Spatial-temporal Characteristics Of Actual Crop Yield And Potential Productivity In The Jing River Basin And Their Relationships With MODIS-GPP

In order to study the increasing potential of grain yield in the Jing River Basin from the perspective of production difference,we investigated the temporal and spatial distribution of gross primary productivity?GPP?,light-temperature production potentiality,climatic potential productivity and grain yield in the Jing River Basin,and compared the difference between crop potential productivity and acutal grain yeild in this study,,.Furthermore,the relationship between GPP and grain yeild was explored to provide references for the yield-estimation of grain crops using remote sensing techniquein the future.The main results of this paper were as follows:?1?During the period of 2001-2012,the average GPP of the Jing River Basin was519.6 g Cm^-2a^-1,which showed an increasing trend from northwest to southest.The lower GPP values were distributed in the northern loess hilly area,but the higher values were mainly occurred in the mountainous forest and river areas on two sides of the basin.The light-temperature production potentiality is increasing spatially from western Jing River Basin to eastern,ranging from 16462 to 21786 kg hm^-2,and the crop climate potential productivity is increasing spatially from north to south,ranging from 4945 to 12412 kg hm^-2.?2?The inter-annual changes of GPP showed a fluctuating upward trend during the study period,but the inter-annual changes of light-temperature production potentiality and climatic potential productivity were not significant.The grain yield per unit area in most of counties and districts of Jing River basin showed an upward trend in the study period,especially in the south of the basin.It has great potential for increasing the grain yield in the Jing River Basin,for example,the difference between the climatic potential productivity and grain yield per unit area was about 6000-7000 kg hm^-2 in the central part of the basin,such as Qingcheng,Kongtong,Jingyuan,and Xifeng,while the difference in the southern part of the basin was more than 7000 kg hm^-2,even more than 8000 kg hm^-2 in some areas.However,the diffierence was relatively low in the northern basin.Note that the values of parameter in this calculation methods were obtained by that existing esperimental results,but the results updated with the new agricultural experiments.?3?There was good correlation between GPP and grain yield in the basin,and the regression model based on the relationshipwas:y=4.093x+774.67,with R² of 0.59,where y was grain yield(kg hm^-2)and x represents annual GPP(g C m^-2 a^-1),and the precision of estimation is 96.8%in the whole basin.The close relationship between MODIS-GPP and grain yeild indictated that the great reference for the yield estimation by remote sensing.