Fertilization measures for preventing chilling injury of Rice

Fertilization case: In 2006, in rice growing areas such as Shangzhi City in Heilongjiang Province, some rice seedlings encountered low temperature weather below 17℃ in the early stage of rice growth, and different degrees of rice chilling damage occurred. In Ningxia and Zhangjiakou rice growing areas in northwest China, the temperature dropped sharply to below 20℃ at the filling season in the late autumn of rice growth, which made rice encounter cold damage, which was very unfavorable for filling, and the seed setting rate decreased by 10-20%, and the serious one decreased by more than 50%.

Expert comment: In the northern rice growing area, in order to prevent the cold damage caused by low temperature weather to rice production, in addition to paying attention to breeding varieties and strengthening cold-proof measures of farmland management, attention should also be paid to cultivating strong seedlings and improving the cold resistance of rice plants, which is conducive to high and stable yield of rice. In order to protect rice from cold injury, the following techniques should be adopted in fertilizer application measures:

1. Control the amount and time of nitrogen fertilizer application. In the early rice growth stage, too much nitrogen fertilizer will accelerate the growth speed of rice, forming young stems and leaves, high water content, easy to be cold, no frost resistance, so the nitrogen fertilizer should be controlled in the early stage, and the nitrogen application period should be moved later. In cold damage years, the total nitrogen fertilizer should be reduced by 20-30% in northern rice growing areas. In the fertilization period, the base fertilizer should account for 40-50%, the tiller fertilizer should be applied 10-15% depending on the temperature, and the top fertilizer should be applied 1-2 times before and after heading.

2. Increase phosphorus and potassium fertilizer application. Phosphorus and potassium fertilizer can improve the cold resistance of rice and promote early maturity, so phosphorus and potassium fertilizer should be increased. The application method should be divided into two layers: deep application of basal fertilizer and shallow application of topdressing, so that phosphorus fertilizer can be distributed in the whole tillage layer, which can not only improve the cold resistance of seedlings, but also improve the seed setting rate without phosphorus deficiency in late filling. Potassium fertilizer can be applied once as base fertilizer, or partially applied again in topdressing, which is more conducive to rice plant health and improve cold resistance and disease resistance.

Third, pay attention to the application of organic fertilizer. The application of decomposed organic fertilizer in paddy field is beneficial to the heat preservation of root soil and the development of rice roots, forming strong seedlings and improving the cold resistance and disease resistance of rice plants. In organic fertilizer, such as the application of plant ash or straw return to the field, not only conducive to soil heat preservation, but also can supply potassium nutrition, conducive to rice plant health and improve rice stress resistance.

The case suggested that the main fertilization measures to prevent rice cold injury were to pay attention to the application of organic fertilizer, control the application amount and period of nitrogen fertilizer, increase the application of phosphorus and potassium fertilizer, cultivate strong seedlings and improve the resistance of rice.