Effect Of Soil Water Stress On Growth And Physiological-Biochemical Characteristics Of Aquilaria Sinensis Seedling

Aquilaria sinensis, our country unique rare and endangered medicinal species, has high medicinal, economic and ecological value. In order to investigate the demand situation of soil moisture and the ability to resist drought environment of Aquilaria sinensis seedlings, then provide certain theoretical basis for its seedling technique promotion. This paper adopted potted water control mode and used two ways:moisture gradient and continuous drought water control, researched effect of different soil moisture on growth, roots, Water physiology, photosynthetic physiology, physiological and biochemical characteristics of Aquilaria sinensis seedlings. Test results are as follow:1. Under soil water stress, the height increment, stem increment, leaf area and biomass of Aquilaria sinensis seedlings are increased with the increase of stress level present a downward trend. Besides existing extremely significant difference among treatments. Comprehensive analysis shows that, influence size of soil water stress on growth characteristics of Aquilaria sinensis seedlings is:20%FC>35%FC>50%FC>65%FC>80FC%(CK)。 The size of plasticity index between each index is:biomass>height>stem>leaf area.2. Under soil water stress, the root length, root surface area, average root diameter, root volume, root number, root activity of Aquilaria sinensis seedlings are increased with the increase of stress level present decreases. Besides existing very significant difference between the various processing level. Comprehensive analysis shows that, influence size of soil water stress on the root system characteristics of Aquilaria sinensis seedlings is:20%FC>35%FC>50%FC>65%FC>80FC%(CK)。The size of plasticity index between each index is:root average diameter>root surface area>the number of root length>root>the root volume>root activity.3. Under soil water stress, the RWC, free water, free water/bound water content of Aquilaria sinensis seedlings are increased with the increase of stress level present decreases, whereas WSD, bound water content increased with the increase of stress level. Besides existing extremely significant difference among the treatments.Comprehensive analysis shows that, influence size of soil water stress on the water physiological characteristics of Aquilaria sinensis seedlings is:20%FC>35%FC>50%FC>65%FC>80FC%(CK)o The size of plasticity index between each index is:free water/bound water>WSD>RWC.4. Under soil water stress, the Pn, Gs, Tr of Aquilaria sinensis seedlings present decreases with the increase of stress level, the WUE increased with the increase of stress level. Besides existing extremely significant difference among treatments.Comprehensive analysis shows that, influence size of soil water stress on the photosynthetic characteristics of Aquilaria sinensis seedlings is:20%FC>35%FC>50%FC>65%FC>80FC%(CK)。 The size of plasticity index between each index is:Gs>Pn>Tr>WUE.5. Under soil water stress, Fo of Aquilaria sinensis seedlings increased with the increase of stress level, whereas Fm、Fv、Fv/Fm、Fv’/Fm’are decreases with the increase of stress level. Besides existing extremely significant difference among treatments. Comprehensive analysis shows that, influence size of soil water stress on the chlorophyll fluorescence characteristics of Aquilaria sinensis seedlings is:20%FC>35%FC>50%FC>65%FC>80FC%(CK).The size of plasticity index between each index i s:Fv>Fv/Fm>F v’/Fm’>Fo>Fm.6. Under continuous drought stress, the cell membrane permeability, MDA content, Proline content of Aquilaria sinensis seedlings increased with the increase of stress level, soluble sugar content and SOD activity increased with the increase of stress level in the change trend of falling after rising first. Besides existing extremely significant difference among treatments.Comprehensive analysis shows that, influence size of continuous drought stress on the physiological and biochemical characteristics of Aquilaria sinensis seedlings is:16d>12d>8d>4d>0d (CK).The size of plasticity index between each index is:proline content>cell membrane permeability>soluble sugar content>malondialdehyde(MDA) content>superoxide dismutase (SOD) activity.To sum up, under the soil moisture content change, the influence on growth and physiological characteristics of Aquilaria sinensis seedlings are significant. Aquilaria sinensis seedlings to water requirement are lax. They can grow rapid under sufficient soil water condition, and also can maintain normal growth in severe drought (20%FC-35%FC) soil environment through themselves adjustment. The result shows that, Aquilaria sinensis seedlings have strong ability to adapt to soil drought environment. But from the perspective of precious tree species and economic forest development analysis:adequate soil water supply helps to improve the quality of Aquilaria sinensis seedlings. In addition to, adequate soil water supply also help Aquilaria sinensis seedlings to grow fast and breed.