刺槐和多花刺槐的有性生殖特性

Sexual reproduction characteristic of Robinia pseudoacacia and Robinia neo-mexicana var.luxurians

为准确掌握刺槐(Robinia pseudoacacia L.)和多花刺槐(Robinia neo-mexicana var.luxurians Dieck)开花结实有性生殖生物学特性,为杂交育种奠定基础,对这两种刺槐的开花物候期、花器官形态结构、人工控制授粉结实率、自然授粉结实率、自花授粉结实率、孤雌生殖结实率、子房胚珠数和空胚率等开展了观测和试验研究。结果表明,刺槐和多花刺槐在鲁中至鲁南地区的开花物候期在4月下旬至5月上旬;刺槐始花期只有1 d,盛花期2 d,末花期2~3 d,而多花刺槐始花期2 d,盛花期3 d,末花期4 d;雌、雄蕊异熟;刺槐自然授粉结实率个体之间差异显著,平均结实率为26.02%,而多花刺槐自然授粉结实率极低,平均仅为0.11%,因此只适宜做杂交父本;刺槐种内无性系之间人工控制异花授粉结实率平均只有1.7%,而刺槐种间人工控制异花授粉结实率只有0.21%;刺槐自花授粉和孤雌生殖结实率分别是1.8%和0;刺槐每个荚果胚珠数平均18个,空胚率很高,平均达53.94%,而多花刺槐每个荚果胚珠数平均22个,空胚率极高,平均达87.61%;刺槐自胚珠受精至种子生长发育成熟需要80~90 d,而多花刺槐仅需要70~80 d。

Observation and experiments were performed on blossom phenophase,flower organ morphology,maturing rate of artificial cross-pollination,natural pollination,self-fertilization and parthenogenesis,ovary ovule number and empty embryo rate etc.to accurately grasp the biological characteristics of flowering,fructification and sexual reproduction of Robinia pseudoacacia and R.neo-mexicana var.luxurians,which can lay a foundation for cross breeding.The results were as follows.The blossom phenophase of the two plants was from the end of April to early May in the middle and the southern region of Shandong Province.Early flowering season of R.pseudoacacia lasted only 1 d,full-bloom stage sustained 2 d,and at the end of the flowering continued2-3 d,while early flowering season of R.neo-mexicana var.luxurians lasted 2 d,full-bloom stage sustained 3 d,and at the end of the flowering was 4 d.The two species were dichogamous.The natural pollination rate of R.pseudoacacia was significantly different between individuals with the average maturing rate was 26.02%,whereas the natural pollination seed setting rate of R.neo-mexicana var.luxurians was extremely low with an average of only 0.11%,therefore it is only suitable for male parent.The manual cross-pollination seed setting rate of R.pseudoacacia intraspecific clones and interspecific acacias was only 1.7%and 0.21%,respectively.The maturing rate of self-fertilization and parthenogenesis in R.pseudoacacia are 1.8%and 0.There were 18 and 22 ovules on average in each pod of R.pseudoacacia and R.neo-mexicana var.luxurians,respectively.Empty embryo rate of each pod in R.pseudoacacia is very high,with an average of 53.94%,while the empty embryo rate of each pod in R.neo-mexicana var.luxurians is extremely high,with an average of 87.61%;The seeds of R.pseudoacacia and R.neo-mexicana var.luxurians needed 80-90 d and 70-80 d from fertilization of the ovule to maturation,respectively.