Hotspot screening of early maturing rice genotypes and genetic variability studies under sodicity
An experiment was conducted with 39 rice genotypes to screen for salt tolerance and evaluate potential variation among the genotypes under sodic conditions. All the 39 rice genotypes along with two check varieties (TRY2 & TRY5) were screened in vitro for salt tolerance by imposing 100 mM NaHCO3 at the seedling stage under hydroponics and a salt injury score was given based on morphological symptoms. Observations on 12 biometrical traits were recorded under field sodic conditions and subjected to variability analysis. The ANOVA revealed that there was a significant difference for the 11 traits among the genotypes except for flag leaf breadth. Among the genotypes, the highest single plant yield was recorded by RG 50 (36.83 g). A correlation study revealed that, single plant yield exhibited significant and positive genotypic and phenotypic relation with panicle harvest index, the number of grains per panicle and panicle length. Path analysis showed that the traits viz., panicle harvest index, plant height and panicle length had a very high and positive direct effect on single plant yield. The traits viz., flag leaf breadth, SPAD meter reading and number of productive tillers per plant had a high and positive direct effect on single plant yield. In vitro studies revealed that the genotype RG113 was found to be highly tolerant to salt stress and it also showed a significantly higher yield (35.42 g) under field sodicity. The genotypes RG22, RG150, RG162 and RG188 which showed tolerance under in vitro screening and the moderately tolerant genotypes RG26, RG50, RG95, RG107, RG123 and RG176 were exhibiting significant yield under field sodicity conditions. Therefore, in order to breed for high yielding salt-tolerant rice varieties, the identified genotypes could be exploited as donor genotypes.
Keywords: Rice, correlation, path analysis, Hydroponics, sodicity
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