The Influence Of Different Mass Percent Of Stone On The Growth And Physiological Characteristics Of Handeliodendron Bodinieri Seedlings

Handeliodendron bodinieri belongs to the Sapindaceae Juss,Handeliodendron Rehd,Mono-species genus,which is one of the rare,endangered and unique plants in our country.This plant currently only distributes in the Karst Limestone area at the border of Guizhou,Guangxi and Yunnan provinces.Handeliodendron bodinieri is a plant with strong drought resistance,poor soil resistance,highly developed root system,root nodules and high seed oil content,therefore,it boasts great ecological and economic value.However,under the natural situations,the Handeliodendron bodinieri is in a low seed germination rate,weak community competition ability.Besides,due to the habitat destruction and natural regeneration difficulty,the quantity of it`s population is decreasing increasingly.Based on the facts the author just mentioned,the initial purpose of this experimental study is to improve the quality of Handeliodendron bodinieri seedlings and build up scientific basis for the recovery of Handeliodendron bodinieri population and its adaptation to the Karst region.In this paper,the author mainly focuses on the influences of different mass percent of stone soils(0%,20%,40%,60%,80%)on the growth and physiological characteristics of Handeliodendron bodinieri.After measuring the growth index,physiological index and photosynthesis characteristics of Handeliodendron bodinieri seedling plants under different mass percent of stone conditions,the author will discuss the influence of different mass percent of stone on the growth and physiological characteristics of Handeliodendron bodinieri seedlings.The main results of the study are as follow:(1)In different mass percent of stone situations,Handeliodendron Rehd seedlings shows a strong growth adaptability,after two growing seasons,with the increase of mass percent of stone,the seedling dry weight and leaf surface show a trend of increasing firstly and then decreasing,and the stem quality shows a decreasing trend.Among them,40% of the biomass and leaf area treated are the largest and significantly higher than those in the matched group.Meanwhile,when the mass percent of stone reaches 40%,the root has larger weight,while the weight of stalk is comparatively smaller.It is proved that different mass percent of stone affects the distribution of the biomass of Handeliodendron bodinieri seedlings,increases the accumulation of biomass in the roots and leaf parts,and reduces the accumulation of biomass in the stalk.According to the practical situations,adaptive adjustments should be made actively for different mass percent of stone treatment Handeliodendron bodinieri seedlings.(2)With the increase of mass percent of stone,Handeliodendron bodinieri seedlings show strong stress resistance.Handeliodendron bodinieri seedlings SOD enzyme activity shows an increasing trend,while POD content changes inconspicuously.When the mass percent of stone are 20%,40% and 60%respectively,there is no evident differences in MDA content in matched groups.However,when the mass percent of stone is 80%,the MDA content of it was the highest and significantly larger than that of the matched group.The results prove that the Handeliodendron bodinieri seedlings have grown well under the condition of low mass percent of stone and show strong stress resistance.When the mass percent of stone level reaches 80%,a large amount of peroxide accumulation will cause damage to plant cells,thus affecting seedling growth.(3)With the increase of soil mass percent of stone,the nitrate nitrogen content of Handeliodendron bodinieri seedlings increase at first and then decrease.Among them,when the mass percent of stone reaches 60%,the nitrate nitrogen content is the highest,which is 11.46% higher than the matched group.when the mass percent of stone reaches 40%,the nitrate nitrogen content is 7.32% higher than the matched group.The results indicate that a certain level of mass percent of stone treatment could promote nitrogen absorption and utilization in Handeliodendron bodinieri seedling.Based on the study,different mass percent of stone treatment has a great influence on the root vitality of Handeliodendron bodinieri seedlings.Furthermore,with the increase of mass percent of stone,the vitality of the root system also shows a trend of increasing firstly and then decreasing.Among them,when the mass percent of stone is40%,the root has the strongest vitality,which is 28.21% higher than the matched group.While the mass percent of stone are 20% and 60% respectively,the root also has obviously higher vitality than the matched group.(4)After comprehensive analysis of the growth and physiological indexes under different mass percent of stone treatment in different seasons,it can be concluded that the optimum growth range of Handeliodendron bodinieri seedling is 40%～60% mass percent of stone.From the perspective of Seedling Quality Index: based on the two growing seasons,when the mass percent of stone is 40%,the quality index of Handeliodendron bodinieri seedlings is the highest and ranks the first,while it is 80%,the quality index inhibits the growth of Handeliodendron bodinieri seedlings.The main component analysis ranking can be carried out by combining the growth and physiological index of seedlings.In the first growing season,seedlings in the treatment group with 40% and 60%mass percent of stone grows well,ranking first and second respectively.In the second growing season,both groups still grow well,among them,40% of the treatment group ranking second and 60% of the treatment group ranking first,but the matched group ranks the last.