大花百子莲的结实和结籽格局及种子产量影响因素分析

在2007和2008年对大花百子莲(Agapanthus praecox subsp.orientalis‘Big Blue’)在群体、果序和单果水平上的结实和结籽格局进行了观测,并依据每花序单花数、单花胚珠数和单粒种子质量推算其单株潜在种子产量;此外,采用人工补充授粉方法研究了不同授粉方式对大花百子莲结实和结籽的影响,并对其种子产量的影响因素进行了分析。结果表明:从始花期、盛花期至末花期,随开花时间的延迟,大花百子莲植株的每花序单花数和座果率均逐渐降低,其中始花期开花的植株每花序单花数和座果率均最高。从果序基部、中部至顶端,座果率和结籽率均逐渐减小且差异显著。在果序基部和中部,果实内种子败育率沿果实基部至顶端依次降低,而单粒种子质量则依次增加;且果序基部的果实各部位的种子败育率均低于果序中部的果实,而单粒种子质量则差异不大。大花百子莲的单株潜在种子产量约为43.18 g,而其单株实际种子产量约为2.87 g,远低于其潜在种子产量。自然授粉的大花百子莲每柱头花粉数为27.5粒,而自花授粉、同株异花授粉和异株授粉的每柱头花粉数均超过100粒;与自然授粉、自花授粉和同株异花授粉植株相比,异株授粉植株的座果率和结籽率均显著增加。研究结果显示:大花百子莲的结实和结籽格局呈现非随机分布规律,在引种地存在有性繁殖障碍;养分和授粉状况是制约大花百子莲种子产量的重要因素。

Analyses on patterns of fruit and seed setting and influence factors on seed yield of Agapanthus praecox subsp. orientalis ‘Big Blue＆#39;

Patterns of fruit and seed setting of Agapanthus praecox subsp. orientalis‘Big Blue’ at levels of population, infructescence and single fruit were investigated in 2007 and 2008, and its potential seed yield per plant was calculated according to flower number per inflorescence, ovule number per flower and single seed weight. In addition, effects of different pollination modes on fruit and seed setting of A. praecox subsp. orientalis ‘Big Blue ’ were studied by artificial supplement pollination method, and influence factors on its seed yield were analyzed. The results show that from early flowering stage, full flowering stage to late flowering stage, flower number per inflorescence and fruit setting rate of A. praecox subsp. orientalis ‘Big Blue’ plants all reduce gradually with delaying of flowering time, in which, those of plants flowering at early flowering stage are the highest. Its fruit and seed setting rates from base, center to apex of infructescence all reduce gradually with significant difference. In base and center of infructescence, seed abortion rate in fruit decreases successively from base to apex of fruit, while single seed weight increases successively. And seed abortion rate of different parts of fruit at base of infructescence is lower than that at center of infructescence, while difference of single seed weight is not obvious. Potential seed yield per plant of A. praecox subsp. orientalis ‘Big Blue’ is about 43. 18 g, while its actual seed yield per plant is about 2. 87 g, which is obviously lower than its potential seed yield. Pollen number per stigma by natural pollination is 27. 5, while that by self-pollination, geitonogamy and xenogamy cross-pollination is more than 100 . Fruit and seed setting rates of plants by xenogamy cross-pollination increase significantly compared to those of plants by natural pollination, self-pollination and geitonogamy. It is suggested that patterns of fruit and seed setting of A. praecox subsp. orientalis ‘Big Blue’ appear a non-random distribution rule, and there is sexual propagation obstacle in induction locality. Nutrition and pollination status are important limitation factors restricting its seed yield.