Ammopiptanthus mongolicus, the only freezing tolerant evergreen broad-leaved shrub, local species of the Alashan desert, northwest sand area of China, can survive -30℃ or even lower temperature in winter. In the pres...Ammopiptanthus mongolicus, the only freezing tolerant evergreen broad-leaved shrub, local species of the Alashan desert, northwest sand area of China, can survive -30℃ or even lower temperature in winter. In the present study, the secondary products phenolics in A. mongolicus cotyledons were determined to study the effects of phenolics on cold tolerance. Cytochemical localization of phenolics in cotyledon cells was observed by electron microscopy and the content of phenolic compounds was assayed by spectrophotometric measurement. The results showed that the freezing tolerance ofA. mongolicus seedlings increased after acclimation at 2℃ for 14 days, which accompanied the increase of the content of phenolic compounds in cotyledons. Cytochemical observation showed that phenolic deposits were mainly localized in vacuoles and in close proximity to tonoplast, and also in the cytoplasm. The amount and the size of phenolics droplets increased obviously in cytoplasm and vacuoles after cold acclimation, predominantly aggregated along membranes of vacuoles and tonoplast. No phenolic deposits were found in cell walls. As hydrogen- or elec- tron-donating agents, phenolics may protect plant cells against reactive oxygen species formed during chilling or freezing stress and improve the freezing tolerance of cold-acclimated A. mongolicus seedlings.展开更多
Today,the world’s population is rising dramatically,and in line with this increase in the population of food and agricultural products,there must be an increasing in the number of problems associated with this proces...Today,the world’s population is rising dramatically,and in line with this increase in the population of food and agricultural products,there must be an increasing in the number of problems associated with this process of agricultural land.Then it is necessary to use the maximum potential of this lands that product maximum yield without any damage.To reach this objective,land suitability evaluation is the most important way that can reach human to this objective.The main objective of this research was to compare different irrigation methods based on a parametric evaluation system in an area of 221402 ha in the Khosouyeh Subbasin of the Fars province,in the south of Iran.After preparing land unit map,37 points were selected for sampling.Soil properties were evaluated and analyzed.Suitability maps for drop and gravity irrigation were generated using GIS technique.The results revealed land suitability of 98.42%of the case study was classified as permanently not suitable(N2)and 1.52%currently not suitable(N1)for gravity irrigation.On the other hand,land suitability of 77.73%of the case study was classified as permanently not suitability(N2),6.05%currently not suitable(N1),12.43%marginally suitable(S3)and 3.79%moderately suitable(S2)for drop irrigation.The limiting factors for both kinds of drop and gravity irrigation are soil depth and slope of land.展开更多
基金the National Natural Science Foundation of China （Grant No. 30671476 , 30271067）.
文摘Ammopiptanthus mongolicus, the only freezing tolerant evergreen broad-leaved shrub, local species of the Alashan desert, northwest sand area of China, can survive -30℃ or even lower temperature in winter. In the present study, the secondary products phenolics in A. mongolicus cotyledons were determined to study the effects of phenolics on cold tolerance. Cytochemical localization of phenolics in cotyledon cells was observed by electron microscopy and the content of phenolic compounds was assayed by spectrophotometric measurement. The results showed that the freezing tolerance ofA. mongolicus seedlings increased after acclimation at 2℃ for 14 days, which accompanied the increase of the content of phenolic compounds in cotyledons. Cytochemical observation showed that phenolic deposits were mainly localized in vacuoles and in close proximity to tonoplast, and also in the cytoplasm. The amount and the size of phenolics droplets increased obviously in cytoplasm and vacuoles after cold acclimation, predominantly aggregated along membranes of vacuoles and tonoplast. No phenolic deposits were found in cell walls. As hydrogen- or elec- tron-donating agents, phenolics may protect plant cells against reactive oxygen species formed during chilling or freezing stress and improve the freezing tolerance of cold-acclimated A. mongolicus seedlings.
文摘Today,the world’s population is rising dramatically,and in line with this increase in the population of food and agricultural products,there must be an increasing in the number of problems associated with this process of agricultural land.Then it is necessary to use the maximum potential of this lands that product maximum yield without any damage.To reach this objective,land suitability evaluation is the most important way that can reach human to this objective.The main objective of this research was to compare different irrigation methods based on a parametric evaluation system in an area of 221402 ha in the Khosouyeh Subbasin of the Fars province,in the south of Iran.After preparing land unit map,37 points were selected for sampling.Soil properties were evaluated and analyzed.Suitability maps for drop and gravity irrigation were generated using GIS technique.The results revealed land suitability of 98.42%of the case study was classified as permanently not suitable(N2)and 1.52%currently not suitable(N1)for gravity irrigation.On the other hand,land suitability of 77.73%of the case study was classified as permanently not suitability(N2),6.05%currently not suitable(N1),12.43%marginally suitable(S3)and 3.79%moderately suitable(S2)for drop irrigation.The limiting factors for both kinds of drop and gravity irrigation are soil depth and slope of land.
