春季低温对小麦花粉育性及粒数形成的影响

小麦拔节后遭遇春季低温,每穗粒数下降,产量降低。为探明春季低温引起每穗粒数减少的生理原因,以春性小麦扬麦16和半冬性小麦徐麦30为供试品种,研究小麦倒二叶出生期(昼夜5℃/–3℃)、孕穗期(昼夜8℃/–1℃)和开花期(昼夜12℃/4℃)分别进行低温处理对小麦花粉育性及每穗粒数形成的影响。结果表明:倒二叶出生期和孕穗期低温均导致2个小麦品种在二胞花粉期和三胞花粉期花药中的多糖物质淀粉和蛋白质的代谢异常,绒毡层解体延迟;孕穗期低温还造成花粉母细胞减数分裂中染色体配对异常、出现微核等情况,影响正常雄配子体形成;花粉败育率表现为倒二叶出生期低温处理>孕穗期低温处理>开花期低温处理,徐麦30败育率高于扬麦16;3个时期低温均显著降低了2个小麦品种结实小穗数、每小穗结实粒数和每穗粒数,以倒二叶出生期低温处理穗粒数降低的幅度最大。相关分析表明,春季低温引起花粉母细胞减数分裂异常、绒毡层延迟解体、花药营养物质供给不足导致的花粉育性下降,是春季低温导致小麦每穗粒数减少的主要原因。

Effects of low temperature in spring on fertility of pollen and formation of grain number in wheat

Grain yield and the number of grains per ear of wheat decreased under the low temperature after jointing stage.In order to explore the physiological reasons of the decrease of grains number per ear by low temperature in spring,the spring wheat variety Yangmai 16 and the semi-winter wheat variety Xumai 30 were used as tested varieties to analyze the effects of low temperature in spring on the fertility of pollen and the formation of grain numbers at the appearance of the penultimate leaf stage(5℃/–3℃,day/night),booting stage(8℃/–1℃,day/night),and anthesis stage(12℃/4℃,day/night).The results showed that low temperature at the appearance of the penultimate leaf stage and booting stage resulted in abnormal metabolism of starch and protein in the anther both at the binuclear and tri-nuclear pollen stages and delayed degradation of the tapetum.The low temperature at the booting stage caused abnormal meiosis of pollen mother cells,abnormalities in chromosome pairing,which affected the formation of male gametophyte.The abortion rate of pollen was more significantly increased under low temperature at the appearance of the penultimate leaf stage than that at the booting stage,and it was the minimum at anthesis stage.The abortion rate of pollen in Xumai 30 was higher than that in Yangmai 16.The low temperature at three stages had significant effects on the number of spikelets,the number of fertile spikelets and the number of grains per spikelet.The effect of low temperature at the appearance of the penultimate leaf stage on grains number per spikelet was the most significant.There was a significant positive correlation between the number of grains per spike and pollen fertility,which was affected by abnormal meiosis,delayed degradation of the tapetum,and undersupply of nutriment for anther development.Therefore,the decline of pollen fertility caused by low temperature in spring is the main reason for the decrease of grains number per spike.