| The shade-endurance of seedling stage ofTorreya grandisis obvious,and the response to light is strong。Therefore,proper shading is necessary.At the same time,the root of Torreya grandis is the fleshy root,which is high for the ventilation and permeability of the soil,so it is suitable for growth in loose soil.In order to understand the influence of growth and development for the shading rate and soil sand content of the seedlings of Torreya grandis,improve survival rate and afforestation survival rateof Torreya grandis,this paper takes 2 years of Torreya grandis seedlings in Yang village,Huizhou District,Anhui,Huangshan City as test materials,studied in different shading rate and different gravel contentunder the soil of the main growth character indexes of Torreya grandis,the determination results combined with the multiple regression analysis,comprehensive evaluated the different response characteristics of the test process of2-yearseedlings of Torreya grandis,to provide the theory basis of Torreya grandis seedling.The results show that:(1)The larvae of 2-year-old seedlings of Torreya grandis were increased with the increase of shading rate,and the highest height was observed at 65% shading rate.In the gravel treatment,the average value of seedling height increased first and then decreased with the increase of gravel content,,and reached the maximum value under the 25% grit content.The results showed that the average diameter of the ground were increased first and then decreased under different shading treatments and different gravel treatments,the inflection point under shading is present at 45% shading,the growth point under gravel treatment occurs in 25% grit content。(2)The mean value of the height ratio of were fluctuating increased in the shading treatment and gravel treatment,The minimum value of the shading process occurs in 45% shading rate,and the minimum value of the gravel treatment appears in the 30% ~ 35% gravel content.The root cap is a variation of the variation in the shading process,and the maximum is seen in the 25% shade.In the case of gravel treatment,the maximum value occurs in 30 to 35 percent gravel treatment.(3)With the shading rate and the increase of sand content,the average lateral root length,the average number of lateral roots,the total biomass of single plant and the biomass of single plant were increased first and then decreased.In the shading,the maximum of the average lateral rootlength、the average lateral rootsnumber,the maximum total biomass and root biomass per plant,respectively was 35% ~ 55%,25% ~ 35%,55% and 45% ~ 55% shading rate;In the gravel processing,the maximum of the average lateral rootlength、the average lateral rootsnumber,the maximum total biomass and root biomass per plant,respectively was 25%~35%,30%,25%and 25%~30% Gravel content.(4)Comprehensive analysis of several sets of test data found that the maximum height was(45.79±5.08)cm,which appeared in 25% grit with 45% shading test.comprehensive analysis showed that the maximum mean diameter is 45% shading and 25% grit content,is(6.03±0.71)mm.Height diameter ratio in the 55% shading rate combined with 25% grit treatment to a minimum,(74.56±5.84);The maximum mean lateral root length mean at 35% shading combined with 25% grit content,is(9.56±1.03)cm;The maximum average number of lateral roots was 35% shading in combination with 35% grit content,is(11.23±1.24);The maximum total biomass of the largest plant was 55% shading with 35% grit content,is(38.24±4.87)g;The maximum plant root biomass was 55% shading in 30% grit content,is(11.98±0.97)g;Root canopy was greater than 55% shading combined with 30% grit,reached to(0.47 ± 0.08).(5)The 2-year-old Torreya grandis seedlings under different shading treatments in July,the mean of relative electrical conductivity was basically the same as that of leaf malondialdehyde(MDA),and both of them decreased first and then increased with the increase of shading rate,and the minimum value appeared at 55% shading rate.In different gravel treatment,the change trend of Torreya grandis leaf relative electroconductivity and leaf MDA content is the same,both fluctuates upwardwith the increase of gravel content,the minimum of relativeconductivity and MDA content areunder 20% sand treatment.By comprehensive analysis found that the average value of relativeconductivity of Torreya leaf were minimize in 55% shading rate combined with 20% grit treatment(14.53±3.78),the average value of MDA content of Torreya leaf were minimize in 55% shading rate combined with 20% grit treatment(30.78±3.53)nmol/g.In July,the mean change trend under different shading treatments of chlorophyll content in the leaves of Torreya grandis showed as increaseed first and then decreased with shading rate increase,and reached to the aaximum in 55% shading rate.But in the different gravel content,the growth of average value of chlorophyll content were fluctuating,andthe change scope is small,the maximum value under 30% grit treatment.Comprehensive analysis of the maximum chlorophyll content is in the 55% shading treatment combined with 30% grit treatment(0.55 ± 0.09)mg·g-1.Indicating that moderate shading is beneficial to the improvement of leaf resistance of 2-year-old seedlings of Torreya grandis.(6)The results of the correlation analysis are obtained that,survival rate and seedling preservation rate of seedlings of Torreya grandis were significantly affected by the physiological and biochemical indicators like seedling height,ground diameter,biomass per plant,malondialdehyde content and so on,it can an be used as the evaluation index of the quality of Torreya grandis.The results of principal component analysis showed that the survival rate of Torreya grandis under different test treatments was mainly affected by diameter,individual root biomass and average number of lateral roots.The preservation rate of seedlings is mainly affected by average lateral root number and relative conductivity.(7)The retention rate and the afforestation survival rate of Torreya grandis seedlings were analyzed,the highest retention rate and survival rate of shading treatment were in 45%~55%and 25%~45%,respectively。The optimal seedling retention rate and survival rate of gravel treatment are highest in 25% ~ 35%.The comprehensive analysis concluded that the seedling retention rate of the seedlings was up to 93.67%,with 55% of the shading rate combined with 35% of the gravel content.The survival rate of afforestation was up to 94.69%,with 45% shading rate combined with 25% gravel content. |
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