Sunflowers are cross-pollination crops. There are 1,000 to 3,000 strong flowers in the disk. The phenomenon of empty shells in sunflower is more common in dry areas. The average empty shell rate is 20% to 35%, and the higher one is more than 50%. Empty shells are important factors that affect sunflower production. The empty shell of the sunflower has the largest number of open grains in the center of the disk. The outer shell is mainly caused by poor pollination; the shell in the center is mainly due to lack of fertilizer and water, resulting from lack of nutrition. Therefore, to prevent the empty shell of the sunflower is to ensure adequate fertilizer and water conditions, followed by artificial pollination. First, to strengthen the water and fertilizer management Sunflower is a happy fertilizer crop. The advantages and disadvantages of water and fertilizer conditions have a close relationship with reducing the shell rate of sunflower and increasing the yield. Tests have shown that the empty shell rate of sunflower with sufficient fertilizer and water is only 3.5% to 5%. 1. The rational use of natural precipitation is an effective way to reduce the empty shell rate. Sunflower has strong adaptability to drought, but it is still a kind of crop that needs more water in terms of growing period. The transpiration coefficient is 2 to 3 times that of cereal crops. When the moisture absorbed by the seed is approximately equal to 56% of its own weight, germination occurs. Moreover, in the 25 to 30 days from the formation of the kwai plate to the final flowering period, the water requirement is the largest, accounting for more than 2/3 of a lifetime. Water shortage during this period will severely reduce production and increase the number of empty shell grains. Experiments have shown that in the dry area, the irrigation ratio at this time is 1 to 1.5 times lower than that of no irrigation. However, in semi-arid areas where irrigation conditions are lacking, natural rainfall is mainly used to meet the water requirement for sunflower growth period. Here there is a question of how to make the flowering and filling stages of more water demand coincide with the peak period of natural rainfall. Choosing the right variety type and determining the best sowing date is the core of solving this contradiction. If Jianping County has rainfall of 300-500 mm and 70% of rainfall is concentrated in June-August, spring drought and autumn drought often occur. According to the characteristics of low water demand during the period before and after the sunflower, more mid-term water demand characteristics and local rainfall patterns, mid-early or mid-maturing varieties should be selected for sowing on May 10 to May 15, and early maturing varieties sown on May 20 to May 25. As long as we grasp the spring seedlings, drought and rain will help seedlings and seedlings grow strong. The demand for water accounted for 60% to 70% of the lifetime. The formation, flowering and filling of the flower disk coincide with the peak of the rainy season from June to August. It is favorable for the development of the flower disk, the formation of flower organs, and the reduction of empty grains. However, too much rain will pollinate and increase the spread of diseases. 2. Scientific fertilization is an effective measure to reduce empty shells. Sunflower is a fertilizer crop, tall plants, need more fertilizer, each production of 100 kilograms of grain consumption of pure nitrogen 4.4 ~ 6.5 kilograms, pure phosphorus 1.5 ~ 2.5 kilograms, pure potassium 6 ~ 18 kilograms, more than cereal crops 1 ~ 2 Times. Moreover, the uptake of fertilizer grains at each stage of growth is not balanced, and more fertilizer is needed from emergence to flowering. Insufficient fertilizer not only has adverse effects on plant development, but also has a direct impact on the formation and development of flower organs. In particular, the empty pods in the central part of the disk have increased, and the empty shell rate is as high as 40.1%. Sunflowers need more fertilizer from emergence to flowering. The demand for nitrogen, phosphorus, and potassium accounted for 67%, 54%, and 66% of the lifetime, respectively. Therefore, based on the application of basal fertilizer, it is necessary to re-apply seed fertilizer to ensure adequate supply of nutrients and to lay the foundation for reducing empty rates. Generally, 4,000 to 5,000 kilograms of organic manure per acre is used as a base fertilizer, 20 kg of diammonium phosphate, 10 kg of urea, 10 kg of potassium nitrate as a seed fertilizer, and a combination of step seeding, planting, application, or application. When the leaves develop 8 to 10 pieces, that is, when the original body of the disk begins to differentiate, 20 kg of urea, 20 kg of superphosphate, and 5 kg of potassium nitrate per mu are applied. Tests show that topdressing at this time can ensure the demand for nutrients in the early period of fertility, promote floret differentiation, increase the number of small flowers by 19% to 44%, increase the output by 25% to 44.4%, and reduce the empty shell rate. 3. Artificial snoring is a good way to reduce nutrient dispersion. Sunflowers have branching characteristics, especially edible varieties are more obvious, each leafhopper can grow branches, open into disk. Branches consume nutrients. The small seeds of the pan, at the same time, make the main stem disk smaller, empty pods increase, yield decline. In order to avoid nutrient consumption, ensure that the main stem disk production should be promptly hit in the outbreak of branch buds. Tests have shown that the artificial shelling rate is below 8%, compared with 41%. Second, to strengthen the insect pollination Sunflower is insect-borne pollen crops, the effect of bee pollination is extremely significant. The experiments conducted by the former Soviet Union on pollination of insects showed that 14.8% of the plants were pollinated by bees and other insects; 59.8% of the empty shells were pollinated by bees without any insects; and natural pollination without insects and insects was not found. It is 85.8%. From this point of view, the development of apiculture, the use of bee pollination to improve the yield of sunflower, reduce the shell rate is of great benefit. Tests have shown that a box of bees is placed every 5 mu of sunflower field and the seed setting rate is above 95%, and the yield increases by 10% to 20%. 3. Artificially assisted pollination Artificially assisted pollination is an effective method to increase the seed setting rate in the case of insufficient insects and bees. After the sunflower blooms, the viability of the pollen and the stigma without pollination are maintained for 10 days. Pollen is most energetic during the first 2 to 3 days of flowering. Therefore, the first artificial pollination should be carried out within 2 to 3 days after the sunflower enters the flowering stage (70% of the whole plant blooms). Every 3 to 4 days after the grant, a total of pollination 2 to 3 times. The pollination time should preferably be performed after the dew falls in the morning and ends at 11 pm. If you cannot finish in the morning, you can do it after 3pm. In the morning there is dew, pollen groups affect the pollination effect; at noon days, the pollen is weak, and the effect is not good. Artificially assisted pollination method, it is best to use a 10 cm diameter round paper shell or wood, a layer of cotton on top of the pad, then covered with gauze, tie in the back diagonally, made with the size of the disk similar to the "puff child." When pollinating, hold the sunflower disk in one hand, and the other hand gently touch the disk with a powder puff. Don't use too much force so as not to damage the stigma of the pistil, so that the pollen grains of the stamens stick to the powder puff, and then use the same method for the powder puff. Another pollen was touched and pollination was performed. When pollinating, pay attention to fresh pollen on flowering florets. The more pollinating plants there are, the more mixed pollen that sticks on the puff, the more opportunities for pollination, and the better the pollination effect. According to tests, artificial pollination was performed 3 times, the sunflower shell rate was only 37%, and the empty shell rate without artificial pollination reached 61%. The Soviet Union test proved that artificially assisted pollination increased production by 8.6% compared with no artificially assisted pollination. In areas without bees, artificial pollination has the most significant effect.
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