Biological characteristics
Carrots are semi-hardy-tolerant vegetables. The suitable temperature for germination is 20-25 °C , the suitable growth temperature is 昼 18-23 °C , and the night temperature is 13-18 °C . The temperature is too high and too low is unfavorable for growth.
Carrot roots are developed. Therefore, deep ploughing of land plays an important role in promoting vigorous root growth and fleshy root hypertrophy. It is required to have a deep sandy loam soil, and PH5-8 is more suitable. The soil moisture is required to be 60-80% of the maximum water holding capacity of the soil . If the water is too much in the early growth stage, the aboveground part will grow too much, which will affect the growth of the fleshy roots. If the water is insufficient in the late growth stage, the straight roots will not expand sufficiently, resulting in a decrease in yield. . Excessively heavy soil or application of unfertilized base fertilizer can impede the normal growth of fleshy roots and produce deformed roots.
Cultivation Techniques
　　 1. Sowing of carrot seedlings on the ground, the growth of the seedlings is slow, the growth period is long, and the filming and unfilming are arranged in the rain and before and after the seeding. It has a straight root into the soil, and it is suitable to choose a sandy loam that is deep in soil and well ventilated and well drained. Plowing 22-26cm , then finely 2-3 times, leveling and fine, and combined with the ground preparation to apply fully decomposed and finely divided organic fertilizer.
Carrots can be sown in high ridges or spread flat. Usually the ridge distance is 50-60cm , two rows per ridge, and the plant spacing is about 10cm . The flat width is 1 to 1.5 m . Under the favorable conditions of fertilizer and water, the row spacing of the plant is 10×10 cm or 12×12 cm .
Carrot seeds have bristles, which prevent the seeds from absorbing water, and are easy to bind into a group and are inconvenient to sow, so the bristles should be removed before sowing. About 0.75kg per acre with seed drill; spreaders 1.5-2kg. In order to make the carrots emerge quickly and neatly, it can also be soaked and germinated, and the germination can be pre-emerged for 3-4 days in advance .
　　 2. Field management
　　 1 ) The seedlings and weeding carrots should be early, and the first seedlings should be taken when the seedlings grow to 1-2 true leaves. The weak seedlings are removed, and the seedlings are kept, and the seedling distance is 3-4 cm . When 4-5 leaves are fixed, the number of seedlings per acre, the number of large species is about 10,000, and the number of medium and small species is 40,000 to 60,000 .
Carrots grow slowly during seedling stage, and weeds grow rapidly. Therefore, timely weeding is the key to ensuring the seedlings are strong. Generally, the inter-planting seedlings are used for cultivating and weeding, and the herbicide can also be used to kill the grass. The commonly used herbicides are herbicide ether ( 25% ), 0.75-1 kg per mu , sprayed on the soil surface before germination after sowing (excluding filming , filming should be carried out during land preparation); herbicide No. 1 can also be used ( 5%), 100-150g per acre, or prometryn (50%) 100, watered 50-60g.
　　 2 ) Although irrigation and fertilization carrots have strong drought tolerance, they must be properly supplied with water and nutrients. From sowing to emergence, it should be continuously watered 2-3 times to ensure smooth emergence. The water requirement during seedling period is not large, and the water should be kept moderate. Into the leaf growth period, it is necessary to properly control the water, strengthen the cultivating, and maintain the balanced growth of the aboveground and underground parts. The fleshy roots are also the most demanding period for water. Water should be watered in time to keep the soil moist. If the watering is insufficient, the fleshy root is thin and rough, and the quality is poor. If the water supply is uneven, it will easily cause the root of the meat to crack.
Carrots absorb slowly in the early stage of growth, and they absorb nutrients in large quantities as the fleshy roots grow rapidly. For every 1000kg of product produced , it absorbs about 3.2kg of nitrogen , 1.3kg of phosphorus and 5kg of potassium . Thus, in addition to enough base fertilizer, fertilizer during its growth should be 2-3 times before and after the first seedling production, 10-15kg per acre topdressing ammonium sulfate, separated after 20-25 days, and a second The third top dressing, each application of compound fertilizer 25-30kg . In addition, carrots are sensitive to the high concentration of fresh manure and soil solution. If fresh manure is used or the amount of fertilizer applied is too large, it is prone to fork roots.
Relationship between cultivation techniques and carrot quality
Under the bad environment and cultivation conditions, carrots often have deformed roots, cracked roots and fork roots, which reduce the yield and quality. As mentioned above, it is not necessary to repeat them here. The most important thing to note is the symptoms of boron deficiency. The manifestations are that the root system is underdeveloped, the growth point is dead, and the outside is blackened. Calcium deficiency symptoms, manifested as vegetative growth blocked, the formation of woody roots.
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