An analysis of historical oxygen data provides evidence on the water exchange between theSouth China Sea (SCS) and the Pacific Ocean (PO). In the vicinity of the Luzon Strait (LS) , the dissolved oxygen concentration ...An analysis of historical oxygen data provides evidence on the water exchange between theSouth China Sea (SCS) and the Pacific Ocean (PO). In the vicinity of the Luzon Strait (LS) , the dissolved oxygen concentration of sea water is found to be lower on the Pacific side than on the SCS side at depths between 700 and 1500 m (intermediate layer) , while the situation is reversed above 700 m (upper layer) and below 1 500 m (deep layer). The evidence suggests that water exits the SCS in the intermediate layer but enters it from the Pacific in both the upper and the deep layers, supporting the earlier speculation that the Luzon Strait transport has a sandwiched structure in the vertical. Within the SCS basin, the oxygen distribution indicates widespread vertical movement, including the upwelling in the intermediate layer and the downwelling in the deep layer.展开更多
In order to examine the effects of the decrease of future precipitation on the eco-physiological characteristics of sea buckthorn (Hippophae rhamnoides Linn.) in Huangfuchuan Watershed in Nei Mongol, a water gradient ...In order to examine the effects of the decrease of future precipitation on the eco-physiological characteristics of sea buckthorn (Hippophae rhamnoides Linn.) in Huangfuchuan Watershed in Nei Mongol, a water gradient experiment was conducted based on the four specially designed water supply levels, including normal precipitation, slight drought, drought and extreme drought. Results of ANOVE showed that different water gradients had a significant effect on (1) microhabitat factors, such as soil water content and soil temperature; (2) gas exchange, such as net photosynthetic rate, stomatal conductance and transpiration rate; (3) resource use efficiency; and (4) leaf water potential. Water use efficiency of H rhamnoides could increase under moderate water stress, i.e. drought condition, while its net photosynthetic rate and transpiration rate decreased. All kinds of eco-physiological characteristics proved H. rhamnoides seedlings under all water supplies were affected by water stress more or less and that mechanism of intrinsic physiological regulation in seedlings under the extreme drought conditions had the appearance of turbulence to a certain extent. Therefore, H rhamnoides seedlings in Huangfuchuan Watershed could not acclimate to extreme drought conditions.展开更多
研究不同水势(SWP)对温室黄瓜花后叶片气体交换及叶绿素荧光参数的影响.结果表明:-10和-30 k Pa分别为黄瓜开始产生干旱胁迫和干旱胁迫由气孔限制转向非气孔限制的水势临界值.在无干旱胁迫阶段(-10 k Pa<SWP≤0 k Pa),各气体交换参...研究不同水势(SWP)对温室黄瓜花后叶片气体交换及叶绿素荧光参数的影响.结果表明:-10和-30 k Pa分别为黄瓜开始产生干旱胁迫和干旱胁迫由气孔限制转向非气孔限制的水势临界值.在无干旱胁迫阶段(-10 k Pa<SWP≤0 k Pa),各气体交换参数和叶绿素荧光参数均无显著变化;在气孔限制阶段(-30 k Pa<SWP≤-10 k Pa),随着SWP下降,气孔导度(gs)、胞间CO2浓度(Ci)、净光合速率(Pn)、表观量子效率(ε)、蒸腾速率(Tr)、羧化效率(CE)、Rubisco限制下的最大羧化速率(Vc max)、最大电子传递速率(Jmax)、磷酸丙糖利用速率(VTPU)、PSⅡ的潜在和实际量子效率(ΦPSⅡ和Fv/Fm)以及光化学淬灭系数(qP)下降,光补偿点(LCP)、暗呼吸速率(Rd)、CO2补偿点(CCP)、气孔限制值(Ls)、瞬时水分利用效率(WUEi)和非光化学淬灭系数(qN)上升,气体交换参数随水势的变化速度快于叶绿素荧光参数,各处理间差异显著;在非气孔限制阶段(-45 k Pa≤SWP≤-30 k Pa),随着SWP下降,光饱和点(LSP)、Rd、CE、Vc max、VTPU、Ls、WUEi、ΦPSII、Fv/Fm和qP下降,CCP、Ci和qN上升,叶绿素荧光参数随水势的变化速度快于气体交换参数,各处理间差异显著.设施黄瓜生产中,当土壤或基质的水势下降到-10 k Pa时应及时灌溉,灌溉到水势上升为-5 k Pa时停止;水势下降到-30 k Pa之前的灌溉可有效恢复作物的气孔性限制,水势降到-30 k Pa以下,干旱胁迫会对作物造成不可恢复的伤害.展开更多
基金This research was funded by Frontier Research System for Global Change through its sponsorship of the International Pacific Research Center (IPRC) and by the U. S. National Science Foundation under contract Grant No. OCEOO - 95906.
