覆膜和补灌对杂交谷子产量形成与水分利用效率的影响

Effects of Plastic-Film Mulching and Supplementary Irrigation on Yield Formation and Water Use Efficiency of Hybrid Millet

针对干旱对杂交谷子的生产限制及耗水与产量的关系尚不明确的问题,通过大田试验研究了不同降水年型下地膜覆盖与补灌对杂交谷子产量形成与耗水的影响。结果表明,播后40~80 d是杂交谷子需水关键期,拔节时补灌增加了单位面积有效穗数,110 mm水分蒸散是提高抽穗期生物产量的充分条件;全生育期耗水400 mm可获得较高籽粒产量。抽穗期生物产量是籽粒产量形成的基础,产量形成具有"递进决定"的特征,覆膜结合补灌显著提高了抽穗期生物产量。丰水年覆盖条件下或在欠水年,补灌增加了花后干物质量;欠水年雨养花后物质在营养器官中累积,补灌促进了营养器官物质向籽粒转移。补灌下覆膜籽粒增产10.1%~18.6%,比露地提高水分利用效率10.7%~19.4%。在欠水年,雨养时覆膜下的籽粒产量较露地更低,补灌是显著提高产量和水分利用效率的必要条件。丰水年覆膜能显著提高籽粒产量和补灌的增产效应,欠水年补灌的增产效果则优于覆盖。地膜覆盖结合拔节期或抽穗期适量补灌是提高杂交谷子产量和水分利用效率的有效方法。

Hybrid millet is a new type of foxtail millet and widely planted in semi-arid plateau area in North China. However, drought is one of the major limited factors for increasing grain yield effectively. So we conducted field experiments in 2013 （wet year） and 2014 （dry year） to examine the effect of supplementary irrigation with plastic-film mulching on yield formation and water use efficiency of hybrid millet. For hybrid millet, 40-80 days after sowing was the critical period of water requirement, the supplementary irrigation at jointing stage helped to increase seed heads quantity, from jointing to heading not less than 110 mm of evapotranspiration （ET） was the sufficient condition for producing enough biomass. Achieving a higher grain yield needed an ET of 400 mm during whole growing season. The biomass at heading stage determined the subsequent grain yield with a characteris- tic of ＂stage hierarchy determination＂, supplementary irrigation with plastic-film mulching increased biomass at heading stage significantly. Under mulching of wet year or in dry year, supplementary irrigation increased dry matter production after flowering. In dry year under rainfed condition dry matter after flowering accumulated in vegetative organs, supplementary irrigation promoted to translocate the dry matter from vegetative organs into grains. Under supplementary irrigation, plastic-film mulching increased grain yield by 10.1%-18.6% and WUE by 10.7%-19.4% compared with un-mulching, respectively. In dry year, because of the persistent drought before heading, under rainfed condition plastic-film mulching resulted in a grain yield lower than un-mulching, supplementary irrigation was a necessary condition for increasing yield and WUE. In wet year, supplementary irrigation decreased WUE, plastic-film mulching increased grain yield and improved the yield-increasing effect of supplementary irrigation. In dry year, the yield-increasing effect of supplementary irrigation was better than that of plastic-film mulching. In conclusion, plastic-film mulching combined with suit irrigation at jointing and/or heading is an effective way to increase yield and WUE of hybrid millet.