Water relations of Alhagi sparsifolia Shap. at the transition zone between oases and sandy desert were studied in the southern fringe of Taklamakan Desert. Results showed that A. sparsifolia maintained the positive tu...Water relations of Alhagi sparsifolia Shap. at the transition zone between oases and sandy desert were studied in the southern fringe of Taklamakan Desert. Results showed that A. sparsifolia maintained the positive turgor during the summer. The steady high predawn water potential (psi(P)) indicated A. sparsifolia had sufficient hydration and water supply in growing season. In July, water deficit caused by drought stress had no effect on the transpiration of A. sparsifolia. Therefore, drought stress is not a main factor affecting the survival of plants. The physiological adaptation to drought of A. sparsifolia was shown mainly at the leaf level by significant difference (DeltaII) and relative water content (RWC) between the osmotic pressure at full turgor and at turgor loss, by occurring of osmotic adjustment, by high percentage of dry mass-related water content ( WCsat), by RWC at turgor loss point ( RWCp) in stable level and low RWC of the saturated symplast (RWCsym). However, the morphological features of transpiring surface reduction and deep root system seem to be the main way for the plant to adapt to the extreme drought environment. Result also suggests that one time of irregular irrigation in summer will not be helpful to recover water status of A. sparsifolia in location where the water table is very low.展开更多
Aims We investigated the regulation of the water status in three predominant perennial C3 phreatophytes(Alhagi sparsifolia,Populus euphratica,Tamarix ramosissima)at typical sites of their occurrence at the southern fr...Aims We investigated the regulation of the water status in three predominant perennial C3 phreatophytes(Alhagi sparsifolia,Populus euphratica,Tamarix ramosissima)at typical sites of their occurrence at the southern fringe of the hyperarid Taklamakan Desert(north-west China).Methods In the foreland of the river oasis of Qira(Cele),we determined meteorological variables,plant biomass production,plant water potentials(WL)and the water flux through the plants.We calculated the hydraulic conductance on the flow path from the soil to the leaves(kSL)and tested the effects of kSL,WL and the leaf-to-air difference in the partial pressure of water vapour(Dw)on stomatal regulation using regression analyses.Important Findings Despite high values of plant water potential at the point of turgor loss,all plants sustained WL at levels that were high enough to maintain transpiration throughout the growing season.In A.sparsifolia,stomatal resistance(rs;related to leaf area or leaf mass)was most closely correlated with kSL;whereas in P.euphratica,~70%of the variation in rs was explained by Dw.In T.ramosissima,leaf area-related rs was significantly correlated with WL and kSL.The regulation mechanisms are in accordance with the growth patterns and the occurrence of the species in relation to their distance to the ground water.展开更多
文摘Water relations of Alhagi sparsifolia Shap. at the transition zone between oases and sandy desert were studied in the southern fringe of Taklamakan Desert. Results showed that A. sparsifolia maintained the positive turgor during the summer. The steady high predawn water potential (psi(P)) indicated A. sparsifolia had sufficient hydration and water supply in growing season. In July, water deficit caused by drought stress had no effect on the transpiration of A. sparsifolia. Therefore, drought stress is not a main factor affecting the survival of plants. The physiological adaptation to drought of A. sparsifolia was shown mainly at the leaf level by significant difference (DeltaII) and relative water content (RWC) between the osmotic pressure at full turgor and at turgor loss, by occurring of osmotic adjustment, by high percentage of dry mass-related water content ( WCsat), by RWC at turgor loss point ( RWCp) in stable level and low RWC of the saturated symplast (RWCsym). However, the morphological features of transpiring surface reduction and deep root system seem to be the main way for the plant to adapt to the extreme drought environment. Result also suggests that one time of irregular irrigation in summer will not be helpful to recover water status of A. sparsifolia in location where the water table is very low.
基金European Union INCO-DC(Project No.ERBIC18CT980275).
文摘Aims We investigated the regulation of the water status in three predominant perennial C3 phreatophytes(Alhagi sparsifolia,Populus euphratica,Tamarix ramosissima)at typical sites of their occurrence at the southern fringe of the hyperarid Taklamakan Desert(north-west China).Methods In the foreland of the river oasis of Qira(Cele),we determined meteorological variables,plant biomass production,plant water potentials(WL)and the water flux through the plants.We calculated the hydraulic conductance on the flow path from the soil to the leaves(kSL)and tested the effects of kSL,WL and the leaf-to-air difference in the partial pressure of water vapour(Dw)on stomatal regulation using regression analyses.Important Findings Despite high values of plant water potential at the point of turgor loss,all plants sustained WL at levels that were high enough to maintain transpiration throughout the growing season.In A.sparsifolia,stomatal resistance(rs;related to leaf area or leaf mass)was most closely correlated with kSL;whereas in P.euphratica,~70%of the variation in rs was explained by Dw.In T.ramosissima,leaf area-related rs was significantly correlated with WL and kSL.The regulation mechanisms are in accordance with the growth patterns and the occurrence of the species in relation to their distance to the ground water.
