Abstract

It is well known that phosphorus (P) addition helps mitigate the adverse effects of water deficit stress on plants. However, the efficiency of spring wheat genotypes in the use of both components has not been addressed. The objective of this study was to evaluate the combined effect of P and water limiting conditions over phosphorus use efficiency (PUE) and water use efficiency (WUE) to categorize different spring wheat genotypes. Eight spring wheat genotypes were selected based on their yield tolerance index score (YTI) obtained from a previous screening of 384 wheat genotypes. They were evaluated for their ability to use P and water. Plants were grown under semi-controlled conditions on an Andisol with soil P-concentration of 3.4 mg P kg(-1) (-P), which was enriched to 30 mg P kg(-1) (+P). Irrigation was applied at two levels: well-watered (+W) and 30% +W (water stressed,-W). Wheat was grown until the end of its phenological cycle. The P and water scarcity produced a delay in wheat development, especially in the first vegetative stages. Genotypic differences in growth, development, P accumulation, and yield were observed in response to P and water limiting conditions. The lowest performance in plant growth and grain yield was regarded when the P and water restrictions were applied. However, differences were observed in terms of PUE and WUE. In this sense, spring wheat genotypes were grouped into three and four classes for PUE and WUE, respectively. The most efficient genotype for all the conditions was "QUP2418 ", which obtained the highest score in the consolidated PUE and WUE ranking. On the contrary, "FONTAGRO 92 "and "F6CL091337 " were the most inefficient genotypes. Strong correlations were observed between PUE components and WUE, enabling the future selection of co-adapted wheat genotypes efficient in the use of P and water.