Dissertation > Excellent graduate degree dissertation topics show

Studies on Evaluation of Drought Resistance of Main Afforestation Tree in the South Edge of Taklimakan Desert

Author: LiLei
Tutor: JiaZhiQing
School: Chinese Academy of Forestry
Course: Soil and Water Conservation and Desertification Combating
Keywords: Drought resistance Drought resistance mechanism Evaluation Photosynthesis Water use efficiency Water potential δ13C
CLC: S728.2
Type: Master's thesis
Year: 2009
Downloads: 154
Quote: 1
Read: Download Dissertation

Abstract

Drought, lack of water is the key constraints in the arid region's economic, social development and protection of the ecological environment. Arid region in western China, study plant drought-resistant mechanism, breeding drought-resistant plants, while improving water-saving cultivation techniques have great significance for China's ecological environment construction and large-scale development of the western region. Hotan Prefecture in Xinjiang Moyu County, and in turn reduce the basis of the local afforestation commonly water irrigation amount, analog reduce soil moisture under drought conditions (soil water content in different treatments for the field capacity of 85%, 70 %, 47% and 24%), detection 6 shelterbelts used physiological characteristics of trees and shrubs, pursuant to compare their drought resistance. Select 2-year-old in Xinjiang Hotan Moyu County Populus (Populus euphratica L) and Xinjiang the Yang (Populs alba var.Pyramidalis) seedlings planted in the nursery to the processing of different irrigation water. Determination of the level of different treatment under Populus Populus water potential in different times, the results show that Populus, Populus day trend showed a \Licor-6400 to the the two poplar net photosynthetic rate and transpiration rate were measured, the results show the daily average of the same processing Populus net photosynthetic rate and transpiration rate greater than the instantaneous water use efficiency is higher than Populus, Populus The Xinjiang Young. Also measured the stable carbon isotope ratio of the two types of poplar leaves, results show the Populus δ ^{13 C values ??significantly greater than Xinjiang Yang (p lt; 0.05). Take a 2-year-old big fruit Elaeagnus (Elaeagnus mooceroftii Wall ex Schlecht.) And tip Elaeagnus angustifolia (Euonymus oxycarpa Schlecht.) Seedlings planted in the nursery to different irrigation treatment. Elaeagnus angustifolia determined by different processing, the sharp fruit Elaeagnus the leaf water potential, net photosynthetic rate, transpiration rate, stable carbon isotopes. The results show that: Elaeagnus angustifolia tip Elaeagnus angustifolia day water potential trend was a \the same treatment under the Elaeagnus angustifolia daily average net photosynthetic rate (10.03 ± 1.19μmol · m ^{-2 · s ^{-1 ) and transpiration rate (11.06 ± 0.88 mmol · the m ^{-2 · s ^{-1 ) than the tip of Elaeagnus angustifolia large; Elaeagnus angustifolia instantaneous water use efficiency (0.80 ± 0.09μmol · mmol ^{-1 ) than sharp Elaeagnus angustifolia high; the vane of E. moorcroftii δ significantly large than the tip of Elaeagnus angustifolia ^{13 value (-26.06 ‰ ± 0.08 ‰). Soil moisture field capacity of 85%, 70% and 47%, Elaeagnus angustifolia and tip fruit the Elaeagnus growth condition good. Soil moisture content of 24% of field capacity, Elaeagnus angustifolia and pointed fruit the Elaeagnus by drought stress, but of Elaeagnus angustifolia net photosynthetic rate and water use efficiency than pointed Elaeagnus angustifolia respectively 3.26μmol · m ^{-2 · s ^{-1 , 0.06μmol · mmol ^{-1 , the average water potential than pointed Elaeagnus angustifolia Elaeagnus angustifolia 0.06 Mpa. Determination of Haloxylon under different processing levels (Haloxylon ammodendron) and spend more of Tamarix (Tamarixhohenackeri) in different moments of the water potential, the results show that the trend showed a \The average day average higher than Haloxylon water potential. Licor-6400 of Haloxylon and spend more Tamarix net photosynthetic rate and transpiration rate were measured and the results show of Haloxylon the same treatment of net photosynthetic rate of the daily average is greater than spend Tamarix transpiration rate of daily averages spend more Tamarix higher than at the spend Tamarix and Haloxylon the instantaneous water use efficiency. Also measured of Haloxylon and spend Tamarix leaves or assimilating branches of stable carbon isotope ratio, the results show that the Haloxylon the δ ^{13 C values ??significantly greater than spend Tamarix Liu (p lt; 0.05) . The Haloxylon Is the C ₄ plants, δ ^{the 13 C value their water use efficiency and drought resistance is not clear. After six trees consistent variation of stomatal conductance, by the early morning maximum gradually reduced, reduced to the minimum, change over time and somewhat elevated. But treated differently under the minimum value of the stomatal conductance appear at different times, and each species has its own characteristics. As the drought intensifies, the stomatal conductance of six plants showed a downward trend, with the net photosynthetic rate, transpiration rate trends have got similar. Under different irrigation treatments, six plants intercellular CO ₂ concentration trend stomatal conductance trend is consistent with the severity of water stress the six plant leaf intercellular CO2 concentration decreased , but the decrease is not large, the different treatment under the intercellular CO ₂ concentrations of daily mean all the difference was not significant. According to the results of the analysis by the membership function method, we tentatively concluded that the Populus drought resistance in Populus, stronger tip Elaeagnus angustifolia Elaeagnus angustifolia drought. The Haloxylon showed better adaptation than spend more Tamarix characteristics. Populus Populus drought formation of Elaeagnus angustifolia and tip Elaeagnus angustifolia, Haloxylon and spend more Tamarix morphology and physiological functions outside the arid environment of long-term adaptation results. Based on the test results of the preliminary view, when the irrigation amount between 600 ~ 800 m ^{3 · hm ^{-2 the two seedling growth conditions and various Drought indicators have a good value, that is, to achieve the purpose of water conservation can also enable the normal growth of plants. Of Haloxylon and spend Tamarix seedlings have a typical drought tolerance characteristics, its the introduction of the Moyu test of time is very short, there is a certain lag in the reaction mechanism of soil drought stress and require the application of multi-index comprehensive evaluation system on the drought ability to conduct a more comprehensive and in-depth research. To learn more about the six plant drought-resistant mechanism and wilting point, also need to do a more in-depth study of two plant physiological characteristics in the future. Make full use of China's rich plant resources, especially psammophytes, and xerophytes resources to study the physiological mechanisms of plant resistance to drought stress, increase drought resistance, has important theoretical and practical significance to alleviate and prevent desertification, protect the environment, etc. . Focus of future work should be more multi-level system to clarify the material basis of plant drought and its physiological function δ ^{13 C values ??should be as reliable indicators reflect the the C3 plant long-term water use efficiency applied to plants Many studies of the ecology, combined with drought-induced protein and gene engineering and technical measures to strengthen research on drought-resistant plants.}}}}}}}}}}}}}}}

Related Dissertations

CLC: > Agricultural Sciences > Forestry > Silviculture, tree breeding and afforestation techniques > Special regional afforestation > Arid area afforestation
© 2012 www.DissertationTopic.Net Mobile