Pollen allelopathy of Stellera chamaejasme on pollen germination and seed set of main species in a High-frigid Meadow on the Eastern Qinghai-Tibetan Plateau
摘 要 ：花粉化感是一类特殊的化感作用,能够抑制其它物种的花粉萌发和种子结实。研究了瑞香狼毒（Stellera chamaejasme）花粉水浸提液对其它物种花粉萌发和种子结实的潜在化感抑制作用，包括：在实验室中，用一系列浓度的狼毒花粉水浸提液对与它同花期的其它6个物种（秦艽（Gentiana macrophylla Pall. var. fetissowii），湿生扁蕾（Gentianopsis paludosa (Hook. f.) Ma var. paludosa），鳞叶龙胆（Gentiana squarrosa Ledeb.），椭圆叶花锚（Halenia elliptica D. Don var. elliptica），高原毛茛（Ranunculus tanguticus (Maxim.) Ovcz. var. tanguticus）和鹅绒委陵菜（Potentilla anserina L. var. anserina））以及自身花粉进行测试，测定花粉萌发率；在野外，在其它4个物种（秦艽，湿生扁蕾，鳞叶龙胆和椭圆叶花锚）的柱头上施用上述浓度的狼毒花粉水浸提液，观察种子结实率。实验室的花粉萌发试验证明，狼毒花粉对自身花粉萌发没有自毒作用，而其它受试的所有物种的花粉萌发率随着狼毒花粉浸提液浓度的增加呈显著地非线性降低。大约3个狼毒花粉的浸提液就可以抑制受试的多数物种的50%的花粉萌发。在野外试验中，发现受试的4个物种种子结实率随狼毒花粉浸提液浓度的增加呈显著地非线性降低。狼毒可能通过花粉化感对其周围其它物种的有性繁殖存在抑制作用，但其它物种可能通过花期在季节或昼夜上的分异避免受到狼毒花粉化感作用的影响，或者通过无性繁殖来维持种群繁衍。
Abstract:Pollen allelopathy is a kind of special allelopathy that may inhibit pollen germination and seed set of sympatric species which receive allelopathic pollens. The present study focused on assessing potential effects of pollen extract from Stellera chamaejasme on pollen germination and seed set of several sympatric species. It also included in-vitro research on the effects of pollen extract from S. chamaejasme on six sympatric species, namely Gentiana macrophylla var. fetissowii, Gentianopsis paludosa var. paludosa, Gentiana squarrosa, Halenia elliptica var. elliptica, Ranunculus tanguticus var. tanguticus and Potentilla anserina var. anserine, as well as pollen from itself. Field experiments on the effects of pollen extract with the same regime of concentration on the seed set of four sympatric species namely G. macrophylla, G. paludosa, G. squarrosa and H. elliptica, were also carried out. The result of in-vitro experiments showed that pollen of S. chamaejasme was not autotoxic, whereas the pollen germination of all the sympatric species decreased nonlinearly as the concentrations of pollen extract from S. chamaejasme was increased. The pollen extract of three-grained pollens of S. chamaejasme in general, inhibited 50% of pollen germination of most of the focal species. The result from field experiments showed that the seed set of four sympatric species decreased nonlinearly as the concentration of pollen extract from S. chamaejasme was increased. It can be inferred that S. chamaejasme may therefore have negative impact on sexual multiplication of the sympatric species through pollen allelopathy. However, these species could sustain themselves by avoiding pollen allelopathy of S. chamaejasme through either seasonal divergence or diurnal flowering phonologies and through asexual reproduction.