种子作为最基础的农业生产资料，在粮食生产中起到十分重要的作用，但国内学者在研究粮食投入要素替代方面，没有把种子投入作为重要变量进行研究。因此，文章以用种量投入作为重要变量之一构建粮食生产模型，测算各投入要素的产出弹性，边际产量及要素间的替代弹性，研究要素替代。研究结果表明，用种量对劳动力具有一定的替代作用，但对劳动力发挥替代作用的主要是农机动力，而用种量主要发挥粮食增产作用。根据研究结果得到相关启示，农机和种子等现代农业生产要素投入在粮食生产中发挥十分重要的作用。为保障粮食产量稳定增长，应提高品种改良技术水平，充分发挥种子投入的增产作用；应加大农业机械补贴政策的支持力度，鼓励农户购买农机并投入生产，充分发挥农业机械的替代作用。

As the most basic agricultural production data, seed plays a very important role in grain production in China. However, the domestic scholars have not studied the seed input as an important variable in the study of the substitution of grain input factors. Therefore, in this paper, grain production model is constructed with seed input as one of the important variables. The output elasticity, marginal product and substitution elasticity of input factors are measured, and the substitution of factors is studied. The research results show that seed input has a certain substitution effect on the labor force, but the substitution effect on the labor force is mainly agricultural power, while seed input mainly plays a role in increasing grain production. According to the results of the study, the input of modern agricultural production factors such as agricultural machinery and seeds plays a very important role in grain production. In order to ensure the stable growth of grain production, we should improve the technical level of variety improvement and give full play to the role of seed input in increasing grain production. We should increase the support of agricultural machinery subsidy policy, encourage farmers to buy agricultural machinery and put it into production, and give full play to the substitution role of agricultural machinery.

F326.11

基金项目：国家社会科学基金项目（编号：15BJY094）；湖南省社会科学基金项目（编号：14YBA199）