干旱区膜下滴灌条件下洋葱水分生产函数与优化灌溉制度

为探索西北内陆旱区膜下滴灌条件下洋葱节水、高产和高效的灌溉制度，开展了2 a田间试验，分析了洋葱的耗水规律及其影响因素，建立了洋葱的水分生产函数，并对洋葱的灌溉制度进行了优化。结果表明：膜下滴灌条件下洋葱的耗水量为170.1～395.7 mm，产量随灌水量和耗水量的增加而增加，水分利用效率则随灌水量的增加而降低。苗期和成熟期亏水对洋葱产量和水分利用效率无显著影响。洋葱水分敏感指数在鳞茎膨大期最大，发叶期次之，苗期和成熟期较小。膜下滴灌条件下，西北旱区干旱年洋葱全生育期灌水量为375 mm时，可获得较高的产量；其优化灌溉制度为苗期灌水30～40 mm，发叶期灌水130～140 mm，鳞茎膨大期灌水170～190 mm，成熟期灌水25 mm，灌水间隔可采用5 d。该优化灌溉制度对西北内陆旱区洋葱的节水灌溉实践具有一定参考价值。

Water production function and optimal irrigation schedules for onion with drip irrigation and mulch of plastic film in arid region

In order to investigate a water-saving, high yield and efficient irrigation schedule for onion in arid region of Northwest China, a two-year field experiment with regulated deficit irrigation for onion has been conducted. Crop evapotranspiration and its influencing factors for onion were analyzed, crop water production function was established, and the optimal irrigation schedule for onion was determined. Results showed that the crop evapotranspiration of onion with drip irrigation under mulch of plastic film was 170.1-395.7 mm. With the increasing of irrigation and crop evapotranspiration, the onion bulb yield increased, while the water use efficiency decreased. Onion bulb yield and water use efficiency were not significantly affected by water stress during the establishment and ripening stages. The sensitive index was found the largest at the bulbification stage, followed by the development stage and relatively small at the establishment and ripening stages. Higher onion bulb yield can be obtained when the irrigation depth was up to 375 mm in drought years in arid region of Northwest China. The recommended amount of irrigation is 30-40, 130-140, 170-190 mm and 25 mm for the stages of establishment, development, bulbification and ripening, respectively, and the irrigation intervals are 5 days. The optimal irrigation schedule is expected to provide scientific implications for water-saving irrigation of onion crops in the arid region of Northwest China.