In recent years, in the southern rice growing areas, farmers' friends have reported that the phenomenon of “not bowing†and the “ear hook†of rice ears is increasing in the late stage of rice growth. So what is meant by "no bow" and "eagle hook"? In fact, it is the filling period of rice. When the grain is firm, those spikes are not pollinated because they are not pollinated. This phenomenon is actually a dry disease of rice, a physiological disease of rice, and a new intractable disease in the growth process of rice.
It is common in the Huaihe River basins such as Anhui, Hubei, and Xinyang, Henan, as well as in the northwestern part of the Yangtze River, and the disease has been expanding and aggravating year by year. There was almost no sign in the early stage of the disease, and it occurred suddenly at the end of the booting stage.
There was no harvest at the time of harvest, and there was no saving measure at this time. High temperature and drought for several consecutive days can cause this disease to become more serious.
What are the main symptoms of drought and drought?
1. The growth in the early stage is normal, and it occurs suddenly at the end of the booting stage, and the heading period is obvious;
2, some plants can not head, some can not be pregnant, the head can not be grouted and firm, even if it can be strong is only small green particles;
3. At the time of booting, the husk has been opened, and the outer stalk is longer than the inner stalk, curved and cannot be closed, and the hull is a bird's beak;
4, the glume is not developed, and some sections are only glume, no guards, and high-node branches (sections 3 and 4);
5. There are inverted roots in the roots.
Grain is not grouted during the late growth stage of rice
The ear of rice cannot be filled normally, and the grain is empty, even if it is grouted, it is mostly green.
Rice spikes in the filling stage "do not bow"
The rice stalk shell is not closed and is in the shape of a bird's beak.
The seedlings are weak and the roots have inverted roots.
The law of onset of drought and green
It is related to the drought and drought conditions: the diseased fields generally occur in newly reclaimed or drought-changed paddy fields, and sandy fields where water and drought rotations are often carried out also occur; the old dry field is lighter, and the field is heavier, Tanaka The inter-onset disease is distributed in strips parallel to the old dry field ditch; the newly leveled ditch section is heavier; the vicinity of the irrigation gate is heavier, and the place farther away from the irrigation port is lighter. ,
It is related to the growth of the seedlings: the same field, the place where the nitrogen fertilizer is sufficient, the growth of the green is serious, and the place with poor growth is lighter.
It is related to crop varieties: generally there are differences among different varieties, the incidence of early-maturing varieties is less, and the incidence of late-maturing varieties is more. Among the same varieties at the heading stage, japonica and japonica rice were more serious than indica rice. Drought-green disease occurs less in japonica rice.
Causes and mechanism of the pathogenesis of drought and green disease
Reason one: It is related to soil nutrient imbalance and drastic changes in water supply. The fertility habits of farmers are diazo and phosphorus, while light potassium and zinc, heavy chemical fertilizers and light organic fertilizers cause serious imbalance of soil nutrients and insufficient zinc and potassium.
Phosphorus and zinc are antagonistic, and sulfur and arsenic are antagonistic. In soil, arsenic exists in the form of arsenic acid. In dry crops, it does not cause crop poisoning. In paddy fields, due to deep water, arsenic acid becomes arsenic acid under flooding conditions. It has strong toxicity, and the activity of arsenic becomes stronger when the drought changes water and floods for a long time.
The most prone to drought and greening in rice life are: pollen mother cell meiosis, spikelet differentiation, heading and flowering. As long as the three soils are susceptible to growth, the soil water content is reduced to 60%~70%, such as sudden flooding, and the soil organic matter is richer. The growth is soaring, so that the rice ears that have been affected by the drought are more abnormal, and there is a drought.
Reason two: low soil organic matter content and lack of nutrients. The drought-to-green disease often occurs seriously in the drought-reformed paddy field. The main reason is that the organic matter content of the dry-flooded paddy field is relatively low, the herbicide residue is serious, the nutrient elements such as potassium and zinc are seriously deficient, and the activities of arsenic and copper are enhanced. There are also long-term excessive application of chemical fertilizers, leaking "running water, running soil, running fertilizer" three running fields, but also easily lead to serious occurrence of drought and disease.
Reason three: It is related to the pollution factor in the water. According to the analysis of relevant data, the phenomenon of gluten deformity, insensitivity and even harvest in rice growth and harvest is mainly affected by the pollution factors such as strong acidity, heavy metal residues and trichloroacetaldehyde in water.
Reason four: phytotoxicity. Inappropriate application of plant regulators such as paclobutrazol or hormonal herbicides such as sodium 2, 4-chlorochloride, etc., especially in rice after jointing, may cause rice hull deformity.
Reason 5: The seedlings are weak and the field management is not in place. The incidence of drought and disease is closely related to the growth of seedlings. All the seedlings are of poor quality, densely planted, poorly ventilated and poorly permeable, or poorly managed by water slurry. The ground is not laid in time, the root system is not deep, or the groundwater level is high, the tillage is too fine, and the nitrogen fertilizer is applied for a long time. The combination of pulping, lack of active iron, black roots and serious pests and diseases will lead to poor growth of rice plants, weak resistance, and serious drought and disease.
In summary, the occurrence of rice dry disease is mainly caused by unbalanced fertilization and unreasonable irrigation. Some of the fields are caused by local irrigation water quality factors and phytotoxicity.
How to prevent rice drought and disease?
1. Improve soil and increase soil aggregate structure. Add organic fertilizer, increase soil aggregate structure, reduce the activity of toxic substances, and improve the detoxification ability of rice. Apply 40~50 kg of quicklime or soil conditioner to the soil to adjust soil acidity. It can not only improve the activity of rice roots, but also improve the absorption capacity of water and fertilizer.
2. Scientific water use. The “dry to water†field tends to be high in terrain, and it is prone to water shortage in the early stage. The water layer should be established early (before the ear differentiation stage) to reduce the concentration of arsenic in the soil and release it in advance to avoid sudden emergence at booting stage. The water layer is established because the rice is extremely sensitive to arsenic at this time, and the poisoning is not strong.
3. Add fertilizer with sulfur content. In the “dry to water†field, pay attention to reduce the use of nitrogen and phosphate fertilizer when applying the base fertilizer, and potassium sulfate should be used for potassium fertilizer.
4. Strengthen cultivation management, skillfully apply base fertilizer and foliar fertilizer. Breeding properly, dilute the seedlings, improve the quality of the seedlings, apply more organic fertilizers, apply sufficient base fertilizer, pay attention to the application of zinc-containing medium and trace element fertilizers, apply top dressing early, prevent the "madness" in the early stage, and "de-fertilize" in the later stage. Enough seedlings are resting on the field." Strictly prevent the delay of the field and strengthen the prevention and control of pests and diseases, and improve the resistance of rice plants. Foliar fertilizer containing phosphorus and potassium can be sprayed once in the rice break period, the initial heading stage and the heading stage, which can better prevent disease and increase yield.
5. Replanting japonica varieties. Indica and japonica rice are more serious than indica rice. Drought-green disease occurs less in japonica rice.
6. Change the farming system. Paddy rice in dry land is vulnerable to drought, and it is easy to cause zinc deficiency and manganese poisoning, boron poisoning and arsenic poisoning. Fields where arsenic poisoning occurs all the year round should be replanted into autumn crops such as vegetables, corn, sweet potatoes, etc., and no rice is used to avoid harm.
This article URL: The cause and mechanism of the disease in the late stage of rice growth
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