Influences Of Compound Sedimentation Of Nitrogen(N) And Sulphur(s) On Physiological Property Of Eucalypt And China Fir Seedlings

Nitrogen(N)and sulphur(S)are the essential mineral elements that are vital to plants.They are also the important components of regulation of life activities,especially playing an important role in photosynthesis and nitrogen fixation reaction.That the nitrogen and sulfur content exceeds a certain range will lead to negative biological effect.Eucalyptus is one of three species fast-growing in world,with significant economic benefits,whose afforestation areas reach about 20000 hm2 in southern and northwest of Fujian.Chinese fir is the typical subtropical forest ecological system in China.It is also the important timber tree species planted in southern China,whose distribution range is very wide,the forest area accounts for more than 60%of the plantatio.The acid deposition of Southern regional is serious,carrying out the acid precipitation of Eucalyptus and cunninghamia lanceolata seedlings has important significance of nutrient absorption、biomass allocation、photosynthesis characteristic and the contrast research to the ecological sustainable development of southern forest.In this experiment,simulated the effect of nitrogen and sulphur combined deposition on nutrient uptake、photosynthesis and biomass of Eucalypt and China fir seedlings,comparing the difference between two seedlings of the changes of physiological index,analyzing the law of Eucalyptus and China fir seedlings growth supplied with different compound sedimentation of N&S.The appropriate concentration of nitrogen and sulfur deposition could increase nitrogen concentration of Eucalyptus seeding,especially in leaves.The leaves、roots and stems of plants showed the sensitive reaction supplied with nitrogen.The maximum nitrogen concentration of leaves and roots presented to high nitrogen deposition(N 1 g/a).The nitrogen concentration of leaves、stems and roots gradually reduced in different seasons,leaves、stems and roots reduced 44.3%、29.0%and 11.9%.The response of China fir on sulphur deposition was more sensitive than Eucalyptus.The maximum nitrogen concentration of leaves and roots both got in the single sulfur deposition.Seasonal variation of nitrogen concentration in the organs of Chinese fir showed a decreasing-increasing-decreasing trendFrom July to November,Phosphorus concentration of Eucalyptus gradually declined.Phosphorus concentration of leaves、stems and roots decreased by 68.0%、53.9%and 68.0%in November compared with the number of July.High sulfur(S 0.3 g/a)could increase the phosphorus concentration of Eucalyptus roots,but inhibit the P concentration in the leaves.In leaves,the maximum phosphorus concentration presented to treatment 8,comparing with phosphorus in treatment 3 and treatment 9,phosphorus concentration increased 6.4%and 13.4%.From July to November,Phosphorus concentration in roots of China fir had been on the rise.Variation of phosphorus concentration in the stems and leaves of Chinese fir showed a decreasing-increasing-decreasing trend.The maximum nitrogen concentration of leaves and roots both got in the moderate sulfur deposition(S 0.15 g/a).The SPAD values of Eucalyptus obtained the maximum value in treatment 2,increased by 4.9%than treatment 7.The SPAD values of Chinese fir obtained the maximum value in treatment 6.The results indicated high nitrogen deposition could cause nutrient stress on Eucalyptus and China fir.The relative chlorophyll content of Eucalyptus was greater than Chinese fir,increased by 13.8%than that of Chinese fir.The protein content in the maximum concentration of Eucalyptus leaves occurred at treatment 8,while the maximum protein content of China fir presented to the moderate nitrogen deposition.In three months,the average protein content of Eucalyptus was slightly higher than that of Chinese fir,only increased by 0.48%.Sulfur deposition could promote the synthesis rate of ALA and PBG concentrations in Eucalyptus,whose maximum values both appeared in treatment 2.The effects of nitrogen deposition on the synthesis rate of ALA and PBG content of China fir was obvious.The synthesis rate of ALA and PBG concentrations in China fir increased with the increase of nitrogen deposition concentration.In three months,the synthesis rate of ALA in China fir was higher than 10.9 times of Eucalyptus,while the PBG concentrations in China fir was also higher than 4.9 times of Eucalyptus.In different seasons,the change trend,two kinds of seedlings of net photosynthetic rate,was almost consistent.The maximum net photosynthesis rate of Eucalyptus and China fir both got in the treatment 5,the minimum both got in the treatment 7,the average of maximum net photosynthetic rate of Eucalyptus increased by 43.1%than that of Chinese fir.In the treatment 4,it reached the maximum value of Fv/Fm in Eucalyptus.The inhibition of high sulfur deposition on Fv/Fm of Eucalyptus was the mostobvious.The value of Fv/Fm decreased by 16.9%comparing with treatment 4.The maximum value of Fv/Fm in China fir presented to the single moderate sulfur deposition.It indicated that the response of Eucalyptus on nitrogen deposition was more obvious than China fir,while the response of China fir on sulphur deposition was more sensitive than Eucalyptus.Sulfur nitrogen supply significantly affected the growth and biomass accumulation of Chinese fir and Eucalyptus.As for nitrogen and sulphur concentration treaments,Eucalyptus and China fir seedlings’ height、collar diameter and biomass increased more or less.The maximum height of Eucalyptus and China fir presented to treatment 5.While high nitrogen and high sulfur had inhibitory effect on the growth of Eucalyptus and China fir.Two seedlings both reached the maximum growth rate of above-ground and underground biomass in the treatment 5.The growth rate of above-ground and underground biomass were 3.8 times and 2.3 times of China fir.