Causes of rice sitting and its prevention and control measures

Rice sitting on the rice, "red blight", is a common physiological disease in rice production. Rice has a great influence on the yield after sitting, which can generally reduce production by 10% to 20%, and severely reduce production by more than 50%. According to the survey, the area of ​​our district is about 40,000 mu per year, accounting for about 10% of the rice planting area. Since the end of April this year, there have been many rains and rains in the district, such as an increase in rainy days, severely insufficient light, and low temperatures. In addition, some rice fields are not properly managed, and the phenomenon of rice sitting is more serious than normal. The cause of sitting on rice is complicated, and it is often the result of interaction of various factors. However, prevention and production are obviously different. In order to provide help to farmers and farmers, I will introduce the types, symptoms and prevention measures of rice sittings as follows.

First, sitting type and symptoms

The growth of rice seedlings was not normal after transplanting, which showed that the rice plants clustered and the leaf stiffness became smaller. Leaf color returned to normal, and some appeared reddish-brown spots or reddish red. Growth stagnation, tiller seldom occurs, root growth is blocked, etc., commonly known as sitting squat, and some people call it "squat".

Rice sitting can be roughly divided into the following categories:

1. The chilling type occurs mostly in muddy fields, deep-footed fields, cold-soaked fields, and back-shadow fields. These fields are flooded for a long time, and the mud temperature is low. When the continuous low-temperature and illuminating weather is encountered, the occurrence of seedlings is more likely to occur. . The symptoms are delayed after planting, the leaves are slow, the new roots are not long, the roots are aging, soft, brown or black, the leaves are yellow, and the tips are mostly accompanied by brown needle-like irregular spots or leaves. The tip is dry.

2. Deficiency type is caused by the lack of certain nutrients and the physiological metabolism of seedlings is blocked, mainly due to phosphorus, potassium and zinc deficiency. Symptoms: 1 Phosphorus-deficient rice fields, early in the tillering stage, the seedlings grow slowly, the plants are short, the plants are short, the new leaves are dark green, the old leaves are purple and purple, the leaves are erect and the stems are small, the sheath is short and the roots are weak. , soft cotton, inelastic, few branches, brown and black roots, axillary clusters, dark brown leaves, few new roots, weak roots; 2 rice fields lacking potassium, one month after planting, peak of disease Red-brown spots appear and spread from the old leaves to the new leaves, forming red-brown spots or streaks. Some varieties have reddish brown leaves, no spots, and the whole plant turns dark red. Only a few leaves are pale green and do not grow new roots. It is easy to become black or even rot. The lack of potassium is often accompanied by chilling, forming a sitting sputum, usually called physiological red blight. 3 The zinc-deficient field, after the saplings return to green, begins to occur, generally 20 days after the planting peak, performance The blade tip of the blade is dry, and brown rust spots appear in the middle of the blade, and rust spots appear gradually from the bottom to the upper blade, and gradually expand, and the blade ages.

3. The poisonous type is mainly caused by the poisonous root system of soil-reducing substances, which occurs mostly in the deep mud field with long-term flooding, the scouring field with poor soil permeability, the muddy field, and the big fat field behind the house. This kind of field contains a large amount of undecomposed organic fertilizer. Due to the decomposition of organic matter or low paddy field and waterlogging, the soil contains a large amount of reducing substances, such as hydrogen sulfide, organic acids, ferrous iron, methane and other toxic substances. Root respiration and nutrient absorption. The main symptom is that the roots become dark and stinky.

In addition, improper cultivation measures may also cause rice sitting, such as deep-water planting, deep-water irrigation, seedling planting deep, planting thin and weak.

Different types of rice sitting, their symptoms and causes are different, but the cold, poison, and deficiency caused by sitting are often mutually influential and mutually causal. Such as low temperature and toxicity not only weaken the resilience and root activity of the seedlings, but also affect the activation of soil nutrients and the absorption of roots, resulting in plant deficiency.

Second, prevention measures

In prevention and control, strategies should be adopted to adapt to the field, prevent prevention, and comprehensive prevention.

(1) Preventive measures. On the basis of cultivating and strengthening the sorghum, it is necessary to focus on improving the growth environment of the seedlings, the shallow water planting, the shallow transplanting, and paying attention to nitrogen, phosphorus, potassium and microfabrication for the fields and muddy fields and cold soaking fields that are prone to rice sitting. The proportion of fat.

1. Prevention of potassium deficiency and zinc deficiency caused rice sitting. When applying the base fertilizer, pay attention to the proportion of nitrogen, phosphorus, potassium and zinc fertilizer, and increase the application of 7.5 kg of potassium chloride and 1.5-2 kg of zinc sulfate.

2, to prevent root poisoning caused by rice sitting. For rotten muddy fields, cold soaked fields, etc., 50 kg of wood ash and 15-20 kg of lime can be applied before planting to neutralize harmful substances such as hydrogen sulfide and organic acids, improve mud temperature and improve the root growth environment of the seedlings.

3, shallow water transplanting. Do the water in the live seedlings, shallow water to promote sputum. Deep water, deep insertion, and low mud temperature affect the absorption of nutrients by seedlings. Therefore, shallow water planting should be carried out to enhance the light, increase the water temperature and mud temperature, accelerate the decomposition of the fertilizer, increase the absorption and utilization of the root system, and promote the robust growth of the seedlings.

(2) Prevention and control measures. 10-15 days after planting, the seedlings are difficult to return to green, the new leaves are less or no new leaves, no separation, the roots are brown, dark brown, less white roots or no white roots, the seedlings are short and thin, the leaves are chlorotic and have rust spots. It is a red blight and should be prevented immediately. Take appropriate remedial measures to promote the rapid growth of seedlings and reduce the harm. First, we must conduct field investigation and diagnosis to find out the main causes of the disease. For deep-foot muddy fields, cold-impregnated fields, and large-fertilizer fields, it is necessary to drain the water immediately, and lightly dry the fields to extract water, reduce the groundwater level, improve soil permeability, increase mud temperature, eliminate poisons, and reduce poison. At the same time, black and white ash (grass ash: lime = 1:0.4) should be applied to neutralize excessive toxins such as organic acids.

It is necessary to promptly apply the deficiency fertilizer to the shortage of the field. If the zinc field is to be supplemented with zinc fertilizer, the soil is sprayed with 1-1.5 kg of zinc sulfate or 0.5 kg of water with 75 kg of foliar spray. In addition, foliar spray application of auxin and trace elements for foliar application 1-2 times, after 5-7 days, the seedlings can return to normal.