Grain yield and phosphorus use efficiency of wheat and pea in a high yielding environment

The aim of the present study was to evaluate the response of grain yield, phosphorus (P) use efficiency (PUE, g yield g–1 P available) and related root traits of wheat and pea to different P availabilities in a high yielding environment (e.g.: yield higher than 10 Mg ha-1 for wheat). Two experiments were conducted in southern Chile. Treatments consisted of the combination of (i) two crops (spring-bred wheat and pea) and (ii) three rates of P fertilization (0 (P0), 100 (P1) and 250 (P2) kg P ha–1). Grain yield of wheat was more sensitive to P deficiency than pea. Wheat showed consistently higher (P < 0.01) PUE than pea, averaging 195 and 125 g yield g–1 P available, respectively. This was principally ascribed to the highest (P < 0.01) P utilization efficiency of wheat (430 vs. 249 g yield g–1 P uptake for wheat and pea, respectively). On the contrary, the P uptake efficiency was slightly different for these crops (0.44 and 0.49 g P g–1 P available, respectively). However, these crops presented different strategies for P acquisition. Wheat had a higher (P < 0.01) soil exploratory capacity than pea, while pea showed a higher (P < 0.01) P uptake per unit of root length than wheat. Wheat showed higher PUE than pea; however, crop differences are ascribed to differences in phosphorus utilization rather than to phosphorus uptake efficiency. This information could contribute to optimized soil P use and improved crop fertilization management.