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Research on Physiological and Ecological Mechanism Response of Eucalyptus Dunnii under Low Phosphorus Stress

Author: ChenXiuLing
Tutor: WuChengZuo;HongWei
School: Fujian Agriculture and Forestry University
Course: Ecology
Keywords: Dunnii Low Phosphorus Stress Response Physiological mechanisms Ecological mechanism
CLC: S792.39
Type: Master's thesis
Year: 2009
Downloads: 96
Quote: 0
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Abstract


Eucalyptus in China has more than 100 years of history, in order to develop high-quality forestry, nearly 20 years, many forestry workers are committed to the introduction of eucalyptus northward. Fujian Forestry province, more successful the Minnan The fast-growing eucalyptus introduction of fast-growing eucalyptus majority in northern Fujian, not cold. In many varieties of eucalyptus, of Dunn eucalyptus (Eucalyptus dunnii Maiden) with its frost-resistant characteristics of fast growing species in the last ten years, as an important industrial raw material species introduction and cultivation of China's large-scale, in our country has a lot to promote afforestation development become an emerging afforestation tree, and our ecological characteristics dunnii little is known about; widespread phosphorus deficiency of soil, soil types, especially in the southern region of typical phosphorus deficiency in red soil area, so dunnii promote the cultivation process is bound to experience growth and phosphorus deficiency reality, due to soil phosphorus deficiency is not \phosphorus pollution in an effective way, so the physiological and ecological response mechanism, under the low phosphorus stress dunnii explore the phosphorus utilization the dunnii potential genetic features, has a very important practical significance. This study two culture by potted plants and nutrient solution pathways, respectively, eight phosphorus concentration level of treatment, the determination of the typical indicators easy to produce changes in the low phosphorus stress conditions on the morphology and physiology, such as root to shoot ratio, acid phosphatase , soil pH, which high more dunnii, tree diameter, chlorophyll content and leaf acid phosphatase enzyme content indicators for the determination of dynamic tracking of five months, and two low-phosphorus stress test dunnii to explore dunnii morphology and physiology of low phosphorus stress response, the main findings are as follows: 1, phosphorus stress on Dunn eucalyptus morphological effects: pot experiment found that with the reduction of phosphorus concentration, high Dunn eucalyptus tree diameter at ground and above ground dry weight of no significant changes in the law, and with the lower concentration of phosphorus treatment, underground dry weight was significantly reduced; phosphorus stress, the stress level of root biomass decreases root to shoot ratio changes also tend so. Phosphorus stress conditions, the distribution of dry matter dunnii mainly in the aerial part; nutrient solution root to shoot ratio of seedlings dunnii the law is inconsistent with potted low phosphorus stress test showed low phosphorus stress test, seven phosphorus stress levels shoot ratio phosphorus levels in the normal supply, showed that root to shoot ratio increased under conditions of severe stress, but the difference was not significant. With the reduction of phosphorus concentration dunnii root dry weight, root volume gradually decreases, total root length also will significantly reduce the root classification results illustrate the fine roots of less than 1mm in diameter Dunn eucalyptus roots part and with the severity of phosphorus treatment, root length of the diameter level is gradually reduced. Phosphorus deficiency Dunn eucalyptus root growth caused by the impact. 2, low phosphorus stress dunnii Physiology: five months of the dynamic determination showed Dunn eucalyptus leaves chlorophyll a, b and total content with the phosphorus concentration decreases significantly increase the photosynthetic rate of change in the law and chlorophyll changes in the law, dunnii chlorophyll content levels and photosynthetic rate significantly; different of phosphorus concentration handle Dunn eucalyptus leaf transpiration rate, stomatal conductance and intercellular CO2 concentration have similar laws, that is, with the prolonged incubation time, the three values ??are reduced. With the the phosphorus treatment time and stress, aggravation, potted to test dunnii blades acid phosphatase enzyme activity leaves acid phosphatase enzyme activity is not increased; decrease of phosphorus concentration, Dunn eucalyptus roots to a significant increase in the secretion of acid phosphatase activity, nutrient solution test phosphorus stress on Dunn eucalyptus root acid phosphatase enzyme activity results with soil Pearson test phosphorus stress Dunn eucalyptus root acid phosphatase activity of the results of the same; dunnii soil acidic phosphate activity of determination that, each phosphorus treatment level Dunne eucalyptus soil rhizosphere acid phosphatase activity was significantly higher than the non-rhizosphere acid phosphatase activity. Soil rhizosphere phosphatase activity was also significantly increased with the severity of phosphorus treatment, plant roots: phosphorus deficiency stress-induced secretion of acid phosphatase organic phosphate rock into soil inorganic phosphorus available for plant uptake and utilization of phosphorus consumption rhizosphere acid phosphatase activity. Low phosphorus stress, dunnii rhizosphere soil invertase, urease activity and rhizosphere soil phosphorus content higher than non-rhizosphere soil; non-rhizosphere and rhizosphere soil urease activity less phosphorus treatment level rhizosphere and the the non rhizosphere urease activity ratios between 1.01 to 1.12. Analysis of variance indicated that different phosphorus concentration dunnii invertase, urease rhizosphere and non-rhizosphere activity had no significant effects; significantly on soil urease activity; soil invertase activity was not significant. This indicates that phosphorus stress on soil urease activity greater impact. Three Species of Soil dunnii activity: enzymatic process compared with the rhizosphere soil, rhizosphere dunnii stronger, with many related research conclusions; phosphorus stress on soil urease activity and Dunn eucalyptus rhizosphere soil acidity phosphatase activity significantly, which may rhizosphere soil in the root exudates and rhizosphere microorganisms active. Low phosphorus stress, the the rhizosphere pH value slightly lower than non-rhizosphere, rhizosphere pH and non-rhizosphere pH value has an increasing trend with decreasing phosphorus concentration, but in non-phosphorus stress level (T8) another decline, non-phosphorus the soil pH environment dunnii different. Different levels of phosphorus treatment dunnii rhizosphere a very significant difference in pH; and nutrition liquid test low phosphorus stress, the pH of the nutrient solution different degrees. Different phosphorus concentration Dunn eucalyptus roots, branches, leaves and total phosphorus were significantly reduced, root dry weight was significantly associated with the phosphorus content of roots. The correlation analysis showed that all measurement indicators, the rhizosphere soil acid phosphatase, leaf acid phosphatase root acid phosphatase, total chlorophyll and the photosynthetic rate of several indicators is closely related to low phosphorus stress conditions. Comprehensive low phosphorus stress conditions dunnii the various indicators of morphological and physiological indicators, Dunn eucalyptus could grow well in low phosphorus soil; their root acid phosphatase activity and rhizosphere phosphatase activity increase most likely dunnii especially one of the low phosphorus stress response mechanism; dunnii increased chlorophyll content, photosynthetic rate increases perhaps dunnii one of the response mechanism.

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CLC: > Agricultural Sciences > Forestry > Forest tree species > Broad-leaved trees > Eucalyptus
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