Discerning of Ahu rice (Oryza sativa L.) landraces of Assam for phosphorus deficiency tolerance using molecular and morphological approaches

A set of 32 Ahu rice landraces was analyzed for the identification of P-efficient genotypes at three levels of P under field conditions. Based on molecular data of 7 Pup1 markers, the genotypes were grouped into two major clusters. Out of the 32 genotypes, 13 having consistent amplification of the entire 7 Pup1 markers and grouped in the same subcluster with Kasalath were identified as Pup1 positive group. Pool mean analysis showed highly significant genotypic variations (p ≤0.01 or 0.05) with G X E interaction for various yield traits, P-uptake and use efficiency. Heat map quantitative clustering groups the genotypes into 4 major clusters, indicating wide variation in response to differential P- levels of the environment. Analysis of genetic variability revealed moderate to high phenotypic and genotypic coefficient of variability, heritability and genetic advance for various critical yield contributing traits. The PCA analysis extracted 4 principal components, of which the first two components accounted for 71.50% of the total variance. Pearson’s correlation analysis revealed a significant positive association of grain yield with various yield parameters, P-uptake and use efficiency, while traits like sterility percent, plant height and days to flowering showed a negative correlation with grain yield. Path co-efficient analysis using yield per plant as the resultant dependent variable revealed direct positive effects by 11 traits with negligible residual effect of (0.0077). The present inquest revealed that genotypes with Pup1 gene have a lesser percent yield reduction than genotypes lacking Pup1. However, landraces like Gopinath with, devoid of Pup1 gene, gave at par yield potential with Pup1 positive genotypes. This indicates the probable presence of unidentified P-deficiency tolerance locus among the landraces. Following landraces Kolong, Ikhojoi, Koimurali and Sadakara with Pup1 positive were identified as promising in P-use efficiency.