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

Abstract

A set of thirty two Ahu rice landraces were analyzed for identification of P-efficient genotypes. Based on molecular data of 7 Pup1 markers, the genotypes were grouped into two major clusters. Out of the 32 genotypes, 13 genotypes having consistent amplification of the entire 7 Pup1 markers and grouped in same subcluster with Kasalath were identified as Pup1 positive group. Field evaluation was conducted in three different levels of P (0, 20 and 40KgP₂O₅/ha). Pool mean analysis showed high significant genotypic variations (P≤0.01 or 0.05) with G X E interaction for various yield traits, P-uptake and use efficiency. Heatmap quantitative clustering group the genotypes into 4 major clusters indicating wide variation in response to differential P- levels environment. Analysis of genetic variability revealed moderate to high PCV, GCV, heritability and GAM for various critical yield contributing traits. The PCA analysis extracted 4 principal components in which the first two components accounted for 71.50 % of the total variance. Pearson’s correlation analysis revealed 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 exhibits negative correlation with grain yield. Path co-efficient analysis using yield per plant as 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 lesser percent yield reduction than Pup1 devoid genotypes. However, landraces like Gopinath with devoid Pup1 gene exhibit at par yield potential with Pup1 positive genotypes. This indicates the probable presence of unidentified P-deficiency tolerance locus among the landraces. Landraces like Kolong, Ikhojoi, Koimurali and Sadakara  with Pup1 positive were identified as promising in P-use efficiency.