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研究了濒危植物四合木种群初次结实年龄 ,果实空间分布、果实数量、果实重量、结籽率、花果转移率随年龄和生境的变化规律。结果表明 :四合木种群初次结实年龄为 4a。果实的空间分布为树冠上部 >中部 >下部 ,上、中部显著高于下部。平均单株果实的数量分布随年龄变化曲线呈山峰型。在 4～ 1 8a范围内 ,随着年龄增大 ,结实量增加 ,到 1 8a以后 ,随着年龄增加 ,结实量逐渐减少 ,1 3～ 2 7a为结实高峰期。果实重量随年龄变化趋势与果实数量随年龄变化趋势基本一致。在自然状态下 ,四合木结籽率为 1 2 6%～ 2 80 % ,花果转移率为 5 4 3 9%～ 71 43 % ,结籽率、花果转移率与年龄的关系呈双峰型。结籽率低的主要原因为 :( 1 )传粉过程受到障碍 ,即传粉媒介 (昆虫 )的访花频率极低 ,使得柱头上的花粉量受到限制。这是结籽率低的内因。( 2 )土壤水分供应不足 ,从而使胚珠不能正常发育。这是导致结籽率低的外因。
The change rule of initial population age, spatial distribution of fruit, fruit quantity, fruit weight, seed setting rate and fruit-fruit transfer rate with age and habitat of endangered plant Tetraena mongolica were studied. The results showed that the initial population age of Tetraena mongolica was 4a. The spatial distribution of fruit was crown upper> middle> lower, upper and middle were significantly higher than the lower part. The average number of fruit per plant distributed with the age curve was mountain type. In the range of 4 ~ 1 8a, with increasing age, the seed setting increased. After 1 8a, the seed setting decreased gradually with age, and 13 ~ 2 7a was the peak of fruit setting. Fruit weight with age trends and the number of fruits with age trends are basically the same. Under natural conditions, the fruiting rate of tetramorum was 126% ~ 280%, the transfer rate of flower and fruit was 543 9% ~ 71 43%, and the relationship between seed-setting rate, flower-fruit transfer rate and age was double Peak type. The main reasons for low seed setting rate are as follows: (1) The pollination process is impaired, that is, pollinators (insects) have a very low frequency of pollination, which limits the amount of pollen on the stigma. This is the end result of low seed factor. (2) inadequate supply of soil moisture, so that ovules can not be normal development. This is the cause of low seed setting.