微喷带灌溉对小麦灌浆期冠层温湿度变化和粒重的影响

2012—2013和2013—2014年度田间试验中设小麦灌浆初期不灌水(W0)、畦灌(W1)和小麦专用微喷带灌溉(W2)3个处理,并在灌浆中后期设置不同微喷时间和水量处理,以明确微喷带灌溉对小麦灌浆期冠层温、湿度和粒重的影响。灌浆初期10:00进行W2处理,当日中午穗层温度降低6.8~11.3℃,降幅明显大于W1处理;灌水后第2~4天与W1无显著差异,第4天与W0无显著差异。W2处理当日叶片水势显著大于W1处理,当日光合速率和次日叶片水势与光合速率及千粒重和籽粒产量均与W1无显著差异,且显著大于W0处理;W2的灌水利用效率显著大于W1处理。在小麦灌浆后期于10:00、12:00、14:00时采用微喷带喷水5 mm和10 mm均显著降低冠层温度,提高冠层相对湿度、旗叶水势和群体光合速率,且微喷时间越早越有利。本试验结果表明,小麦灌浆初期微喷补灌或中后期在预报高温当天10:00时微喷补水5~10 mm,可显著提高粒重和籽粒产量。

Effects of Irrigation with Micro-sprinkling Hoses on Canopy Temperature and Humidity at Filling Stage and Grain Weight of Wheat

We carried out a two-year field experiment in 2012–2013 and 2013–2014 growing seasons of winter wheat, with treatments of no irrigation (W0), border irrigation (W1), and irrigation with micro-sprinkling hoses special for wheat (W2). The W2 treatment was conducted at different time of a day in early or late grain filling stage with different amounts of irrigation in the middle and late filling stages. The results showed that the spike layer temperature of W2 decreased by 6.8–11.3°C after irrigating with micro-sprinkling hoses at 10:00 a.m. in early grain filling stage, and the decline was significantly greater than that of W1. However, no significant difference in temperature of spike layer was observed between W2 and W1 from the 2nd day to the 4th day after irrigation and between W2 and W0 at the 4th day after irrigation. The leaf water potential on the irrigation day was significantly higher in W2 than in W1. In contrast, leaf photosynthetic rate on the irrigation day, as well as leaf water potential and leaf photosynthetic rate on the next day were similar between W2 and W1. As a result, the grain weight and the grain yield in W2 and W1 were higher than those in W0 treatment. Besides, the irrigation water use efficiency of W2 was significantly higher than that of W1. When 5 or 10 mm of water was sprayed by micro-sprinkling hoses at 10:00, 12:00, and 14:00 hours in the late grain filling, the canopy temperature decreased significantly whereas the canopy relative humidity, the flag leaf water potential, and the canopy apparent photosynthetic rate tended to increase. During a day, earlier irrigation resulted in better improvement of water status and photosynthetic performance for wheat leaf. Our results suggest that supplementary irrigation with micro-sprinkling hoses should be conducted at early grain-filling stage or at 10:00 on a day during middle-to-late grain filling with 5–10 mm water spray each time when daily high temperature is forecasted.