Studies On The Photosynthetic Characteristics Of Water Consumption Of Two Tree Species In Mu Us Sandland

The transpiration of plants and its adaption of drought condition are determined by water properties of the plants. Hence, water is the most important affecting factors of the ecological construction in arid and semiarid regions. In this thesis, the photosynthesis and transpiration of Salix Mongolica and Populus Simonii in Mu Su Sandland are discussed combining the microscopic images of stomata in addition to correlation of affecting factors. The water consumption of the two psammophytes is also analyzed.1、Salix Mongolica and Populus simonii photosynthetic rate diurnal variation curves of different, Salix Mongolica curve for double peaks which were found in the morning9:00and11:00, Populus simonii is a single peak curve, the maximum peak at10:00. During the growth season, Salix Mongolica has apparent photosynthetic" lunch break" phenomenon. But nor rthe Populus simonii.2、Salix psammophila transpiration rate curves of smooth, showed a double-peaks a day two peaks have some differences, and have a transpiration trough appeared June transpiration" lunch break" in12:00,July and August at14:00, September until16:00. This is mainly due to the change of environmental factors. Populus simonii transpiration rate presented a single peak curve, seasonal changes, in September6, the peak appeared in10:00,and have the1.38mmolCO2m-2s-1and8.06mmolCC2m-2s-1. In July, appeared in8:00,5.40mmolCO2m-2s-1, August peak appeared at12:00, the peak value is3.59mmol mmolCO2m-2s-1. In September the most strong transpiration rate.3、Salix psammophila leaf water use efficiency mainly focused on1.53mmolmol-1～3.11mmolmol-1,7July and September relatively higher than May and August. Populus simonii leaf water use efficiency of maximum value appeared in June, September the minimum, In the whole growth season, compared with single water consumption are worth, Salix psammophila (7.31kg)<(11.43kg) of Populus simonii.4、Soil moisture, Solar radiation, Stomatal conductance, Leaf water vapor pressure deficit and intercellular CO2concentration is two kind of main internal and external influence factors. Solar radiation, vapor pressure deficit, stomatal conductance, intercellular CO2concentration change, cause two kinds of plant photosynthesis and transpiration rate of increase and decrease. On the various environmental factors and photosynthetic and transpiration rate of related analysis, influence of Salix psammophila photosynthetic rate is the main factor and intercellular CO2concentration and photosynthetic active radiation. Stomatal conductance and photosynthetic active radiation effect and is the main factor of photosynthetic rate leaf Populus simonii.. Stomatal conductance and transpiration rate of leaves of Salix psammophila fitting equation is Tr=2.496+5.246cond. Effect of transpiration rate of Populus simonii is the main factor of stomatal conductance and solar radiation.5、In the growth season, the photosynthesis and transpiration rates, and water use efficiency of Salix Mongolic are higher than Populus Simonii. Thus, Salix Mongolic is a better water-saving and drought-tolerant species than Populus Simonii in desert of arid and semiarid regions.