Straw mulching enhanced the photosynthetic capacity of field maize by increasing the leaf N use efficiency

Abstract Better understanding on the photosynthetic regulation of yield will be useful to improve agricultural water use efficiency under straw mulching. The yield, photosynthetic parameters and related leaf traits were measured and compared between straw mulching (SM) and non-mulching (NM) treatments in a maize field of North China Plain in 2013–2015. Total aboveground biomass of the SM treatment increased by 7.1%, 11.2% and 14.7%, and grain yield increased by 11.5%, 6.8% and 12.1%, respectively for the three years, comparing to those of the NM treatment. Such increases were related to higher leaf area index (LAI) and leaf area duration, photosynthetic capacity per unit of area ( A max ) and the apparent quantum efficiency ( α ) for the SM treatment. Maximum LAI of the SM treatment were 17.2%, 19.2% and 20% higher than those of the NM treatment, respectively, for the three years. A max and α of the SM treatment were 7.9%–36.8% and 7.7%–16.7% higher than those of the NM treatment during different growth stages in the three years. A max and α were linearly correlated to leaf nitrogen content on mass basis ( N mass ). Liner regressions between A max and N mass , and between α and N mass were affected by straw mulching treatment, under which the slopes were similar but the intercepts were higher. With no significant increase of N mass in most measurements, the results suggested that the SM treatment improved N-use efficiency, which may be due to lower leakiness of the bundle-sheath cells to CO 2 ( L ) under the SM treatment. Collectively, the results help understanding the physiological basis of positive effect of the straw mulching on yield and quantified the photosynthetic parameters of summer maize in this area.