冬小麦小花发育及结实特性对叶面喷硼的响应

【目的】硼是植物生长发育所必需的微量元素,与植物的细胞与功能、 花粉管发育伸长以及受精过程的正常进行有特殊作用。本研究通过小花发育后期叶面喷施硼肥,探讨硼肥对小麦小花发育及结实成粒的调控效应,以期为增加小麦穗粒数、 提高产量调控技术的研究提供参考。【方法】试验于2012~2014年在河南农业大学科教示范园区(3486N, 11359E)进行,以当前主推的半冬性品种豫麦49-198为供试材料,在拔节后25 d叶面喷施清水(对照S0)、 硼肥(硼砂Na2B4O710H2O,含硼11.3%,处理S1),观察记载不同小穗位小花发育的动态变化及形态特征,按常规考种法记载不同小穗位(基部、 中部和顶部)结实粒数、 每小穗结实粒数和每小穗不同花位结实粒数。【结果】喷硼处理麦穗基部、 中部小穗位的可孕小花小花数显著高于对照,其可孕小花的结实率较对照分别提高5.85%、 12.55%。进一步分析可知,喷硼处理抑制了基部和中部小穗小花的退化速率及可孕小花的败育速率,其中基部小穗位的小花退化速率降低7.47%,可孕小花败育速率降低20.07%; 中部小穗位小花的退化速率降低12.06%,可孕小花败育速率降低35%。然而,喷硼处理对顶部小穗位的小花退化速率和可孕花败育速率均无抑制作用。喷硼处理还可显著促进不同小穗位的不同花位小花结实,尤其对促进第4花位弱势小花成粒效果显著。【结论】在冬小麦小花退化高峰之前(拔节后25 d),采取叶面喷施硼肥,可明显降低基部小穗和中部小穗小花的退化速率与可孕小花的败育速率,从而提高单穗的可孕花结实率,最终获得较高的结实粒数。

Responses of floret development and grain setting characteristics of winter wheat to foliar spray boron

Objectives] Boron, one of the essential trace element for plant growth and development, has special function on the normal development of pollen tube elongation and fertilization process. This study explored influences of applying boron on floral development and grain-setting for providing references to the chemical regulation of increasing the number of grains per spike and the yield.Methods] Field experiments were conducted in the Science and Technology Demonstration Park of Henan Agricultural University during the 2012-2013 and 2013-2014 growing seasons.Wheat cultivar Yumai 49-198 was chosen for test material and 0.2%borate solution was foliar sprayed 25 days after the jointing stage ( S1 ) , with water as control ( S0 ) .EMZ-TR dissecting microscope was used to observe and record the young spikelets'differentiation process in the main stem, and that of differentiation of young spikelet at different stages.At the maturity period, the grain number in spikelet at basal, central, and apical of wheat plant, and those in each spikelet at different floret positions were counted.Results]The grain-setting rates of fertile floret on the basal and central spikelet of wheat sprayed with borate were increased by 5.85%and 12.55%respectively, compared with control, the floret's degeneration rates at the basal spikelet were decreased by 7.47%, and the infertility rate is decreased by 20.07%.The floret's degeneration rate at the central spikelets of the borate treatment is decreased by 12.06% and the infertility rate is decreased by 35%.The significant decrease in the degeneration and infertility rate by borate was mainly happened in the basal and central spikelet floret, not in the apical spikelet floret.Further analysis showed that the boron spraying could significantly promote florets grain-setting at different floret positions of different spikelets, especially promote seeds of the fourth floret position which is weak floret.Conclusions]The degeneration rates of florets and the abortion rates of fertile florets at basal and central spikelet positions can be significantly reduced by spraying boron at the 25 days after the jointing stage, as a result, improving the grain-setting rates of single spike and getting the more grain number.