Internal and External Phosphorus Requirements for Optimum Grain Yield are Associated with P-utilization Efficiency of Wheat Cultivars

ABSTRACTConsiderable variation exists among wheat cultivars for phosphorus (P) acquisition and utilization to produce higher yields. We investigated critical P requirements for optimum grain yield of two wheat cultivars contrasting in P-use efficiency, i.e., NIA-Sunder (P-efficient) and NIA-Saarang (P-inefficient). Grain yield, P accumulation, and other P-efficiency relations of both cultivars increased with progressive addition of P, but at variable rates. NIA-Sunder exhibited higher grain yield, grain P concentration, harvest index, and P-use efficiency at all P levels as compared to NIA-Saarang. Internal P requirement for achieving 95% relative grain yield in NIA-Sunder and NIA-Saarang was obtained when P concentration in their grains was 4.07 and 3.48 mg g−1 recorded at external P levels of 57.2 and 78.1 mg kg−1 soil, respectively. Overall, NIA-Sunder accumulated 15% more grain P and required 27% less external P for attaining 95% relative yield than P-inefficient cultivar. Results suggested that inter...