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Studies On Evaluation Of Drought Resistance Of Main Afforestation Tree In The South Edge Of Taklimakan Desert

Posted on:2010-05-04Degree:MasterType:Thesis
Country:ChinaCandidate:L LiFull Text:PDF
GTID:2143360275497151Subject:Soil and Water Conservation and Desertification Control
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The key environmental stress is the drought and short of water resource, which restrict the economy, society development and environment protection of arid zones in our country. In the arid zones in west China, researching the mechanisms of drought resistance, selecting the plant species with higher drought resistance, and increasing the technique of saving water, which are important especially to the environment improvement of our country and to the development of the West Regions. Imitating the condition of drought how to release the water of soil in Moyu County, Xinjiang province.The relative mean soil water contents of different irrigating treatment were 85%, 70%, 47% and 24%. By measuring the Physiological Characteristics of 6 plant species in order to compare the drought resistance.Two years old seedlings of Populus euphratica and Populus bolleana were chosen and planted in field, then were treated by different amount of irrigation in Moyu County, Xinjiang province. According to measuring the water potential of P. euphratica and P. bolleana under different conditions and at different time, it was shown that their variation trends are"V"figures in a day. The mean daily leaf water potential of P. euphratica was higher than P. bolleana. Comparing the net photosynthetic rate, transpiration rate and water use efficiency of two species, it is turned out the net photosynthetic rate, the transpiration rate and water use efficiency of P. euphratica was higher than P. bolleana. The leafδ13C value of P. euphratica was significantly higher than P. bolleana.Two years old seedlings of Elaeagnus mooceroftii and Elaeagnus oxycarpa were chosen and planted in field, then treated by different mount of irrigation in Moyu County of Xinjiang province. By measuring the leaf water potential of E. mooceroftii and E. oxycarpa under different conditions and at different time, it was shown that their variation trends followed a"V"shape in whole day. The mean daily leaf water potential of E. mooceroftii (-0.87±0.18 Mpa) was higher than that of E. oxycarpa. Comparing the net photosynthetic rate, transpiration rate and water use efficiency of two species, it is turned out the net photosynthetic rate (10.03±1.19μmol·m-2·s-1), the transpiration rate (11.06±0.88 mmol·m-2·s-1) and water use efficiency (0.80±0.09μmol·mmol-1) of E. mooceroftii were higher than that of E. oxycarpa. The leaf δ13C value of E. mooceroftii (-26.06±0.08‰) was significantly higher than that of E. oxycarpa. Elaeagnus mooceroftii and E. oxycarpa grew well under higher soil water contents (85%, 70% and 47%), whereas they showed significantly drought stress under irrigation of 24% soil water content. And then the net photosynthetic rate and water use efficiency of E. mooceroftii were higher (3.26μmol·m-2·s-1, 0.06μmol·mmol-1) than that of E. oxycarpa. The leaf water potential of E. mooceroftii was lower 0.06 Mpa than that of E. oxycarpa.Two years old seedlings of Haloxylon ammodendron and Tamarix hohenackeri were chosen and planted in field, then were treated by different mount of irrigation in Moyu County, Xinjiang province. According to measuring the leaf water potential of H. ammodendron and T. hohenackeri under different conditions and at different time, it was shown that their variation trends are"V"figures in a day. The mean daily water potential of .T. hohenackeri was higher than H. ammodendron. Comparing the net photosynthetic rate, transpiration rate and water use efficiency of two species, it is turned out the net photosynthetic rate and water use efficiency of H. ammodendron was higher than T. hohenackeri. Its transpiration rate was lower than T. hohenackeri. Theδ13C value of H. ammodendron was significantly higher than T. hohenackeri.The law of variation of the Stomata conductance of six plants which reach the maximum and then slow down in the morning . the Stomata conductance rise after reach the minimum .Following the drought aggravation, the donwtrend of the Stomata conductance of six plants is similar to Pn and Tr .The Intercellular CO2 concentration of six plants is similar to the Stomata conductance, and it drops under the water stress. But the range is not wide, and the daily averages of the Intercellular CO2 concentration under the six diffrient treatment were non-significant difference.We can conclude primarily the drought resistance of P. euphratica is above P. bolleanad and E. mooceroftii is above E. oxycarpa and Haloxylon ammodendron is above Tamarix hohenackeri by Subordinate Function Value a. The drought resistance of P. euphratica and P. bolleanad, E. mooceroftii and E. oxycarpa , Haloxylon ammodendron and Tamarix hohenackeri are the result of the phonological and physiological which adapt to the drought improvement for long. By the result of the experiment we can consider the drought indexes were good data when the mount of irrigation was between 600 m3·hm-2 and 800 m3·hm-2. Haloxylon ammodendron and Tamarix hohenackeri seedling have the tapical drought resistance. Drought tress of soil mechanism subsist some definite backward factors because of the time is short to import the plant in moyu. So we need apply multi-index and Integrated Assessment System to do across-the-aboard research. We should research the drought resistance mechanism and emarcid point and physiological characteristics of 6 plant species in future experiment.We take full advantage of the abundant plant resource in particular of sandy plant and xerophytes to reaserch the physiological mechanism of drought resistance in china. Increasing drought resistance of plant, we can mitigate and combat desertification and environment protection theoretics and realistic significance. The important point of research in the future study was how to illuminate systemicly the drought resistance of the substance and physiological function of plant. We should useδ13C as the credible indexes of water use efficiency of the C3 plant in researching plant ecology. Combining technique and measure of the drought induced protein and genetic engineering and reinforcing the research of xerophytes.
Keywords/Search Tags:drought resistance, drought resistance mechanism, evaluated index, photosynthesis, water use efficiency, water potential, δ13C
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