Celery is a leafy green leafy vegetable, belonging to the umbelliferae family, a biennial plant, cultivated everywhere, and is one of the varieties of vegetable supply.
( 1 ) Fertility and nutritional characteristics
   Celery is eaten with a soft petiole or stem. Celery is planted at a high density and grows fast, requiring high levels of fertilizer and water. According to the study, for each 1000 kg of celery ( fresh vegetables ) , the nutrient uptake: N 2.55 kg, P2O5 1.36 kg, K2O 3.67 kg, nitrogen, phosphorus, potassium absorption ratio is 1 : 0.54 : 1.44 . Nitrogen mainly affects the length and number of leaves of celery petioles, leaves significant differentiation of insufficient nitrogen, petiole hollow aging; P has a great influence on the product quality of celery, and elongated fiber but leaves will increase too much phosphorus; K It not only promotes nutrient operation, but also promotes the petiole to be thick and full, with good gloss, which is beneficial to increase yield and improve quality.
   Growth stage to celery leaves mainly fat trees into a long lifetime in the later stage based thickening elongated petioles and petioles. The nutrients absorbed by celery during its growth period increase with the increase of growth, and the absorption dynamics of various nutrients show an " S " curve. Celery early growth absorbed nitrogen and phosphorus nutrients mainly to promote root development and growth of leaves, grown to mid-term (4-5 to 8-9 leaf leaf stage) nutrient absorption dominated by nitrogen, phosphorus, nitrogen is gradually transferred to Potassium-based, promoting heart and leaf development. With the extension of the number of days of growth, nitrogen, phosphorus and potassium absorbed increased rapidly in the primrose celery growth (8-9 leaves to 11 to 12 leaf stage) are the most nutrient uptake period. Celery has a large demand for calcium, magnesium and boron. Boron deficiency in the soil due to drought or low temperature absorption suppression boron celery, celery petioles disease like disease prone to transverse cracking, celery calcium deficiency can lead to heart rot, thus affecting the quality of celery.
( two ) application technology
  Celery fertilization has seedbed fertilization and Honda fertilization. Because the seedling age of celery is long, in order to cultivate strong seedlings, the fertilization of the seedbed should be based on organic fertilizer, applying 15 kg of urea per mu , 50 kg of superphosphate , 10 kg of potassium sulfate or potassium chloride , according to the growth of the seedlings after emergence. Apply appropriate amount of nitrogen fertilizer in the middle and late stages . Honda fertilizes the base fertilizer and top dressing.
   1. Base fertilizer. To Shizujifei before planting, preferably in administration of organic fertilizer 3000 kg mass on the basis of high concentrations of fertilizer per acre 35 to 40 kg, or 10 to 15 kg urea, 50 kg of calcium superphosphate, potassium (KCl name) 10 to 15 kg.
   2. Topdressing. Usually 2 times. After the initial growth of celery planting Huanmiao, slow development, nutrient uptake is less, you can not fertilize. When the plant grows 5 to 6 leaves, it enters the growth period, and the first top dressing is applied, and 10 to 15 kg of urea per acre is applied . When the plants grow 8 to 9 leaves after 15 to 20 days apart , the second top dressing is carried out. The fertilizer should be re-applied, and the requirements of nitrogen, phosphorus, potassium, chemical fertilizer, may be administered per acre of nitrogen, phosphorus and potassium ratio of 1: 0.5: 1 high fertilizer concentrations of 20 to 30 kg. In the vigorous growth period, foliar topdressing can also be carried out, such as spraying 0.5% urea solution or 0.2% potassium nitrate solution. In autumn, drought is prone to boron deficiency, and it can be sprayed with 0.2% to 0.5% borax solution to prevent rough and cracked petiole.
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