Effect of conservation tillage on growth and grain yield of wheat under simulated rainfall conditions

The objective of this study was to investigate the effect of conservation tillage (CT) on growth and grain yield of wheat under different precipitation levels. In the present study, CT was compared to traditional bare soil tillage (BT) under different precipitation conditions simulated during the wheat growth stage, and the grain yield, dry matter weight and leaf area of plant, the photosynthesis of flag leaves and the soil moisture were measured. The results indicated that the effect of CT on growth and grain yield of wheat was significantly related to precipitation. At the 220 and 260 mm rainfall levels, CT significantly increased the dry matter weight, leaf area, photosynthesis of wheat and by this to increase the grain yield. In contrast, CT had no significant effect on the dry matter weight, leaf area, photosynthesis characteristics and grain yield of wheat at 300 mm rainfall level. In addition, both precipitation and CT significantly increased the soil moisture during wheat growth stage. Thus, we suggest that the reason CT had a different effect on the growth and grain yield of wheat at different precipitation levels may be that the soil moisture was sufficient for wheat growth at 300 mm rainfall; accordingly, CT had no significant effect on the growth and grain yield of wheat, even though it significantly increased the soil moisture. In contrast, as the soil moisture was significantly decreased at the 220 and 260 mm rainfall level, the plant growth was inhibited because the soil moisture was insufficient for wheat growth. CT significantly increased the soil moisture, thus promoting the plant growth and by this to increase the grain yield of wheat. Based on the results of the present study, we suggest that, in the case of wheat, the adoption of CT practices, including no tillage and straw mulching, in areas receiving 220-300 mm rainfall will provide benefits during the entire growth period.