风箱果的花部综合特征及繁育系统研究

风箱果属濒危灌木且分布范围狭窄,自然条件下有性更新能力差,局部种群有消失的趋势。通过野外观察和人工授粉试验对风箱果的传粉生物学特征和繁育系统进行研究。结果表明:单花花期(5.1±0.23)d,花序花期(8.4±0.98)d。单花花期依其形态和散粉时间可以分为5个时期,即初花期、散粉前期、散粉初期、散粉盛期、散粉末期。通过花粉/胚珠测定,结合人工授粉和套袋试验可以确定风箱果的繁育系统属于专性异交、自交不亲和、传粉过程需要传粉者。自然状态下风箱果的结实率(23.02±6.08)%和结籽率(9.86±2.86)%均较低,这与当前片断化生境中传粉昆虫种类和数量少、效率低下等有关,说明生境片断化影响风箱果植株的早期生殖成功。异株异花授粉可显著提高结实率及结籽率,分别可达(60.17±4.67)% 和(49.61±4.04)%。 

Floral syndrome and breeding system of Physocarpus amurensis

Physocarpus amurensis is an endangered shrub with an extremely narrow distribution in fragmented habitats.Its sexual reproductive capacity is low,and local population may be disappeared gradually.We studied the characteristics of pollination biology and breeding system of P.amurensis in the fragmented habitats through field observation and artificial pollination.Results showed that the life spans of single flowers and inflorescences were (5.1 ± 0.23) d and (8.4 ± 0.98) d,respectively.The flowering phase of a single flower can be divided into five periods in terms of flower morphology and dehiscence:"flower bud","pre-dehiscence","initial dehiscence","full dehiscence",and "end-dehiscence".Based on the results of pollen/ovule ratio,emasculation,bagging and artificial pollination studies,we found that the breeding system of P.amurensis is outcrossed and self-incompatible,and demands for pollinators.The fruit-setting ratio and seed-bearing ratio under natural conditions were low,(23.02 ± 6.08)% and (9.86 ± 2.86)%,respectively.The main reason might be that there are less species and quantities of pollinators and the pollination efficiency was lower in the fragmented habitats,suggesting that habitat fragmentation affects the early-stage reproduction success of P.amurensis.Artificial xenogamous pollination can significantly promote the fruit-setting and seed bearing ratios,reaching (60.17 ± 4.67)%and (49.61 ± 4.04)%,respectively.