苜蓿结实格局及其影响因素的研究

Study on the Patterns of Fruit and Seed Production and Effect Factors in Alfalfa

用生殖生态学的相关方法,对不同生长年限的新牧1号杂花苜蓿结实格局进行测定,并对其影响因素进行分析。不同生长年限的苜蓿,在群体水平上上、中、下不同冠层和花序水平上上、中、下不同位置,均具有明显不同的结实特点。1年生在初花期光合产物积累不足,到末花期又出现了资源的限制,从而制约了种子产量的形成。3年生初花期传粉不足,盛花期的营养生长和生殖生长的资源争夺,结荚期的资源限制,成为产量形成的重要制约因素。传粉和资源限制是影响苜蓿结实格局的主要原因。在荚果水平上,苜蓿荚果内种子在形成过程中表现出明显交替败育的趋势,其中从果实基部算起偶数位置的胚珠形成种子的机会更大。资源限制和邻近种子争夺资源的干扰是导致荚果内种子交替性败育格局的主要原因。

The patterns of fruit and seed production and effect factors in alfalfa were determined and analyzed with the relative methods of reproductive ecology. The alfalfa has remarkablly different characters of fruit and seed production under different circumstances, such as varied growth fixed number of year, different crown layer on community level,different position on raceme level. There was the shortage of photosynthesis outcome at first florescence and the resource at end florescence has limited the seeds yield for one-year-old-alfalfa-plant . There was the pollen limitation at first florescence, the competition of resource between the nutritional growth and reproductive growth at anthesis and the resource limitation at fruit-set period has limited the seeds yield for three-year-old-alfalfa-plant. The pollen limitation and resource limitation are the main reason for leading to different fruit-set pattern. On pod level, seed aborted in turn with seed-set being much higher in even-numbered ovule positions, which correspond to the upper valve of the pod if the fruit is viewed from the peduncular end, than in odd-numbered positions in alfalfa pod. The resource limitation and the interference of adjoining seed competing resource lead to the seed abortion patterns in turn of alfalfa pod.