Why is high yield not the only goal of breeding?
As grain production ushers in an “eleventh consecutive increase,” the role of seeds in national food security is becoming increasingly prominent. With the development of science and technology, improved varieties are being introduced and upgraded, directly driving the per-mu grain yield upward year by year. Therefore, for a long time, the high-yield trait of seeds has always been the dream pursued by breeders.
Among the many traits of seeds, some cannot be reconciled at the same time. If the pursuit of extreme high yield is carried too far, other beneficial traits are very likely to be overlooked and sacrificed. In recent years, some varieties have passed approval because of outstanding yield performance, but their stress resistance is relatively weak, for example wheat varieties that are not cold-resistant, corn varieties that are not lodging-resistant, rice varieties that are not disease-resistant, and so on. In actual production and application, if they encounter extreme conditions such as outbreaks of related diseases or severe weather, they can easily lead to reduced yield or total crop failure.
⟦NL> Liu Shi, a visiting professor at China Agricultural University, believes that agricultural production today is no longer traditional agricultural production that only pursues yield, but rather one that pursues improvement in comprehensive efficiency and benefits. If the returns of the agricultural industry are far lower than those of other industries, how can agriculture continue to develop?”
Indeed, with the development of the economy and society, changes in the organizational forms and production methods of agriculture and rural areas have brought new issues to grain production, and changes in consumer demand and grain uses have also imposed new requirements on grain production.
For example, among the main entities engaged in grain farming, large grain growers have gradually become a force that cannot be ignored. Their demands for variety traits differ from those of small farmers. The impact of disaster and reduced yield on one mu and three fen of land for small farmers is far lower than the loss of losing everything when several hundred mu of land fail for large grain growers. In interviews, the author felt that large growers have a poorer ability to bear risk and a higher demand for stable yield. Many large growers hope to plant varieties with relatively stable yields that are lodging-resistant, disease- and pest-resistant, drought-resistant, and wind-resistant. Especially for wheat, blindly pursuing high-yield varieties and ignoring lodging resistance will not only cause yield losses, but lodging wheat is also inconvenient to harvest mechanically, thereby increasing the cost of manual harvesting. In this case, lodging resistance is the first indicator for large growers when selecting seeds, and only after that comes yield benefit.
Suitability for mechanized harvesting is also a new demand for variety traits arising with the rise of large grain growers and the improvement of mechanization levels. During this year's corn harvest period, varieties suitable for direct grain harvesting such as “Jingke 968” attracted attention from all sides and were regarded as a major transformation in corn production. Changing “harvesting corn cobs” to “harvesting corn kernels” for many large grain growers, especially farmers in Northeast China with several hectares of land, saves enough labor and money to make up for the benefit gap with those varieties that only emphasize high yield.
In addition, excellent taste has also become an increasingly important indicator. With the improvement of living standards, people are becoming more and more particular about “eating well,” with ever higher demands. “Old flavors” and good-quality varieties such as Jingxi rice and Daohuaxiang, which were almost eliminated because of low yield, are once again in demand, sell at good prices, and are therefore welcomed by farmers.
Among the different variety traits of high yield, high resistance, mechanization, and high quality, how to carry out differentiated breeding and balanced breeding still requires finding a way forward through breeding technology. At the same time, a diversified indicator system must also be established in variety approval. However, at present, according to Xie Conghua, a professor at Huazhong Agricultural University and a potato breeding expert, it is basically a case of yield having “one-vote veto,” which is not conducive to variety specificity. He believes that relevant indicators should be revised so that increased yield is not the only goal. A variety with stable yield but outstanding resistance or quality and good market prospects should be an excellent variety.
Liu Shi also believes that the pursuit of extreme yield should not be followed in breeding. He believes that agricultural production should pursue high yield on the basis of stable yield, and that blindly pursuing extreme yield will bring great risks to farmers. Due to changes in the environment, climate, and even diseases and pests, fluctuations in yield are a blow to farmers' income, the market's capacity to absorb supply, prices, and consumers. In addition, blindly pursuing extreme yield will lead to a decline in the marginal benefit of input and output.
As for enterprises, how to determine breeding needs in a differentiated way, and how enterprises can grasp well the environment of different places and the needs of farmers, means they should obtain information on breeding direction on the front line. If a variety has one or several resistances but cannot be used in a suitable place, it will often lead to its traits not being fully brought into play. The yield reduction that occurs in this case often cannot be attributed to the seed being bad, but rather to “good steel not being used on the blade.”