四合木种群生殖对策的研究

REPRODUCTIVE STRATEGIES OF TETRAENA MONGOLICA MAXIM

通过研究四合木 (Tetraena mongolica Maxim )种群的生殖对策 ,发现四合木既可进行有性生殖 ,又可进行营养繁殖 ,以有性生殖为其主要的生殖方式。有性生殖过程中具以下特征 :1)具有自交和异交相结合的交配系统 ,异交比例 (5 0 % )高于自交比例 (15 % ) ;2 )具有花多果少的生殖格局 ,其开花率与生境、降水、植株年龄关系密切 ,不同种群的开花率有一定差异 ,种群的年龄结构对开花率有较大影响。在 3～ 5月降水丰富的情况下 ,不仅开花比例高 (40 %～ 80 % ) ,且每一植株的花量很大。不同年份种群结实率普遍偏低 ,3～ 5月降雨较少的 1996年平均结实率为 19.8% ;3～ 5月降雨较多的 1998年为 12 .2 %。只是由于开花基数大 ,对四合木种群种子的总产量不会造成较大威胁 ;3)胚胎发育过程中败育比率极高 ,只有约 10 %～ 2 0

While sexual reproduction is the major reproductive process in Tetraena mongolica Maxim vegetative propagation is also important. The following are the characteristics of sexual reproduction: 1) a mixed breeding system with self (15%) and cross breeding (50%); 2) a pattern of fruit and seed yield in which plants produce many more flowers than fruits; the flowering rate contacts with environment,amount of rainfall,age of plant, which is different in different populations; age structure has a significant effect on the flowering rate of populations; in high rainfall years, both flowering rates (40% 80%), and flowers per plant are high; population seeding rates were low in all of the three years studied (from 19.8% in 1996 to 12.2% in 1998); because of the large amount of flowers produced, the yield of populations is not greatly affected by this low seeding ratio; 3) the embryo abortion rate is very high, with only 10% 20% of embryos maturing.