[Fighting the "Three Summers" to Ensure a Good Harvest] In addition to the "rotten rain", wheat harvests also need to guard against these meteorological disasters

At present, wheat has gradually entered the concentrated harvest period across the country. Some areas have encountered "rotten field rain", which has had a great impact on wheat harvest and has attracted widespread attention. Is it possible to resist natural disasters through variety improvement? In addition to "rotten field rain", what other diseases or special weather should be paid attention to during the mature harvest period of wheat? How to prepare for defense in advance? Dr. Zhang Jinpeng, a researcher at the Institute of Crop Sciences of the Chinese Academy of Agricultural Sciences and an expert in the expert team of wheat scientific knowledge dissemination of the Chinese Society of Crop Science, gave answers to these questions.

Q: It is distressing to encounter "rain that rots the wheat field" during the wheat harvest. When scientists are breeding wheat varieties, do they breed or do they already have varieties that can resist "rain that rots the wheat field"? Is it possible to resist natural disasters through variety improvement?

Zhang Jinpeng: "Rotten rain" during the wheat harvest season can easily cause wheat grain spikes to sprout. There are differences in the resistance to spike sprouting among wheat varieties. Generally speaking, red-skinned wheat has a higher resistance to spike sprouting than white-skinned wheat. The resistance of a variety to spike sprouting is related to the maturity period and its own resistance. In terms of the incidence of spike sprouting in my country's Huanghuai wheat region, late-maturing varieties are relatively mild, and red-skinned wheat has a higher resistance than white-skinned wheat. For example, most wheat in the United States is hard-grained red-skinned winter wheat, which generally has much better resistance to spike sprouting than white-skinned wheat. Most of the wheat varieties in my country's northeastern spring wheat region, southwestern wheat region, and the middle and lower reaches of the Yangtze River are red-skinned wheat.

Relatively speaking, these three wheat regions have frequent rainfall during the wheat maturity period, so local breeders have paid attention to the disaster of ear sprouting and prefer red-skinned wheat in variety selection. However, rainfall in the Huanghuai wheat region is not frequent, and the consumer market and storage companies tend to lower the price of red-skinned wheat or are unwilling to purchase it, which has led breeders to gradually give up red-skinned wheat and reduce the requirements for ear sprout resistance.

Among the germplasm resources, there are also very few white-skinned resources that are resistant to ear sprouting, which may play a role in improving the variety's ability to resist ear sprouting in the future.

Q: In addition to the "rotten field rain", what other diseases or special weather conditions should be paid attention to during the mature harvest period of wheat? How can we prepare for prevention in advance?

Zhang Jinpeng: When wheat is about to be harvested, in addition to "rain that rots the field", we must also be careful to prevent dry and hot winds and stormy climate disasters.

Dry hot wind is caused by high temperature and dry air in the late stage, which leads to high temperature forcing ripening, premature termination of grain filling, reduced grain weight and unfull grains, resulting in reduced yield. Stormy weather will cause lodging problems, making mechanical harvesting difficult and increasing the loss rate.

To deal with the above problems, foliar fertilizers and growth regulators that delay leaf senescence are generally sprayed during the grain filling period to extend the greening function of wheat leaves, while increasing grain weight to ensure that grains are full. In order to deal with the lodging problem caused by storms, breeding and production have focused on the selection and promotion of short-stalked and lodging-resistant varieties to reduce the risk of lodging. For example, the dwarf wheat bred by the Institute of Crop Sciences of the Chinese Academy of Agricultural Sciences has greatly reduced the risk of lodging.

Q: The flood season is approaching. In addition to the Huanghuai and Haihe regions, how should other summer harvest areas take rain prevention measures?

Zhang Jinpeng: Abnormal climate change brings uncertainty about rainfall, so the way to actively deal with the "rotten field rain" disaster is to pay close attention to weather dynamics, harvest early and avoid the impact of adverse weather. This requires attention to the construction and improvement of infrastructure such as storage, drying and drying. On the other hand, we must increase the publicity and promotion of red-skinned wheat varieties that resist ear sprouting, reduce the prejudice of storage and processing companies against red-skinned wheat, and do more scientific popularization to consumers that the nutritional value of red-skinned and white-skinned wheat is equally high, so as to gain more initiative in variety layout.

Question: In the race to seize grain from Longkou and against the flood season, are there any scientific technologies or means that can accelerate or delay the maturity of wheat and avoid the peak of the flood season?

Zhang Jinpeng: Technically, the ear germination problem caused by the flood season can be reduced by arranging varieties with different maturity periods. However, my country's wheat production areas are mainly concentrated in the Huanghuaihai Plain, the middle and lower reaches of the Yangtze River wheat area and the southwest wheat area, all of which are double-cropping farming models. The next crop of corn or rice requires wheat varieties to mature early and be stubbled early, so the current situation that late-maturing varieties are unpopular is difficult to change for the time being.

Q: As the saying goes, "When the wheat is 90% ripe, harvest it; when it is 100% ripe, throw it away." How do you understand this saying? When is the best time to harvest wheat? What are the precautions for wheat harvesting? How can you reduce losses during the harvesting process?

Zhang Jinpeng: The so-called "90% maturity" refers to the late waxy stage of wheat, which is the best time to harvest wheat. How to judge the waxy stage of wheat? Take an ear of wheat and rub off the bran that wraps the wheat grains. The wheat grains have lost their green color and appear yellow in different shades. At this time, the wheat grains are somewhat soft. Cut open the surface of the wheat grains and the inside is waxy. This stage of wheat is the so-called waxy stage.
"Ten mature" refers to the fully mature stage of wheat. At this stage, the wheat stalks have completely withered and yellowed, and the wheat grains have become dry and hard. If wheat is harvested at this stage, the yield of wheat will be reduced. In serious cases, the yield per mu of land can be reduced by about 100 kilograms.

Therefore, it is recommended to advance the wheat harvest period appropriately to reduce the loss rate of mechanical harvesting. my country also attaches great importance to the improvement of agricultural machinery equipment to reduce the loss rate. Some harvesters with improved design and technology have been updated and put into production.

Q: Meteorological experts said that from June to August, there may be both drought and flood. How can crops such as wheat resist both? How can we ensure the safety of summer grain?

Zhang Jinpeng: June to August is a critical period for wheat harvest and corn or rice planting. Therefore, we must first rush to harvest wheat to ensure that every grain is stored in the warehouse; second, we must ensure timely irrigation after planting the next crop to preserve the seedlings. From July to August, the flood season is coming, and we must do a good job in building drainage channels in the fields to prevent long-term flooding caused by floods. The Ministry of Agriculture and Rural Affairs also issued a notice requiring all localities to speed up the dispatch of disaster relief seeds, drought-resistant and flood-draining machinery and other material reserves; to set up a regular emergency service team, organize agricultural technicians and scientific and technological teams to go deep into the production front line for guidance, promote scientific disaster prevention and mitigation by zoning and classification, and strive to win a bumper harvest of summer grain and annual grain.

Author: Song Yajuan, Wu Yuetong

Scientific review: Dr. Zhang Jinpeng, researcher at the Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, and expert of the wheat science knowledge dissemination expert team of the Chinese Society of Crop Science