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Drought, drought!
Affected by continuous drought, the water levels of major rivers and lakes in Hunan Province will be low and dry in the next week, and the number of small and medium-sized rivers with no flow may increase.
Without effective rainfall, 95.7% of counties, cities, and districts in Jiangxi Province experienced severe meteorological drought.
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The water body of Poyang Lake has shrunk and shrunk, with dry tree branches on the lake bed (Image source: Southern Metropolis Daily)
Since July, the southern region of China has experienced the most severe meteorological drought since 1961. A certain cooperative has transferred and planted over 10000 acres of rice, and it is expected that there will be a yield reduction of 1000 acres at harvest, resulting in a total crop failure of 295 acres.
According to statistics from the Ministry of Emergency Management, as of now, the drought has caused 38.305 million people in 21 provinces (regions, cities) including Sichuan, Chongqing, Hubei, and Hunan to be affected. 4.3 million people need life assistance due to the drought, and the affected area of crops has reached 4076 thousand hectares, resulting in direct economic losses of 32.8 billion yuan.
The National Climate Center predicts that the precipitation in the middle and lower reaches of the Yangtze River in autumn will be significantly lower than the same period in previous years, and close attention should be paid to possible summer and autumn droughts.
What is the reason for a seed setting rate below 20%?
Rice will wither and die as long as it lacks water for 10-15 consecutive days. If combined with sustained high temperatures during this period, it will affect the heading rate of rice, ultimately leading to a decrease in yield.
Hubei, Hunan, Jiangxi, Anhui, Zhejiang and other regions in the middle and lower reaches of the Yangtze River in China are the main areas affected by this drought, and rice growth has been threatened to varying degrees.
Anhui Mingguang, Large Area Rice Death from Drought
It is understood that one season rice and double season rice are generally planted in the Yangtze River Basin, with double season rice being replaced by early and late season rice. One season rice with a sowing period between the two is called medium rice. Starting from mid August, southern mid season rice gradually enters the heading and flowering period, which is sensitive to temperature and water. High temperature and drought will lead to a decrease in pollen activity, seriously affecting yield.
Jiangxi is a major grain producing province, while the area around Poyang Lake is the main production area. On August 20th, data showed that 75 counties and cities in Jiangxi Province experienced moderate or above meteorological drought. The person in charge of a seed company in Jiangxi stated that there has been no rainfall in the past two months since July. The continuous high temperature and drought have caused many varieties of poplar to be unable to grow normally during the booting and flowering stages, and the yield has been affected.
Jiangxi has been severely affected by disasters
The current high temperature and drought in Hunan has a long duration and high intensity, with rainfall 70% less than usual. A salesperson from a seed company in Hunan province told reporters that the middle rice, regenerated rice, and late rice in his region have been affected by high temperature and drought, resulting in a decrease in plant heading rate, poor seedling height and leaf length, and an increase in withered grains.
Zhejiang Province is affected by drought and high temperatures
The staff of a seed company in Zhejiang also stated that early maturing varieties in the central, southern, and northern regions of Zhejiang are greatly affected, and the seed setting rate in some areas may be less than 20%. There are two main reasons for this situation. On the one hand, the high temperature during the differentiation period of young panicles leads to a decrease in the number of grains per panicle, and on the other hand, the high temperature during the heading and flowering period leads to poor fruit setting of the variety. In some areas, there is still high temperature forced ripening.
Growth of Rice in Henan Province
Who is responsible for the loss of billions of yuan?
This year's Yangtze River Basin is completely different from what we have seen in previous years.
Researcher Yu Xinqiao from the Shanghai Agricultural Biotechnology Gene Center visited Henan, Hubei, Jiangxi, Anhui, and Hunan provinces, and saw many scenes of disaster. The scene was very serious and unbearable. He believes that the main cause of this rice disaster is the sustained high temperature and drought.
However, the differences in drought resistance performance among varieties may also directly affect the degree of damage caused by disasters. "Some varieties have strong resistance to high temperature and drought, and the losses may be smaller, but the vast majority of varieties have experienced a significant decline in seed setting rate under the extreme and sustained high temperature weather this year," said Yu Xinqiao.
A staff member from a seed company in Zhejiang believes that the maturity and sowing dates of varieties are different, and their degree of impact from high temperature and drought is also different. Varieties with early ripening are severely affected by disasters, while those with later ripening are much better.
"Some have reduced their yields by 20% -30%, some have reduced their yields by 40% -60%, and some even have a crop failure. The most critical influencing factor is not the variety, but the weather. In addition, the disaster situation varies depending on the different sowing dates of rice," said the person in charge of a seed company in Jiangxi. If the booting or flowering period happens to encounter high temperatures, the yield reduction may be severe. Therefore, it is necessary to adjust the sowing time based on the characteristics of the variety, while reminding major growers to pay attention to the sowing time and do a good job in risk prevention and control.
High temperature heat damage affects the growth of rice in Jiangxi province
Yu Xinqiao stated that hot and dry weather is becoming more and more normalized. In the future, in the breeding of water-saving and drought resistant rice varieties, attention should not only be paid to drought resistance, yield, disease and insect resistance, quality, but also to the high-temperature tolerance of the varieties.
