The function of stomata in plants is controlling gas exchange and modulating water balance. The distribution pattern of stomata in most vascular plants follows a certain regulation with at least one normal epidermal c...The function of stomata in plants is controlling gas exchange and modulating water balance. The distribution pattern of stomata in most vascular plants follows a certain regulation with at least one normal epidermal cell between two stomata. However, some plants restricted in several genera of vascular plants have stomatal clusters in which more than one stoma is adjacently arranged with no epidermal cells among them. The developmental process of stomatal clusters in plants, especially in non-mutant (wild type) vascular plants, has rarely been documented, and very few studies concerning the distribution pattern of stomatal clusters on leaf epidermis have been carried out. We reported the developmental mechanism and distribution pattern of stomatal clusters in Begonia peltatifolia Li native to China. The results indicated that the clustered arrangement of meristemoids at the juvenile stage of the leaf development contributed greatly to the pattern of stomatal clusters. Additionally, satellite meristemoids derived from subsidiary cells around the mature stomata also had an impact on the development as well as the pattern of stomatal clusters. Regarding stomatal cluster and singly occurring stoma both as a stomatal unit, we found that the stomatal unit density (i.e., number of stomatal unit per area) increased gradually from the middle part to the edge and the apex of the leaf, while stomatal unit size (i.e., number of stomata per stomatal unit) decreased. The possible reason of this pattern was discussed.展开更多
The reuse of wastewater for the irrigation of farmlands is gaining popularity, and the nutrient leaching associated with wastewater irrigation is becoming a matter of concern. The variability of nitrogen and phosphoru...The reuse of wastewater for the irrigation of farmlands is gaining popularity, and the nutrient leaching associated with wastewater irrigation is becoming a matter of concern. The variability of nitrogen and phosphorus frac- tions in wastewater-irrigated soil was investigated in both horizontal and vertical directions in Kongjiaxiang, Tongliao, Inner Mongolia, China. The results showed that wastewater irrigation resulted in the concentrations of available N and P being 40.36% and 66.49% higher, respectively, than those with groundwater irrigation. Different forms of N and P exhibited significantly different distribution pattems. Higher concentrations of NO~ and total available N, as well as of those of Ca-P and total available P were observed near wastewater irrigation channels. Ca-P has a spatial distribu- tion pattern similar to that of available P. The concentrations of NO3 and NH4 were the highest in top soil and de- creased with depth. The complex interactions between nitrate leaching and nitrogen transformation processes （e.g., nitrification, denitrification, and mineralization） determined the vertical profile of NO3. The significant amount of NH~ loss inhibited its deep seepage. The Ca-bound compound contained more P than other inorganic fractions as a result of high Ca levels throughout the soil profile. The differences in the concentrations of Ca-bound P at different depths could be due to the upward flux or translocation of Ca from subsurface to surface soil and the sequestration of P.展开更多
文摘The function of stomata in plants is controlling gas exchange and modulating water balance. The distribution pattern of stomata in most vascular plants follows a certain regulation with at least one normal epidermal cell between two stomata. However, some plants restricted in several genera of vascular plants have stomatal clusters in which more than one stoma is adjacently arranged with no epidermal cells among them. The developmental process of stomatal clusters in plants, especially in non-mutant (wild type) vascular plants, has rarely been documented, and very few studies concerning the distribution pattern of stomatal clusters on leaf epidermis have been carried out. We reported the developmental mechanism and distribution pattern of stomatal clusters in Begonia peltatifolia Li native to China. The results indicated that the clustered arrangement of meristemoids at the juvenile stage of the leaf development contributed greatly to the pattern of stomatal clusters. Additionally, satellite meristemoids derived from subsidiary cells around the mature stomata also had an impact on the development as well as the pattern of stomatal clusters. Regarding stomatal cluster and singly occurring stoma both as a stomatal unit, we found that the stomatal unit density (i.e., number of stomatal unit per area) increased gradually from the middle part to the edge and the apex of the leaf, while stomatal unit size (i.e., number of stomata per stomatal unit) decreased. The possible reason of this pattern was discussed.
基金Supported by Major State Basic Research Program of China ("973" Program, No.2009CB118607)Inner Mongolia Science and Technology Foundation (No. 2009058)
文摘The reuse of wastewater for the irrigation of farmlands is gaining popularity, and the nutrient leaching associated with wastewater irrigation is becoming a matter of concern. The variability of nitrogen and phosphorus frac- tions in wastewater-irrigated soil was investigated in both horizontal and vertical directions in Kongjiaxiang, Tongliao, Inner Mongolia, China. The results showed that wastewater irrigation resulted in the concentrations of available N and P being 40.36% and 66.49% higher, respectively, than those with groundwater irrigation. Different forms of N and P exhibited significantly different distribution pattems. Higher concentrations of NO~ and total available N, as well as of those of Ca-P and total available P were observed near wastewater irrigation channels. Ca-P has a spatial distribu- tion pattern similar to that of available P. The concentrations of NO3 and NH4 were the highest in top soil and de- creased with depth. The complex interactions between nitrate leaching and nitrogen transformation processes （e.g., nitrification, denitrification, and mineralization） determined the vertical profile of NO3. The significant amount of NH~ loss inhibited its deep seepage. The Ca-bound compound contained more P than other inorganic fractions as a result of high Ca levels throughout the soil profile. The differences in the concentrations of Ca-bound P at different depths could be due to the upward flux or translocation of Ca from subsurface to surface soil and the sequestration of P.
