Effect of different supplemental irrigation strategies on photosynthetic characteristics and water use efficiency of wheat

Abstract

Water resource scarcity has been increasingly becoming a threat to wheat (Triticum aestivum L.) production in North China Plain. Thus, a water-saving irrigation strategy should be urgently developed. We conducted a 2-yr field experiment to examine the effects of supplemental irrigation (SI) on the photosynthetic characteristics and water use efficiency (WUE) of wheat. This study employed two SI strategies: A quota SI using 60 mm water at jointing and anthesis stages (W1) and soil moisture testing SI (W2), which brings the target relative soil water content of 0-40 cm soil layer to 70% field capacity at jointing and anthesis stages. A non-irrigated treatment (W0) was used as control. Results showed that W2 significantly improved the water uptake in 80-160 cm soil layer compared with W1. Moreover, flag leaf photosynthetic rate, stomatal conductance, and transpiration 14-28 d after anthesis were highest in W2 successively followed by W1 and W0, and the difference was significant. Dry matter (DM) at maturity, DM accumulation post-anthesis and its contribution ratio to grain were significantly higher in W2 than in the other treatments. 13CO2 labeling results indicated that W2 promoted δ13C-photosynthate accumulation in grain. In 2012-2013 growing season, the grain yield increased by 56.05% and 5.74% and WUE increased by 26.17% and 6.34% in W2 compared with those in W0 and W1, respectively. In 2013-2014 growing season, the grain yield increased by 41.82% and 5.90% and WUE increased by 28.24% and 13.03% in W2 compared with those in W0 and W1, respectively. Therefore, W2 is a high-yield and water-saving treatment.