黄淮海地区不同播期夏玉米籽粒脱水过程和产量形成的比较

以“浚单29”夏玉米为试验材料，于2014年和2015年在山东泰安农业气象试验站进行3个播期的播种试验，3个播期分别为6月5日（M−10处理）、6月15日（M处理）和6月25日（M+10处理），分析播期对夏玉米生育阶段、籽粒脱水过程和干物质积累以及产量的影响。结果表明：随着播期的推迟，夏玉米全生育期持续时间缩短，其中抽雄−成熟期的变化幅度最大，M−10处理较M和M+10处理缩短了7～10d。提前播期（M−10）下，夏玉米的籽粒含水率、籽粒干物重均高于晚播，生理成熟前早播的夏玉米比晚播处理脱水慢，而生理成熟后早播的夏玉米比晚播脱水快。不同播期使夏玉米处于不同的气象条件下，显著影响了产量及产量构成因素。与当地常年正常播期（6月15日）相比，播期提前（M−10处理）增加夏玉米百粒重和收获指数，减少秃尖比；与晚播（6月25日）相比，提前播期下夏玉米穗粒数显著提高4.5%（2014年）和7.8%（2015年），百粒重显著提高12.3%（2014年）和16.8%（2015年），秃尖比显著降低21.4%（2014年）和12.5%（2015年），可见，播期越晚，产量越低。因此，夏玉米“浚单29”在黄淮海地区可以适当早播，而播种过迟容易导致生育期延后，易遭遇低温，严重影响产量。

Comparison of Grain Dehydration Process and Yield Formation for Summer Maize under Different Sowing Dates in Huanghuaihai Plain

To reveal the impacts of sowing date on growth stage, grain dehydration process, dry matter accumulation and yield of summer maize, an experiment with three sowing dates was conducted at the agrometeorological experimental station of Taian in Shandong province in 2014 and 2015, in which the summer maize variety of Jundan 29 was used. The three sowing dates were June 5 (denoted as M−10), June 15 (denoted as M) and June 25 (denoted as M+10). The results showed that under the delay of sowing date (M+10), the duration of the summer maize at the whole growth period was shortened. Among them, the duration change from tasseling to maturity period was the largest, which was 7−10 days shorter than that of M and M+10. The water content and dry matter accumulation in kernels in summer maize of M−10 were higher than those of M+10. The grain dehydration rate of early sowing before physiological maturity was slower than that of late sowing, while that of early sowing after physiological maturity was faster than that of late sowing. The yield and yield structure factors of summer maize were significantly affected by different sowing dates under different meteorological conditions. Compared with the normal sowing date (June 15) of local summer maize, early sowing date (M−10) could increase the 100-grain weight and harvest index of summer maize, and reduce the bald point ratio. Compared with late sowing date (June 25), the grains per spike of summer maize under early sowing was significantly increased by 4.5% (2014) and 7.8% (2015) respectively. The 100-grain weight under early sowing was significantly increased by 12.3% (2014) and 16.8% (2015), and the bare tip ratio was significantly decreased by 21.4% (2014) and 12.5% (2015). It could be seen that the later the sowing date, the lower the yield. As a result, summer maize of Jundan 29 could be sown appropriately early in Huanghuaihai plain. Later sowing might easily lead to the delay of growth period and the occurrence of low temperature, which seriously affected the yield.