Rhizobium and phosphorus influence on lentil seed protein and lipid

Abstract

Root nodulation by rhizobial bacteria and P fertilization may affect seed protein and lipid composition in plants by altering nitrogen (N) and phosphorus (P) nutrition or by eliciting metabolic responses by the host plant. This study was conducted to determine the effects of rhizobium and P fertilization on seed protein and lipid contents and yield of lentil (Lens culinaris Medik). Lentil was grown to maturity in a greenhouse with P levels of 0 (low) and 50 (high) mg kg^‐1 soil with or without inoculation with Rhizobium bacteria. At the low level of P, protein and lipid concentrations and protein contents were significantly higher in inoculated than in uninoculated plants. Seed dry weight and protein concentrations and contents were higher in inoculated than in uninoculated plants at the high level of P. Seed protein/lipid (Pro/L) concentration ratios varied between inoculated and uninoculated plants at both P levels, and was related to the intensity of root nodulation. Lipid and protein contents were highly correlated with P content in lentil seeds. Seed lipid and protein contents were lower at the high level of P in uninoculated than inoculated plants. The data indicate different patterns of seed P accumulation and different relationships between seed P content and protein and lipid contents in inoculated and uninoculated plants. This might indicate that the intensity of nodulation altered the response of seed protein and lipid metabolism to increasing P availability, which affected protein and lipid ratios.