What is the reason for the yellowing of bean seedlings?

Bean is a common vegetable, which is rich in nutrition and loved by people, and can be cultivated in most parts of our country. So, what is the reason for the yellowing of bean seedlings?

What is the reason for the yellowing of bean seedlings?

The yellowing of bean seedlings may be caused by root rot, lack of fertilizer, high temperature and so on. If you are infected with root rot, you can choose carbendazim, thiram, carbendazim, oleic acid copper root irrigation control. If there is a lack of fertilizer, some foliar fertilizers, such as amino acids, can be sprayed in the middle and later stages of bean seedling development, combined with elemental fertilizers such as boron, calcium, magnesium, iron and zinc, which can significantly reduce the yellowing of the upper leaves. If the temperature is too high, it should be shaded properly.

2. Planting techniques of beans

1. Soil

It is suitable to choose fertile and loose loam or sandy loam and rotate with legume crops for 2-3 years, but heavy soil or low-lying land with poor drainage should not be selected.

two。 Sowing and raising seedlings

Extra-early 30: extra-precocious varieties. The branches are few, and the main vines bear pods. In conventional open field cultivation, it takes about 35 days from sowing to the beginning of flowering, and pods can be harvested after 10-12 days. The harvest period is as long as 20-40 days, and the whole growth period is 80-100 days. The position of the first flower node is low, and pods can be produced generally after an average of about 3 nodes. At the same time, the initial flowering date and initial harvest date of cowpea 28-2 were 2-5 days earlier than that of cowpea 28-2, and the total yield was slightly higher than that of cowpea 28-2. Tender pod light green, symmetrical, about 60 cm long, a single pod weight of about 20 grams, good commodity.

Cowpea 28-2: medium-early maturity, plant height of about 2.5 meters, few branches, sparse leaves. The main vine begins to bear pods at 4-6 nodes, with many pods, green and white pods, 60-80 cm long pods, 0.9-1.1 cm transverse stems, and 25 grams per pod. Thick meat, less fiber, not easy to aging, good quality. Resistant to high temperature, drought and mosaic virus. The growth period is 90-100days and the yield per mu is 2000-2500 kg.

3. Fertilizer application

Heavy application of base fertilizer: the base fertilizer is mainly based on the application of mature organic fertilizer, combined with appropriate compound fertilizer, such as Jinkai nitro compound fertilizer (15-15-15, 16-16-16) with high phosphorus and potassium content, the general recommended amount is 50-60kg/ mu, and deep into the soil.

Skillfully applying topdressing: beans need less fertilizer at the seedling stage, and heavy water is easy to cause overgrowth. In order to control the excessive growth of stems and leaves, promote reproductive growth, and prevent excessive growth leading to less flowers and fruits, the supply of fertilizer and water should be properly controlled. When the seedling potential is weak, Jinkai liquid seedling fertilizer can be applied, and 5kg can be applied per mu. In the podding stage, the fertilizer requirement of beans begins to increase. Jinkai nitro compound fertilizer 22-8-15 and 17-5-23 can be applied after flowering, usually 15-20kg each time. Top dressing of pods was applied once every two times, and 10kg was applied with Jinkai nitro compound fertilizer 22-8-15 and 17-5-23.

4. Reasonable close planting

Sowing time should be determined according to different cultivation methods, such as greenhouse + small arch greenhouse + plastic film cultivation, can be sowed and raised seedlings in the middle or late of February, and nutrition bowl can be used to raise seedlings if possible. At the seedling stage, we should appropriately strengthen ventilation and reduce humidity to prevent the excessive humidity of the seedling bed from forming tall seedlings or the occurrence of quenching disease. It was planted in the greenhouse in the first and middle of March, the planting density was two rows per row, the plant spacing was 15-20 cm, and there were 3 plants in each hole. After planting, the planting mouth was sealed with soil. Or direct seeding in the greenhouse in early March, the plant spacing is 15-20 cm, and 3-4 seeds are sown in each hole. Open-field cultivation in Henan Province is generally suitable for sowing in late March.

5. Field management

Strengthen the temperature of the greenhouse and promote the early slowing down of seedlings. After planting in the greenhouse, the greenhouse was closed for 5-6 days, and the high greenhouse was maintained.

Warm, promote early slow seedling, in case of cold current, must be covered with grass curtain on the small arch shed to prevent frost injury, when the greenhouse temperature exceeds 30 ℃, it should be ventilated and cooled in time.

Build a fight in time and prune it reasonably. When the vine grows to 20 cm, it should be set up to draw the vine in time, and all the lateral buds below the first inflorescence of the main vine should be erased. In the case of lateral branches growing, one leaf can also be left to pick the heart, and the first node of lateral vines can be used to form inflorescences. In the middle and later stage of the main vine, the side branches should be picked in time and early. If the conditions of fertilizer and water are sufficient and the plants grow vigorously, these lateral branches should not be excessively heavy, and lateral vines can be used to bear fruit as appropriate. When the main vine grows to more than 2.2 meters, hit the top and pick the heart in time to control the growth and promote the formation of lateral flower buds so as not to consume nutrients. Such as enough fat and water, when the plant vegetative growth is too prosperous, poor ventilation, too many leaves, branches, old leaves, diseased leaves can be removed.

When planting beans, it is necessary to ensure that the soil is loose and ventilated and the plants are nutritious so that bean seedlings can avoid yellowing.