Analysis of Correlation and Path Coefficients among Yield and Biochemical Traits under Irrigated and Reproductive Stage Drought Stress in Oryza sativa L.

Inter-relationships among yield and fourteen biochemical traits were studied under NS and RSS in eighteen genotypes of upland rice. None of the biochemical traits showed significant phenotypic correlation with grain yield plant−1 under irrigated (NS), while grain yield plant−1 had highly significant and positive correlation with chlorophyll a, chlorophyll b, nitrate reductase, soluble sugar at flowering starch at re-watering and soluble sugar in leaf under reproductive stage drought stress (RSS). This indicated that these biochemical traits were important associates of grain yield under RSS. Out of 124 character pairs, the significant estimates of phenotypic correlations in either direction were shown by nine character pairs in NS and 21 character pairs under RSS. In path analysis, high order positive direct effects was exerted by soluble sugar upper root and starch at re-watering under NS and starch at maturity, followed by leaf starch and chlorophyll a under RSS. Nitrate reductase, soluble sugar at flowering and starch in leaf emerged as most important indirect yield contributors due to their high order positive indirect effects on grain yield under NS. While, in RSS, nitrate reductase, amylase, starch at flowering stage, soluble sugar at maturity, soluble sugar at flowering, soluble sugar in leaf, starch upper and lower root and chlorophyll a showed high order positive indirect effects via three to five other traits to appear at important indirect yield attributes. The results revealed that fairly greater number of correlations and path effects attained high estimates under RSS than the NS. This indicated that adverse reproductive stage drought stress played crucial role in conditioning the interrelationships between different characters. The biochemical traits identified as important direct and indirect yield contributors should be given due consideration in formulating selection strategy for isolating high yielding rice genotypes for favorable and drought prone condition.