Genetic analysis of introgression lines of Oryza rufipogon for improvement of low phosphorous tolerance in indica rice

Soil phosphorus (P) deficiency is one of the major challenges for rice cultivation. The present study was carried out under low soil P condition (available P, < 2 kg ha-1) to study the genetic variability, correlation, path and principal component analysis (PCA) in a set of 40 introgression lines derived from Samba Mahsuri (Oryza sativa ssp. indica) × Oryza rufipogon. High genotypic coefficient of variation and phenotypic coefficient of variation was recorded for productive tillers (PT), seed weight (SW), and grain yield (GY). High heritability coupled with high genetic advance was recorded for plant height (PH), PT, SW, number of spikelets/panicle (SPP), spikelet fertility, and GY. Correlation analysis revealed that grain yield had a significant positive association with PH, PT, panicle length, SPP, and SW. Regression analysis revealed that the grain yield was mainly influenced by PT and SW. This was confirmed by path analysis, wherein PT and SW exerted the highest direct positive effect on grain yield. The PCA revealed that the first two PCs contribute to maximum variability, which together accounted for 60% of the total variability. The traits PT and SW contributed the maximum to load/variance the total variability. Thus, the selection of introgression lines with a greater number of PT and higher SW would be the most appropriate strategy for yield improvement under low soil P condition in rice. Cluster analysis grouped introgression lines along with checks into three clusters. Overall, the study revealed the pattern genetic variability for low P tolerance in the introgression lines. This further helps in designing appropriate breeding strategies for the improvement of rice cultivars for low P tolerance.