Enviromnental pollution is serious social concern. The inflow of heavy metals in the ecological food chain and their subsequent bio-magnification in human bodies is cascading its harmful effects. The metabolism of pla...Enviromnental pollution is serious social concern. The inflow of heavy metals in the ecological food chain and their subsequent bio-magnification in human bodies is cascading its harmful effects. The metabolism of plants is being hampered by these heavy metals. In the present studies, effect of heavy metal especially cadmium has been studied on stomatal diffusive resistance （SDR）, transpiration rate, leaf surface humidity and leaf temperature of soybean plants growing in hydroponic cultures. Cadmium treatment decelerates the rate of transpiration. The inhibition of transpiration associated with increased SDR leads to dehydration of leaf surface, thereby, increasing temperature of leaves in comparison to control plants. In the present study, temperature difference between stressed and non-stressed plant leaves was as high as 3℃ Moreover, any such rise in leaf temperature due to uptake and induced toxicity of heavy metals can possibly be a good bio-indicator having wide applications in thermal remote sensing and geospatial monitoring of metal polluted soils.展开更多
After exposure of one-year old seedlings of Swietenia macrophylla to an overnight temperature (13 C, 19 C, 25 C, 31 C or 35 C), the leaf net photosynthetic rate (Pn) was researched through measuring photosynthetic lig...After exposure of one-year old seedlings of Swietenia macrophylla to an overnight temperature (13 C, 19 C, 25 C, 31 C or 35 C), the leaf net photosynthetic rate (Pn) was researched through measuring photosynthetic light-response curves at 360 mmolmol-1 CO2, and photosynthetic CO2-response curves at light-saturated intensity (1500 mmolm-2 s-1). The optimal temperature for photosynthesis measured at 360 mmol穖ol-1 CO2 was from 25 C to 31 C, but which was from 31C to 35 C at saturating CO2 concentration. At temperature of below 25 C, the decline in Pn was mainly due to the drop in carboxylation efficiency (Ce), while as temperature was over 31 C, the reduction in Pn resulted from both decrease in Ce and increase in leaf respiration. The CO2-induced stimulation of photosynthesis was strongly inhibited at temperatures below 13 C. The results showed that, the leaf photosynthesis of tropical evergreen plants should not be accelerated at low temperature in winter season with elevated CO2 concentration in the future.展开更多
Removing fruit (RF) and retaining fruit (CK) were carried out during different phenological stages of fruit development onone-year-old shoot of Okubo peach trees [Prunus persica (L.) Batsch.] under preventing exportat...Removing fruit (RF) and retaining fruit (CK) were carried out during different phenological stages of fruit development onone-year-old shoot of Okubo peach trees [Prunus persica (L.) Batsch.] under preventing exportation of the assimilates tothe non experimental parts of the tree by girdling one-year-old shoot and keeping the same leaves between RF and CK.The results showed that fruit removal significantly decreased net photosynthetic rate (Pn), stomatal conductance (Gs)and transpiration rate (E), but significantly increased leaf surface temperature (TLeaf ) at about midday as compared with CK.Internal CO2 concentration, soluble sugar content, reductive sugar content, starch content except that during the finalrapid fruit growth stage, ADP-glucose pyrophosphorylase and amylase activities in source leaves were not significantlyaffected by fruit removal. There was a significantly positive parabolic correlation between Pn and Gs, and a strongpositive linear correlation between Pn and E. Moreover, Pn increased with increased TLeaf if TLeaf was below 38°C, thendecreased sharply when TLeaf exceeded the above critical temperature for both RF and CK. Pn of RF was lower, however,than that of CK in the same TLeaf , especially if TLeaf exceeded 38°C. It is suggested that the decreased stomatal aperture andincreased TLeaf may be the important mechanism in regulating photosynthesis under a decreased strength of sink demandby RF in fruit trees.展开更多
Grapevines are preferentially grown under mild to moderate water stress conditions to achieve the best compromise between wine quality and quantity.Water status detection for advanced irrigation scheduling is frequent...Grapevines are preferentially grown under mild to moderate water stress conditions to achieve the best compromise between wine quality and quantity.Water status detection for advanced irrigation scheduling is frequently done by predawn leaf water potential(ΨPD)or leaf stomata conductance(gL)measurements.However,these measurements are time and labor consuming.Therefore,the use of infrared thermography(IRT)opens up the possibility to study large population of leaves and to give an overview on the stomatal variation and their dynamics.In the present study IRT was used to identify water stress of potted grapevines.In order to define the sensitivity of IRT measurements to water stress,the IRT-based water status information were compared with simultaneously measuredΨPD and gL data.Correlations between IRT-based CWSI data on the one hand and gL andΨPD on the other showed the potential of IRT for water stress detection.However,the CWSI calculation procedure is laborious and the sensitivity of CWSI for water stress detection still needs to be improved.Therefore,further improvements are necessary in order to apply remote IRT-based systems for irrigation scheduling in the field.展开更多
文摘Enviromnental pollution is serious social concern. The inflow of heavy metals in the ecological food chain and their subsequent bio-magnification in human bodies is cascading its harmful effects. The metabolism of plants is being hampered by these heavy metals. In the present studies, effect of heavy metal especially cadmium has been studied on stomatal diffusive resistance （SDR）, transpiration rate, leaf surface humidity and leaf temperature of soybean plants growing in hydroponic cultures. Cadmium treatment decelerates the rate of transpiration. The inhibition of transpiration associated with increased SDR leads to dehydration of leaf surface, thereby, increasing temperature of leaves in comparison to control plants. In the present study, temperature difference between stressed and non-stressed plant leaves was as high as 3℃ Moreover, any such rise in leaf temperature due to uptake and induced toxicity of heavy metals can possibly be a good bio-indicator having wide applications in thermal remote sensing and geospatial monitoring of metal polluted soils.
