| Phyllostachys edulis is the most important economic and ecologic bamboo specie inChina. In recent years, in order to achieve the maximum economic benefits from bamboostands, the operating measures of successive cultivation and fertilization have been used,widely, and which have result in a series of problems including soil structural damage, soilerosion and stand productivity decline. In this context, aiming at the issues in stand fertilizationoperations: fertilizer volume, object and time are unclear, different opinions or by experiencemostly, the fertilization problems for P. edulis stands had been put forward and studied in thepaper.The tested P. edulis stand locates in Huangshan district of Anhui province. Based on thegrowing and developmental characteristics, the nutrient accumulation rules of P. edulis fromwinter shoots to adult one which could be harvested were studied. Nutrient high-speedaccumulation period and volume were determined and the key fertilization objects andscientific fertilizer volume were proposed. At the same time, P. edulis leaves and soil nutrientcontents and their correlation with productivity in one biennial cycle, four key physiologicalstages: stage which is after leaves changed (S1), pregnant stage (S2), stage which is in winterfor nutrient accumulation (S3) and stage which is before bamboo shoot pushing the soil up (S4).The better stage for fertilization were determined and proven in practice. The main conclusionswere as follows.1. from winter shoot to adult bamboo which could be harvested, the nutrient accumulationrules were different in each growing period. Among the nutrient elements, N accumulation in P.edulis was most, and followed by K, and the accumulation of P and trace elements weresmaller. N accumulated in shoots and young bamboo growing periods mainly, accounting for88.9%of whole life, and P, K accumulated mainly in young and1,2-year-old bamboo growing period, and ca, si accumulated more in3,4year-old bamboo. Accordingly to that, the keyfertilization objects and demanding volume were determined for each nutrient element.(1) Winter shoots growing and nutrient accumulation rule. The nutrient and size of shootfrom early bud were better than that from late bud. The average height, basal diameter andfresh weight of winter shoots from early buds were18.02cm,5.41cm and266.13g respectively,and these indexes were slightly lower with the eruption of the mid-late shoots. In the standscale, winter shoots biomass maintained a faster growth rate, and fresh weight in January hadincreased21.1kg·hm-2compared with that in December last year, and increased176.9.1kg·hm-2in February compared with that in January. Based on the analysis of biomassand nutrient content, the accumulation was accounted, and N, P, K accumulation in wintershoots had reached2807.6g·hm-2,305.6g·hm-2and610.2g·hm-2。(2) Spring shoots growing and nutrient accumulation rule. Spring shoots height growingrate was significantly greater than winter shoots, and complied with "slow-fast-slow" growthlaw. To the end of April, average height of shoots in stand had come up to71.50cm, however,the average ground diameter changed small. Biomass showed upward Straight, and for the firstinvestigation (27, March), fresh weight of spring shoots had reached81.1kg·hm-2, and it hadchanged to1426.8kg·hm-2for the last survey (30, April), and increased5.9times. With thebiomass rising, nutrient accumulated rapidly, and at the end of April, N, P, K accumulation inspring shoots had reached24002.3g·hm-2,387.2g·hm-2and6558.1g·hm-2respectively.(3) Young bamboo growing and nutrient accumulation rule. Dry matter accumulated inyoung bamboo rapidly before July, and the accumulation rate was significantly reduced next.Through the models of nutrient accumulation to DBH, accumulation in the standard singlebamboo (DBH was9.95cm) within the young bamboo growing period had been accounted,and the net accumulation of N, P, K had reached26.89g,0.52g and20.86g in the two months.(4) Adult bamboo growing and nutrient accumulation rule. Dry matter accumulatedrapidly relatively when the age was younger than2du, and then the accumulation rate sloweddown quickly. Among the nutrient elements, N, K accumulation was more, and in the standard single bamboo, accumulation had reached84.68g and57.97g within the adult bamboo growingperiod. Compared with the shoots and young bamboo growing period, nutrient accumulationrate decreased significantly in adult bamboo, especially after growing3years.2. In one biennial cycle of P. edulis, metabolism was more active in pregnant stage, and inthis stage, the correlation of nutrient content in bamboo leaves and soil with productivity washigher. So, the pregnant stage could be regarded as high nutrient efficiency stage forfertilization management.(1) Nutrient and photosynthetic conditions of leaves. The leaf nutrient content variationwas different in each bamboo age for four photosynthetic stages, and the content of N, P, K etc.in pregnant stage were stable and had a higher correlation with productivity. There were ninenutrients had arrived significant correlation at0.01level. The content of photosyntheticpigments a, pigments b, carotenoids and photosynthetic products were high and had largecorrelation in two stages which were pregnant and before bamboo shoot pushing the soil up.(2) Soil nutrient. In pregnant stage, soil nutrient content changed greatly. pH decreased;organic matter, total phosphorus and available phosphorus content were lower; and totalnitrogen, total potassium content was higher, but the hydrolysis of nitrogen, availablepotassium content were lower. In this stage, the correlation of effective nutrient content in soilwith productivity were high especially nutrient in20~40cm soil layer.3. In one biennial cycle of P. edulis, fertilization in different physiology stage haddifferent effect. Fertilization in two stages which were pregnant (F2) and before bamboo shootpushing the soil up (F4) had better stand productivity and soil moisture-physical properties.The biomass increasing rate of whole bamboo was highest in F2(133.61%), and thesecond one was in F4.(130.33%) About the effect of fertilization in different physiologicalstage on soil moisture-physical properties, the soil tended to loose and had less dense of1.052g·cm-3and1.095g·cm-3respectively in F2and stand of fertilization after leaves changed (F1).At the same, the two stands had a better porosity and higher water holding capacity. The effect of F4was a little worse, and stand of fertilization in winter for nutrient accumulation (F3) hadlittle effect, which was similar to the blank control.In summary, through the research, the key fertilization objects, fertilizer volume and timefor P. edulis stand had been proposed. Fertilizer of N, P, K, Fe and Mg were demanded mainlyin young and1,2years old bamboo and Ca, Si mainly in3,4years old bamboo, and eachnutrient had its own scientific amount. About the fertilization time, in one biennial cycle, thepregnant stage was the higher nutrient and soil efficiency, which was the suitable stage forfertilizer operation. Additionally, the best soil layer was located in20~40cm for fertilization,and it should not be too deep.
|
PDF Full Text Request