Effect Of Acid Aluminum Composite Stress On Physiological Indicators And Absorption Of Nutrients Chinese Fir Seeding Differing Aluminum Tolerance

Chinese Fir is one of the most fast-growing timber tree species in the Southern China, It is widely cultivated with a high yield, high quality, pest and disease resistance and other characteristics, area of Chinese fir plantation, and the volume and the output value of forestry come out in front in the national forestry tree species, has a pivotal position and play a decisive role in the ecological environment and forestry economy. Soils in South China is acidic aluminum-rich red loam, organic acids and phenols substances secreted by fir self-allelopath exacerbated soil acidification coupled with the growing of acid rain pollution t intensified acidification in southern region in recent years, the activation of soil aluminum exacerbate toxicity towards fir, fir is sensitive to aluminum toxicity trees, fir forest soil organic matter and nutrient loss resulting from soil degradation by artificial fir serialise and fir self-allelopath.In this study, with the one year of differential aluminum tolerance(Al-sensitive, resistant aluminum) fir seedlings as experimental material, we adopted hydroponics culture experiments and investigated the effect of acid aluminum composite stress on fir seedlings differing aluminum tolerance physiological and biochemical characteristics, photosynthetic and the corresponding effect on the role of accumulated mineral elements. In theory provides a theoretical foundation for the sustainable development of Chinese fir.The main results are as follows:1under acidic aluminum composite stress, with the extension of stress time, the MDA content of the aluminum sensitive and aluminum resistant Chinese fir seedlings compared with the initial values were more than the initial value, and showed a trend of rising. Al-sensitive families, Under the condition of the same pH, with the increasing of Al concentration, MDA content showed a trend of rising in aluminum-sensitive and resistant aluminum fir seedlings, Under the condition of the same concentrations of aluminum stress, aluminum-sensitive and aluminum-resistant fir MDA content in the leaves with acid stress intensifies and showed a trend of rising. Under the condition of the same pH and the same concentration of aluminum, MDA content in fir seedlings with the extension of stress time and the greater the increase in the growth rate, MDA content in aluminum-sensitive fir seedlings is higher than resistant aluminum.2under acidic aluminum composite stress, Al-sensitive fir seedlings, with increments of stress time, only Under the condition of pH4.0and without aluminum, the aluminum-sensitive fir seedlings CAT showed a trend of rising,then falling, under other conditions CAT activity in aluminum-sensitive fir seedlings with increasing stress time are enhanced. With increments of stress time, CAT activity in fir increased magnitude larger than aluminum-sensitive. Under the condition of the same pH, Under the condition of high alumina and aluminum CAT activity in sensitive fir seedlings is stronger than aluminum-resistant.3POD activity of Chinese fir seeding differing aluminum tolerance, with the extension of acid aluminum composite stress, is falling after first rising.POD activity in two differing aluminum tolerance of Chinese fir seedlings are stronger than the initial value, the POD activity of fir seedlings, are strongest when stress15d Under the condition of the same pH and the same concentration of aluminum, POD activity of Chinese fir seeding showed a trend of rising with time when the upward trend in amplitude, aluminum-resistant is higher than aluminum-sensitive, while POD activity decreased with stress time increment, the decrease in resistance is lower than sensitive.4SOD activity of Al-scnsitive pedigree fir seedlings under acidic aluminum composite stress, with the extension of stress time, was reduced after the first rising, After stress30d, SOD activity is the strongest, in the stress section45d, SOD activity stell higher than the initial value. Under the condition of the same concentrations of aluminum stress, SOD activity of aluminum-sensitive fir seedlings with enhanced acidity enhanced; SOD activity of fir aluminum-resistant under acidic aluminum composite leaf SOD is shown in Figure8:SOD activity increased with the passage of time was downward trend after the first rise, in stress first15d, SOD activity is the highest. 5Under acid aluminum composite stress on Chinese fir seeding differing aluminum tolerance, with the extension of stress time, chlorophyll content in aluminum-sensitive and aluminum-resistant fir seedlings showed a trend of falling, with the stress time increments, chlorophyll a content in aluminum-resistant fir compared with the initial rate of decline is less than the aluminum-sensitive; chlorophyll b in aluminum-resistant and aluminum-sensitive content with increasing stress time showed a decreasing trend.6Fo in aluminum-sensitive and aluminum-resistant fir seedlings with stress time increments show a rising trend, Fm, Fv, Fv/Fm are all declining, under the same conditions, Fo in aluminum-resistant fir is less than the initial increase in aluminum-sensitive, Fm fir in resistant aluminum is declined greater than aluminum-sensitive and aluminum-resistant, while Fm of fir in resistant aluminum is always greater than aluminum-sensitive Fm. Fv change with the different treatment of irregular variation. Under the of the pH3.S, Fv/Fm in aluminum-sensitive and aluminum-resistant of fir was no significant regular variation, other acidity condition with stress time increments, the amplitude of Fv/Fm of Chinese fir seedlings in aluminum-sensitive is decreased more than aluminum-resistant Fv/Fm.7Abouting mineral nutrients accumulation, K content of fir in aluminum-sensitive in roots, stems and leaves of each part are lower than the corresponding aluminum-resistant site, Ca content of Chinese fir in aluminum resistant, under the condition of pH4.5,5.0and the same concentration of aluminum, is higher than aluminum-sensitive in the leaves. Al content of Chinese fir seedlings aluminum-resistant and aluminum-sensitive in roots is highest than in stems and leaves, under the condition of high aluminum and mid-aluminum, Al content of Chinese fir in aluminum-sensitive in roots more than aluminum-resistant.