| Alnus rubra is one of the non leguminous nitrogen-fixing trees, which is barren resistant treespecies and has strong adaptability, so it can be used as an excellent tree species of plantation.Based on the different ages of Alnus rubra as the experimental material, the article systematicallystudies the Alnus rubra's nutritional characteristics; with annual Alnus rubra seedlings as testmaterials, the experiments involves pot experiments and field experiments, it discusses that thedifferent ratios of fertilizer have different effects on the growth of Alnus rubra. Then by way offitting the second order regression current rotation design and seedlings growth's probity model,we can draw the best fertilization ratios of N, P and K, which provides the theory basis for thecultivation of Alnus rubra and rational fertilization. The main results are as follows:(1)The amount of different elements in two-year-old, four-year-old and six-year-old of Alnusrubra are different. The average content of N in the leaves, the branches and the roots are17.12mg/g(15.40～18.83mg/g),5.11mg/g(3.94～6.27mg/g),13.69mg/g(8.08～19.30mg/g);theaverage content of P in the leaves, the branches and the roots are0.507mg/g(0.413～0.600mg/g),0.571mg/g(0.430～0.711mg/g),0.443mg/g(0.318～0.567mg/g);the averagecontent of K in the leaves, the branches and the roots are6.99mg/g(6.55～7.44mg/g),9.27mg/g(6.93～11.61mg/g),5.36mg/g(4.11～6.61mg/g);the average content of Ca in the leaves, thebranches and the roots are0.698mg/g (0.564～0.832mg/g),0.566mg/g (0.511～0.621mg/g),0.865mg/g(0.605～1.125mg/g); the average content of Ca in the leaves, thebranches and the roots are0.191mg/g (0.166～0.215mg/g),0.136mg/g (0.124～0.148mg/g),0.159mg/g(0.132～0.186mg/g).(2) The distribution rules of the content of mineral nutrious elements in different organs ofAlnus rubra are as follows: in different organs of Alnus rubra, the distribution of the content of Nand Mg are leaves>roots>branches; the distribution of the content of P and K arebranches>leaves>roots; the distribution of the content of Ca is roots>leaves>branches; the ordersof the mineral elements in the Alnus rubra organs are as follows: in leaves and roots, the order isN>K>Ca>P>Mg; in branches, the order is K>N>P≥Ca>Mg.(3) Compared with the amount of mineral nutrition elements in organs of two-year-old,four-year-old and six-year-old of Alnus rubra, we get the change rule of nutrition elements: alongwith the growth of Alnus rubra, in the leaves, the content of P increases, and the contents of N,Ca and Mg decrease, but the content of K is unchanged; in branches, the contents of N, P and Kincrease, and the content of Mg decreases, but the content of Ca remains basically unchanged; inthe roots, the contents of N, P, K and Ca increase, but the content of Mg decreases. (4) In the pot experiments, according to the current rotation design, we carry out theexperiment of ratios of fertilizer. Then we draw all the indicators of the maximum and the ratio offertilization. The height of one-year-old Alnus rubra's maximum is98.03cm, and ratios offertilization are as follows:0.34g/pot,0.61g/pot and0.29g/pot; the maximum of diameter is11.909mm, and the ratios of fertilization0.75g/pot,0.64g/pot, and0.29g/pot; the maximum ofbiomass is57.401g, and the ratios of fertilization are as follows:0.75g/pot,0.50g/pot and0.25g/pot.(5) In the field experiments, according to the current rotation design, we carry out the ratiosof fertilizer test of N, P and K. Based on the mathematical modeling, through the method ofoptimal solution, we can solve Alnus rubra's maximum seedlings height and diameter ratios offertilization in the field. The maximum of height is237.99cm, and the ratios of fertilization areas follows:5.96g/plant,12.32g/plant,5.84g/plant; The maximum of diameter is29.80mm, andthe ratios of fertilization are as follows:10.00g/plant,12.72g/plant,6.64g/plant. |
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