Studies On The Sex Allocation And Reproductive Allocation Of Saussurea DC. In The Easten Of Qinghai-Tibet Plateau

There are limitative resources during the plant whole life, so the plant has to allocate resources between growth and reproduction. The mode of resources allocation can reflect the character of the plant life history, which is central to study of plant life history. Studies on resource allocation were focused on two aspects: sex allocation and reproductive allocation. Sex allocation is about optimal allocation of reproductive resources between the male and female; Reproductive allocation is about the ratio of reproductive resources in total, the factors which influence the ratio, and the relationship between the ratio and the influence factors.The environment of Qinghai-Tibet Plateau is changefully and the ecological factors are unstable. Saussurea has a widely distribution at easten of Qinghai-Tibet Plateau, Therefore, we selected it as the experiment material, studied the reproductive strategies, such as sex allocation, reproductive allocation, to understand how the plants adapt to the especial environment of Alpine environmental conditions.The results showed:(1) The resources allocate for the female function, the male function and the attraction structure (petal) all increase with the increase of the above ground biomass, bigger plant has more resource, and it will input more resource into reproductive organs;(2) The weight of 18 species floret didn't present accordant change trend with the hoist of elevation, the interspecific difference existed plants in the same genus may adopt different adaptable strategies under the same survival stress;(3) Saussurea plant showed size-dependent sex allocation, bigger plant individual was tend to female-biased sex allocation, smaller plant individual was tend to male-biased sex allocation;(4) With the hoist of elevation, the plant size decreased;(5) With the hoist of elevation, the seed didn't present accordant increase or decrease trend, did not support the theoretic predictions;(6) As the above ground biomass increased, so did the reproduction devotion, but the reproduction allocation decreased;(7) There was trade-off of resources allocation between the seeds number and size which indicated the existence of trade-off within the capitulum.