Preliminary Study On Seed Germination Physiology Of Ostrya Rehderiana Chun

Ostrya rehderiana Chun belongs to Ostrya,Betulaceae,which is a rare and endangered species.There are only 5 wild plants left alive at present,which are scattered at the periphery of Tianmu Mountain National Nature Reserve in Lin'an.About 200 artificial offsprings have been obtained in the whole province by the off-site preservation methods using natural seedlings by now,however,no natural regenerated seedlings can be found in the plantation.There are no reports about the seed physiology of this plant,whose endanged mechanism still remains unclear.In this project,we will focus on this rare and endangered species of Ostrya rehderiana Chun,use the seeds of both wildtype and artificial offsprings as materials,detect and compare the contents and distribution of several endogenous nutrients,activities of some enzymes related to seed viability and contents of several phytohormones.We will also use 3 other seeds from the high yield and germination trees in Betulaceae,named Betula platyphylla Suk,Carpinus turczaninowii Hance,and Corylus heterophylla Fisch,as controls.We studied the physiological activities of Ostrya rehderiana Chun seed and preliminarily illustrated its impact on germination rate and breeding,in order to provide a new theoretical basis for the endangered mechanism of this species.The main results are as follows:1.The 1000-seed-weight of wildtype seeds is 1.48 g with a plump-seed percentage of 21.4%,which is obviusly higher than that of 0.94 g and 17.9% of artificial offspring seeds.Both seeds have a empty rate above 35%.TTC staining showed that only about 9% wildtype seeds were viable.2.Wildtype seeds have more protein(138.1 mg/g)and less starch than artificial offspring seeds,but they are equal in soluble sugar content.The contents of soluble sugar,starch and protein varied among other 3 seeds with no obvious differences,however,the nutrients in Ostrya rehderiana Chun seeds are fewer.3.Wildtype seeds have a higher activities of ?-amylase(2.5 U/g),protease(9.0 U/g),lipase(0.48 U/g)and acid phosphatase(13.1 U/g)than artificial offspring seeds.Howenver,the related enzyme activites in both Ostrya rehderiana Chun seeds are much lower than the other seeds.4.Wildtype seeds have a higher content of GA(4.8 ng/g),Auxin(IAA: 15.0 ng/g),CTKs(DZ: 0.45 ng/g),SA(1121.4 ng/g)and JAs(3.5 ng/g)than in artificial offspring seeds(2.3 ng/g,5.6 ng/g,0.27 ng/g,1175.9 ng/g,2.9 ng/g,respectively),all of which are germination-promoted.In the opposite,the germination-inhibited ABA is much higher in artificial offspring seeds(36.6 ng/g)than in wildtype seeds(26.7 ng/g).5.Paraffin section staining was used to display the seed structure of Ostrya rehderiana Chun.The plump seed from wildtype trees showed a complete structure including embryo,cotyledon and seedcoat.The nutients of starch,protein and fat accumulated most in cotyledon,less in embryo and least in seedcoat.6.The viability of the Ostrya rehderiana Chun seed is obviously lower than the other 3 high yield and germination trees in Betulaceae.The physiological activity and viability of wildtype seeds is higher than the artificial offspring seeds.