Morpho-agronomic evaluation for delineation of salinity stress specific response and tolerance status of rice genotypes

Analysis of variance revealed significant differences amongst eighteen rice genotypes evaluated in randomized block design with two replications under normal (pH 8.15 and EC 0.28 dsm-1) and salt affected (pH 9.18 and EC 1.22 dsm-1) field conditions. Considerably higher relative mean values for the eleven morpho-agronomic traits, such as, panicles per plant, panicle length, 100 seed weight, spikelets per panicle, filled grains per panicle, unfilled grains per panicle, root length, root volume, root dry weight, biological yield and grain yield per plant, were recorded in tolerant genotypes compared to moderately tolerant and susceptible genotypes. Root volume, root dry weight and unfilled grains per panicle were observed to be more affected in susceptible genotypes. Keeping into consideration the relative mean performance, the genotypes were categorized as highly tolerant, moderately tolerant and susceptible to saline condition. Eigen vectors from the three principal component axes revealed the importance of panicle length, filled grains per panicle, 100-seed weight, root length and root dry weight as main contributors to genetic divergence among the genotypes. Average taxonomic distance based hierarchical classification and principal component analysis based spatial distribution patterns unambiguously discriminated the tolerant and susceptible genotypes.