| Drought stress is an important environmental factor that affect survival plant and growth. Natural condition in the Semiarid Loess Region of China is badly, where is serious drought and wild evaporation. It is effect on plant distribution, growth and yield . Therefore, It,s play a very important role in ecological restoration and reconstruction, protecting and developing of regional vegetations.Growths and physiological responses and exploring ecophysiological characteristics was studied in the Semiarid Loess Region of China. This research basised for observation of long-term experiment field and made use of the GSF-3000 Portable Photosynthesis System and MINI-PAM Photosynthesis Yield .Analyzer were carried the research on water physiological characteristics of Tamarix ramosissma,Caragana microphylla, Reaumuria soongorica Maxim and Salsola passerina Bge by periodical sample. Studied the relationships between the leaf projection area and the leaf dryweight. Analied moisture physiology of shrubs and Comparative studied the soil water storage and moisture physiology under different environmental conditions in Ecological Agriculture Station Gaolan of Cold and Arid Regions Environmental and Engineering Research Istitute,China. On the basis of all above researches obtain conclusions as following:(1)Diurnal variations of photosynthesis of Tamarix ramosissma and Caragana microphylla were studied under natural conditions. The results indicated that the daily course of Tamarix ramosissima photosynthetic rate (Pn) and transpiration rate (E) were sing-peak curve. And the daily course of water use efficiency was two-peak curve. By the methods of correlation analysis and stepwise multiregression analysis, the correlations between them and environ mental factors were assessed. The related equations were also constructed in this paper, and the photosynthetic rate (Pn) correlation coefficients were 0.99 and 0.5, respectively.And ranspirationate (E) correlation coefficients were0.998, 0.994, respectively.(2)The photosynthesis characteristic, soil moisture content, water characteristics and plants growth of Tamarix ramosissima under different environments were researched. The results showed that the daily course of Tamarix ramosissima under different environments photosynthetic rate(Pn) and transpiration rate(E) were sing-peak curve. But the maximizing time was different. And it was not all significant differences in the photosynthesis characteristic of the special temporal pointers, soil moisture content, water characteristics and the relations between the leaf projection area and the leaf dry weight of Tamarix ramosissima under different environments. The moisture of surface soil was significantly higher for the C treatment than the control, but no significant differences in moisture of surface soil was found between B treatment and control treatment.Rainwater harvesting and moisture conservation treatments increased growth of Tramosissima, tree height was significantly higher for the rainwater harvesting and moisture conservation treatments than the control.It was obviously slow growth the in 2004 to 2007 than 2002 to 2004.(3) The measurement of daily chlorophyll fluorescence parameters with sunlight as the photochemical light indicated that the ETR of Cartagena microphylla was higher than that of Tamarix ramosissima but the qP and NPQ of the former was lower than that of the latter. The Yield was no significant difference between Caragana microphylla and Tamarix ramosissim.After sufficiently adapting to darkness, the chlorophyll fluorescence parameters such as Fo increasing along with the luminous intensity increase,and showed little change.The Caragana microphyll change was smoother than Tamarix ramosissim. The Fv/Fm of the two kinds of plants become lower with the increasing of light's intensity and reached the lowest at 15:30, then it begins to increase as the light become weak.Under normal conditions,making full dark adaptiong by all-night showed that FV/FM is 0.76 and 0.77 of Tamarix ramosissima and Caragana microphylla.Its lower than 0.80～0.85.Perhaps this is FV/FM decreased in the light intensity far away the energy photosynthesis of sun plants.(4)Comparison of water physiological characteristics in four species, the results indicated that doughty resistance of four species Tamarix ramosissima and Reaumuria soongorica Maxim were the strongest, and Caragana microphyll was lowest.(5) The relationships between the leaf projection area and leaf dry weight of Tamarix ramosissima,Caragana microphylla,Reaumuria soongorica Maxim and Salsola passerina Bge were studied using scanning image processing system and image processing software Photoshop. The relations between the leaf projection area and the leaf dry weight of Tamarix ramosissima,Caragana microphylla and Reaumuria soongorica Maxi were linear. The regression equation were Y=0.055X+0.0085; R2=0.92; Y=0.0488X+0.0297,R2=0.80;Y=0.30X+0.0129,R2=0.53;respectively.The Salsola passé- rine Bge leaf is the multi- thick liquid juice leaf, and the shape is extremely irregular, so its projected area cannot be calculated using the present scanning technology.(6) By the methods of stepwise multiregression analysis to establish the biomass model of Caragana microphylla.The relations between the biomass and the high ground diameter had obtained. The biomass of Solola passerina Bge and Reaumuria soongorica Maxim were 135g, 43.5g, respectively. It was showed that the Solola passerina Bge capacity accumulated dry matter higher that Reaumuria soongorica. |
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