Potassium(K)deficiency significantly decreases photosynthesis due to leaf chlorosis induced by accumulation of reactive oxygen species(ROS).But,the physiological mechanism for adjusting antioxidative defense system to...Potassium(K)deficiency significantly decreases photosynthesis due to leaf chlorosis induced by accumulation of reactive oxygen species(ROS).But,the physiological mechanism for adjusting antioxidative defense system to protect leaf function in maize(Zea mays L.)is unknown.In the present study,four maize inbred lines(K-tolerant,90-21-3 and 099;K-sensitive,D937 and 835)were used to analyze leaf photosynthesis,anatomical structure,chloroplast ultrastructure,ROS,and antioxidant activities.The results showed that the chlorophyll content,net photosynthetic rate(P_n),stomatal conductance(G_s),photochemical quenching(q_P),and electron transport rate of PSII(ETR)in 90-21-3 and 099 were higher than those in D937 and 835 under K deficiency treatment.Parameters of leaf anatomical structure in D937 that were significantly changed under K deficiency treatment include smaller thickness of leaf,lower epidermis cells,and vascular bundle area,whereas the vascular bundle area,xylem vessel number,and area in 90-21-3 were significantly larger or higher.D937 also had seriously damaged chloroplasts and PSII reaction centers along with increased superoxide anion(O_2^-·)and hydrogen peroxide(H_2O_2).Activities of antioxidants,like superoxide dismutase(SOD),catalase(CAT),and ascorbate peroxidase(APX),were significantly stimulated in 90-21-3 resulting in lower levels of O_2^-·and H_2O_2.These results indicated that the K-tolerant maize promoted antioxidant enzyme activities to maintain ROS homeostasis and suffered less oxidative damage on the photosynthetic apparatus,thereby maintaining regular photosynthesis under K deficiency stress.展开更多
We document that in China the maturity dates of bank-issued wealth management products(WMPs)cluster toward the end of a month and then decrease significantly at the beginning of the following month.Our empirical work ...We document that in China the maturity dates of bank-issued wealth management products(WMPs)cluster toward the end of a month and then decrease significantly at the beginning of the following month.Our empirical work detects a negative relationship between a bank’s loan-to-deposit ratio(LDR)at month-ends and the number of its issued WMPs expiring within several days of the month-end.Moreover,this WMP clustering and the negative relationship disappear after the reform in which regulators bring up measures for banks with a high deposit deviation degree in 2014.We also document that the banks tend to arrange the high-return WMPs to expire around month-ends to attract customers,and this clustering of high-return WMPs also disappears after the reform.Our findings suggest that banks actively,rather than passively,use WMPs as vehicles for their regulatory arbitrage or window dressing behaviours.展开更多
基金supported by the National Natural Science Foundation of China (31771725 and 31301259)the National Key Technology R&D Program of China (2013BAD07B03)
文摘Potassium(K)deficiency significantly decreases photosynthesis due to leaf chlorosis induced by accumulation of reactive oxygen species(ROS).But,the physiological mechanism for adjusting antioxidative defense system to protect leaf function in maize(Zea mays L.)is unknown.In the present study,four maize inbred lines(K-tolerant,90-21-3 and 099;K-sensitive,D937 and 835)were used to analyze leaf photosynthesis,anatomical structure,chloroplast ultrastructure,ROS,and antioxidant activities.The results showed that the chlorophyll content,net photosynthetic rate(P_n),stomatal conductance(G_s),photochemical quenching(q_P),and electron transport rate of PSII(ETR)in 90-21-3 and 099 were higher than those in D937 and 835 under K deficiency treatment.Parameters of leaf anatomical structure in D937 that were significantly changed under K deficiency treatment include smaller thickness of leaf,lower epidermis cells,and vascular bundle area,whereas the vascular bundle area,xylem vessel number,and area in 90-21-3 were significantly larger or higher.D937 also had seriously damaged chloroplasts and PSII reaction centers along with increased superoxide anion(O_2^-·)and hydrogen peroxide(H_2O_2).Activities of antioxidants,like superoxide dismutase(SOD),catalase(CAT),and ascorbate peroxidase(APX),were significantly stimulated in 90-21-3 resulting in lower levels of O_2^-·and H_2O_2.These results indicated that the K-tolerant maize promoted antioxidant enzyme activities to maintain ROS homeostasis and suffered less oxidative damage on the photosynthetic apparatus,thereby maintaining regular photosynthesis under K deficiency stress.
文摘We document that in China the maturity dates of bank-issued wealth management products(WMPs)cluster toward the end of a month and then decrease significantly at the beginning of the following month.Our empirical work detects a negative relationship between a bank’s loan-to-deposit ratio(LDR)at month-ends and the number of its issued WMPs expiring within several days of the month-end.Moreover,this WMP clustering and the negative relationship disappear after the reform in which regulators bring up measures for banks with a high deposit deviation degree in 2014.We also document that the banks tend to arrange the high-return WMPs to expire around month-ends to attract customers,and this clustering of high-return WMPs also disappears after the reform.Our findings suggest that banks actively,rather than passively,use WMPs as vehicles for their regulatory arbitrage or window dressing behaviours.
