外源硅对花期高温胁迫下杂交水稻授粉结实特性的影响

Effects of exogenous silicon on the pollination and fertility characteristics of hybrid rice under heat stress during anthesis

以杂交中熟籼稻品种金优63、汕优63为供试材料,采用盆栽试验,在水稻生长前期连续喷施3次硅酸钠(Na2SiO3·9H2O),于人工气候箱内在水稻开花期进行常温(日均温26.6℃,日最高温度29.4℃)和高温(日均温33.2℃,日最高温度40.1℃)处理5 d,研究施硅在花期高温胁迫下对杂交水稻剑叶叶绿素含量、光合性能、抗氧化酶活性、丙二醛(MDA)含量、花粉活力、花药酸性转化酶活性、柱头授粉性能和结实率等的影响.结果表明:与对照相比,施硅可显著提高高温胁迫下水稻剑叶叶绿素含量,提高净光合速率和气孔导度,减少胞间CO2浓度,增强叶片光合作用,减少MDA含量,提高超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性;提高花药中可溶性酸性转化酶活性和花粉活力,增加花粉囊基部裂口宽度,提高水稻每柱头上授粉总数、萌发数、花粉萌发率和萌发数大于10粒者所占的比例,降低花粉总数小于20粒者所占的比例;使金优63、汕优63结实率的降低分别减轻13.4%、14.1%.因此,在水稻生长前期喷施外源硅,可减轻水稻在开花期结实率的降低,提高杂交水稻的抗热性.

Taking two medium-maturing indica rice hybrids Jinyou 63 and Shanyou 63 as test mate- rials, this paper studied the effects of applying silicon fertilizer on the flag leaf chlorophyll content, photosynthetic properties, antioxidant enzyme activities, malondialdehyde （MDA） content, pollen vigor, anther acid invertase activity, pollination, and seed-setting of hybrid rice under the heat stress during anthesis. This study was conducted in pots and under growth chamber. Soluble solu- tion of silicon fertilizer applied as Na2 SiO3 . 9H2O was sprayed on the growing plants after early jointing stage, with three times successively and at an interval of one week. The pots were then moved into growth chamber to subject to normal temperature vs. high temperature （termed as heat stress） for five days. In treatment normal temperature, the average daily temperature was set at 26.6 ℃, and the maximum daily temperature was set at 29.4 ℃ ; in treatment high temperature, the average and the maximum daily temperature were set at 33.2 ℃ and 40.1 ℃, respectively. As compared with the control, applying silicon increased the flag leaf chlorophyll content significantly, improved the net photosynthetic rate and stomatal conductance, decreased the accumulative inter-cellular C02 concentration, improved the leaf photosynthesis, reduced the MDA content, and im- proved the activities of SOD, POD and CAT under heat stress. In addition, applying silicon im- proved the anther acid invertase activity and the pollen vigor, increased the anther basal dehiscence width, total number of pollination per stigma, germinated number, germination rate of pollen, and percentage of florets with more than 10 germinated pollen grains, decreased the percentage of florets with fewer than 20 germinated pollen grains, and thus, alleviated the fertility loss of Jinyou 63 and Shanyou 63 under heat stress by 13.4% and 14.1%, respectively. It was suggested that spraying exogenous silicon in the early growth period of rice could mitigate the decrease of seed-setting at flowering stage, and improve the heat resistance of hybrid rice.