What exactly does crop yield mean?

What is crop yield? This seemingly simple question has had different understandings and connotations in different eras. Over the long course of agricultural production practice, breeders' and farmers' understanding of yield has undergone several important shifts, from experimental plots to large fields, from small environments to large environments, and from a single year to different yearly conditions.

All of our crops today were originally wild "weeds" that were transformed and evolved through the efforts of many generations, and the fruits of crops have also evolved from shriveled, bitter "wild fruits" into today's large, delicious fruits. Therefore, starting from traditional agriculture, which developed from intuition and experience, the size of crop fruits has for thousands of years been the most intuitive and core standard for measuring yield, and large fruits and "large ears" became the common pursuit of traditional breeders and agricultural producers. In the 1920s, genetic breeders in the United States discovered that through hybridization and selection, it was very easy to increase the size of corn ears while also enhancing their ability to resist stress, so hybrid breeding became the mainstream idea in genetic breeding. In an era of food scarcity, breeders, farmers and consumers all had to choose crop varieties with large fruits. Therefore, the understanding of traditional breeders was: large fruits mean high yield.

With the development of modern agricultural technology, the widespread use of chemical fertilizer technology has made it possible to fully and in a balanced way supplement the nutritional needs of crops, the development of pesticide technology has greatly improved the ability to prevent and control pests and diseases, and the development of cultivation technology has revealed the internal laws of crop growth, and so on, so that crops can withstand higher planting densities. Breeders, genetic statisticians and farmers found that in the process of continuously enlarging the ears, they encountered an insurmountable bottleneck, while higher planting density could more easily obtain more yield. On the contrary, fruits that were too large made it impossible for the crop to withstand high-density planting. Therefore, modern breeders took increasing crop planting density as a more important breeding objective. Thus, the understanding of modern breeders and farmers is: dense planting means high yield.

In the production practice of constantly pursuing high yield, due to differences between years in climate, soil, cultivation conditions and planting techniques, especially under increased planting density, varieties that showed high yield under ideal environmental conditions could not show stable high yield in harsh environments. Instead, varieties whose yield was not particularly outstanding under ideal environmental conditions but which had better stress resistance could show higher yield and stability in different years and different regions. Breeders began to attach importance to selecting varieties with good adaptability and strong stress resistance, and to eliminating those varieties that, although high-yielding, required pampering. Therefore, breeders and farmers gradually realized in production practice: good resistance means high yield.

With the adjustment of industrial structures in countries around the world, a large agricultural population has been transferred to urban industry and services, fewer and fewer rural people are engaged in agricultural labor, and the aging of the agricultural population is also relatively common. Under such circumstances, the implementation of mechanization in agricultural production has become inevitable. In this way, in agricultural production, some varieties with relatively short growth periods, fast fruit dehydration and good lodging resistance have been promoted and popularized, because only varieties with these characteristics can meet the needs of mechanized harvesting. Although varieties of various crops with shorter growth periods have no advantage in yield, because they are suitable for mechanized operations, can greatly reduce labor intensity, improve production efficiency and bring farmers higher benefits, such varieties have been widely accepted and planted over large areas, while traditional varieties with long growth periods have been gradually eliminated. After escaping the era of food scarcity, agriculture, like other industries, is competing for social resources, and an industry without economic benefits will not be favored by social resources. Therefore, how to obtain higher efficiency and returns through industrial development is the key to the sustainable development of the agricultural industry and to obtaining actual high yield. Thus, in the era of industrialization, people's understanding of yield is: efficiency means high yield.

Based on such laws of industrial development, the breeding direction of our country's crops will undergo a profound transformation, and breeding aimed at high yield will gradually be replaced by breeding aimed at efficiency. From the innovation and screening of breeding materials, the design ideas for combinations and the formulation of promotion standards, to the evaluation of various characteristics and the assessment of priorities, all will change accordingly.