Why do sunflower seeds produce empty seeds?

Why does planting sunflowers produce empty chaff? Please introduce the reasons why planting sunflowers will produce empty chaff. Please refer to the following: 1. Empty chaff caused by drought: sunflower is a kind of crop with strong drought resistance and adaptability. However, the water requirement is the highest from the formation of the disk to the final flowering stage, accounting for about 60% of the water requirement during the whole growth period. The shortage of water in this period will increase the number of empty grains, resulting in a serious reduction in production. Supplementary irrigation due to drought stress and lack of water resources is an important factor leading to the increase of empty chaff in production. 2. The empty chaff caused by temperature: sunflowers have strong adaptability to temperature, like temperature and drought, and have strong ability to tolerate low temperature from seed germination to seedling stage. Seeds can germinate at 4 ℃, emerge at 5 ℃, and meet the needs of normal emergence at 8-10 ℃. The suitable temperature for germination is 31-37 ℃, and the highest temperature is 38-44 ℃. Due to improper sowing time and unsuitable temperature after sowing, the development of sunflower was hindered, which affected the coordinated development of vegetative growth and reproductive growth. 3. Empty chaff caused by light: sunflower is a short-day crop, and its young leaves, leaves and disk have strong phototropism. There is plenty of sunshine. seedling growth is robust, middle growth can promote stem and leaf growth exuberant, normal flowering and pollination, improve seed setting rate; late growth can promote grain fullness. In production, due to climatic factors, the light intensity is affected, resulting in poor flowering and pollination and an increase in the rate of empty grain. 4. Empty chaff caused by continuous cropping: when sunflowers are repeatedly planted on the same plot, the yield is reduced due to the harm of diseases, pests and weeds and the imbalance of soil nutrients. 5. Empty chaff caused by excessive density: the density requirements of sunflowers vary greatly due to different varieties. The plants of general edible varieties are tall and suitable for sparse planting, while those of oil varieties are short and suitable for close planting. In order to pursue high yield, people blindly increase density in production, resulting in unreasonable population structure, prominent contradiction between water and fertilizer and glory, and decrease in light energy utilization efficiency, which leads to the increase of sunflower empty chaff grains, the decrease of yield and the decrease of quality. 6. empty chaff caused by fertilization: sunflower is a fertilizer-loving crop, so it is necessary to apply sufficient base fertilizer and topdressing in time. It is reported that the production of 100kg sunflower seeds requires 4. 4-6.5kg of pure nitrogen, 1. 5-2.5kg of pure phosphorus and 6-18kg of pure potassium, which is 1-2 times more than that of cereal crops. 7. Empty chaff caused by poor pollination: sunflower is a cross-pollinated crop. There are 1000-3000 fruiting florets in the disk. Generally, the seed setting rate of self-pollination is very low, while that of cross-pollination is high. And the normal fertilization process is determined by the appropriate temperature, light, atmospheric humidity, insect activity, wind and so on. The high temperature and drought weather from June to July is easy to weaken the living ability of pollen, affect the activity of bees and other insects, affect normal fertilization, resulting in sunflower seed setting rate decreased and empty grain rate increased due to poor pollination. Click to get more sunflower planting techniques click to get more food crop planting techniques