Improved Salinity Tolerance by Phosphorus Fertilizer in Two Phaseolus vulgaris Recombinant Inbred Lines Contrasting in Their P-Efficiency

Legumes' sensitivity to salt is exacerbated under growth conditions requiring nitrogen fixation by the plant. Phosphorus (P) deficiency is widespread in legumes, especially common bean (Phaseolus vulgaris L). To examine the performance of P. vulgaris under salt stress conditions, a field experiment was conducted using two recombinants inbred lines (RILs) 115 (P-deficiency tolerant) and 147 (P-deficiency susceptible), grown under different salinity levels (L) (1.56, 4.78, and 8.83 dS m(-1) as LI, L2, and L3, respectively) and supplied with four P rates (0, 30, 60, and 90 kg ha(-1) P as P0, P30, P60, and P90, respectively) in order to assess the impact of P on salt tolerance. Results indicate that growing both RILs at P60 or P90 under all salinity levels (especially L1) significantly increased total chlorophyll, carotenoids, total soluble sugars, total free amino acids, and proline. Increasing P supply up to P60 under all salinity levels significantly induced higher accumulation of P, K+, Ca2+ and Mg2+ leaves in both RILs. Based on quadratic response over all locations, the maximum seed yield of 1.465 t ha(-1) could be obtained at application of P 81.0 kg ha-1 in RIL115, while seed yield of 1.275 t ha(-1) could be obtained with P rate of 78.3 kg ha(-1) in RIL147. RIL115 exhibited more salt-tolerance with positive consequence on plant biomass and grain yield stability. Improved salt tolerance through adequate P fertilization is likely a promising strategy to improve P. vulgaris salinity tolerance and thus productivity, a response that seems to be P-rate dependent.