Due to insufficient accumulated temperature, the growth of rice is slow, and the production period is delayed. After the early frost in autumn, the grain can not be normalized and matured, and the yield is reduced.
(1) Reasons for production
1. Climatic factors The frost-free period of the cold region is short, the activity accumulated temperature is low, the early warming is slow, the medium-term high temperature time is short, the late temperature drop is fast, the low temperature cold damage is frequent, the annual accumulated temperature is insufficient, and the whole growth period temperature is low, which causes the rice growth retardation to cause delayed cold damage.
2. Variety factors The accumulated temperature required for cultivars exceeds the local accumulated temperature. There is no suitable variety in the mature period according to the local accumulated temperature conditions, blindly pursuing high-yield and planting late-maturing varieties, blindly introducing and planting in the cross-region, so that it cannot be safely matured.
3. Cultivation factors are planted too early or too late, causing premature buds and seedlings to be damaged by freezing, rooting is unfavorable, and weak seedlings are formed. The accumulated temperature was wasted too late, which led to the delay of the growth period. Improper transplanting can also cause delays in childbirth. Improper application of fertilizers, such as excessive nitrogen fertilizer and late topdressing, can cause rice plants to grow and prolong their growth.
(2) Defensive measures for delayed cold damage
1. Select suitable varieties according to the local accumulated temperature conditions, select the suitable maturity varieties, take the safe heading period as the center, determine the birth limit period, implement the planned cultivation, make full use of the local light and heat resources, ensure the safety and maturity, and do not blindly pursue high yield and plant For late-maturing varieties, the accumulated temperature of selected varieties should be 100-150 °C less than the local accumulated temperature.
2. The large-scale medium-sized nursery shed has the functions of warming and heat preservation, so it can raise seedlings and raise seedlings early, make full use of the shed temperature, and achieve the purpose of preventing cold and cold damage in the seedling stage.
3, seed treatment sunning: drying for 15 to 15 days before sowing, can increase the permeability of the skin, improve the germination rate, germination potential. Soaking seeds: soaking seeds at a water temperature of 11 to 15 °C for 7 days, when the water absorption reaches 25% by itself, and when the accumulated temperature reaches 80 to 100 °C, it is an invasive species. Germination: 30 °C high temperature to break the chest, 25 °C germination, 20 °C to bud, to reach the bud, full, strong, to lay the foundation for timely sowing.
4. Timely sowing and timely transplanting According to the characteristics of the variety and the local temperature conditions, determine the appropriate sowing date, and timely transplant the seeds at the right time to ensure that the ears are in front of the safe heading period. Rice planting in the second accumulated temperature zone in Heilongjiang Province generally begins in mid-April (south morning and north night). After the temperature is stable at 5 °C, the seedlings need to be planted before April 20, and the latest seeding period of the seedlings does not exceed April 25. . The transplanting period starts after the local temperature is stable at 13 °C, generally starting around mid-May, and May 15-25 is the high-yield transplanting period, not exceeding the end of May.
5, scientific fertilization, reasonable irrigation according to soil fertility and variety characteristics to determine the amount of fertilizer, nitrogen, phosphorus, potassium, the next year to apply fully decomposed farmyard manure per hectare 30 ~ 45 ° C, the conditions can be put into the field. The total fertilizer growth period is determined by factors such as soil fertility, variety and planned yield. Generally, the ratio of nitrogen, phosphorus and potassium is 2:1:1, that is, about 100 kg of diammonium phosphate per hectare, about 100 kg of potassium sulfate, and about 200 kg of urea.
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