吐丝前高温胁迫对不同耐热型夏玉米产量及穗发育特征的影响

Effects of Pre-Silking High Temperature Stress on Yield and Ear Development Characteristics of Different Heat-Resistant Summer Maize Cultivars

【目的】吐丝前高温是影响玉米雌雄穗发育的重要因素之一,对玉米产量形成至关重要。探明吐丝前高温胁迫对玉米产量及雌雄穗发育进程的影响,为玉米稳产高产提供保障。【方法】以花粒期耐热型玉米品种郑单958和热敏感型玉米品种联创808为供试材料,采用盆栽试验,在第9片叶展开期至吐丝期,移入人工智能温室进行高温胁迫(最高温度/最低温度为40/30℃),对照的最高温度/最低温度为35/25℃,研究高温胁迫对不同耐热型玉米产量、雌雄穗生长发育及外观形态结构、花粉花丝微观结构和光合特性的影响。【结果】第9片叶展开期至吐丝期高温胁迫显著降低了夏玉米穗长、行粒数、穗粒数和粒重,进而导致产量显著下降。与对照相比,高温胁迫下郑单958和联创808行粒数分别降低22.21%和24.59%,穗粒数分别降低29.85%和27.80%,千粒重分别降低24.04%和17.47%,导致籽粒产量分别降低44.98%和40.88%,差异均达显著水平。高温胁迫抑制了2个玉米品种雌雄穗发育,雌、雄穗干重和雌穗长度显著降低,光合性能显著降低,开花吐丝间隔期(ASI)拉长。高温胁迫后,郑单958和联创808吐丝期雄穗干重分别降低39.42%和15.60%,雌穗干重分别降低22.50%和15.56%,穗位叶净光合速率分别降低48.70%和56.48%,开花吐丝间隔期(ASI)分别达7 d和6 d,雌穗吐丝时间推迟是ASI拉长的主要原因。高温胁迫对玉米花粉及花丝表面超微结构均产生了明显影响,2个玉米品种花粉粒表面均出现干缩褶皱,外壳出现网状纹突起,萌发孔内陷;玉米花丝表面褶皱,花丝毛数明显降低,且存在的花丝毛几乎全部倒伏于花丝表面上,造成花丝接受花粉面积减少,且郑单958花粉花丝受损程度明显重于联创808。【结论】第9片叶展开期至吐丝期高温胁迫,对耐热型品种郑单958的产量形成、光合特性和雌雄穗发育的影响均高于热敏感型品种联创808。第9片叶展开期至吐丝期高温胁迫导致粉花丝微观形态受损,抑制雌雄穗发育,显著降低玉米光合能力,使得穗粒数和粒重减少,籽粒产量显著降低。因此,生产中适宜玉米品种的选用需参考不同区域高温逆境易发生阶段来确定。

【Objective】Pre-silking high temperature is likely to cause large negative impacts on maize yield, which is one of the important factors affecting ear development. This study was aimed to clarify the influence of pre-flowering high temperature on grain yield and ear development process, which was one of great significance for the stable and high yield of maize. 【Method】In this study, heat-resistant maize varieties Zhengdan958 and heat-sensitive maize varieties Lianchuang808 at flowering stage were used as research materials in artificial intelligence greenhouse, and then the influence of different high temperature of 40/30℃ and 35/25℃ on grain yield, ear development, ultrastructure of pollen and filament and photosynthetic characteristics from V9 to silking period were investigated.【Result】High temperature stress from V9 to silking period reduced the ear length, grain number and kernel weight of different genotypes summer maize, which led to a significant decrease in yield. Compared with control(35/25℃), the row grain number of Zhengdan 958 and Lianchuang 808 under high temperature significantly decreased by 22.21% and 24.59%, respectively;The kernel number per ear decreased by 29.85% and 27.80%, respectively;The thousand kernel weight decreased by 24.04% and 17.47%, respectively;The grain yield decreased by 44.98% and 40.88%, respectively. The dry weight of tassel, dry weight of ear, ear length and net photosynthetic rate of Zhengdan958 and Lianchuang808 under high temperature stress from V9 to silking period were significantly decreased 39.42% and 15.60%, 22.50% and15.56%,48.70% and 56.48% compared with control(35/25℃), respectively. The anthesis silking interval(ASI) of Zhengdan958 and Lianchuang808 increased to 7 d and 6 d as a result of delay of silking period rather than tasseling period. High temperature stress had obvious influence on the ultrastructure of maize pollen and filament surface of two maize varieties. Under high temperature stress, the surface of the pollen grain shriveled and collapsed, net vein protuberance and collapsed germinal aperture. At the same time, the filament surface shrank horizontally, the number of filament hair significantly reduced, and almost all residual filament hair lodged on the surface of the filament, which reduced the filament area of accepting the pollen.【Conclusion】High temperature stress from V9 to silking period were more serious on yield formation, photosynthetic characteristics and ear development of Zhengdan958 than Lianchuang808. High temperature stress from V9 to silking period significantly damaged the pollen and filament morphology, inhibited the development of tassel and ear, reduced the photosynthetic capacity, and decreased the kernel number per ear and kernel weight of two maize varieties, which significantly reduced the grain yield of maize. Therefore, the selection of maize varieties in field depended on the period of high temperature stress.