The role of phosphorus supply in maximizing the leaf area, photosynthetic rate, coordinated to grain yield of summer maize

Understanding the responses of the leaf area index (LAI) and photosynthetic rate to phosphorus (P) fertilization is important for optimizing P management and obtaining high grain yield for summer maize. A field experiment with six rates of P application (0, 12.5, 25, 50, 100, 200 kg ha−1) was conducted in a maize field in 2014 and 2015. P application significantly increased the soil Olsen-P concentration, and the critical level of soil Olsen-P concentration for maximal shoot P concentration was 20.5 mg kg−1. As the shoot P concentration increased to 2.01 g kg−1 in 2014 and 2.40 g kg−1 in 2015, the LAI and net photosynthetic rate got maximum but then plateaued at higher shoot P concentration. The highest grain yield (11.6 Mg ha−1) was attained when the critical LAI and net photosynthetic rate was 4.85 m2 m−2 and 28.5 μmol CO2 m−2 s−1, respectively. The length of barren ear tips was reduced by optimizing the P application rate then increased grain yield. By properly managing P fertilization, maize growers can maximize the LAI and net photosynthetic rate and thereby attain high grain yields without applying excessive P.