Effects Of Seed Genetic Quality On Fate Of Seed And Seedlings Of Tetracentron Sinense Oliv.

In this paper,the seed characteristics and seedling growth of the endangered plant Tetracentron sinense Oliv.after different pollination treatments was comparatively analyzed seeds,and the effects of genetic quality on the seed and seedling quality of T.sinense were also discussed.In addition,the controlled seedling experiments were conducted by simulating the wild habitats of T.sinense,and then the fate of seed and seedling of T.sinense from different pollination treatments under different habitats were analyzed,and the effects of seed genetic quality on the regeneration of T.sinense.Population were also discussed,which can contribute to provide effective strategies for the conservation and management of T.sinense.to reveal the mechanism of T.sinense.The main results are as follows:1.Effect of genetic quality on seed characteristics and seedling initial growth of T.sinense.There were significant differences in the width,thickness,thousand-grain weight,plumpness,germination rate and germinative force of T.sinense seeds among different pollination treatments.The thickness,thousand-grain weight,germination rate and germination force of seeds from xenogamy were significantly higher than those from self-pollination and geitonogamy,and the growth of seedling stem was better than that from self and natural pollination,and the growth of seedling root in the later period also exceeded these from other treatments.The width,thickness and germination rate of seeds from natural pollination were significantly less than those from the self-pollination and geitonogamous,but there were no significant difference in the length,thousand-grain weight,and germination force of seeds between natural and self pollination.The results showed that:(1)seed genetic quality of T.sinense had a significant effect on the fitness of seeds and seedlings;(2)The fitness of seeds and seedlings from xenogamy were the highest;(3)In the natural habitat,T.sinense took a reproductive strategy of inbred,which may be attributed to the harsh environmental conditions(flowering period coincided with the rainy season)and the lower population density.2.The effects of different habitats on seed germination,and seedling survival and initial growth of T sinense from different pollination treatmentsThe germination rate of T.sinense seeds from different pollination treatments in the forest edge was higher compared to other habitats.The seed germination rate in the open or under an overstory was relatively low.The germination rate of the seeds from xenogamywas the highest,and that from self-pollination treatments was the lowest.There are significant difference in seed germination rate from different pollination treatments under different habitats except for the forest edge.In different habitats,the survival rate of T.sinense seeds from different pollination treatments decreased gradually with months of age increasing,while the mortality increased.The survival curves of seedlings from different pollination treatments all showed a downward trend in different habitats.The downtrend of the survival curves in the open and under an overstory showed the most significant,and that in the forest edge and the central of the forest gapwere relatively gentle.In the same habitat,the seedlings of T.sinense from xenogamy were generally more viable compared to other treatments.In different habitats,the cumulative survival rate of seedlings from different treatments showed monotonic decreasing with months of age increasing,while the cumulative mortality rate showed monotonically increasing.The changing trend was the most significant in the first two months,and then became gentle.additionally,the changing trend in the open or under the forests were more faster compared to other habitats.In the same habitat,the changing trend of the cumulative survival rate and cumulative mortality rate of seedlings from xenogamy were the most gentle,while those from natural pollination and self-pollination were relatively larger.The death density of T.sinense seedlings gradually decreased with the increase of the months of age.In different habitats,the trend of risk rate curve of seedlings from different pollination treatments was basically the same,and the peak value also appeared in the second month.With the increase of months,the root and stem length of T.sinense seedlings from different pollination treatments increased gradually.The root and stem growth status of T.sinense seedlings from xenogamywas higher than those from the treatments of natural pollination and self-pollination.The cotyledon area of T.sinense seedlings from different pollination treatments increased gradually with the increase of months.In the same habitat,the cotyledon area of seedlings from xenogamywas significantly larger than that from the treatments of self-pollination and natural pollination.With the increase of months,the dry matter content of T.sinense seedlings from different pollination treatments increased gradually.In the same months of age,the content of dry matter in the seedlings of T.sinense.from xenogamy was significantly higher compared to self-pollination and natural pollination,except the undergrowth habitats.In the natural habitat of Meigu Dafengding National Nature Reserve.The seeds T.sinense were produced from self-pollination(self-pollination and geitonogamous).The seed genetic quality significantly affected the quality of seeds and seedlings.Theadaptability to external environment for the seedlings of T.sinense were relatively weak,and the first two months after emergence was the bottleneck period for seedling survival.Seed genetic quality had great effects on the fitness of seeds and seedlings.The fitness of T.sinense from xenogamy was better than that from the natural pollination and the self-pollination.The results showed that seed genetic quality of T.sinense played an important influence on the population regeneration,which is not the deciding factor limiting its population regeneration.