Causes and control of scorched buds and yellowing of broccoli

Broccoli is a 2012 herb, originated in the eastern Mediterranean coastal area, a small amount of cultivation in China, mainly for Western food use. Broccoli is rich in nutrition, containing protein, sugar, fat, vitamins and carotene, ranking first among similar vegetables and known as the "vegetable crown". A variety of cabbage species of the genus Brassica in Cruciferae that uses green flower balls as products. Originated in Italy along the Mediterranean coast of Europe, it was introduced into China at the end of the 19th century.

Growth habits of broccoli

Light

Broccoli does not have very strict requirements for light, but it likes sufficient light in the process of growth. When the light is strong, the plant can form a strong nutrient, which is conducive to the accumulation of photosynthesis and nutrients, and make the flower bulb compact and compact. Bright green color is good, too strong sunshine in midsummer is also not conducive to the growth and development of broccoli.

Temperature

In the range of 5 Mel 20 ℃, the higher the temperature, the faster the growth and development of broccoli. The optimum temperature for germination was 20 ℃, and the optimum temperature for growth at seedling stage was 15 ℃. Broccoli has strong cold and heat tolerance, the suitable temperature for growth at rosette stage is 20 ℃ 22 ℃, and the suitable temperature for flower head development is 15 ℃ 18 mol. When the temperature is higher than 25 Mel, the quality of flower head is easy to deteriorate, but as long as it is not damaged by freezing, it can still grow slowly at low temperature of 5 ℃ or below. There are great differences in temperature requirements for vernalization among different varieties and seedling ages, so the selection of varieties in annual cultivation is very important.

Water content

Broccoli needs more water in the whole growth process, especially in the period of vigorous leaf growth and flower head formation, even if it is short-term drought, it will reduce the yield. Rainy or high soil moisture at seedling stage can easily cause diseases such as black rot and black spot. During the period of flower head formation, the soil moisture and field capacity are about 70% and 80% in order to meet the growth needs.

Soil

Broccoli is not strict on soil conditions, but if it is too barren, the plant will develop poorly, the yield and quality will be low, and the over-fertile soil will lead to loose buds and hollow moss. Broccoli is suitable to be planted on loam and sandy loam with good drainage and irrigation, deep plough layer, loose and fertile soil and strong water and fertility conservation. The range of soil PH was 5.5 Mel 8, but 6 was the best. Broccoli needs sufficient fertilizer during the whole growth process, and its ratio of N, P and K is 14:5:8. The demand for nitrogen was relatively high at the seedling stage, and the demand for P and K was relatively increased after flower bud differentiation. It is noted that boron, molybdenum, magnesium and other trace elements are also needed in broccoli during the development of the corm, so the application of appropriate trace element foliar fertilizer before budding will significantly improve the yield and quality.

Causes and control of scorched buds and yellowing of broccoli

In the process of cultivation, broccoli often produces hairy flowers or scorched buds, and some bulbs are loose, buds withered or yellowed, which seriously affects the edible value and commerciality of broccoli.

The etiology of broccoli burnt bud and yellowing broccoli is suitable for cultivation in summer and autumn. when cultivated in early spring, broccoli is in a period of low temperature in the early growth stage, although the plant grows slowly, but if low temperature is conducive to flower bud differentiation, it is easy to bud early and produce small flower bulbs. However, in the later growth stage, when the temperature is too high or the temperature in the greenhouse is too high, the flower bud development is restrained, and the abnormal flower bulbs such as hairy flowers and coke buds are prone to increase in temperature near the flower ball harvest period, and the flower heads grow and develop rapidly. If the harvest is not timely, the buds become loose and easy to yellowing, especially the daytime temperature is too high, resulting in flower ball withering and yellowing, storage for a long time is also prone to the above situation. The disease is serious in out-of-season cultivation.

Prevention and treatment of burnt buds and yellowing of broccoli:

The main results are as follows: (1) to select mid-early-maturing varieties or early-maturing species which are not sensitive to low temperature in the early growth stage, such as Lvling, Shanghai No. 1, Ludi, Qinglu, early green and so on.

(2) sowing at the right time, early sowing due to low temperature after planting, plants differentiate in case of low temperature, at this time malnutrition, few leaves, small leaves, early budding, then the flower ball is small; sowing too late, the temperature rises rapidly, the bud development period is in the high temperature period, it is easy to produce high temperature obstacles, resulting in scorched buds.

(3) temperature management is the main way to cultivate strong seedlings. After sowing, the night temperature is above 12 ℃ and the daytime temperature is less than 30 ℃. 5-6 true leaves should be planted in time, the seedlings will age too late, and the rosette will be small. About 3000 plants were planted in 667 square meters.

(4) if the harvest period is in the stage of high temperature, it must be harvested timely and arranged in the morning to avoid withered buds and yellowing and prolong the fresh time of the bouquet.

(5) broccoli should not be hidden for a long time and should be eaten as soon as possible after harvest.