播种至苗期不同阶段低温对玉米幼苗生长及生理抗性的影响

为应对未来气候变化所产生的阶段性低温对寒地玉米幼苗建成的不利影响,以先玉335为试验材料,基于对寒地玉米田间温度条件的动态模拟,采用二因素完全随机设计,分别设置低温处理阶段（播后第1~5、6~10、11~15、16~20、21~25和26~30天）和低温持续时间（0、1、2、3、4和5d）处理,探讨了不同处理组合条件下玉米出苗进程、幼苗生长、生物量积累及抗性生理指标的变化差异。结果表明,播后至苗期各阶段经历1~5d低温处理后,均可降低玉米出苗速率和成苗率,抑制玉米幼苗的生长及生物量积累,并引起叶片叶绿素含量与最大光化学效率下降,以及渗透调节物质含量与膜脂过氧化水平的增加,其影响程度随低温持续时间的延长不断加剧,且以播种后11~25d特别是16~20d,即处于破土至出苗临界期的玉米植株对低温响应最为敏感。

Effects of Low Temperature under Different Phases between Sowing and Seedling Periods on Growth and Physiological Resistance of Maize Seedlings

In order to cope with the adverse effects of periodic low temperature caused by the future climate change on the maize seedlings establishment in cold region, maize variety Xianyu 335 was used as test material, and based on the dynamic simulation of maize field temperature condition in cold region, two-factor completely randomized design was applied at different low temperature treatment phases (1-5, 6-10, 11-15, 16-20, 21-25, 26-30 days after sowing) and durations (0, 1, 2, 3, 4, 5 days) were set up, respectively. The changes in differences of maize seedling emergence process, seedling growth, biomass accumulation and resistance physiological indexes among every treatment combination were compared and analyzed. The results showed that 1-5 days of low temperature treatment, no matter at which phase, could reduce the emergence rate and survival rate, inhibit the growth and biomass accumulation of maize seedlings, and caused the decrease of chlorophyll content and the maximum photochemical efficiency of leaves, as well as the increase of osmoregulation substance content and membrane lipid peroxidation level. The degree of influence was increasing with the low temperature durations, and the plants during 11-25 days after sowing, especially 16-20 days (the critical period of coleoptile break through the soil and seeding emergence) were most sensitive to low temperature.