Wei Yang1, Shiwen Guo2, Pinfang Li1,3, Riquan Song4, Jian Yu4. 1. Department of Soil and Water sciences, College of Resources and Environmental Sciences, China Agricultural University, Beijing, China. 2. Department of Ecological Sciences and Engineering, College of Resources and Environmental Sciences, China Agricultural University, Beijing, China. 3. Key Laboratory of Arable Land Conservation (North China), Ministry of Agriculture, Beijing, China. 4. Water Resources Research Institute of Inner Mongolia, Hohhot, China.
Abstract
BACKGROUND: Two lysimeter experiments with maize plants were conducted to investigate the effect of combined superabsorbent polymer (SAP) and fulvic acid (FA) application on photosynthetic gas exchange and water use efficiency (WUE) under deficit irrigation conditions. Soil SAP (45 kg hm-2 ) was applied while sowing, and FA solution (2 g L-1 ) was sprayed onto the crop canopy three times at later plant growth periods. RESULTS: Combining SAP and FA application significantly improved plant photosynthesis, chlorophyll contents and instantaneous WUE while maintaining optimal leaf stomatal transpiration. The effect of using the combined chemicals on photosynthesis and leaf instantaneous WUE was superior to the effects of their individual applications. Compared with plots not treated with chemicals, soil SAP significantly improved the yield by 12% and grain WUE by 10% when averaged across the two experiments, whereas foliar FA application did not affect yield and grain WUE. In contrast, the combined use of the two chemicals significantly increased the yield by 20% and grain WUE by 26%, largely attributed to the increase in grain number. CONCLUSION: Soil SAP and foliar FA use under low rainfall conditions had little influence on crop water consumption but improved plant WUE by enhancing photosynthesis and increasing kernel number.
BACKGROUND: Two lysimeter experiments with maize plants were conducted to investigate the effect of combined superabsorbent polymer (SAP) and fulvic acid (FA) application on photosynthetic gas exchange and water use efficiency (WUE) under deficit irrigation conditions. Soil SAP (45 kg hm-2 ) was applied while sowing, and FA solution (2 g L-1 ) was sprayed onto the crop canopy three times at later plant growth periods. RESULTS: Combining SAP and FA application significantly improved plant photosynthesis, chlorophyll contents and instantaneous WUE while maintaining optimal leaf stomatal transpiration. The effect of using the combined chemicals on photosynthesis and leaf instantaneous WUE was superior to the effects of their individual applications. Compared with plots not treated with chemicals, soil SAP significantly improved the yield by 12% and grain WUE by 10% when averaged across the two experiments, whereas foliar FA application did not affect yield and grain WUE. In contrast, the combined use of the two chemicals significantly increased the yield by 20% and grain WUE by 26%, largely attributed to the increase in grain number. CONCLUSION: Soil SAP and foliar FA use under low rainfall conditions had little influence on crop water consumption but improved plant WUE by enhancing photosynthesis and increasing kernel number.