Studies On Nutrition And Roots Regulation Of Poplar Closed Forest

Poplar has grow fast, short rotation and consume more nutrients characteristics. But the soil nutrient supply generally poor. It has low total nutrients and low nutrient content available. Even to do cultivation the producers attention to harvest only, not importance return of nutrients in a timely manner. So that poplar growing conditions deteriorate further. How to improve conditions for poplar growth, especially in conditions of nutrient needs in order to promote poplar growth has been a concern. Science fertilization is the important technical measures to maintain soil fertility, regulation of nutrient balance and improve per unit area of wood production. After poplar closed, the underground root systems are intertwined and reduced root growth. This period the roots gradual aging, root hairs less and the ability to absorb nutrients is poor. With the growth of poplar it's easy to form'small tree'and spread diseases and insectpests. Therefore, to study the nutrition control of poplus root is necessary. It's important to improve nutrient absorption capacity of the root system, increase timber cumulation and promote the poplar fast-growing. In this study, based on the regeneration capacity of the root system by cutting technology, and with reasonable root fertilization method to study the tree's physiological characteristics and soil environmental. The purpose of this research was to provide the necessary and the basis of theoretical support on poplar plantation. The main results are as follows:1. The different age of the root activity measured results show that the one-year-old ,capillary roots and apical parts of root activity and root active absorption area is the highest, followed by two years.So the main nutrients in poplar fine roots based young. Its absorption of moisture and nutrients and the synthesis, catabolism strong and help to resist and prevent the invasion of pathogens and spread. And root growth to four or five years of its root activity and root active absorption area of significantly reduced. This study provide a theoretical basis for cutting roots experiment.2. Different fertilizer treatments have different effects on the poplar growth. From 80cm both sides of the tree fertilization and cutting roots measure can significantly promote tree growth, compared with the control diameter at breast height growth increased 60.5%, tree growth was enhanced by 145%. So proper fertilization and cutting roots measure can promote the growth of the tree. During late April and late May, the leaves of nitrogen, phosphorus and potassium contents on the fertilization treatment were higher than control, and all others treatment were less than control. This is because the main impact factor of this period is the roots size. The fertilizer is not effect in time after cutting roots. But after about a month to restore the root system, the leaves of nitrogen, phosphorus and potassium contents in treatment 5, 6, 7, 8, 2 gradually higher than the control. This is because the absorption of fertilizer during this period shown to promote on the elements, and with the passage of time the processing elements continue to be reduced to a leaf until the latter part of the growing season is also higher than the control.3.The pH value in rhizosphere soil of treatments poplar plantation were lower than that in non-rhizosphere soil, but the content of organic,available nitrogen, phosphorus, potassium, utility cuprum and utility zincum were all higher than those in non-rhizosphere soil. The available nutrient content of 80cm cutting roots fertilizer treatment on both sides was significant more than other treatments both in rhizosphere and non-rhizosphere soil. 80cm cutting roots fertilizer treatment increased the activity of soil urease, invertase, catalase, polyphenol oxidase, peroxidase significantly, compared with CK. Five soil enzyme activities by fertilizer treatment increased little, but cutting roots treatment decreased the activity. The quantities of microbe were the largest growth rate.4. Compared with the control, cutting roots fertilization measure can increase the leaf content in GA, CTK, IAA and lower content of ABA, in order to promote the tree growth. The study of the 80cm on both sides cutting roots fertilization treatment to promote the growth of poplar is the best. Compared with the control and root cutting, reasonable root cutting fertilization can increase photosynthesis and water use efficiency and reduce consumption than to breathe. That appropriate application of these changes can significantly improve the photosynthetic performance of poplar leaves. The study shows that both sides of the cutting roots fertilization in the 80cm can improve the tree's photosynthetic performance higher, and increase water use efficiency.5. After 8 months recovery by cutting roots, the number of the fibrous roots and lateral root have incresed and increased the absorption area of roots. Cutting roots fertilizer treatments deal with just cutting roots to stimulate germination, and that may be due to the efficiency of fertilization effect, making the restoration of a better root system. Different cutting degrees have different impacts, with 80cm both sides of cutting roots fertilizer treatment to restore roots most obvious and increase the trees growth.6. Different fertilizer treatments significantly increased poplar growth, and humic acid fertilizer have a clear role in promoting on the growth of poplar, compared with control annual average tree height and diameter at breast height increased by 82% 55%; followed is treatment 9, compared with control annual average tree height and diameter at breast height increased by 68%, 46.2%. N, P, K three elements fertilizer is the best to promote poplar leaves for the N, P, K absorption and accumulation. And treatment 9 with three elements in the leaves until the end of the growing season are the highest.7. All fertilizer treatments compared with the control can improve the soil nutrient content, soil enzyme activity. The studies showed that fertilization will not change adversely on soil nutrient, nor affect seriously on soil ecological environment. Fertilization significantly increased the number of soil microorganisms, compared with the control treatment 10 and treatment 9 in the total number of microorganisms increased by 158%, 147%.