypes for the traits conferring drought resistance. The genotypic coefficient of variation (GCV), phenotypic coefficient of variation (PCV), heritability in broad sense (h2bs) and genetic advance (GA) as percent mean were estimated for all the eight quantitative traits. Small difference between GCV and PCV estimates was observed for shoot length (cm), root length (cm), number of primary roots, shoot weight (g), number of tillers/plant
and root:shoot ratio by length suggesting that these characters were little influenced by environment and could be substantially improved through selection breeding program. Out of 39 rice genotypes, 7 genotypes including 2 checks (Ranjit and Monohar Sail) were selected on the basis of morphometric traits for drought resistance. Fifteen day old seedlings of seven selected rice genotypes were subjected to different osmotics of PEG-6000 (0.0, -0.4 and -0.8 MPa) to evaluate the effect of drought stress on proline, protein and antioxidant enzyme catalase. Poline content and catalase activity analyses further suggested that five selected bold grained rice genotypes (excluding two checks) namely Halodhar, George Sail, Kapili Dhan, Karmi Sail and Baodum were potentially drought tolerant.