Effects of soil improvement agents on photosynthesis and transpirationof saline-water irrigated winter wheat

Field experiment were conducted to determine the effects of soil improvement agents on photosynthetic rate, transpira-tion rate, stomatal conductance, chlorophyll content index of saline-water irrigated winter wheat. The experiment was conducted in high water table and sticky soil fields in coastal areas of Tianjin. The results of the study showed that adoption of appropriate soil improvement agents before winter wheat sowing increased photosynthetic rate, chlorophyll content index at heading or grain filling stage, and decreased stomatal conductance and transpiration rate at the same stages. 75 kg·100m^?2 soil improvement agent Ⅱ (40% weathered lignite + 40% phosphogypsum + 20% desulfurized gypsum) application before winter improved photosynthetic rate of winter wheat at grain-filling stage, and lowered transpiration rate of wheat at heading and grain-filling stages. 45 kg·100m^?2 soil im-provement agent I (20% weathered lignite + 40% phosphogypsum + 20% desulfurized gypsum + 20% zeolite powder) application before winter improved both photosynthetic and transpiration rates of winter wheat at heading stage. Saline-water irrigation significantly reduced winter wheat stomatal conductance. Stomatal conductance of winter wheat under 30 kg·100m^?2 soil improvement agent Ⅲ (40% phosphogypsum + 20% desulfurized gypsum + 40% zeolite powder) application reduced by 52.28% at heading stage and 39.51% at grain-filling stage compared with that of winter wheat without soil improvement agent. Application of 45 kg·100m^?2 soil improvement agent Ⅱ plus 30 kg·100m^?2 soil improvement agent Ⅲ, or 75 kg·100m?2 soil improvement agent Ⅱ before winter significantly increased chlorophyll content index of winter wheat at both heading and grain-filling stages. Application of 45 kg·100m^?2 soil improvement agent I plus 30 kg·100m^?2 soil improvement agent Ⅲ before winter maintained photosynthetic rate of saline-water irrigated winter wheat at high levels even under higher soil salt content. This shielded winter wheat transpiration rate from the effects of soil salinity.