Photosynthetic characteristics and grain yield of winter wheat (Triticum aestivum L.) in response to fertilizer, precipitation, and soil water storage before sowing under the ridge and furrow system: A path analysis

The ridge and furrow (RF) system can improve the soil moisture and temperature conditions, as well as increasing the grain yield and water use efficiency. However, the combined effects of the fertilizer amount, precipitation during the growing season (PGS), and soil water storage before sowing (SWSS) on the photosynthetic characteristics and yield under this system are still unclear in winter wheat. Thus, in this study, we used path analysis to determine the effects of these three factors based on a field experiment conducted for five years in a semiarid region of Northwest China. Path analysis showed that precipitation during the sowing to filling stage (PSF) in winter wheat had the greatest influence on the photosynthesis gas exchange characteristics of flag leaves in the filling stage, followed by the fertilizer amount. And the determination coefficients of PSF on the photosynthetic rate (Pn), transpiration rate, stomatal conductance (Gs), leaf instantaneous water use efficiency (WUE) and relative chlorophyll content (SPAD value) were 0.331, 0.868, 0.864, 0.820, and 0.414, respectively. The most important factor for the grain yield was SWSS, where the coefficient of determination was 0.838, followed by the fertilizer amount and PGS, and the indirect effect of the fertilizer amount on SWSS was negative. Therefore, our results suggest that SWSS has an important effect on the grain yield in winter wheat under the RF system in semiarid regions, and thus improving the SWSS can obtain better increases in the grain yield compared with fertilizer amount.