Holm S O
Department of Ecological Botany, University of Umeå, S-901 87 Umeå, Sweden.
New Phytol. 1994 Mar;126(3):541-547. doi: 10.1111/j.1469-8137.1994.tb04253.x.
The aim of this study was to test the hypothesis that increased pollination enhances the probability of'pollen competition'in Betula pubescent. In an in vitro test, the germination of pollen from three B. pubescens trees, increased with increasing pollen density (r = 0·82, 0·81 and 0·82, respectively). Pollen tubes grew at different rates in styles when testing different paternal/maternal combinations. Evidence was obtained to suggest that these differences might be attributed to both maternal and paternal effects. Further, increasing the number of tubes per style tended to increase the length of the longest tube per style, but had no significant effect on the mean length of the tubes. The r values, for the correlations of lengths with numbers of pollen tubes per style, were lower in two natural B pubescens populations than in the data from a controlled pollination experiment, is concluded that selection among male gametes may occur after supplementary pollination in B. pubescens, but in natural situations, pollen deposition is usually too low for pollen Selection to be a common occurrence.
授粉增加会提高毛桦中“花粉竞争”的概率。在一项体外试验中，来自三棵毛桦树的花粉萌发率随花粉密度的增加而提高（相关系数分别为0.82、0.81和0.82）。在测试不同父本/母本组合时，花粉管在花柱中的生长速度不同。有证据表明，这些差异可能归因于母本和父本效应。此外，增加每个花柱中的花粉管数量往往会增加每个花柱中最长花粉管的长度，但对花粉管的平均长度没有显著影响。在两个天然毛桦种群中，花粉管长度与每个花柱中花粉管数量的相关性r值低于控制授粉实验的数据。由此得出结论，在毛桦中，补充授粉后可能会在雄配子间发生选择，但在自然情况下，花粉沉积量通常过低，以至于花粉选择很少发生。
