June 21 is the "Summer Solstice" solar terms. At this time, the sun is almost directly above the Tropic of Cancer (North latitude 2326'), and the sun is highest at noon. The summer solstice is the longest day in the northern hemisphere and the shortest day in the night. After the summer solstice, the temperature in most parts of China is high, the sunshine is sufficient, the crops are growing vigorously, and the water needs more fertilizer. At this time, the weeds in the farmland are also growing very fast. They compete with the crops for water and fight for the sun. The farmer said: "The summer solstice does not lick the roots of the grass, just like raising a snake bite," indicating that it is necessary to hurry and plough the grass. At the same time, the summer solstice is also an important period for a variety of spring crops.
The early rice is just before and after heading, and the paddy field has finished the stage of drying the field. It is required to moisten the soil moisture to facilitate flowering and grouting. It not only satisfies the need of rice for water, but also makes the soil breathable well and ensures the vitality of the roots, so as to effectively absorb and utilize soil nutrients. Fertilization in the summer solstice period is the period of early rice heading and flowering in the south of the Huaihe River. It takes 30 to 40 days from heading to maturity in the fruiting stage of early rice to complete the flowering insemination and grain filling and fruiting process. The nutrient supply at this stage directly affects the grain number and grain weight of early rice, which is the key period to determine the formation of yield. The grain weight of rice is composed of two parts: “grain size†and “fullnessâ€. The degree of solidity is determined by the synthesis and transportation of grouting material during this period, and the later management of nutrients is enhanced to promote the early grain and large grain to prevent empty shells. The key time. The grouting of rice is the continuous transportation of photosynthetic products from stems and leaves to grain, and the peak of filling occurs 15 to 20 days after flowering; while in the 25 to 45 days after flowering, the dry weight of rice grains reaches the maximum and is mature.
Generally, the growth period of early rice varieties is characterized by overlapping of vegetative growth and reproductive growth in some time periods. The growth of the ear is preceded by jointing, the differentiation of young ears is early, the period of simple vegetative growth is short, and the reproductive growth period begins earlier and longer. The traditional fertilization mode has been promoted in the past, and only the base fertilizer has been emphasized. In fact, the nutritional status of the late rice plants is important in that there is no premature aging, and it is possible to provide the possibility of grain number and grain weight and to benefit high yield. Rice leaves are the main organs of photosynthesis, and the photosynthesis of leaves in different parts of late rice plants is the strongest. After the heading, the second to third leaves are mainly supplied with grain. At this time, fertilization can maintain a higher nutrient level in the upper functional leaves of the rice plant, ensuring that it maintains a strong photosynthetic capacity, and also promotes sufficient nutrition for the late-open vulnerable flowers, prevents premature aging, prolongs grouting, and increases the seed setting rate and 1000-grain weight.
At this time, the topdressing should mainly consider the characteristics of the demand for nitrogen and potassium nutrients in early rice. Compared to late rice, early rice requires less nitrogen and requires more potassium. Therefore, the topdressing should be combined with nitrogen and potassium fertilizers, and late potassium supplementation is very important. Suggestion: The proportion of potassium fertilizer in early rice is better than half of base fertilizer and topdressing; the proportion of nitrogen fertilizer is one-third or one-quarter of the discretion, which is equivalent to 4 kg/mu of pure nitrogen.
In short, we must pay attention to the fertilization of seedlings. For those early rice fields where leaf color chlorosis has appeared during the jointing stage, the appropriate amount of nitrogen fertilizer can increase the seed setting rate and promote the grain fullness, which is beneficial to the yield increase; however, the period and dosage of top dressing should be appropriate. If it is too late, it will lead to late maturity or rice blast.
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