Starting from the research on and collection of the damaging factors andindex of the cold and hot damages to citrus, this peper systematically studies the apparent properties in temporal and spatial distribution, diff...Starting from the research on and collection of the damaging factors andindex of the cold and hot damages to citrus, this peper systematically studies the apparent properties in temporal and spatial distribution, differences, relationship of the twokinds of disasters and their impact on citrus production in the Three Gorges area inHubei. It also reveals the important faCt that it is warmer in winter and hotter in springsince the 1980s, which is the cause of departing to two poles of the cold and hot damages, and discusses the alleviating effect to the disasters by the Three Gorges Project.Finally some countermeasures are proposed.展开更多
Citrus is one of the major fruit crops in Cuba. Its perennial nature, the planted area and the time of productive exploitation turn it into a potential sink of atmospheric carbon. The present study was focused on the ...Citrus is one of the major fruit crops in Cuba. Its perennial nature, the planted area and the time of productive exploitation turn it into a potential sink of atmospheric carbon. The present study was focused on the obtainment of two models that allow the quantitative estimation of carbon retention by citrus groves. The research was done in two commercial groves: orange [Citrus sinensis (L) Osbeck] cv. “Valencia Late” and grapefruit (Citrus paradisi Macf.) cv. “Marsh Seedless” both on sour orange (Citrus aurantium L.) and planted on a typical red ferralitic soil of Artemisa province. Groves are located at 22°55' North and 82°40' West. Cuba’s climate is tropical, seasonally humid, with sea influence and semicontinentality features. Three issues were dealt with: 1) Determination of the total mean quantity of retained carbon by the aerial part of the trees using a destructive sampling method (Pattern Method) to estimate: the total volume of the tree, wood densities and green and dry biomass;2) Determination of the total mean quantity of retained carbon by the aerial part of the trees using two Allometric Methods;and 3) Determination of the most effective Allometric Method to estimate the carbon retention by the aerial part of the trees. From the results, it is concluded that the evaluated methods were effective to reach a first quantitative approximation to carbon retention by citrus groves and under equal conditions, the Allometric Method 2 was more accurate to estimate the Total Carbon Content in “Valencia Late” orange, while for “Marsh Seedless” grapefruit the Allometric Method 1 provided the best estimate.展开更多
Abstract： The aim of this paper is to investigate the relative contribution of technical efficiency, technological change and increased input use to the output growth of the Tunisian citrus growing farms using a stoc...Abstract： The aim of this paper is to investigate the relative contribution of technical efficiency, technological change and increased input use to the output growth of the Tunisian citrus growing farms using a stochastic frontier production function approach applied to panel data for the period 2003-2005. Knowledge of the relative contribution of factors productivity and input use to output growth and improvements in technical efficiency is crucial to provide a comprehensive view of the state of the citrus producing sector in the country and help farm managers and policy makers draw appropriate policy measures. The proposed methodology is based on the use of a flexible translog functional form. Results indicate that technical efficiency of production in citrus producing farms investigated ranges from a minimum of 11.19% to a maximum of 96.82% with an average technical efficiency estimate of 49.97%. This suggests that citrus producers may increase their production by as much as 50.03% through more efficient use of production inputs. Furthermore, the production is characterized by increasing returns to scale, which on average was 1.057. Finally, investigation of the sources of production growth reveals that the contribution of total factor productivity is found to be the main source of that growth.展开更多
Based on the citrus temperature, precipitation, sunlight and climate risk degree, the article divides subtropics of China into three types： the low risk region, the moderate risk region and the high risk region. The ...Based on the citrus temperature, precipitation, sunlight and climate risk degree, the article divides subtropics of China into three types： the low risk region, the moderate risk region and the high risk region. The citrus temperature risk increases with increasing latitude （except for the western mountainous area of subtropics of China）. The citrus precipitation risk in the central part of subtropics of China is higher than that in the northern and western parts. The distributions of citrus sunlight risk are not consistent to those of the citrus precipitation risk. The citrus climate risk is mainly influenced by temperature. There is latitudinal zonal law for the distribution of the climate risk, that is, the climate risk increases with increasing latitude At the same time the climate risk in mountainous area is high and that in eastern plain area is low. There are differences in the temporal and spatial changes of the citrus climate. In recent 46 years, the citrus climate risk presents a gradual increasing trend in subtropics of China, especially it has been increasing fast since the 1980s. Because of the global warming, the low risk region in the eastern and southern parts has a gradual decreasing trend, however, the high risk region in the northern and western parts has an increasing trend and the high risk region has been extending eastward and southward. The article analyses the distribution of the citrus climate risk degree of reduction rates of 〉10%, 〉20% and 〉30% in subtropics of China, and studies their changes in different time periods. Results show that the risk is increasing from southeast to northwest.展开更多
文摘Starting from the research on and collection of the damaging factors andindex of the cold and hot damages to citrus, this peper systematically studies the apparent properties in temporal and spatial distribution, differences, relationship of the twokinds of disasters and their impact on citrus production in the Three Gorges area inHubei. It also reveals the important faCt that it is warmer in winter and hotter in springsince the 1980s, which is the cause of departing to two poles of the cold and hot damages, and discusses the alleviating effect to the disasters by the Three Gorges Project.Finally some countermeasures are proposed.
