Study On The Seed Dormancy Mechanisms And Breaking Dormancy Technologies Of Taxus Wallichiana Var.chinensis

Taxus wallichiana var.chinensis is an endemic tree species in China.It is a national first-class protected plant and has important medicinal and ornamental value.However,its seeds have long dormancy time under natural conditions and are difficult to renew,which seriously affects the expansion of population size and restricts its application in garden production.In this paper,the dormancy mechanism of T.wallichiana var.chinensis seeds was explored by embryo endosperm germination test and seed coat and endosperm extract on Chinese cabbage seed germination inhibition test.The techniques of relieving seed dormancy of T.wallichiana var.chinensis were studied by mechanical peeling,hormone interference and stratification sand storage.At the same time,the physiological and biochemical characteristics of different treated seeds in the stratification process were studied,which laid a foundation for further exploring the efficient treatment technology of T.wallichiana var.chinensis seeds and expanding the large-scale reproduction and forestry production application of T.wallichiana var.chinensis.The main research results are as follows:1.The seeds of T.wallichiana var.chinensis in Qinling forest area were completely mature in late November,and the embryo structure was complete.Endosperm inhibited the germination of embryo.The germination rate of naked embryo of mature seeds was83.63%.The germination rates of embryo with 1/4 endosperm and 1/2 endosperm were52.00%and 26.87%,respectively.There are germination inhibitors in the endosperm and seed coat of T.wallichiana var.chinensis seeds,which is the main reason for seed dormancy.Both extracts can significantly inhibit the germination and radicle growth of Chinese cabbage seeds,and the inhibition of seed coat is stronger than that of endosperm.Low temperature stratification can promote the reduction of inhibitory substances in seeds.With the prolongation of stratification time,the inhibitory effect of endosperm and seed coat extract on Chinese cabbage seeds gradually weakened.After 12 months of stratification,there was no inhibitory effect.2.The variable temperature stratification,low temperature stratification and hormone treatment can all play a role in relieving the dormancy of T.wallichiana var.chinensis seeds,among which the combination of warm temperature 180 days and low temperature180 days has the most significant effect,and the seed germination rate can reach 58.67%.The combination of running water washing and outdoor stratification had the best effect on low temperature stratification,and the seed germination rate was 43.34%.The combination of 200 mg·L^-1GA₃and 10 mg·L^-16-BA was the best for hormone soaking.The germination rate was 22.33%after 6 months of stratification,and the germination rate was55.00%after 12 months of stratification.3.The changes of nutrient contents in seeds treated by variable temperature stratification and hormone soaking were the most severe.The soluble protein content increased first,then decreased and finally increased again with the increase of stratification.The soluble sugar content decreased first and then increased with the stratification.Starch and crude fat were the main energy supply substances in T.wallichiana var.chinensis seeds,and their contents decreased with the stratification.After the treatment,the starch content of the two seeds with the most dramatic changes decreased by 0.45%and 0.48%,respectively,and the crude fat content decreased by 20.4%and 19.9%,respectively.