基于光能利用率模型的河南省冬小麦单产估算研究

目的]快速、准确估算空间尺度上作物产量,对于评价农田生态系统对气候变化的响应、制定科学合理的粮食政策、对外粮食贸易等具有重要意义。河南省冬小麦产量占全国1/4,准确估算河南省冬小麦产量对维护国家粮食安全具有重要作用。单产估算作为农作物估产中的关键技术,也是作物估产的难点之一。方法]文章首先利用VPM(Vegetation Photosynthesis Model)估算冬小麦NPP(Net Primary Product),结合收获指数、冬小麦收获部分的含水量、含碳量、NPP分配到地上或地下部分比例等一系列符合该研究区的经验指数,进行河南省冬小麦单产估算研究,并分析了引起模拟误差的原因。结果]模拟单产较实测单产低估4.4%(实测单产为6 810kg/hm~2,模拟单产为6 519kg/hm~2),但两者之间存在显著相关关系,两者相关系数的平方R2=0.70(n=50,p0.01)。通过与MODIS-GPP产品获得的冬小麦单产数据比较,基于VPM模型的模拟结果优于MODIS-GPP产品。结论]基于VPM可快速、准确估算河南省空间尺度冬小麦单产,该方法具有较好的适用性。

YIELD ESTIMATION OF WINTER WHEAT IN HENAN PROVINCE BASED ON THE VEGETATION PHOTOSYNTHESIS MODEL

It is of great significance to evaluate the response of farmland ecosystem to climate change and estimatecrops yield on spatial scale timely and accurately. At the same time, it is crucial for making scientific and reasonable grain policy and grain international trade.Winter wheat production in Henan province accounted for one quarter of the whole country wheat yield.Therefore, it has an important role in maintaining national food security for estimating accurately of winter wheat yield in Henan province. As a crucial technique in estimating the yield of crops, yield per hectare estimation is difficult. With the development of remote sensing technology, a remote sensing model based on the physiological processes can be used for continuous dynamic yield analysis at regional and global scales with high spatial and temporal resolution. A representative model of vegetation photosynthesis model which fully considered the limitation of light, temperature, water and vegetation phenology on GPP, can reflect the influence of environmental conditions on the growth of vegetation. This paper used the vegetation photosynthesis model(VPM) model to estimate regional winter wheat gross primary productivity(GPP) and net primary productivity(NPP) based on the quantitative relationship between GPP and NPP. And then, the yield per hectare was carried out by combining harvest index, water and carbon content of winter wheat, and the proportion of NPP distribution to the ground or underground part. The results showed that the correlation was significant between simulated and measured data(R2=0.7, n=50, p<0.01 ).The average yield per hectare was 6 810kg/hm2, and the simulated yield was 6 519 kg/hm2 with a underestimation of 4.4%. By comparing with MODIS-GPP products, the simulation results based on VPM were better than MODIS-GPP products. The study demonstrated that VPM can quickly and accurately estimate the spatial scale winter wheat yield per hectare in Henan province.