文摘Citrus is one of the major fruit crops in Cuba. Its perennial nature, the planted area and the time of productive exploitation turn it into a potential sink of atmospheric carbon. The present study was focused on the obtainment of two models that allow the quantitative estimation of carbon retention by citrus groves. The research was done in two commercial groves: orange [Citrus sinensis (L) Osbeck] cv. “Valencia Late” and grapefruit (Citrus paradisi Macf.) cv. “Marsh Seedless” both on sour orange (Citrus aurantium L.) and planted on a typical red ferralitic soil of Artemisa province. Groves are located at 22°55' North and 82°40' West. Cuba’s climate is tropical, seasonally humid, with sea influence and semicontinentality features. Three issues were dealt with: 1) Determination of the total mean quantity of retained carbon by the aerial part of the trees using a destructive sampling method (Pattern Method) to estimate: the total volume of the tree, wood densities and green and dry biomass;2) Determination of the total mean quantity of retained carbon by the aerial part of the trees using two Allometric Methods;and 3) Determination of the most effective Allometric Method to estimate the carbon retention by the aerial part of the trees. From the results, it is concluded that the evaluated methods were effective to reach a first quantitative approximation to carbon retention by citrus groves and under equal conditions, the Allometric Method 2 was more accurate to estimate the Total Carbon Content in “Valencia Late” orange, while for “Marsh Seedless” grapefruit the Allometric Method 1 provided the best estimate.
文摘Abstract： The aim of this paper is to investigate the relative contribution of technical efficiency, technological change and increased input use to the output growth of the Tunisian citrus growing farms using a stochastic frontier production function approach applied to panel data for the period 2003-2005. Knowledge of the relative contribution of factors productivity and input use to output growth and improvements in technical efficiency is crucial to provide a comprehensive view of the state of the citrus producing sector in the country and help farm managers and policy makers draw appropriate policy measures. The proposed methodology is based on the use of a flexible translog functional form. Results indicate that technical efficiency of production in citrus producing farms investigated ranges from a minimum of 11.19% to a maximum of 96.82% with an average technical efficiency estimate of 49.97%. This suggests that citrus producers may increase their production by as much as 50.03% through more efficient use of production inputs. Furthermore, the production is characterized by increasing returns to scale, which on average was 1.057. Finally, investigation of the sources of production growth reveals that the contribution of total factor productivity is found to be the main source of that growth.
基金National Natural Sciences Foundation of China,No.40771033Special Item Funds of Climate Change Supported by China Meteorological Administration,No.CCSF-09-11
文摘Based on the citrus temperature, precipitation, sunlight and climate risk degree, the article divides subtropics of China into three types： the low risk region, the moderate risk region and the high risk region. The citrus temperature risk increases with increasing latitude （except for the western mountainous area of subtropics of China）. The citrus precipitation risk in the central part of subtropics of China is higher than that in the northern and western parts. The distributions of citrus sunlight risk are not consistent to those of the citrus precipitation risk. The citrus climate risk is mainly influenced by temperature. There is latitudinal zonal law for the distribution of the climate risk, that is, the climate risk increases with increasing latitude At the same time the climate risk in mountainous area is high and that in eastern plain area is low. There are differences in the temporal and spatial changes of the citrus climate. In recent 46 years, the citrus climate risk presents a gradual increasing trend in subtropics of China, especially it has been increasing fast since the 1980s. Because of the global warming, the low risk region in the eastern and southern parts has a gradual decreasing trend, however, the high risk region in the northern and western parts has an increasing trend and the high risk region has been extending eastward and southward. The article analyses the distribution of the citrus climate risk degree of reduction rates of 〉10%, 〉20% and 〉30% in subtropics of China, and studies their changes in different time periods. Results show that the risk is increasing from southeast to northwest.
