Pay attention to the prevention of physiological blue-green dead seedlings during grain filling

In recent years, rice physiological wilting dead seedlings have occurred in the local rice-wheat cropping area from time to time, concentrated in the rice filling stage, and have a great impact on the yield and quality. Due to the continuous low temperature and rainy weather in the early stage of rice growth this year, the effect of paddy field is not ideal, the growth process of rice has been postponed, and the possibility of physiological blueness caused by cold damage in the later period is very high. Therefore, attention should be paid to production.

Occurrence

The rice plants with a sudden loss of water and wilting during the grain filling stage had wilting, grayish blue, and no diseased spots in the leaves. The stems were dry and contracted and the plants were lodging. The hulls were grayish blue and formed into a valley. The roots were yellow or black. Often occurs suddenly in a large area within 1 to 2 days. The green dead seedlings suddenly died from the whole point and appeared in the form of flakes in the field, which was different from the damage of the single stem yellow stem, and was different from the progressive death of pathological diseases. The grouting time of the diseased plants was shortened and matured in advance. The seed setting rate and 1000-grain weight decreased significantly.

Most of the occurrences occurred in late September to early October, and the symptoms were acute and sudden. In case of sudden changes in temperature, it is difficult to recover after symptomatic symptoms. The severity of symptoms and loss varies according to the time of occurrence. There are differences in the incidence of different rice varieties, usually large panicle type and easy lodging of the species occurs more severe.

Causes

1. Long-term continuous cropping of rice and wheat, shallow cultivation, poor soil permeability, decreased fertility and water holding capacity, and adverse growth of rice.

2. Unbalanced fertilization. The amount of organic fertilizer input decreased year by year, the amount of potash fertilizer was insufficient, and the amount of nitrogen fertilizer was high, which resulted in a decline in soil fertility and premature rice plant decay.

3. Direct seeding rice, long-term deep-water irrigation, and incomplete planting of rice fields resulted in shallow distribution of rice roots and vulnerability to external environment. Rapid changes in air temperature during the ear period resulted in poor root absorption and physiological blue-green.

4. The sudden change in temperature is a direct cause. Rice is a thermophilic plant, and the suitable temperature for indica rice grouting is 20-28 °C. From late September to early October, it is the grain filling period, where the temperature changes greatly and the minimum temperature can drop below 13°C. Under low temperature conditions, the resistance of rice decreased, the weather became fine after rainy days, the temperature rose sharply, and the transpiration of the above ground accelerated, causing physiological water loss, which caused the rice plant to suddenly die. For example, on September 22, 2010, the temperature in the region dropped sharply, with a drop of 15°C. It was low and rainy for 6 consecutive days, which led to the physiological blueness of nearly 20,000 mu of rice in the county.

Prevention measures

There is no effective measure to remedy the physiological decline of rice after the emergence of physiological, production should take appropriate preventive measures to delay the premature decline of rice, increase production and improve rice quality.

1. Strengthen water slurry management. Put a good field in the early stage of rice growth and promote the root bar. Avoid long-term deep-water irrigation, insist on intermittent irrigation after heading (2 to 3 days after irrigation 2 to 3 days), hard water plate, water and gas to promote root, enhance the vitality of the roots, dry and wet replacement of old rice. The water cutoff during the late growth period of rice cannot be premature, and the water is cut off after the last horse racing water 7 to 10 days before harvest.

2. Reasonably manage fertilizer. Through the application of organic fertilizer, balanced fertilization and other measures to change the situation of partial application of nitrogen fertilizer, nitrogen fertilizer, potassium fertilizer and nitrogen fertilizer were added, and foliar fertilizer was sprayed at the later stage to maintain the root activity and enhance the stress resistance of rice plants.

3. In case of low temperature cold wave, when the temperature is below 17.5°C and the temperature difference is above 10°C, the water layer should be established in advance in the field, and it should be drained when the weather turns to be better. In particular, the low-lying fields must do this work before they can use water to adjust the temperature, maintain the vitality of the roots, and reduce the physiological blue-green dead seedlings.

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