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Northwest A&F University (2017)

Water Source and Water Use Efficiency of Typical Shrubs in the Wind and Water Erosion Area

杨国敏;

Titre : Water Source and Water Use Efficiency of Typical Shrubs in the Wind and Water Erosion Area

Auteur : 杨国敏;

Grade : Master’s Theses 2017

Université : Northwest A&F University

Résumé
This study was taken the typical shrubs Caragana microphylla and Salix psammohila in the wind and water erosion as the research object.The water source and water use efficiency of Caragana microphylla and Salix psammohila was analyzed in the different seasons,and the influence of meteorological factors and plant physiological parameters on the water use efficiency was discussed throughout the growing season.The main results were as follows:Water use strategies of Caragana microphylla and Salix psammohila were different in the dry season and wet season.Both used deep soil waterduring the dry season,Caragana microphylla used 48.1% water from the 40-80 cm layer,and Salix psammohila used 49% water from 40-80 cm layer.In the wet season the various levels of soil water utilization of two shrubs changed obviously,which showed to reduce the use of deep soil water and tended to use shallow soil water.Caragana microphylla used more than 57.5% water from the surface soil layer(0-10cm)and shallow layer(10-40cm) ;Salix psammohila used more than 76% water from shallow layer(10-40cm).Non-rectangular hyperbolic model was adopted to match the photosynthetic parameters of Caragana microphylla and Salix psammohila in different seasons.The result showed that : the maximum net photosynthetic rate(Pnmax),apparent quantum efficiency(α)and dark respiration rate(Rd)of two kinds of plants in the dry season were less than the wet season.The utilization capacity of low light level and highlight of Caragana microphylla in the wet season were less than in the dry season,while the utilization capacity of low light level of Salix psammophilai was not much different in the dry and wet season and the utilization capacity of highlight of it in the wet season was greater than in the dry season.The photosynthetic rate(Pn)and transpiration rate(Tr)of the two kinds of plants increased with the increasing light intensity in the dry and wet season,and the range of Pn and Tr were different.The WUE increased with the increasing light intensity and then kept stable.And for the two kinds of plants,the WUE in the dry season was greater than the wet season.The photosynthetic parameters of Caragana microphylla and Salix psammohila in May-September showed that : The Caragana microphylla diurnal variation of photosynthetic rate of leaves was gentle in May,and showed a double peak curve in June and September and a single peak curve in July and August.The Salix psammophila diurnal variation of photosynthetic rate of leaves showed a single peak curve in May and June and a double peak curve in July to September.The Caragana microphylla diurnal variation of transpiration rate appeared as a single-peak curve in June to September and a double peak curve in May.The Salix psammophila diurnal variation of transpiration rate appeared as a single peak curve in June,August and September and a double peak curve in July.Light intensity,stomatal conductance and CO2 concentration of intercellular were the main factors to the photosynthesis and transpiration rate of Caragana microphylla and Salix psammophila.The diurnal variation of curves of water use efficiency of the two kinds of plants showed “V”,and it was minimum at 13:00.The water use efficiency of Caragana microphylla was in sequence of August>September>May>July>June,while it was July>May>August>September>June of Salix psammophila.During the whole growing season,the δ13C of the Caragana microphylla and Salix psammophila leaves was 29.60 ± 0.90 ‰ to-24.93 ± 0.92 ‰ and-28.28±0.45‰ to-26.65±0.17‰,with an average value of-27.08‰ and-27.40‰.It indicated that Caragana microphylla and Salix psammophila belong to C3 plant.The seasonal variation of δ13C and water use efficiency of the two plants showed a decreasing trend.The highest water use efficiency of Caragana microphylla was 2.70μmol·mmol-1 in May,and then decreased to a minimum of 0.75μmol·mmol-1 in July.The water use efficiency has an increasing trend from July to August,but the difference was not significant.The highest water use efficiency of Salix psammophila was 2.12μmol·mmol-1,and then decreased to a minimum of 0.63μmol·mmol-1 in September.The water use efficiency of Caragana microphylla was slightly higher than Salix psammophila in the growing season.The δ13C of Caragana microphylla and Salix psammophila was not correlated with precipitation,temperature,and P and K content of the leaf.And there was a significant negative correlation with the N and water content of leaf.

Mots clés : Wind and water erosion; Caragana microphylla; Salix psammohila photosynthetic rate; transpiration rate; water resource; water use efficiency; δ13C value;

Présentation (CNKI)

Page publiée le 22 janvier 2018