Reasons for the delay in tillering of small rice seedlings

1. Rice evil seedling disease:

The law of disease and route of transmission: the pathogen of rice evil seedling disease overwintered on grain and straw, and the diseased seeds or straw were used the following year. The pathogen propagated with the seed germination and invaded from the coleoptile or wound of the seedling, causing the seedling disease to grow. Diseased seedlings often wither and die. The unwithered diseased seedlings are yellowish green, grow slender, generally about 1/3 higher than healthy seedlings, and have poor root development, few tillers, or even no tillers. After transplanting the diseased seedlings, the germs are brought to the field, causing the disease of rice seedlings. When the rice is heading and blooming, the pathogen is transmitted to the flower organ through wind and rain, which makes the grain and straw carry the pathogen and cause cyclic infection to damage the rice. Germs are easy to invade from the wound and sow mechanically damaged rice seeds, or if the roots of the seedlings are seriously injured, the disease will be serious. The disease of dry seedling raising is often more serious than that of water seedling raising.

Control methods: the prevention and control of rice evil seedling disease focuses on the treatment of seeds.

The main results are as follows: (1) choose disease-free seeds to stay. This is the most reliable and effective method.

(2) disinfect the seeds strictly. Soak the seeds with strong chlorine, 100 grams of 50% carbendazim, 50 kg of water, or 120 grams of 35% chlorpromazine, 50 kg of water, or 3% of raw lime water for 48 hours. We must pay attention to that the liquid level must be 15cm-20cm higher than the seed level for seed absorption. At the same time, in the process of seed soaking, the liquid level of the drug remains static, and it can not be stirred or reused to ensure that the bacteria are suffocated.

(3) No matter in the seedling field or in the field, the diseased plants should be pulled out in time to prevent the expansion of infection.

(4) to properly handle diseased straw, it should not be thrown casually, nor should it be stacked on the edge of the field, nor should it be used as a covering for seed germination, nor can it be used to tie up seedling handles. it can be piled up at high temperature and burned seriously with fire.

two。 Rice red blight:

Rice red blight is a physiological disease, commonly known as "red stiff seedling" and "iron rust". In recent years, the disease has been aggravated in various places, and the yield of the affected fields has been reduced by 1-20%.

The disease generally begins to occur 10-15 days after seedling transplanting, with a short course of about 1 month and a long course of up to two months. The symptoms are that the seedlings do not turn green, or grow poorly after turning green, stiff seedlings do not send, and even dead seedlings occur. The aboveground part of the diseased plant is short, and the tiller decreases or does not tiller. At the beginning, the leaf color was dark green, and then the lower leaves appeared reddish brown spots along the midrib, and gradually expanded, causing the whole leaf to dry and zoom, looking like a "burning field" from afar. Rice roots begin to turn dark brown, then turn black, rotten and stink.

The causes of red blight are: first, excessive application of raw fertilizer, poisoning of rice seedling roots; second, serious lack of phosphorus, potassium and zinc in soil, and malnutrition of rice plants; third, long-term deep-water irrigation, plough layer rotten, roots do not root, and soil anoxia; fourth, the soil is barren, cold, plank and thin, resulting in poor root development of rice.

Control measures: immediately after seeing the disease in ①, Huimanfeng was sprayed with 100ml / mu, 500ml / mu to water, and 1kg zinc sulfate / mu to degrade toxic substances, enhance root activity and promote seedling transformation. ② increased the application of phosphorus, potassium and zinc fertilizer. 25 kg of calcium superphosphate per mu of phosphorus deficiency, 10 kg of potassium chloride or potassium sulfate per mu of potassium deficiency, and 1 kg of zinc sulfate per mu of zinc deficiency. Advocate basal application of phosphorus, potassium and zinc fertilizer, because most of the red blight occurs in the seedling stage, and the effect of basal application is good. It can also be applied after seeing an illness. ③ drains open fields, breathes and increases oxygen. If the paddy field floating mud is deep, bubbling and smelly, soft squatting should be drained in time to improve soil ventilation and promote the occurrence of new roots of seedlings. ④ organic fertilizer was applied after full ripening. ⑤ vigorously promotes the return of straw to the field.

3. Zinc deficiency

Rice seedlings do not grow long after transplanting, or even do not turn green, or do not tiller or even shrink after turning green, which is generally called "sitting pocket". "sitting pocket" fields are mostly found in low-lying shady and humid areas and cold, rotten and thin fields, but sometimes fertile fields also occur. There are many reasons for this phenomenon, and zinc deficiency is one of the most important reasons.

The symptom of zinc deficiency in rice showed that the leaf tip of the basal leaf of rice plant was dry, and irregular patches of yellowish brown or even reddish brown appeared in the middle of the leaf, and gradually developed from the old leaf to the upper adjacent leaf. When the disease is serious, the plaque on the old leaf expands into strips, the speed of leaf emergence slows down, the new leaf becomes smaller, the green is white, the plant is dwarfed, and the leaf color fades.

The main soils prone to zinc deficiency are: relatively fertile fields, calcareous paddy soils with soil organic matter content more than 1% or large amounts of green manure are prone to zinc deficiency; acidic soils with strong leaching, especially sandy soils with less zinc content, are prone to zinc deficiency. In the uneven land that did not show zinc deficiency in the past, when a large area of land leveling was carried out in the comprehensive agricultural development in recent years, the soil that lost more topsoil and the cold-soaked field with lower temperature were also prone to zinc deficiency; after years of increasing phosphorus and supplying potassium, in the soil with high available phosphorus content, a large amount of nitrogen fertilizer will increase the zinc requirement of crops, which is easy to cause zinc deficiency.

Zinc deficiency can lead to the decline of crop yield and quality, so zinc must be replenished in time. But too much zinc in the soil can also lead to crop poisoning. Therefore, the amount and concentration of zinc in zinc deficiency fields must be strictly controlled, otherwise, it will be overcorrected and counterproductive.

The correct method of zinc application is: when diagnosed as "sitting pocket" of zinc deficiency in seedlings, 0.1%-0.3% zinc sulfate solution is used to spray diseased rice seedlings for 2 times continuously, each time at an interval of 7 days; zinc sulfate can also be used for 1-1.5 kg per mu, evenly sprinkled on the field after mixing dry fine soil, and artificially ploughed once. Using the above methods, we have successfully solved the problem of zinc supplement in more than 2000 mu of paddy fields, and the effect is obvious.