Dissecting the Genetic Relationship between Root Morphological Traits with Grain Yield of Introgression Lines (ILs) Derived from Wild Rice (Oryza rufipogon Griff) under Low Soil Phosphorous Condition

Soil phosphorous (P) deficiency is one of the limiting factors in rice production in both upland and rainfed lowland ecosystems. Since P is diffusion limited in depleted root zones, understanding the link between root morphological traits and yields is crucial for improving rice productivity. To understand this link, phenotypic screening experiment was conducted for the 38 ILs (BC1F6) derived from the wild rice (Oryza rufipogon Griff) along with the six checks in specialized low P plots and normal soil P (RDF) plot at ICAR-IIRR, Hyderabad during rice growing season Kharif-2020 by adapting augmented block design. The genotypes were screened for grain yield along with root traits such as tiller number per plant (TN), shoot length (SL), root length (RL), root volume (RV), shoot fresh weight (SFW), shoot dry weight (SDW), root fresh weight (RFW), root dry weight (RDW), root to shoot ration on wet weight basis (RSRWW), root to shoot on dry weight basis (RSRDW), SPAD chlorophyll meter reading (SCMR). The results from ANOVA revealed that, MSS due to genotypes, (checks + genotypes) were significant ((p<0.01 and p<0.05)) for most of the root architectural traits and for two different regime of P under investigation. Wide range of genetic variation was recorded for the traits such as RL, RV, SFW, SDW, RFW, RDW, RSRWW, RSRDW and GYP with high GCV and PCV and high h2 coupled with high GAM under both P gradient conditions. Strong inter-correlation among the component traits was observed for the root traits such as RV (0.43**: 0.50**), SFW(0.81**:0.60**), SDW (0.65**: 0.81**), RFW (0.87**:0.64**), RDW (0.83**: 0.87**) and RL (0.36**: 0.43**) along with GYP (0.52**) under low soil P and normal soil P. Principal component analysis with first four PCs revealed existence of 69.40 and 70.30% of total variance and clustering analysis identified the promising genotypes as IL-9-10, IL-11-2, IL-21-8, IL-19-3, IL-22-1, IL-23-2, IL-23-7, IL-31-3, IL-42-3, IL-67-2, IL-69-1, IL-75-2, Swarna and Rasi with root traits RV, RDW, RFW, RL, and GYP are effective traits for rice cultivation.