Evidence exists of nighttime transpiration and its potential impact on plant/water relations for species in a diversity of ecosystems. However, relevant data related to typical desert riparian forest species remains l...Evidence exists of nighttime transpiration and its potential impact on plant/water relations for species in a diversity of ecosystems. However, relevant data related to typical desert riparian forest species remains limited Accordingly, we measured sap flow velocity of Populus euphratica using the heat ratio method between 2012 and2014. Nocturnal stem sap flow was separated into nighttime and stem refilling using the ‘‘forecasted refilling''method. Nighttime transpiration was observed for each phenophase. The highest value was during the full foliation period but lowest during leaf expansion and defoliation periods. The contribution of nighttime transpiration to daytime transpiration was an average of 15% but this was comparatively higher during the defoliation period. Relationships between nighttime transpiration, vapor pressure deficits, and air temperatures were more closely associated than with wind speed in all phenophases. Moreover, we found that nighttime transpiration linearly correlated to vapour pressure deficit during the first and the full foliation periods, but nighttime transpiration showed exponential correlations to air temperatures during the same phenophases. Additionally, environmental drivers of transpiration were significantly different between nighttime and daytime(P \ 0.05). Driving forces behind nighttime transpiration were characterized by many factors, and integrated impacts between these multiple environmental factors were complex. Future studies should focus on these integrated impacts on nighttime transpiration, and the physiological mechanisms of nighttime transpiration should be investigated, given that this could also influence its occurrence and magnitude during different phenophases.展开更多
[Objective] The study is aimed to timely grasp the growth and develop- ment process of summer maize and comprehensively evaluate the impact of envi- ronmental factors on the growth and development of maize in north Hu...[Objective] The study is aimed to timely grasp the growth and develop- ment process of summer maize and comprehensively evaluate the impact of envi- ronmental factors on the growth and development of maize in north Huanguaihai re- gion. [Method] The phenophase, leaf unfolding rate, grain filling rate and yield char- acteristics of Zhengdan 958 and Xianyu 335 were analyzed at N 37°53′, E115°42′. [Result] The summer corn Zhengdan 958 and Xianyu335 emerged in 6 days after sowing with the growing period of 111 d, grain-filling stage lasting 66 days, and the leaf unfolding rate and grain filling rate were accelerated with the increase of tem- perature. In the last 6 d before harvest （October 5-11）, Zhengdan 958 and Xi- anyu335 contributed to the yield by 6.61% and 4.20%, respectively. The two crops a year cropping system made it hard for the summer maize to achieve maturing harvest in north Huanghuaihai region. [Conclusion] The maize production could be significantly improved through selecting early maturing varieties, early sowing, timely late harvest, ensuring maize effective accumulated temperature and sufficient grout- ing time after pollination.展开更多
This paper considers the upper orthant and extremal tail dependence indices for multivariate t-copula. Where, the multivariate t-copula is defined under a correlation structure. The explicit representations of the tai...This paper considers the upper orthant and extremal tail dependence indices for multivariate t-copula. Where, the multivariate t-copula is defined under a correlation structure. The explicit representations of the tail dependence parameters are deduced since the copula of continuous variables is invariant under strictly increasing transformation about the random variables, which are more simple than those obtained in previous research. Then, the local monotonicity of these indices about the correlation coefficient is discussed, and it is concluded that the upper extremal dependence index increases with the correlation coefficient, but the monotonicity of the upper orthant tail dependence index is complex. Some simulations are performed by the Monte Carlo method to verify the obtained results, which are found to be satisfactory. Meanwhile, it is concluded that the obtained conclusions can be extended to any distribution family in which the generating random variable has a regularly varying distribution.展开更多
China English is an objective existence as a performance variety used in China.It is based on standard English and possesses Chinese characteristics.The Chinese characteristics of China English are reflected in the ph...China English is an objective existence as a performance variety used in China.It is based on standard English and possesses Chinese characteristics.The Chinese characteristics of China English are reflected in the phonology,vocabulary,syntax,rhetoric and text,particularly in the vocabulary.This essay will discuss the features of China English from the following three aspects: the development of English in China;the comparison between China English,Pidgin English and Chinese English and the Chinese words borrowed by English.展开更多
