花期前后高温对玉米花粉发育及结实率的影响

Effects of high temperature during flowering on pollen development and seed setting rate of maize(Zea mays L.)

为明确花期不同梯度高温对玉米开花特性和花粉活力的影响,以热敏感基因型玉米品种‘驻玉309’为试验材料,于花期(吐丝前8d~吐丝后8d)进行不同程度高温(31、34和37℃)处理,测定受精结实率、雄穗性状、开花时间、花粉活力及花粉超显微结构,分析生育期前后的高温对受精结实、开花特性及花粉活力的影响。结果表明,花期高温胁迫显著降低玉米受精结实率,对抽雄吐丝间隔期无显著影响,但盛花期提前;极端高温则导致玉米抽雄期显著提前、开花期和盛花期延后,抽雄吐丝间隔期延长;花期高温使花粉粒形态皱缩、萌发孔内陷,显著降低花粉活力,且温度越高,花粉活力降低幅度越大。因此,花期前后高温通过影响玉米影响雄穗开花特性、延长抽雄吐丝间隔期、影响花粉粒形态、降低花粉活力,从而降低玉米的小花受精率和籽粒结实率。

In order to clarify the effects of different gradient high temperature(31,34 and 37℃)on the flowering characteristics and pollen viability of maize,a heat-sensitive genotype‘Zhuyu 309’was used as the experimental material at the flowering stage(0-8 dbefore silking to 0-8 dafter silking).The fertilization rate,ear traits,flowering time,pollen viability and pollen ultrastructure of maize were investigated.The results showed that the high temperature stress during flowering significantly reduced the fertilization rate of maize,and had no significant effect on the interval between tasselling and silking.However,the full flowering stage of maize was advanced.The extreme high temperature advanced the tasseling stage significantly,postponed the stage of flowering and full flowering and prolonged the interval between tasselling and silking.The surface of pollen grain shriveled and collapsed,the germinal aperture became invaginated and the pollen viability decreased significantly at high temperature during flowering.The higher the temperature,the greater the decrease of pollen viability.In conclusion,high temperature at the flowering stage affected the flowering characteristics of tassel,prolonged the interval between tasselling and silking,affected the morphology of pollen grains and reduced the pollen viability,thus reduced the fertilization rate of florets and seed setting rate of maize.