The shift in corn's identity becomes a new direction for breeding

Editor's note: In this round of structural adjustment of the planting industry, corn restructuring is the absolute priority. As China's largest food crop by planted area, corn used to be a "granary." In the future, by continuously developing high-quality specialized varieties and promoting the structural adjustment of corn varieties, the "granary" can be turned into "granary" + "milk bottle" + "vegetable basket" + "oil bottle," etc., creating new economic growth points for farmers.

So, whether it is grain corn, silage corn, fresh-eating corn, or high-oil corn, from a breeding perspective, which advantages should be brought into play and which variety defects should be improved?

Grain corn—— "Moisture reduction": dry grain is what makes mechanical harvest possible

As early as 2011, the Shandong Academy of Agricultural Sciences successfully bred its first new grain corn variety suitable for mechanical harvest, "Ludan 9066," and began promoting and applying it in Shandong in 2014. What are the key points of grain corn breeding? What are the benefits of choosing grain corn? How is the promotion of this variety going at present? What difficulties still lie ahead for large-scale promotion? With these questions, the reporter interviewed relevant experts from the Corn Research Institute of the Shandong Academy of Agricultural Sciences.

According to researcher Meng Zhaodong, the breeder of "Ludan 9066," Party secretary of the Corn Research Institute of the Shandong Academy of Agricultural Sciences, and a scientist in the National Corn Industrial Technology System, rapid dehydration and lodging resistance are the necessary conditions and most important factors for grain suitable for mechanical harvest. Meng Zhaodong said: "For corn to achieve grain harvest, the lower the moisture content of the variety, the better; otherwise it will cause an excessively high grain breakage rate. Moreover, the later the harvest period, the lower the grain moisture content, and the more suitable it is for mechanical harvest, so the variety is required to have good lodging resistance."

Based on the above reasons, Meng Zhaodong's research group clearly defined the breeding direction of new grain corn varieties as "two lows and one high," namely lowering moisture content, lowering biological yield per plant, and increasing planting density. "Lowering biological yield per plant is to meet the requirements of reducing moisture content and improving lodging resistance; increasing planting density is needed for high yield. For grain corn varieties to be competitive, they must achieve high yield under mechanized harvest conditions, and only then will farmers accept them," Meng Zhaodong said.

As one of the main promoted grain corn varieties in the Huang-Huai-Hai region, "Ludan 9066" had a minimum moisture content of only about 26% in a 100-mu demonstration plot in Liaocheng, lower than other similar varieties. At the same time, its high-yield performance was outstanding: the two-year regional trial average yield was 638.5 kg per mu, 3.7% higher than the control "Zhengdan 958"; the production trial yield was 557.6 kg per mu, 1.9% higher than the control "Zhengdan 958."

"Ludan 9066" is being continuously promoted, and in the process it also faces the practical difficulty of the speed of "moisture reduction."

In 2014, the reporter once attended the on-site mechanized grain harvest demonstration of "Ludan 9066" held in Yanglankou Village, Taiping Town, Jiyang County. As the harvester drove past, complete corn kernels along with crushed corn cobs were poured out.

"In this way, procedures such as ear picking, husking, threshing, cleaning, and straw crushing and returning to the field are all completed in one pass. After harvest, the corn kernels are clean, unbroken, and have an extremely low loss rate. Farmers can sell them after drying them for one day, so the autumn harvest task can be completed in two days. With traditional corn varieties, the ears need to be sun-dried for two or three days before threshing, and after threshing the kernels still need to be dried, which takes about a week, is time-consuming and labor-intensive, and it is also hard to find a drying site," said Li Wencai, associate researcher at the Corn Research Institute of the academy.

Grain corn has many benefits, but how is its promotion going? Meng Zhaodong admitted frankly: "At present, promotion in the Huang-Huai-Hai summer corn production area still faces practical difficulties. The main reason is rotation with wheat, and the farming season waits for no one. The wheat sowing period is fixed, and it is difficult for farmers growing corn to meet the requirement of harvesting grain at 110 days; most harvest at around 100 days. In this way, the grain moisture content is still relatively high, and the grain breakage rate in mechanical harvest is high. Mechanical grain harvest requires a moisture content below 25%, while at present it is generally above 30% at harvest."

Over the past 3 years, "Ludan 9066" has been promoted in the summer corn production area of Shandong, with an annual promotion area of about 1 million mu, and it has not achieved a major breakthrough. Meng Zhaodong said that the next steps are: first, to continue working in the direction of "moisture reduction" and intensify variety breeding; second, to make combination efforts by selecting seed enterprises with strong strength and strong promotion capacity to undertake the task of promoting improved varieties; third, to actively connect with new business entities such as cooperatives and family farms to build demonstration bases for grain corn planting and mechanized harvest.