Effect Of Different Seedling-raising Measures On Growth Characteristics Of Seedlings And Cutting Seedlings Of Taxus Chinensis Var.mairei

This thesis aimed to probe into the optimum planting density and shading rate through comparing the growth character and survival rate of the Taxus chinensis var.mairei seedling under different cultivation conditions,such as density and shading rating.In order to reduce costs and improve the survival rate during seedling,this thesis had studied seedling cuttings,which was one of the effective means of rapid propagation,in terms of cutting age and cutting medium.The main results were as follows:(1)In regards to the different shading,significant difference was found in survival rate and growth potential,the seedling survival rate increased firstly with increasing shading rate and then decreased,the highest survival rate reached 79.1% under 65% shading rate,which is 2.84 times of 25% shading rate,1.76 times of 45% shading rate,and 1.22 times of 85% shading rate.Seedling height and ground diameter growth increased firstly with increasing shading rate and then decreased.The seedling height had significant difference between different shading rate,the highest under 65% shading.Diameter growth did not have significant difference in the group,but it had significant difference between groups.Seedling survival rate,seedling height and ground diameter size order corresponding shading rate are 65% shading rate > 85% shading rate > 85% shading rate > 25% shading rate.Four groups of seedlings were under different shading rate,the chlorophyll a/b value decreased with increasing shading rate,the chlorophyll b increased with increasing shading rate,which indicated the seedlings' tolerance of shade increased with shading rate.At the same time,the total chlorophyll increased with the shading rate,its ability of using the blue-violet light strengthened gradually,the low level of illumination could make better use of the blue-violet light in the scattered light.Regression analysis showed that the highest seedling survival rate is under the 76% shading rate,the highest ground diameter under 69.50% shading rate,and the highest height growth under 67.63% shading rate.(2)Using orthogonal experiment design,there were seven groups of seedlings of different planting density and three of different shading,respectively were density ?(44 plants/m2),?/m2(33 cases),?/m2(27 cases),?/m2(20 cases),?(17 plants/m2),?/m2(16 cases)and ?/m2(13 cases)and shading rate is 25%,45% and 65%,a total of 21 groups.Experimental results showed that under the same shading rate,there was significant difference of seedling biomass,survival rate,seedling height,ground diameter,root number,and average root length among density I,?,and ?.The seedling biomass,ground diameter,and average root length decreased with the increasing density.Under the 25% shading rate,the seedling height increased with the increasing density.There was no significant difference among density I,?,and ?.With the same density,the root cap ratio,seedling height,and ground diameter of the seedling placed under 45% shading rate were higher than seedling placed under 45% shading rate and 65% shading rate.The seedling lateral root number and average lateral root length of the seedling placed under 25% shading rate were higher than seedling placed under 45% shading rate and 65% shading rate.The relative electrolytic leakage and malondialdehyde content of seedlings grew in July were not relevant to the density.The relative electrolytic leakage and malondialdehyde content of seedlings under 25% shading rate were significantly higher than those under 45% shading rate and 65% shading rate.The relativey appropriate planting density of the biennial Taxus chinensis var.mairei seedling was ? and ?,and the optimum shading rate was 45%,which could guarantee that there was intensive and sufficient space.(3)1-year-old spring cutting is the most appropriate cottage in October.1(2 year old),II(1 year old branches,including spring,III(1 years old and spring branches)were not significantly different between the callus rate,reached more than 90%.The annual shoot rate,rooting number and average root length were the best,and the annual shoots were the worst.B3 matrix(river sand and perlite volume ratio 1:2 mixed)rooting rate,root number and average root length than the B1 matrix in the cuttings(peat and perlite volume ratio 1:1 mixed)and B2 matrix(peat and sand volume ratio 2:1 mixed).