Changing the phenomenon of "six more and six less" is the key to improve the per unit yield of double cropping rice in Jiangxi.

Rice is the most important food crop in Jiangxi. Improving the per unit area yield of double-cropping rice is an important way to ensure Jiangxi's status as the main grain producing area and to ensure Jiangxi to make greater contribution to national food security. In recent years, although the per unit yield of double-cropping rice in Jiangxi has increased steadily, the phenomenon of low yield has not changed much. Compared with neighboring Hunan, each 667m2 is lower in 50~60kg. The analysis shows that the phenomenon of "six more and six less" is the main reason for the low per unit yield of rice in Jiangxi.

The main results are as follows: 1. The amount of sowing is more and the amount of seed is less. The cultivation of strong seedlings and reasonable close planting are the basis of high yield of rice. In the production of double-cropping rice in Jiangxi, medium or large seedlings are generally used, and the quality of seedlings plays a particularly important role in high yield. Among the many factors affecting the quality of seedlings, the sowing rate is the most important one. Taking moist seedling raising as an example, according to the investigation, the sowing rate of Jiangxi double-cropping early hybrid rice is more than 15kg/667m2, and the sowing rate of double-cropping late rice is generally above 15kg/667m2. The sowing rate is generally higher than the 15%-20% required for cultivating strong seedlings, and the uniformity is poor. When transplanting (throwing), the tillers occurred in the seedling stage have died.

One of the important characteristics of double-cropping rice is that the effective tillering stage is short. Ensuring basic seedlings and basic tillering is an important guarantee for high yield of rice. In terms of high yield, double-cropping early hybrid rice should keep basic seedlings 60 ~ 70 000 / 667m2 (excluding tillers in seedling field), basic seedlings 2 ~ 22000 / 667m2, that is, seed amount 1.75~2.Okg/667m2; double-cropping late hybrid rice should ensure basic seedlings 40 ~ 50 000 / 667m2 (without tillers in seedling fields), basic seedlings 1.8 ~ 20000 / 6672, that is, seed consumption 1.25~1.4kg/667m2. However, the seed consumption of double-cropping early hybrid rice in Jiangxi is less than 1kg/667m2, which is less than 15000 / 667m2, while that of double-cropping late hybrid rice is less than 0.75kg/667m2, only 0.4~0.5kg/667m2 and less than 10000 / 667m2.

The phenomenon of more sowing but less seeds leads to low seedling quality, large panicle advantage of hybrid rice can not be brought into full play, and effective panicle is seriously insufficient. In many places, under the condition of not changing other cultivation measures, as long as the amount of seed is increased and the density is guaranteed, the per unit yield can be greatly increased. Therefore, in order to improve the per unit yield of double-cropping rice in Jiangxi, the first thing is to completely change the phenomenon of more sowing and less seeds, cultivate strong seedlings and reasonable close planting.

2. The amount of nitrogen application is more than that of potassium application. "A single flower in a crop depends entirely on fertilizer." It shows the importance of fertilizer to the high yield of crops. Nitrogen, phosphorus and potassium fertilizer is the three most important elements of crop growth and development. It is a common phenomenon that more nitrogen and less potassium are applied in rice production in Jiangxi. In general, the amount of nitrogen applied to rice (pure nitrogen) can reach 1Okg/667m2, and the amount of potassium fertilizer (K20) is often less than 5kg/667m2, while the amount of potassium fertilizer (K20) is often less than 5kg/667m2. The study on high-yield cultivation of rice showed that the N ∶ K20 of high-yield rice was 1 ∶ 0.8%. The reasons leading to the phenomenon of more nitrogen application and less potassium application are as follows: first, the role of nitrogen fertilizer is relatively largest among the three elements; second, the effect of nitrogen application is easy to appear. The consequence of this phenomenon is that there are more grass and less grain, more diseases and insect pests, and easy to lodge. To change this phenomenon, one is to improve rice farmers' understanding of the yield-increasing effect of potash fertilizer, and the other is to truly realize soil testing and formula fertilization.

3. There was more nitrogen application in the early stage and less nitrogen application in the middle and later stage. The application of nitrogen by "one bombardment" is a traditional and common method in rice production in Jiangxi Province. In the case of insufficient basic seedlings and basic crops, the use of this nitrogen fertilizer management method can play some role in increasing effective panicles, which is the root cause of the widespread use of this nitrogen fertilizer operation method in rice production in Jiangxi Province. Many studies have shown that the "one-bombardment" nitrogen application method has the advantages of low nitrogen use efficiency, many ineffective tillers and serious diseases and insect pests, which is a nitrogen fertilizer operation method under low yield level. In order to achieve high yield in double-cropping rice, basal tillering fertilizer generally accounts for 70%-80% of the total nitrogen application, and panicle-grain fertilizer should account for 20%-30%. By using this nitrogen fertilizer operation method, not only the nitrogen utilization rate is high, it can save cost and increase efficiency, but also the panicle rate is high and the diseases and insect pests are light. it is a scientific fertilization method with high yield and high efficiency.

