| Chinese fir (Cunninghamia lanceolata) is a unique fine-breeding of fast-growing native trees in sub-tropical regions in southern China. Most of the existing Chinese fir forest has been planted on site of continuously planting, some of which have entered the third generation of forest plantation. However, with the increasing generations of the planting of Chinese fir, the volume of timber production per unit area has been dwindled. Chinese fir plantation and purification has caused soil acidification, and aluminum (Al) toxicity in the acid soil is one of the main factors limiting the plant growth. It is widely and traditionally recognized that the crop rotation and mixed plantation would do good in improving soil fertility and productivity.In this study, one-year-old Chinese fir clones and seedlings are used as experimental materials, taking broad-leaved Cinnamomum camphora forest soil, broad-leaved mixed forest fir soil, first generation of Chinese fir forest soil, second-generation Chinese fir forest soil as the test soils to explore the impact of aluminum stress on different cropping patterns (lanceolata×Schima, pure plantations of Chinese fir) fir seedlings biological index and soil enzyme activity by potting experiments.This study is to analyse the effect of aluminum toxicity on the Chinese fir artificial forest and find the way to degrade aluminum toxicity theoretically and lay the theoretic foundation for durable running the Chinese fir artificial forest. The main findings are summarized below:1. In the same concentration of aluminum under duress, coercion prior to 15 d, 8 to deal with the Chinese fir seedlings changes at a relatively general speed, after 30 d the sharp rise; 8 to deal with stress tends to increase as the volume; the same time under stress, handle 8 increased with the stress and concentration. The amount of increase are as follows: second-generation plantation of Chinese fir (for 8)> second-generation plantation of Chinese fir×S.superba (for 7)> first-generation plantations of Chinese fir (for 6)>first- generation plantations of Chinese fir×S.superba (for 5)> planting Chinese fir with mixed forest soil (for 4)> China fir planting with broad-leaved forest soil (for 2)> China fir planting×S.superba by broad-leaved forest soil (for 1)> Chinese fir cultivation×S.superba mixed forest soil (for 3). Under aluminum stress, to deal with 7,8 has the largest membrane permeability 2,4,5 in the middle, and 1,2,3 has a stronger degradation capacity.2. In the same aluminum concentration of stress, dealing with eight seedlings of Chinese fir MDA stress is reflected the increase as time lengthened. The amount of increase is as follows: Handling 8> to deal with 4> for 6> Treatment 2> to deal with 7> to deal with 1> for 3> to deal with 5. That is, to deal with 4,8 membrane lipid peroxidation is most serious, to deal with 2,6,7, is in the middle, while dealing with 1,3,5, performs a stronger degradation capacity of aluminum stress. 3. Al-stress, eight deal with Chinese fir seedlings stress free proline content in 15 d, Al concentration of 10 mg·L-1, demonstrating the downward trend, and then increases as the concentration of aluminum increased. Aluminum concentration in the same stress, the seedlings of Chinese fir leaf free proline content increased with the stress time lengthened. The amount of increase is as follows: Handling 7> to deal with 8> for 6> Treatment 2> to deal with 5> for 3> for 4> 1. Under aluminum stress to deal with 7,8 the maintenance of cell water is poor, to deal with 2,5,6, is in the middle, while dealing with 1,3,4, while dealing with 1,3,5, performs a stronger degradation capacity of aluminum stress.4. Al stress, the determination of invertase activity in soil, soil urease activity of soil acid phosphatase activity, soil catalase activity all decresed firstly and then increased with the increase of aluminum concentration, which is basically as follows: after 15d-45d of the Al stress, the soil enzyme activities decreased with the increase of aluminum concentrations. Al stress in 15 d 45 d after the soil enzyme activity increased as the aluminum concentration decline. The Comprehensive Assessment of soil enzyme activities under the Al stress is: handling with 1,2,3 the soil enzyme activity is the strongest , to deal with 4,5,6 is in the middle, and to deal with 7,8 is weakest.5. Under the Al stress, the Chinese fir rhizosphere soil has stronger soil activity than non-rhizosphere soil. Under the Al stress after 15 d in the amount of decrease activity of the soil is slower in rhizosphere soil than in non-rhizosphere soil, Under the Al stress after 30 45 d with the same stress concentration and different treatments the ratio of the Chinese fir rhizosphere soil and non-rhizosphere soil is small.To sum up, under aluminum stress in different soil types of the eight processing, processing of aluminum 1,2,3 to a certain degree has effects on alleviating the Al poison, the effects resulted from dealing with 4,5,6, while dealing with 7,8 is the smallest. This shows that different ways of dealing with biological stress on the aluminum have significant difference in the ability to put up with the Al stress, which provides a theoretical basis for fir plantation in the future.
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