基金financially supported by the Key Research Program of Frontier Sciences CAS(QYZDJ-SSWDQC031)Key Project of the Chinese Academy of Sciences(KZZDEW-04-05)+1 种基金the National Natural Science Foundation of China(91025024)the ‘‘Western Light’’ project of the Chinese Academy of Science
文摘Evidence exists of nighttime transpiration and its potential impact on plant/water relations for species in a diversity of ecosystems. However, relevant data related to typical desert riparian forest species remains limited Accordingly, we measured sap flow velocity of Populus euphratica using the heat ratio method between 2012 and2014. Nocturnal stem sap flow was separated into nighttime and stem refilling using the ‘‘forecasted refilling''method. Nighttime transpiration was observed for each phenophase. The highest value was during the full foliation period but lowest during leaf expansion and defoliation periods. The contribution of nighttime transpiration to daytime transpiration was an average of 15% but this was comparatively higher during the defoliation period. Relationships between nighttime transpiration, vapor pressure deficits, and air temperatures were more closely associated than with wind speed in all phenophases. Moreover, we found that nighttime transpiration linearly correlated to vapour pressure deficit during the first and the full foliation periods, but nighttime transpiration showed exponential correlations to air temperatures during the same phenophases. Additionally, environmental drivers of transpiration were significantly different between nighttime and daytime(P \ 0.05). Driving forces behind nighttime transpiration were characterized by many factors, and integrated impacts between these multiple environmental factors were complex. Future studies should focus on these integrated impacts on nighttime transpiration, and the physiological mechanisms of nighttime transpiration should be investigated, given that this could also influence its occurrence and magnitude during different phenophases.
基金Supported by the Foundation of China Agricultural Research System for Maize Industry(CARS-02-48)~~
文摘[Objective] The study is aimed to timely grasp the growth and develop- ment process of summer maize and comprehensively evaluate the impact of envi- ronmental factors on the growth and development of maize in north Huanguaihai re- gion. [Method] The phenophase, leaf unfolding rate, grain filling rate and yield char- acteristics of Zhengdan 958 and Xianyu 335 were analyzed at N 37°53′, E115°42′. [Result] The summer corn Zhengdan 958 and Xianyu335 emerged in 6 days after sowing with the growing period of 111 d, grain-filling stage lasting 66 days, and the leaf unfolding rate and grain filling rate were accelerated with the increase of tem- perature. In the last 6 d before harvest （October 5-11）, Zhengdan 958 and Xi- anyu335 contributed to the yield by 6.61% and 4.20%, respectively. The two crops a year cropping system made it hard for the summer maize to achieve maturing harvest in north Huanghuaihai region. [Conclusion] The maize production could be significantly improved through selecting early maturing varieties, early sowing, timely late harvest, ensuring maize effective accumulated temperature and sufficient grout- ing time after pollination.
基金The National Natural Science Foundation of China(No.11001052,11171065)the National Science Foundation of Jiangsu Province(No.BK2011058)the Science Foundation of Nanjing University of Posts and Telecommunications(No.JG00710JX57)
文摘This paper considers the upper orthant and extremal tail dependence indices for multivariate t-copula. Where, the multivariate t-copula is defined under a correlation structure. The explicit representations of the tail dependence parameters are deduced since the copula of continuous variables is invariant under strictly increasing transformation about the random variables, which are more simple than those obtained in previous research. Then, the local monotonicity of these indices about the correlation coefficient is discussed, and it is concluded that the upper extremal dependence index increases with the correlation coefficient, but the monotonicity of the upper orthant tail dependence index is complex. Some simulations are performed by the Monte Carlo method to verify the obtained results, which are found to be satisfactory. Meanwhile, it is concluded that the obtained conclusions can be extended to any distribution family in which the generating random variable has a regularly varying distribution.
文摘China English is an objective existence as a performance variety used in China.It is based on standard English and possesses Chinese characteristics.The Chinese characteristics of China English are reflected in the phonology,vocabulary,syntax,rhetoric and text,particularly in the vocabulary.This essay will discuss the features of China English from the following three aspects: the development of English in China;the comparison between China English,Pidgin English and Chinese English and the Chinese words borrowed by English.
