Phosphorus acquisition and utilization related variables of pigeonpea germplasm by correlation, principal component and path analysis approaches

Phosphorus (P) acquisition and utilization related variables of fifty two geographically diverse genotypes of pigeonpea [Cajanus cajan (L.) Millsp.] were studied by using principal component, pearson correlation coefficient and path analysis in response to varied P levels. Principal component analysis depicted that root length, volume and ratio of root to shoot dry weight were not closely related while, root dry weight, area, perimeter and root acid phosphatase activity were highly correlated to each other under recommended dose of phosphorus [40 kg ha⁻¹ P nutrient (+P)]. A significant and moderate positive correlation was observed between ratio of root to shoot dry weight and root area, root volume and root length, while ratio of root to shoot dry weight had no correlation with root length under P fertilizer not (−P) in soil condition. Path analysis revealed that stem P content, root P content, leaf area and root area exhibited positive direct effects under +P condition. Principal component, correlation and path analysis approaches may be used in identification of selection criteria for genotypes from large pool of germplasm for breeding purpose.