粮食作物不仅是人类主要的食物来源，还是世界人口膳食中蛋白质的重要来源。而籽粒蛋白质含量是表征粮食作物营养品质的重要指标，因此了解未来籽粒蛋白质含量的变化对保障粮食安全具有特殊意义。气候变暖在全球范围内被广泛观测到。气候变化对粮食作物的产量及品质等存在重要影响。关于气候变化对粮食作物的影响的研究越来越多，但是作物的营养价值总量才是决定粮食安全的真正标志。因此，本文从粮食作物营养品质出发，对主要粮食作物籽粒蛋白质含量进行研究和预估，有助于我们了解蛋白质含量的变化规律及其对未来气候变化的响应，有助于确保人类的粮食安全。

本文通过收集1980年以来的中国小麦、水稻和玉米的籽粒蛋白质含量数据，并记录其年份、地点、品质及对应气象站点等信息。首先应用相关分析方法探索主要粮食作物籽粒蛋白质含量与气候条件的关系。其次通过多元线性回归方法构建气候与籽粒蛋白质含量关系模型，定量分析各气象要素对作物籽粒蛋白质含量的贡献。最后，本研究将气候与籽粒蛋白质含量关系模型与未来气候变化情景数据相结合，对不同共享社会经济路径（SSP）情景下21世纪中叶中国三种主要粮食作物的籽粒蛋白质含量及产量进行了预估。主要结论如下：

（1）通过对中国主要粮食作物籽粒蛋白质含量与各个气象要素进行分析，发现作物籽粒蛋白质含量受到气候条件的影响显著。其中，影响最显著的时间段发生在作物籽粒形成期至成熟期间。在各气象要素中，平均气温、最高气温、气温日较差和降水量等气象要素的影响显著。

（2）根据各关键气象要素对作物籽粒蛋白质含量的影响，构建了气候与籽粒蛋白质含量关系模型，验证结果表明，该模型能有效反映中国主要粮食作物籽粒蛋白质含量分布特征。综合考虑气候条件等要素对作物籽粒蛋白质含量的影响，通过逐步多元线性回归方法，构建了中国主要粮食作物气候与品质关系模型。模型可通过有效性检验，能真实的反映中国历史时期主要粮食作物籽粒蛋白质含量的情况。

（3）分别对历史时期及未来不同气候变化情景下的中国主要粮食作物籽粒蛋白质含量及产量进行模拟，结果表明全球变暖不利于粮食作物籽粒蛋白质产量的形成。未来情景下小麦和玉米籽粒蛋白质含量以增加为主，水稻籽粒蛋白质含量相较于历史时期变化较小，籽粒蛋白质含量降低的格点集中在长江中下游地区。作物生育期内关键气象要素变化的差异是导致籽粒蛋白质含量变化离散度大的重要原因。在作物产量和籽粒蛋白质含量变化的综合作用下，小麦籽粒蛋白质产量增加，而水稻和玉米籽粒蛋白质产量减少。在不同SSP情景下中国主要粮食作物蛋白质总产量相较于历史时期均降低。

Grain crops are not only the main source of human food but also an important source of protein in the diet of the world’ s population. Grain protein content is an important indicator to characterize the nutritional quality of grain crops, so understanding the changes in grain protein content in the future is of special significance to ensure food security. Climate warming is widely observed worldwide. Climate change has important effects on grain yield and quality. There are more and more studies on the impact of climate change on food crops, but the total nutritional value of crops is the real symbol of food security. Therefore, starting from the nutritional quality of grain crops, this paper studies and estimates the grain protein content of major grain crops, which helps us understand the change law of protein content and its response to future climate change, and helps to ensure human food security.

In this paper, we collected the grain protein content data of wheat, rice, and maize in China since 1980, and recorded their years, locations, quality, and corresponding meteorological stations. Firstly, the correlation analysis method was used to explore the relationship between the grain protein content of major grain crops and climatic conditions. Secondly, the relationship model between climate and grain protein content was established by the multiple linear regression method, and the contribution of meteorological factors to grain protein content was quantitatively analyzed. Finally, this study combined the relationship model between climate and grain protein content with the future climate change scenario data to predict the grain protein content and yield of three major grain crops in China in the middle of the 21st century under different shared socioeconomic paths (SSP) scenarios. The main conclusions are as follows :

(1) Through the analysis of grain protein content and meteorological factors of major grain crops in China, it was found that grain protein content was significantly affected by climatic conditions. Among them, the most significant period occurred in the period of grain formation to maturity. Among the meteorological elements, the effects of average temperature, maximum temperature, diurnal temperature difference, and precipitation are remarkable.

(2) According to the influence of key meteorological factors on the grain protein content of crops, the relationship model between climate and grain protein content was established. The verification results showed that the model could effectively reflect the distribution characteristics of grain protein content of major grain crops in China. Considering the effects of climatic conditions and other factors on grain protein content, the relationship model between climate and quality of major grain crops in China was constructed by stepwise multiple linear regression method. The model can truly reflect the grain protein content of major grain crops in the historical period of China through the validity test.

( 3 ) The grain protein content and yield of major grain crops in China under different climate change scenarios in the historical period and the future were simulated. The results showed that global warming was not conducive to the formation of grain protein yield. In the future, the protein content of wheat and maize kernels is mainly increased, and the protein content of rice kernels has little change compared with the historical period. The grain protein content decreases in the middle and lower reaches of the Yangtze River. The differences in key meteorological factors during the crop growth periods are the important reason for the large dispersion of grain protein content change. Under the combined effect of crop yield and grain protein content, grain protein yield of wheat increased, while grain protein yield of rice and maize decreased. Under different SSP scenarios, the total protein production of major grain crops in China decreased compared with the historical period.

In summary, under the future climate change scenarios, the total grain protein production of the three kinds of grain crops in China decreases, and global warming is not conducive to the formation of grain crop quality and yield.