甜荞结实性及授粉受精过程中花粉管的生长动态

Fecundity of common buckwheat and dynamic growth of pollen tube in pollination and fertilization

【目的】探究甜荞的结实性及授粉受精过程中花粉管的生长动态，为甜荞自交不亲和性机理的研究奠定基础。【方法】以同型花和异型花甜荞品种为材料，在温室条件下利用自然和人工杂交授粉， 调查结实率，并对异型花品种的自交和杂交花柱进行荧光显微观察。【结果】1）同型花品种结实率31.5%～72.7%，其为自花结实性品种；异型花品种的结实率为0～6.3%，其为自花不结实品种。2）异型花的异类型花之间杂交结实，其中以长花柱为母本杂交时的结实率高于以短花柱为母本杂交时的结实率；异型花的同类型花之间杂交时不结实或结实率很低，少量的结实发生在长花柱与长花柱类型杂交之间。3）在异型花品种中，长花柱与长花柱杂交授粉，花粉萌发，花粉管伸长，但在花柱的2/3处（时间为1～1.5 h）被抑制，其识别部位尚不清楚；短花柱与短花柱杂交授粉，花粉萌发，但花粉管没有伸长，因此其识别和抑制部位均在柱头；异类型花之间杂交花粉管发育正常，并且花粉发育速度快于同类型花之间杂交。【结论】异型花甜荞自交或同类型花之间杂交，花粉管在柱头或花柱中被抑制使甜荞结实率降低，从而降低产量。同型花品种自交可育，结实率提高，培育同型花甜荞是提高产量的有效手段。

[Objective] This study investigated fecundity of common buckwheat and dynamic growth of pollen tube in pollination and fertilization to provide foundation for the study of self-incompatibility mechanism of common buckwheat. [Method] In greenhouse, same type flowers and heteromorphic flowers were chosen to study seed-setting rates by naturally and artificially pollinating and to examine the self-pollinated and cross-pollinated styles by fluorescence microscopy. [Result] （1） The seed setting rate of same type flower was 31.5%--72.7% ,so it belonged to self-pollinated species. The heteromorphic flowers were self-incompatibilities with seed setting rate of 0--6.3%. （2） Common buckwheat species crossed with heteromorphic flowers presented higher seed setting rates with their long style flowers as the female parents than with their short style flowers as the female parents. No seeds or very low seeds occurred when own differ- ent types of flowers were cross-pollinated. （3） In different heteromorphic flower species, when different long style were cross-pollinated, their pollens germinated but their pollen tubes got inhibited at two third of the style length （1--1.5 h after pollination）. Recognition and inhibition sites of the pollen tubes were still elusive. When crossed between different short style, their pollens could germinate but their pollen tubes could not elongate,so both recognition and inhibition sites were at the stigma. When the different hetero- morphic flowers were cross-pollinated, their pollen tubes developed normally and pollen developed faster than that of the same type flowers formed when they were cross pollinated. [Conclusion] When common buckwheat and heteromophic flowers were self-pollinated or their different types of flowers were cross-poi linated, their pollen tubes were inhibited at the stigma or the style,which was the main reason of decreased seed setting rate and production. When same type flowers were self fertile, the seed setting rate increased. Therefore, breeding for same type flower variety is an effective tool to improve the yield of common buck- wheat.