Causes and Control of bolting and malformed Roots of Carrot

Carrot (carrot), alias carrot, clove radish, gourd gold, also known as carrot, red vegetable head, yellow radish, etc., is an umbrella-shaped biennial herb with fleshy roots as vegetables to eat. Carrots contain 1.67-12.1 mg carotene per 100 grams of fresh weight, which is 5-7 times higher than that of tomatoes. After eating, carrots are digested and decomposed into vitamin A, which can prevent night blindness and respiratory diseases. Can be fried, cooked, eaten raw, pickled, pickled, etc., resistant to storage. It is distributed all over the world, and it is cultivated in both the south and north of China, and its output accounts for the second place in root vegetables. Anti-cancer, known as underground "little ginseng".

Growing environment of carrots

Temperature

Temperature carrot is a semi-cold-tolerant vegetable, and the temperature requirements of vegetative growth period and reproductive growth period are different. The seeds germinated at 4-6 ℃, began to grow at 8 ℃, and emerged after 10 days at 18-20 ℃. The seedlings can endure the low temperature of-3 ~-4 ℃ for a short time, and can also grow normally under the high temperature of more than 27 ℃. The optimum temperature for carrot germination period is 20: 25 ℃, the optimum temperature for leaf growth is 20: 25 ℃ in daytime and 15: 18 ℃ at night, and the suitable temperature for fleshy root expansion is 20: 22 ℃ and stop growing below 3 ℃. The root of carrot can be planted when the soil temperature reaches 8: 10 ℃. The suitable temperature for carrot flowering, pollination and seed setting is 22: 28 ℃ in daytime and 15: 20 ℃ at night. If the daytime temperature exceeds 35 ℃, it can not pollinate and bear seeds.

Light

Light carrots are light-loving, long-day plants, especially in the vegetative growth period, which need more than medium intensity of light.

Moisture content

Keep the soil moist when sowing to promote seed germination and emergence neatly. In the seedling stage and the peak leaf growth stage, dry and wet, it is necessary not only to ensure the normal growth of the aboveground, but also to increase the air permeability of the soil to promote the good development of straight roots. Fleshy root expansion period is the period of the most water demand, to achieve uniform watering to meet the needs of fleshy root expansion, but also to prevent root cracking caused by drastic changes in irrigation. Carrots are generally stopped watering 10-15 days before the fleshy root is harvested to reduce cracking and facilitate storage and transportation.

Soil

Carrots like sandy loam and loam with deep soil layer, loose soil, good drainage and high porosity. In the viscous and heavy soil with poor permeability, the fleshy root is light in color, has many whisker roots, is prone to tumor, and is of poor quality; in low-lying areas with poor drainage, the fleshy root is easy to break, often causing decay and increasing forked roots. Carrots have a wide range of adaptation to soil acidity and alkalinity. Carrots can grow well in soils with pH of 5 to 8, but grow poorly in soils with pH below 5.

The area of off-season spring sowing carrots is increasing day by day. however, due to the improper selection of spring sowing varieties and the discomfort of cultivation techniques, it often leads to large area bolting and a large number of abnormal roots, which brings great economic losses to the majority of growers. So what is the cause of carrot bolting and abnormal root formation and how to prevent and cure it? Let's introduce it next.

Causes and prevention of bolting

Reasons for bolting:

Carrot belongs to green vernalization long-day crop. According to the sensitivity of different varieties to low temperature, carrot can be divided into easy bolting varieties, bolting tolerant varieties and bolting tolerant varieties. The varieties that are easy to bolting can feel the low temperature and carry out flower bud differentiation when they have 4-5 or even 2-3 true leaves at the seedling stage, and then bolting and flowering under long sunshine in May and June. According to the research of Japanese scholars, "Heida five-inch" type varieties have the risk of bolting when the low temperature is less than 10 ℃ and accumulate for more than 360 hours at the seedling stage. The lower the temperature is, the longer the low temperature lasts, the higher the bolting rate is, and the highest is more than 90%.

Prevention and control methods of bolting:

It is understood that at present, spring sowing varieties in most parts of China still choose Japanese autumn sowing varieties "New Black five inches" or Kuroda five inch varieties, such as "Juyang five inches" and so on. These varieties are easy to bolting, so in order to avoid loss, varieties insensitive to low temperature and bolting resistance should be selected for sowing in spring.

The causes of malformed roots and the causes of prevention and treatment of abnormal roots:

The malformed roots of carrots often have bifurcations, split roots, bends, verrucous protuberances, green shoulders, long-whisker roots and color variation. The formation of carrot fleshy root requires good soil conditions, cultivation techniques and climatic conditions. If the tillage layer is too shallow, the soil is rough and stony, or if immature organic fertilizer is applied, it is easy to bifurcate and bend; the viscous weight of the soil is not easy to be breathable, and it is easy to produce nodular protuberances and fibrous roots; during the growth period, the water supply is uneven, dry and wet, which can easily lead to the increase of split roots. Plough layer is too shallow, root expansion period does not pay attention to soil cultivation, easy to produce root expansion period in July and August high temperature period, resulting in the accumulation of carotene and lycopene blocked, resulting in color variation, whitening or yellowing. Prevention and treatment of malformed roots:

Therefore, in order to obtain high quality and high yield of spring sowing carrots, sandy soil with loose and fertile soil and better irrigation and drainage conditions should be selected; at the same time, attention should be paid to the depth of the tillage layer not less than 25 cm, the application of rotten organic fertilizer and uniform water supply during the growth period. and pay attention to soil cultivation in the early stage of fleshy root expansion. The suitable temperature for carrot fleshy root expansion is 1825 ℃, so central China should finish from mid-March to early April, and the suitable sowing date should be selected according to the local air temperature in other parts of China.