What are some practical methods to reduce empty shells in sunflowers?
I. Symptom identification 1. Sunflower rust is a major disease of sunflowers, reducing yields by 40-80% in pandemic years. After infection, rust-like spore piles can form on leaves, petioles, stems, flower disks and other parts. When leaves are infected, small brown blisters first appear on the underside of the leaves; these are the uredinia of the pathogen, and after the surface ruptures, brown...
The main causes of empty shells in sunflowers are drought and water deficiency and poor pollination. Ways to reduce empty shells include:1. Water in time. Especially from budding to flowering, do not let the plants lack water.
2. Fertilize reasonably. The principle for fertilizing sunflowers is to combine base fertilizer, seed fertilizer and topdressing; combine farmyard manure, chemical fertilizer and micronutrient fertilizer; combine nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer. The base fertilizer is mainly farmyard manure, applied at more than 2000 kg per mu. The amount of seed fertilizer used is small; phosphorus fertilizer and plant ash can be used, applying 15 kg of diammonium phosphate and 40 kg of plant ash per mu. Topdressing is mainly quick-acting ammonium nitrate, urea, ammonium bicarbonate and potassium fertilizer. Nitrogen fertilizer and potassium fertilizer are generally applied when there are 7-8 pairs of leaves, which gives better results. Topdressing methods are divided into band application and hole application, with hole application being better. A fertilization depth of 10-15 cm is suitable, improving the utilization rate of chemical fertilizer.
3. Hand pollination. The time for supplementary hand pollination is generally from 9-11 a.m. each day, that is, after the dew has dried, and at the latest no later than 12 o'clock. Generally, pollination can be done 2-3 times or 3-4 times.