文摘After exposure of one-year old seedlings of Swietenia macrophylla to an overnight temperature (13 C, 19 C, 25 C, 31 C or 35 C), the leaf net photosynthetic rate (Pn) was researched through measuring photosynthetic light-response curves at 360 mmolmol-1 CO2, and photosynthetic CO2-response curves at light-saturated intensity (1500 mmolm-2 s-1). The optimal temperature for photosynthesis measured at 360 mmol穖ol-1 CO2 was from 25 C to 31 C, but which was from 31C to 35 C at saturating CO2 concentration. At temperature of below 25 C, the decline in Pn was mainly due to the drop in carboxylation efficiency (Ce), while as temperature was over 31 C, the reduction in Pn resulted from both decrease in Ce and increase in leaf respiration. The CO2-induced stimulation of photosynthesis was strongly inhibited at temperatures below 13 C. The results showed that, the leaf photosynthesis of tropical evergreen plants should not be accelerated at low temperature in winter season with elevated CO2 concentration in the future.
基金This study was supported by the National Natural Science Foundation of China(30170654).
文摘Removing fruit (RF) and retaining fruit (CK) were carried out during different phenological stages of fruit development onone-year-old shoot of Okubo peach trees [Prunus persica (L.) Batsch.] under preventing exportation of the assimilates tothe non experimental parts of the tree by girdling one-year-old shoot and keeping the same leaves between RF and CK.The results showed that fruit removal significantly decreased net photosynthetic rate (Pn), stomatal conductance (Gs)and transpiration rate (E), but significantly increased leaf surface temperature (TLeaf ) at about midday as compared with CK.Internal CO2 concentration, soluble sugar content, reductive sugar content, starch content except that during the finalrapid fruit growth stage, ADP-glucose pyrophosphorylase and amylase activities in source leaves were not significantlyaffected by fruit removal. There was a significantly positive parabolic correlation between Pn and Gs, and a strongpositive linear correlation between Pn and E. Moreover, Pn increased with increased TLeaf if TLeaf was below 38°C, thendecreased sharply when TLeaf exceeded the above critical temperature for both RF and CK. Pn of RF was lower, however,than that of CK in the same TLeaf , especially if TLeaf exceeded 38°C. It is suggested that the decreased stomatal aperture andincreased TLeaf may be the important mechanism in regulating photosynthesis under a decreased strength of sink demandby RF in fruit trees.
文摘Grapevines are preferentially grown under mild to moderate water stress conditions to achieve the best compromise between wine quality and quantity.Water status detection for advanced irrigation scheduling is frequently done by predawn leaf water potential(ΨPD)or leaf stomata conductance(gL)measurements.However,these measurements are time and labor consuming.Therefore,the use of infrared thermography(IRT)opens up the possibility to study large population of leaves and to give an overview on the stomatal variation and their dynamics.In the present study IRT was used to identify water stress of potted grapevines.In order to define the sensitivity of IRT measurements to water stress,the IRT-based water status information were compared with simultaneously measuredΨPD and gL data.Correlations between IRT-based CWSI data on the one hand and gL andΨPD on the other showed the potential of IRT for water stress detection.However,the CWSI calculation procedure is laborious and the sensitivity of CWSI for water stress detection still needs to be improved.Therefore,further improvements are necessary in order to apply remote IRT-based systems for irrigation scheduling in the field.
