The cause of the increase of empty grains in Helianthus annuus and control measures

First, the cause of the increase in sunflower empty grains 1. Drought. It is well known that sunflower is a drought and salt-tolerant crop, but this does not mean that sunflower does not require water or only a small amount of water for its growth and development. On the contrary, sunflower is a crop that requires more water, and it is measured that every sunflower produces. 1 kg of dry matter requires 469-569 kg of water. Before the emergence of sunflower to budding, it is the stage with the strongest drought-resistance ability. However, from the bud to the end of flowering, the sunflower needs the largest amount of water, which accounts for about 60% of the water requirement for the whole growing period. If there is water shortage during this period, Will cause poor pollination or abortion after pollination, resulting in increased empty grains, production decline. 2, neglect management. Most of the planting of sunflower in our city is to fill crops or grow crops next door. Farmers only plant and harvest, but there are no other basic agricultural operations such as watering, fertilization, pest control, etc., which results in lack of water and lack of fertilizer during the sunflower reproductive period, especially during the key growth period. , Growth and development are hindered, empty pods increase, and production declines. 3, lack of media. The position of the stamens and stamens of sunflower florets is different, the stamens mature first, and the pistil matures. It has no affinity and is self-yarning. Sunflowers are cross-pollination crops that rely on insects for pollination. If there is a lack of media, it will affect pollination and fruition, resulting in an increase in empty grains. In recent years, due to the heavy use of chemical pesticides, the reduction in the number of insects in the media has also contributed to the low rate of sunflower pollination and the increase in empty grains. 4. Variety factors. According to foreign studies, the sunflower seed setting rate is negatively related to the thickness of the stalk and the diameter of the flower disk. That is to say, the thicker the stem, the larger the disk and the more empty pods. The planting density of summer sunflower in some farmers in our city is too low and the stems are large, which is also the reason for the increase of empty grains. Second, improve the rate of sunflower seeding measures 1, timely watering. During the period from flowering to flowering, the sunflower needs a large amount of water. If there is no large rainfall during this period, it should be watered to facilitate flower development, seed formation, and improvement of kernels. Oil content. 2, scientific fertilization. Sunflower is a crop that requires more fertilizer. According to tests, it is generally required to have more phosphorus during the emergence from flowering to flower disk formation, more nitrogen is needed from flower disk formation to the end of flowering, and more potassium is absorbed from flower disk formation to wax ripening. Therefore, sunflower fertilization should pay attention to the application of total fertilizer, the main pre-P fertilizer, in the middle and late to nitrogen and potassium fertilizer. In addition, spraying potassium dihydrogen phosphate on buds and flowering stages can also effectively reduce the production of empty pods and increase the yield. 3. Artificially assisted pollination. Artificial pollination should be conducted for 2-3 days after the flowering stage (70% of the entire plot is planted) for the first pollination, and once every 3-4 days for a total of 2-3 pollinations. Pollination is carried out from 8 am to 11 am or after 3 pm. It is too early, the dew does not dry, the humidity is high, pollen is easy to form into a group, pollination effect is affected, the temperature is too high at noon, pollen life is low. Pollination should be pulverized or contacted with the flower disk, but I suggest that the best puff effect would be better. 4. Develop apiculture industry and use honeybees to pollinate. This is also an economic and effective measure to increase the sunflower seed settling rate. According to foreign reports, 1-2 boxes of bees per hectare are not only 200-300 kg more than natural pollination, but also improved seed quality and improved oil content. At the same time, 22.5-45 kg of honey can be collected per hectare. It can be said that both increase production and increase income. 5, do a good job of good seed selection, crop rotation, reasonable dense planting, pest control and other routine management. Chinese Agricultural Editor