4. More ineffective tillers and less effective tillers. It is a common phenomenon in rice production in Jiangxi that large panicles are few and panicle rate is low. According to the survey, the panicle rate of double-cropping rice in Jiangxi is generally only 40% to 50%. The production practice shows that the population with high yield and super high yield of rice is the population with high yield and super high yield from early onset population to high panicle rate population in the middle stage to high light efficiency population in the later stage. Improving the panicle rate is the key to realize the evolution of this kind of population. There are many reasons for the low panicle rate, such as applying too much nitrogen in the early stage, not drying the field in time and so on. If the panicle rate can be increased from the current 40% to about 70%, there will be a big leap in the yield of double-cropping rice in Jiangxi. In order to change this situation, we should sun up the field timely on the basis of "more sowing amount, less seed quantity, more nitrogen application, less potassium application, more ineffective tiller and less effective tiller".

5. More drugs are used, less water is used. In crop production, the prevention and control of diseases and insect pests is the guarantee of high yield. The prevention and control of diseases and insect pests include biological control, agricultural control, physical control and chemical control. Prevention and comprehensive control are the basic principles for the prevention and control of diseases and insect pests. In recent years, although biological, agricultural and physical control measures such as duck pest control, water pest control, frequency vibrating lamp and other biological, agricultural and physical control measures have been widely used, the use of pesticides for pest control is still essential in rice production. Many rice farmers believe that the use of pesticides for the control of diseases and insect pests can be well controlled as long as the amount of medicine is sufficient. Under the guidance of this misunderstanding, the dosage of many rice agricultural chemicals is twice as high as the suitable dosage, but the water consumption is only 1: 1, 3, 3, 1, 2 of that amount. This pest control method, which uses more medicine and less water, not only increases the cost of medicine, but also fails to achieve the control effect (especially the control effect of rice diseases and insect pests at the base or stem of rice, such as sheath blight, rice planthopper, rice stem borer, etc.). Sometimes the phenomenon of burning seedlings occurs because the pesticide concentration is too high. Therefore, no matter from the point of view of high yield, or from the point of view of cost saving and the development of green agriculture, it is necessary to change the phenomenon of more pesticide consumption and less water consumption in rice production, and carry out pest control according to the instructions of pesticide control.

6. Irrigation is more in the early stage and less in the later stage. Water can regulate fertilizer, gas and temperature. Rice likes water and is afraid of water. Scientific irrigation is another key to obtain high yield of rice. The irrigation method for high yield of rice is aerobic irrigation, that is, during the whole growth period of rice, except for water sensitive stage (booting stage, heading stage) and intermittent shallow water irrigation during the period of fertilizer application, there is generally no water layer or wet irrigation, which makes the soil in a state of oxygen enrichment, promotes root growth and enhances root activity. Specifically, it is to transplant seedlings in shallow water, thin exposed roots to promote tiller, to apply tiller fertilizer requires no water on the field surface, combined with fertilization irrigation shallow water, to achieve the purpose of carrying fertilizer with water: when the number of tillers reaches about 180000 / 667m2 (about 9 tillers per tiller), the highest seedling per 667m2 is controlled at about 300000, and the field with excessive vegetative growth is properly shelved. The second leaf age (about 15 days before heading) began to use dry-wet alternative irrigation, so that the front water can not see the back water, in order to coordinate the demand for water vapor of the root system until maturity. Practice has proved that aerobic irrigation can increase soil oxygen content, increase soil temperature, improve soil environment for rice growth, promote root growth and deep binding, improve root activity, increase fertilizer utilization rate, increase seed setting rate and plumpness, reduce the irrigation amount and discharge of field water, and effectively control the discharge of chemical fertilizers and pesticides to pollute the environment. However, in rice production in Jiangxi, flood irrigation in the early stage, inappropriate drying in the middle stage, and water cut off too early in the later stage (high yield requires water cut off 5-7 days before panicle formation, but in many places it begins to cut off water 10-15 days before rice becomes stable, resulting in low seed setting rate and poor plumpness), that is, the phenomenon of more irrigation in the early stage and less irrigation in the later stage is common. In order to further improve the per unit yield of rice in Jiangxi, the existing irrigation methods should be changed and aerobic irrigation should be popularized in a large area.