Studies On Seed Characterization And Vigor Of Toona Ciliata Var. Pubescens In Mount Jiulian

Toona ciliata var. pubescens is a kind of deciduous, broad-leaved tree species of Toona ciliata in Meliaceae. The plant known as "Chinese mahogany" is under state protection(categoryii).It distributes in Jiangxi,Yunnan,Sichuan,Anhui,Guangxi,Hunan,Guangdon,Guizhou,India and Indonesia. At present, T. ciliata var. pubescens is facing a serious situation because of its low ability of recruitment and population decline. To explore the possible factors restricting seedling renewal, and then to provide scientific basis for natural regeneration of T. ciliata var. pubescens, this research focus on seed vigor and takes T. ciliata var. seed in Mount Jiulian National nature reserve as the study materials.The effects of different temperature and soaking treatment on seed vigor and seedling growth traits were explored. The differences in seed quality and contents from different plants of T. ciliata var. were compared. The results showed that :(1)When the soaking temperature was 0℃, 4℃,25℃, 37℃,water absorption rate of T.ciliata var. pubescens seed at the first 4h was the fastest. When the soaking time reached16 h, the water absorption tended to saturation. Water absorption rate increased with temperature increased. at 25 ℃, soaking time had significant effect on relative electric conductivity.(2)The increasing of soaking time at 25℃ had no significant effect on fresh weight,root length, shoot length of the Seedling of T. ciliata var. pubescens, but it was direct proportion with dry weight.(3)The seed of T. ciliata var. pubescens was stored under 1℃,4℃,-18℃.We could find little damage of germination was caused and there was no evident difference in seed germination between the three temperatures when it suffered a short time chilling injury after imbibition. The influence degree of chilling injury was direct proportion with the soil moisture content and the storage time. Dry weight of seedling had extremely significant negative correlation with chilling injury time that the seed suffered. Chilling temperature and humidity had no significant effect on the seedling’s root length and shoot length.(4)Enough soaking time(20h) increased field germination rate of T. ciliata var.pubescens. Field germination rate of 20 h was 3.5 times more than the one of 1h, reached32.18%.(5)Seed quality and inclusions of 4 single T.ciliata var.pubescens’ plants in Mount Jiulian was comparatively analyzed. The index of thousand grain weight, soluble sugar,starch, protein content showed the same trend:Hengkenshui(M3)>Xiagongtang(M2)>Rundong(M4)> Xiagongtang(M1), the thousand grain weight of M3 was the biggest, reached 8.535g; There was significant difference in activity of POD、CAT、SOD between the 4 single T.ciliata var.pubescens’ plants. MAD content of M1 was significant different form M2’s. But there was no significant differencebetween M1, M3 and M4. Among them, M3’s MAD content was the highest and M2’s content was the lowest. There was no significant difference in seed germination between M1, M3 and M4.but M4.is the highest, 69.33%. M2(32.67%)was the lowest and significant different form the others.