播期对雨养旱地春玉米生长发育及水分利用的影响

为了解决陕西渭北旱塬地区玉米播种期干旱缺水造成出苗不全、不整齐,导致产量低而不稳的问题,设置6个不同播期,研究对春玉米生长发育、干物质生产、产量形成、水分利用及环境因子的影响。结果表明,随着播期的推迟,玉米的生育期明显缩短,营养生长期、营养生长与生殖生长并进期变化范围为2~19 d,生殖生长阶段则相对稳定,变化范围仅为?3~5 d。在一定的时间范围内,不同播期处理间的单株干物质生产没有明显差异,但由于受播期调整后的土壤含水量变化影响,适宜播期的玉米花后雌穗干物质积累量、籽粒产量及水分利用效率分别较早播和晚播提高4.0%~23.6%、3.9%~24.5%和6.6%~14.5%。早播影响产量的主要因素是播种期土壤含水量低而造成的出苗差,实际收获穗数不足;晚播影响产量的主要因素是生殖生长期后移,有效积温和日照时数减少造成的花后干物质积累减少、千粒重下降。适期播种可以增加田间实际收获穗数,促进雌穗花后干物质积累,提高玉米的水分利用效率。结合该区生态因素,5月4日以前适墒播种是玉米高产的有效避旱播期。研究结果可为该区春玉米抗逆避旱高产栽培提供有效的技术参考。

Effects of Sowing Time on Spring Maize (Zea mays L.) Growth and Water Use Efficiency in Rainfed Dryland

To solve the problem of incomplete and irregular maize seeding growth and low and unstable yield in the semiarid region of Weibei Shaanxi Province, we designed six sowing times to study their impact on spring maize growth and development,, dry matter production, grain yield, water use efficiency and environmental factors. The results showed that maize growth period was shortened with postponing sowing time, the vegetative growth stage and the overlapping stage of vegetative and reproductive growth had the variations from 2 to 19 days. But reproductive growth stage was relatively stable, with the change from –3 to 5 days. In a certain range of time, dry matter production per plant in different sowing treatments was not obvious different, however, dry matter accumulation in spikes after flowering, yield and water use efficiency in treatments with appropriate sowing time were 4.0%–23.6%, 3.9%–24.5% and 6.6%–14.5% higher respectively, than these with early sowing time or delayed sowing time, resulting from the changed soil water content by adjusting the sowing date. Yield was highly correlated with soil moisture content in a certain sowing date, rainfall before flowering, effective accumulated temperature after flowering and sunshine hours after flowering. Thousand grain weight was highly correlated with sunshine hours after flowering. In the treatments with early sowing time, the main factor affecting maize yield was the poor soil moisture content that caused less low effective panicle in unit area and low emergence rate. In the treatment with later sowing time, the main factors affecting yield were the decreased effective accumulated temperature and sunshine hours during the reproductive growth stage, resulting in less dry matter accumulation after flowering and lower thousand grain weight. In the treatment with suitable sowing time, actual harvesting panicles and dry matter accumulation of female ear after flowering increased, and water use efficiency was improved. Considering ecological factors and result in this study, the best suitable maize sowing time should be before May 4th for drought avoidance and maize high yield in this region. The research results provide effective cultivation techniques to avoid drought stress for spring maize in this area.