Photosynthetic light response characteristics of winter wheat at heading and flowering stages under saline water irrigation

Abstract

In order to reveal the photosynthetic physiological response mechanism for winter wheat under saline water irrigation, a field experiment was conducted in Yellow River Delta, Shandong, North China. Two irrigation treatments(irrigating 80mm with fresh water each at jointing, heading and milking stages, irrigating 80mm with fresh(0 g/L)-saline(3 g/L)-saline(3 g/L) water each at jointing, heading and milking stages) were designed. Leaf photosynthesis and photosynthetic light response characteristics were observed. The results show that, in comparison with fresh water irrigation (CK), saline water irrigation decreased net photosynthetic rate before noon at heading stage and flowering stage, but it can increase net photosynthetic rate in the afternoon due to the non-stomatal factors improved. The C3 plant new model of light response were introduced, compared with fresh water treatment, the maximum net photosynthetic rate (Pnmax) of winter wheat under saline water were increased by 2.27 and 1.58 μmol/m2/s at the heading and flowering stages respectively, light saturation point (LSP) were increased by 29.27 and 70.11 μmol/m2/s, light compensation point (LCP) decreased by 19.38 and 4.63 μmol/m2/s, dark respiration rate (Rd) decreased by 0.96 and 1.53, it showed that the saline water treatment enhanced the adaptability against strong light and high temperature conditions, promoted the ability using weak light of winter wheat. Therefore, saline water irrigation did not negatively affect leaf photosynthesis at heading and flowering stage of winter wheat.