花期弱光胁迫对玉米穗粒数的影响

为明确花期弱光对玉米穗粒数的影响规律,采用人工遮光模拟弱光胁迫,设置抽雄始期和吐丝期持续10 d60%和90%两个不同遮光强度的弱光处理,研究了花期弱光对雌穗小花受精、结实,干物质积累及其向雌穗分配的影响。结果发现,花期弱光胁迫导致玉米地上部总干物质日增重量降低,干物质分配到雌穗的比例减少,雌穗生长变慢,受精结实率降低,影响程度随遮光率的增加而增大。抽雄始期60%和90%遮光处理10 d后恢复自然光照结实率较处理结束时的受精率均明显提高,吐丝期60%和90%遮光处理10 d后恢复自然光照结实率较处理结束时的受精率降低和持平。抽雄始期光照不足导致穗粒数较对照下降57%~91%;吐丝始期光照不足导致穗粒数较对照下降43%~81%。无论对于抽雄始期还是吐丝期,遮光处理期间的日平均光合有效辐射强度在穗粒形成中作用最大,其次为处理期间的地上部总干物质日增重。对于吐丝期,处理期间的日平均温度对穗粒数也具有直接的正效应。

Effect of Low Light Stress at Flowering Stage on Kernel Number per Ear of Maize

In order to explicit the effect of low light at flowering stage on the kernel number per ear of maize,we simulated low light stress through artificial shading,conducted two shading rate（60%,90%）treatments for continuous 10 days at initial tasseling stage and at silking stage,and studied the effects of low light at flowering stage on the fertilization and seed setting of florets on fe-male ears,as well as the accumulation of dry matter and its distribution to female ears. It was found that low light stress at flowering stage led to the decrease in daily weight gain of aboveground total dry matter,the reduction in distribution proportion of dry matter to female ears,the slowing of female ear growth,and the decline in rate of fertilization and seed setting;the influence of low light en-larged when the shading rate increased. Compared with the floret fertilization rate at the end of both 60% and 90% shading rate treatments at initial tasseling stage,the final seed setting rate was markedly increased. While in comparison with the floret fertiliza-tion rate at the end of both 60% and 90% shading rate treatments at silking stage,the final seed setting rate was decreased or simi-lar. The final kernel number per ear of maize was decreased by 57% -91% and 43% -81% due to the light insufficient at initial tasseling stage and at silking stage,respectively. The daily average photosynthetically active radiation intensity in shading treatment period of both initial tasseling stage and silking stage had the greatest effect on the formation of kernels,followed by daily weight gain of aboveground total dry matter in shading treatment period. The daily average temperature in shading treatment period of silking stage also had directly positive effect on the kernel number per ear of maize.