Rice cultivation in cold regions requires water-saving irrigation, selection of improved varieties, making the most of accumulated temperature, and growing strong seedlings

Heilongjiang Province is located in a high-cold region, where heat and water resources are relatively scarce, annual atmospheric precipitation is extremely unevenly distributed, spring is windy with little rain, and drought is quite severe. The author discusses how to achieve water-saving, high-quality, and high-yield rice cultivation in cold regions.

1. Selecting excellent varieties is the prerequisite for ensuring high-quality and high-yield rice

The varieties that rice farmers plant directly affect the quality and yield of rice. Therefore, in production, varieties with a suitable maturity period, excellent quality, stable and high yield, and strong stress resistance should be selected. First, select varieties that have passed national approval, been named, and promoted, which can ensure relatively stable rice traits, steady and rising yields, and safe and reliable use; second, introduce varieties with suitable maturity periods according to different accumulated temperature zones, and never introduce varieties across zones; third, pay attention to seed quality, and select first-grade improved seeds with a purity above 98%, a germination rate above 90%, and a moisture content no higher than 14% for production use; fourth, purchase seeds from nationally certified seed companies, research institutes, and agricultural colleges, and eliminate blind planting; fifth, in actual planting, unify varieties as much as possible, plant in contiguous fields, form scale, and achieve industrialized planting.

2. Grasping the agricultural timing and making the most of accumulated temperature is the guarantee of high-quality and high-yield rice

Rice production in Heilongjiang Province has characteristics such as a short growth period, little active accumulated temperature, slow warming in the early stage, a short high-temperature period in the middle stage, rapid cooling in the late stage, and frequent low-temperature cold damage. In particular, during the 40 days from 15 days before rice heading to 25 days after heading, it is most sensitive to low temperatures. In the spring of 2002, there was drought, the rice transplanting period was delayed by 5-7 days, and in late July the average temperature for 5 consecutive days was below 17°C, causing a large reduction in rice yield and quality. Therefore, grasping the agricultural timing and making the most of accumulated temperature is very important. It is recommended to start sowing in early to mid-April, when the temperature steadily reaches 5°C, and finish sowing before April 25; start transplanting after the local temperature steadily reaches 13°C, with May 15-25 being the high-yield transplanting period, and at the latest no later than the end of May, ensuring that rice enters young panicle differentiation in late June and early July, safely heads in late July and early August, and safely matures before the temperature drops to 13°C in early to mid-September.

3. Strong seedlings and sparse transplanting are important links for obtaining high yield and high quality in rice cultivation in cold regions

Growing strong seedlings and sparse transplanting are based on dry seedling raising, with early planting and sparse sowing as the premise, and temperature regulation and water control as the means, using large and medium sheds for seedling raising, preparing soil in autumn, making beds in autumn, ultra-sparse sowing, controlling temperature and water to cultivate multi-tiller strong seedlings, and transplanting with tillers at the appropriate time. Generally, the sowing rate is 250 grams of germinated seed per square meter for medium seedlings, with a seedling age of 35-40 days; 200 grams of germinated seed per square meter for large seedlings, with a seedling age of 40-45 days; for transplanting density, the specification for hand transplanting medium seedlings is 9×3 cun, with 3-4 plants per hill; the specification for hand transplanting large seedlings is 9×5 cun, with 2-3 plants per hill.

4. Scientific fertilization is the key to high-quality and high-yield rice

Rice is a crop with a relatively high fertilizer requirement, with the largest demand for nitrogen fertilizer, followed by phosphorus and potassium fertilizers. Fertilization should be carried out under the condition of a yield target of 500 kg per mu and medium soil fertility. First, the fertilization amount: generally apply 6.6-10.6 kg of diammonium phosphate, 8.3-17.3 kg of urea, and 4.0-6.0 kg of ammonium sulfate per mu. Second, the fertilization ratio: apply 40-60% of nitrogen fertilizer, 100% of phosphorus fertilizer, and 60-70% of potassium fertilizer as base fertilizer; apply 20-40% of nitrogen fertilizer at the tillering stage; apply 10-15% of nitrogen fertilizer and 30-40% of potassium fertilizer at the heading stage. Third, the fertilization time: the base fertilizer should be evenly broadcast into the rice field after soaking the field and before water harrowing, and evenly mixed into the plough layer through water harrowing; tillering fertilizer should be applied as early as possible when tillering begins after transplanting; ear fertilizer should be applied before 15-18 days before rice heading. Fourth, fertilization requirements: for base fertilizer, old rice fields with low soil organic matter content should be applied more appropriately, and vice versa less; alkaline soil is suitable for physiologically acidic fertilizer, and acidic soil is suitable for physiologically alkaline fertilizer. For tillering fertilizer, fields with low soil fertility, low transplanting density, and weak late-transplanted seedlings can appropriately increase the fertilization amount, and vice versa reduce it. And combine the application of tillering fertilizer with chemical weeding, maintain a water layer of 3-5 cm on the field surface, keep water for 5-7 days, and avoid cross-irrigation or drainage, so as to improve fertilizer efficiency and ensure the weeding effect. For ear fertilizer, apply less when soil fertility is high, plant growth is good, and leaf color is dark green, and vice versa apply more.

5. Adopting advanced water-saving irrigation technology is the guarantee of increased yield and high efficiency in rice

According to the water requirement patterns of rice and local water source conditions, effectively using rainfall and reducing useless consumption of irrigation water is the fundamental guarantee for obtaining the best economic, social, and ecological benefits of rice production. In actual production, three aspects of work should be done well. First, reduce water conveyance losses. This includes seepage prevention treatment of channels, cutting curves and straightening, improving supporting engineering facilities, and timely repair and maintenance of structures, etc. Make the water conveyance process safe, rapid, and reliable, and improve the utilization efficiency of irrigation water. Second, strengthen water use management. Focus on strengthening the publicity and enforcement of industry laws and regulations, implement water management according to law to the greatest extent; comprehensively improve the overall quality of management personnel and improve service quality. Third, scientifically irrigate. After rice transplanting and recovery, irrigate the field surface with shallow water, which can accelerate recovery and advance tillering; during the tillering stage, use moist irrigation, establish a water layer of about 2 cm, and irrigate the second time after soil moisture drops to 50-60% of saturated soil water content; from jointing and booting to heading and flowering, adopt the method of irrigating once and exposing the field for several days, and irrigate the second time when soil moisture drops to 70-80% of saturated water content, do not irrigate when it rains, and drain after heavy rain; the soil moisture requirement during the grain-filling stage is dry field surface and moist soil, which is conducive to aeration, root protection, and preservation of the "three leaves", promoting grain filling, early maturity, high quality, and high yield.

In summary, as long as rice cultivation in cold regions selects good seeds, grasps the agricultural timing, makes the most of accumulated temperature, uses strong seedlings and sparse transplanting, applies scientific fertilization, adopts water-saving irrigation, and manages carefully, it will certainly be able to achieve water-saving, high-efficiency, high-quality, and high-yield rice production.