Regarding drought accompanied by prolonged high temperatures in the early stages, Liu Dingfu, Chairman of Wuhan Jinyuliang Seed Technology Co., Ltd., believes that one thing the government's seed regulatory department should do is to truly go deep into the fields, investigate the heat resistance of rice and corn varieties, and forcefully eliminate a batch of heat-resistant varieties that have caused losses to farmers, in order to prevent unscrupulous merchants from pitting farmers again.
Taking Hubei Province as an example, the high temperature ended on August 23rd. Most of the previously flowering mid season rice has been harvested. The management department can conduct a detailed data investigation on which varieties are tolerant to high temperature and which are not.
Hubei is not sturdy due to high temperatures
No water source, can only rely on the weather for food?
Statistics show that there are 356 large and medium-sized irrigation areas in Hubei, Hunan, Jiangxi, Anhui, and Jiangsu provinces in the middle and lower reaches of the Yangtze River in China, with surface water as the water source. The irrigation area is 28.56 million mu, and the main crop is rice. Due to economic and topographical constraints, some rice growing areas have outdated water conservancy facilities and inadequate supporting facilities, resulting in aging and disrepair of agricultural irrigation projects, severe decline in irrigation efficiency, and can only rely on weather for survival.
"For example, in our mountainous areas where rice is grown, some areas do not have water sources. This year, the weather is dry and hot with little rain, and some soil has already cracked. There are about 2000 acres of dry cracked farmland in 200000 acres of the county," said a staff member of the Agriculture and Rural Bureau of Jinyun County in an interview with Qianjiang Evening News.
In addition, mid September is the peak and critical period for irrigation water use for crops such as late rice and medium rice in the middle and lower reaches of the Yangtze River, with a high and concentrated demand for agricultural irrigation water. Farmland that mainly relies on natural rainfall has extremely high drought resistance costs. With the continuous high temperature and drought, some areas of mountain ponds and small reservoirs have almost dried up, making it impossible to ensure basic crop production.
A 60 year old farmer stands in a dry pond, the water used to irrigate rice. The 200 acre rice he contracted has seen a significant reduction in yield due to drought and pest infestation (Image source: Southern Metropolis Daily)
Li Guoxiang, a researcher at the Institute of Rural Development of the Chinese Academy of Social Sciences, analyzed in a previous public report that this drought is mainly concentrated in areas such as "Wangtiantian", which is related to the abundant precipitation in the Yangtze River Basin in the past, the reliance on surface water for agricultural irrigation, and insufficient attention to machine wells.
What measures can we take to mitigate the impact of drought?
One is to master the physiological habits of rice and maximize the irrigation benefits of effective water resources. For example, during the non sensitive period of rice, it is possible to irrigate less or no water. During the sensitive period of rice, water shortage should be avoided as much as possible, and rice should not be dehydrated for two consecutive stages as this can cause a greater reduction in yield. For rice in the heading and flowering stage, if there is a possibility of heat damage in high temperature weather above 35 ℃, the following measures can be taken in a timely manner: first, adjust the temperature with water and irrigate the field with deep water to reduce the temperature of the panicle layer; The second is to improve resistance by spraying 3% calcium superphosphate or 0.2% potassium dihydrogen phosphate solution on the leaves.
The second is to vigorously develop water conservancy and irrigation facilities, strengthen the management and protection of water conservancy and irrigation facilities, solve engineering water shortages, further improve the management and protection mechanism of agricultural irrigation and water conservancy facilities, explore new mechanisms for the construction of agricultural irrigation and water conservancy infrastructure, and deepen the comprehensive reform of agricultural water prices.
The third is to promote water-saving cultivation techniques for rice, including dry seedling cultivation and water-saving irrigation techniques, promote the application of multifunctional seed mixing agents in rice drought resistance and water-saving, and use water retaining and drought resistant agents to enhance crop drought resistance.
The fourth is to establish a rice drought detection and early warning system, and to address the lack of drought detection and prediction for major grain crops in major grain provinces, establish a drought detection network. We will gradually improve the rice drought monitoring and prediction system by updating and supplementing the basic drought database, improving and optimizing the system model, calibrating the model parameters, and verifying regional drought evaluation indicators, continuously improving the reliability and accuracy of the system analysis results.
Regarding post disaster field management remediation, fields with low seed setting rates often have darker leaf colors and require shallow water irrigation. Efforts should be made to prevent and control pests and diseases to ensure the grouting and fruiting of weak flowers. For fields with particularly low seed setting rates, early application of 5 kilograms of urea per acre can promote the tillering of dormant buds at low nodes into panicles. It is required to control the heading before or after September 20th.
The meteorological drought is still ongoing, looking forward to the arrival of a rain
Reference: Wang Shaohua, 斳 Weirong, Liu Genshui. Factors and countermeasures affecting rice drought in Jiangxi Province [J]. Anhui Agricultural Science, 2017: 181-182
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