文摘An analysis of historical oxygen data provides evidence on the water exchange between theSouth China Sea (SCS) and the Pacific Ocean (PO). In the vicinity of the Luzon Strait (LS) , the dissolved oxygen concentration of sea water is found to be lower on the Pacific side than on the SCS side at depths between 700 and 1500 m (intermediate layer) , while the situation is reversed above 700 m (upper layer) and below 1 500 m (deep layer). The evidence suggests that water exits the SCS in the intermediate layer but enters it from the Pacific in both the upper and the deep layers, supporting the earlier speculation that the Luzon Strait transport has a sandwiched structure in the vertical. Within the SCS basin, the oxygen distribution indicates widespread vertical movement, including the upwelling in the intermediate layer and the downwelling in the deep layer.
文摘In order to examine the effects of the decrease of future precipitation on the eco-physiological characteristics of sea buckthorn (Hippophae rhamnoides Linn.) in Huangfuchuan Watershed in Nei Mongol, a water gradient experiment was conducted based on the four specially designed water supply levels, including normal precipitation, slight drought, drought and extreme drought. Results of ANOVE showed that different water gradients had a significant effect on (1) microhabitat factors, such as soil water content and soil temperature; (2) gas exchange, such as net photosynthetic rate, stomatal conductance and transpiration rate; (3) resource use efficiency; and (4) leaf water potential. Water use efficiency of H rhamnoides could increase under moderate water stress, i.e. drought condition, while its net photosynthetic rate and transpiration rate decreased. All kinds of eco-physiological characteristics proved H. rhamnoides seedlings under all water supplies were affected by water stress more or less and that mechanism of intrinsic physiological regulation in seedlings under the extreme drought conditions had the appearance of turbulence to a certain extent. Therefore, H rhamnoides seedlings in Huangfuchuan Watershed could not acclimate to extreme drought conditions.
文摘研究不同水势(SWP)对温室黄瓜花后叶片气体交换及叶绿素荧光参数的影响.结果表明:-10和-30 k Pa分别为黄瓜开始产生干旱胁迫和干旱胁迫由气孔限制转向非气孔限制的水势临界值.在无干旱胁迫阶段(-10 k Pa<SWP≤0 k Pa),各气体交换参数和叶绿素荧光参数均无显著变化;在气孔限制阶段(-30 k Pa<SWP≤-10 k Pa),随着SWP下降,气孔导度(gs)、胞间CO2浓度(Ci)、净光合速率(Pn)、表观量子效率(ε)、蒸腾速率(Tr)、羧化效率(CE)、Rubisco限制下的最大羧化速率(Vc max)、最大电子传递速率(Jmax)、磷酸丙糖利用速率(VTPU)、PSⅡ的潜在和实际量子效率(ΦPSⅡ和Fv/Fm)以及光化学淬灭系数(qP)下降,光补偿点(LCP)、暗呼吸速率(Rd)、CO2补偿点(CCP)、气孔限制值(Ls)、瞬时水分利用效率(WUEi)和非光化学淬灭系数(qN)上升,气体交换参数随水势的变化速度快于叶绿素荧光参数,各处理间差异显著;在非气孔限制阶段(-45 k Pa≤SWP≤-30 k Pa),随着SWP下降,光饱和点(LSP)、Rd、CE、Vc max、VTPU、Ls、WUEi、ΦPSII、Fv/Fm和qP下降,CCP、Ci和qN上升,叶绿素荧光参数随水势的变化速度快于气体交换参数,各处理间差异显著.设施黄瓜生产中,当土壤或基质的水势下降到-10 k Pa时应及时灌溉,灌溉到水势上升为-5 k Pa时停止;水势下降到-30 k Pa之前的灌溉可有效恢复作物的气孔性限制,水势降到-30 k Pa以下,干旱胁迫会对作物造成不可恢复的伤害.
