有限供水下冬小麦全程耗水特征定量研究

Quantitative study of water consumption characteristics of winter wheat under deficit irrigation

为明确冬小麦不同水分条件下全生育过程日耗水及阶段耗水特征,在北京地区利用蒸渗仪系统连续监测了几种灌溉处理(W4:起身水+孕穗水+开花水+灌浆水;W2:拔节水+开花水;W1:拔节水;W0:无灌水)耗水动态变化。结果表明:冬小麦全生育期的耗水动态可分为3个阶段:(1)播种至11月底的冬前阶段,这个阶段日耗水量波动明显,一般低于3 mm/d;(2)12月上旬至来年2月底的冬季阶段,这个阶段日耗水量低于0.4 mm/d,且波动很小;(3)3月初小麦返青至收获的春后生长阶段,这个阶段日耗水量总体上是一个先升高后降低的过程,但波动很大,每次灌水都会引起1个日耗水高峰的出现。耗水日变化呈单峰或双峰曲线,高峰出现在正午前后,高峰值因灌水处理而有明显差异,灌水多则耗水峰值显著升高,而夜间耗水量及其在不同处理间差异均很小。拔节至成熟期是冬小麦耗水的主要时期,该期耗水占总耗水60%以上。减少灌溉会增加土壤贮水消耗,但降低了总耗水量。综合比较表明,在有限灌溉下,拔节水和开花水组合是高产和高水分效率相统一的灌溉模式。

From October of 2011 to June of 2012, water consumption of a winter wheat cultivar Jingdong 22 under four irrigation treatments was monitored continuously using 24 weighing lysimeters in Beijing, China. The weighing lysimeters monitored water consumption of winter wheat at an interval of five minutes. Soil water content within all the lysimeters was adjusted to field capacity before plantation. The four irrigation treatments were W0 （no irrigation after plantation） , W1 （one irrigation after plantation at the jointing stage）, W2 （two irrigations after plantation at the jointing and flowering stages, respectively） , and W4 （ four irrigations after plantation at the erecting, booting, flowering and grain-filling stages, respectively）. The amount of water applied in each irrigation was 40 mm. Rainfall during the growth season was kept away from the lysimeters with an automatic rain-proof shelter. The experiment results showed that water consumption during this winter wheat season could be divided into three stages. The first stage was from the plantation date to the stable freezing date at early December of 2011. Daily water consumption during this stage fluctuated significantly and was usually less than 3 mm/day. Total water consumption during this stage was between 32 to 35mm. The second stage was during freezing season spanned from early December of 2011 to early March of 2012. During this stage, daily water consumption was less than 0.4 mm/d and fluctuated little. Total water consumption during this stage was between 21 to 24 mm. The third stage was fromgreen-up in early March of 2012 to harvest. During this stage, daily water consumption increased first, reached the highest value around heading stage, remained at high value until mid-grain-filling and decreased quickly approaching ripening, with large increase of daily water consumption after each irrigation Changes of evapotranspiration rates showed patterns of single or double peak curves for each day, with different peaks appearing around midday for the four treatments. Evapotranspiration rates were significantly correlated to total radiation, temperature, and relative humidity, with the highest correlation coefficient with total radiation. Night water consumption and its variation were small for all irrigation treatments. Water consumption of winter wheat mainly happened after the jointing stage. With increasing irrigation amount, more irrigation water and less soil water were consumed. In the treatments of W1 and W0, soil water contributed 62% and 76% of total water consumption, respectively. In the W2 treatment, irrigation water contributed 32%, and soil water contributed 50% of water consumption. Irrigation water contributed to 50%, and soil water contributed 36% of water consumption of the W4 treatment. Grain yield levels of the four treatments were in the order of W4〉W2 〉WI〉 W0, whereas water use efficiencies of the four treatments were W2〉W4〉WI〉W0. Among the deficit irrigation treatments, incorporation of irrigations at the jointing and flowering stages leaded to high grain yield and water use efficiency, while water use efficiencies for the four treatments were similar （about 15 kg/hm2/mm）.