弱光胁迫对不同耐荫型玉米果穗发育及内源激素含量的影响

2010—2011年以耐荫性较弱的玉米杂交种豫玉22和耐荫性较强的玉米杂交种郑单958为材料,在抽雄前3 d开始进行弱光胁迫处理,吐丝后10 d恢复自然光照,研究弱光胁迫及光恢复对不同耐荫型玉米果穗生长发育及其内源激素含量的影响。结果表明:弱光胁迫下,玉米果穗生长发育明显减缓,穗长、穗粗和果穗干物质积累显著减小,秃尖度变大;穗行数、穗粒数和籽粒库容显著降低;吐丝期果穗顶部小穗子房发育停滞,已有败育迹象的籽粒在恢复自然光照后无明显改善;豫玉22果穗和籽粒性状在处理间的差异程度均大于郑单958。弱光胁迫下,两玉米杂交种果穗的ABA和ZR含量均升高,而GA含量和GA/ABA比值均降低;IAA含量和IAA/ABA比值在郑单958果穗中表现为升高,而豫玉22则表现为下降。

Effects of low-light stress on maize ear development and endogenous hormones content of two maize hybrids (Zea mays L.) with different shade-tolerance

Light is one of the most important environmental factor influecing the growth and development of maize (Zea mays L.). Sufficient light during the growing period is the basis of high yield formation of maize. However, there are always prolonged rainy days during maize growing season in the Huang-huai-hai region, which are detrimental for maize yield formation. And prolonged rainy days at flowering stage bring more severe damage to maize production. Low-light environment leads to a decrease in photosynthetic rate, a reduction and redistribution of biomass, an extension of anthesis to silking interval, and a significant reduction of ear kernel number and grain yield. And there are significant differences in maize genotypes responses to low light stress. Previous studies have elucidated the effects of endogenous hormones on the apical kernels abortion and under low-light stress. However, whether the endogenous hormones have influence on the whole ear development process is unknown. A split plot experiment was conducted under field conditions during 2010 and 2011, to study the effects of shading and light recovery on the growth and development of maize ear and endogenous hormones of two maize hybrids. The main plots are light treatment (natural light and 50% shading) and sub-plots are cultivars (low light sensitive hybrid YY22 and low light tolerance hybrid ZD958). In the low light treatment, maize plants were shaded with 50% transmittance shading nets from 3 days before tasselling to 10 days after silking. The results showed that the growth and development of maize ear was delayed, ear length, ear diameter, ear dry weight, ear row number, kernel number and kernel sink capacity were significantly decreased while barren tip increased under low light conditions with low light sensitive maize hybrids changed more. Spikelet ovary in ear apical showed signs of abortion at silking stage. The abortion progress of the kernel could not be disrupted by the recovery of natural light. ABA and ZR content of both maize hybrids ears increased under low-light stress while GA content and GA/ABA ratio of both maize hybrids decreased. IAA content and IAA/ABA ratio of ZD958 was increased while YY22 decreased. The recovery of natural light in a short time had little effect on the established hormone synthetic mechanisms.