【目的】及时、有效地预测籽粒蛋白质含量,能够为优质小麦品种的收购和加工提供科学合理的决策支持信息。本研究从籽粒蛋白质形成的氮素运转规律出发,研究冬小麦籽粒蛋白质遥感预测的可行性及在区域与年际间的扩展性,为高分辨率遥感卫星进行大面积蛋白质预测提供理论依据。【方法】利用2012—2013年4个冬小麦品种×4个氮肥梯度的试验数据和地面高光谱数据进行建模;基于小麦籽粒蛋白质形成的氮素运转机理,通过分析籽粒氮素累积量的两个主要来源及其之间的比例关系,重点抓住开花前的植株氮素累积量再运转这一主要来源,而灌浆期根际的氮素直接吸收则通过其与前者的比例关系来确定,通过相关农学参数模型的耦合,同时加入温度影响因子对籽粒氮素运转的影响,初步阐明了利用开花期小麦叶片氮含量可以预测籽粒蛋白质含量的应用机理;然后选择与叶片氮含量相关的植被指数,利用灰色关联分析-偏最小二乘算法(GRA-PLS)选择与叶片氮含量关联度较高的植被指数并进行小麦叶片氮含量的估算,通过与氮素运转模型的耦合构建了基于氮素运转原理的籽粒蛋白质含量遥感预测模型;最后利用2009—2010年的品种×播期×肥料试验和2012—2013年的其他品种氮肥处理试验进行验证。【结果】(1)通过GRA方法对叶片氮含量和植被指数间的关联度进行计算,选择关联度较大的前5个植被指数进行叶片氮含量建模,其植被指数分别为mND705、NDVIcanste、Readone、DCNI和NDCI;(2)通过PLS方法构建的叶片氮含量模型,建模结果的预测值与实测值的决定系数(R2)和均方根误差(RMSE)分别为0.859和0.257%,验证结果的R2和RMSE分别为0.726和0.063%,利用GRA-PLS方法估算叶片氮素含量具有较好的稳定性;(3)构建的蛋白质预测模型,建模结果和验证结果的预测值与实测值的R2和RMSE?
【Objective】Prediction of grain protein content(GPC) can provide effective decision-making supporting information for acquisition and processing of high quality wheat. The objective of the study is to demonstrate the feasibility of remote sensing monitoring of wheat grain protein content based on nitrogen translocation theory, and its expansibility between regional and annual level. 【Method】Field experiments of four winter wheat cultivars by four nitrogen applications in Beijing during 2012-2013 growing seasons were carried out for model building. Firstly, the two main sources of grain nitrogen accumulation and their relationships were analyzed based on nitrogen translocation theory and agronomy parameters modeling. The nitrogen remobilization from vegetative organs to grain was considered as the key point, while the nitrogen uptake from the root absorption during grain filling stage was simply calculated as the nitrogen remobilization from vegetative organs to grain multiplied by a factor. Mechanism of predicting GPC with leaf nitrogen content(LNC) at the flowering stage was clarified through integrating agronomy parameters modeling. Meanwhile, the temperature factor was considered. Secondly, twenty-four vegetative indices were selected according to the good relationship between vegetative indices and leaf nitrogen content, and remote sensing estimating of LNC was established by using grey relational method and partial least squares method(GRA-PLS). Therefore, a prediction model of GPC with remote sensing was established. 【Result】The results showed that the selected five vegetative indices according to grey relational grade were mND705, NDVIcanste, Readone, DCNI and NDCI. For the LNC estimating, the determination coefficient(R2) and corresponding to root mean square error(RMSE) of modeling and validation results were 0.859, 0.257% and 0.726, 0.063%, respectively. Estimation of LNC has good robustness by using GRA-PLS method. The R2 and RMSE of predicted and measured GPC of modeling