| Chinese fir[Cunninghamia lanceolata(Lamb.)Hook]is a unique evergreen coniferous species with high yield,good material and easy breeding.It is widely planted in the subtropical regions of China.In recent years,with the improvement of fir wood prices,fir forest fertilization become more and more popular,and achieved a good yield effect.At the same time as the breeding of Chinese fir varieties to speed up the genetic improvement of the Chinese fir seed garden,it has been a large area to promote in the production.However,the previous research on the fertilization of Chinese fir,all focus on the primary seed orchard plantation.The formula of Chinese fir was significantly different from that of genetically modified Chinese fir.On the other hand,in recent years,the decline of Chinese fir continuous planting is becoming more and more serious,and the nutrient deficit of multi-cropping plantations is obvious,so the problem just depend on traditional Chinese fir fertilization method cannot be solved.That greatly limits the yield of second-generation genetic improvement about Chinese fir plantation.Therefore,how to choose the soil testing and fertilization techniques to suitable for second-generation genetic improvement of Chinese fir plantation has become a major problem in the current forestry production.In view of this,this paper aims at the improvement of the fertility on the forest requirement and the decline of the fertility about Chinese fir planted forest,second-generations of Chinese fir seeding and Chinese fir plantations at different stages were selected as the research object,through the "3414" soil test formula fertilization additionally the application of trace fertilizer B,Zn method,to research the suitable fertilization range and fertilizer order of second-generation Chinese fir,and compare the differences of morphological,physiological and biochemical effects of different formula on second-generation Chinese fir.The final purpose is discussed the perspective of nutrition requirement about second-generation genetic improvement in Chinese fir,reduced the operating cost of Chinese fir and alleviated the decline of soil fertility in Chinese fir plantation.The main findings are as follows:(1)The effects of different soil fertilization treatments on the growth of potted Chinese fir seedlings were different.The fertilization treatments showed a significant level of plant height,ground diameter and biomass.Among them,the proportion of fertilizer with high height growth was treatment 25,11 and 13,which were 27.75%,27.55%and 23.76%more than the control.The worst is the lack of potassium treatment,7.28%more than the control.The greater effect of the growth on the diameter is treatment 11,25 and 5,compared with the control increased by 48.58%,30.82%and 25.90%.The worst is high phosphorus treatment,2.08%more than the control.The greater impact on total biomass is equilibrium,low nitrogen and potassium treatment,high nitrogen treatment.The ratio of trace to fertilizer was higher than that of the treatment 12,8 and 28,which was 22.70%,16.38%and 15.53%higher than the control.The worst is low potassium treatment.The effect on the diameter of the larger treatment 8,24 and 12,compared with the control increased by 56.47%,48.20%and 40.71%.The worst is high potassium treatment.The greater impact on total biomass is high nitrogen,equilibrium and high phosphorus treatment.(2)The differences treatment cause to superoxide dismutase,peroxidase,catalase activity and malondialdehyde(MDA)in different parts of Chinese fir were significantly different(p<0.01).From the different parts of view,superoxide dismutase activity showed a total of leave>stem>root.With the increase of single element fertilizer,the superoxide dismutase of roots,stems and leaves showed a tendency to decrease first and then increase,and the equilibrium fertilization treatment was the lowest.The activity of peroxidase was consistent with that of catalase,and there was no significant difference in leaf,stem and root.With the increase of fertilizer application,the catalase of root and stem showed the trend of decreasing first and then increasing,while the change of catalase in leaf was opposite.The content of malondialdehyde(MDA)in the stems and leaves was significantly lower than that in the roots.(3)With the prolongation of the planting time,the initial fluorescence F0 values of each treatment showed a significant increase and then a further downward trend,the maximum fluorescence FM value first showed a significant decrease followed by a rising trend,while PSII maximum photochemical efficiency gradually stabilized trend.With the increase of planting time,SPAD value besides blank processing continued to decline,the rest of the treatment have a certain degree of increase.Chlorophyll ab,total chlorophyll a+b and carotenoid content showed a tendency to increase first and then decrease.The chlorophyll a was 0.73±0.00 mg/g,the chlorophyll b was 0.59±0.03 mg/g,the total chlorophyll content was 1.31 mg/g and the carotenoid content was 0.11±0.00 mg/g in balance treatment.From the view of overall accumulation,there are trace fertilizer treatment than the leaf area and cell membrane permeability than non-trace fertilizer treatment.(4)The contents of N,P and K in different growth sites were as follows:nitrogen>potassium>phosphorus>boron>zinc,the contents of nitrogen,phosphorus and boron in Chinese fir were leaf>root>stem.While the contents of potassium and zinc were shown:leaf>stem>root.(5)Diagnosed by DRIS nutrition,NII composite index of equilibrium treatment(treatment 12),high potassium treatment(treatment 20)and high phosphorus treatment(treatment 14)is smaller,and it is the optimal yield of Chinese fir seedling.It is available from the fertilizer effect function,the optimum fertilization of N,P and K were 1.13 g/kg,0.68 g/kg and 0.92 g/kg,respectively.The optimum fertilization rates in trace fertilizer were N 1.66 g/kg,P 0.72 g/kg,K 0.96 g/kg,B 4mg/kg and Zn 4mg/kg,respectively.(6)Different fertilization treatments had different effects on the growth of Chinese fir plantations at different developmental stages,160 g/plant of nitrogen fertilizer,450 g/plant of phosphate fertilizer and 60 g/plant of potassium fertilizer on young will play a more positive role to height of Chinese fir.Then 160 g/plant of nitrogen fertilizer,300 g/plant of phosphate fertilizer and 60 g/plant of potassium fertilizer on young play a more positive role to DBH and single volume of Chinese fir.When 360 g/plant of nitrogen fertilizer,600 g/plant of phosphate fertilizer and 150 g/plant of potassium fertilizer on middle,150 g/plant of nitrogen fertilizer,800 g/plant of phosphate fertilizer and 200 g/plant of potassium fertilizer on mature will play a more positive role to height、DBH and single volume of Chinese fir.(7)Different fertilization treatments had different effects on soil microbial biomass and soil enzyme in different developmental stages of Chinese fir plantation.The fluctuation range of microbial biomass nitrogen in young forest was 4-12 mg/kg,and in middle age forest was 5-25 mg/kg,and in mature forest was 5-15 mg/kg.The fluctuation range of microbial biomass carbon in young forest was 50-250 mg/kg,and in middle age forest was 200-500 mg/kg,and the fluctuation range of mature forest was 200-500 mg/kg.The effects of different fertilization treatments on soil urease,sucrase and catalase activity in the same soil layer were not significant,except that catalase did not show significant in 10-20 cm soil layer.(8)The optimum growth rate of young forest was nitrogen fertilizer 185 g/plant,phosphate fertilizer 253 g/plant,potassium fertilizer was fixed 60 g/plant,the optimum ratio of nitrogen,phosphorus and potassium was 3.08:4.22:1.The optimum amount of fertilizer for the middle age forest is nitrogen fertilizer 360 g/plant,phosphate fertilizer 600 g/plant,potassium fertilizer is 150 g/plant,the optimum ratio of nitrogen,phosphorus and potassium is:2.4:4:1.The optimum fertilization rate for the aged forest is 399 g/plant,368 g/plant of phosphate fertilizer,200 g/plant of potassium fertilizer,the optimum ratio of nitrogen,phosphorus and potassium is 1.99:1.84:1. |
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