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一、苗期管理大白菜幼苗期是从拉十字到团棵(发生1个叶环——中晚熟品种由8片叶组成),这时适宜气温日平均20～22℃,若超过25℃,呼吸作用强,营养消耗多,生理衰弱,易发生病害.大白菜幼苗期需要水分虽然不多,但这时期气温高,土壤水分蒸发快,同时幼苗根系入土浅,地面稍于就会影响生长,而且还会引起病毒病。因此苗期要小水勤浇,最好早、晚浇,每次浇水可降低地温6～8℃,有利小苗健壮生长。大白菜幼苗拉十字时就要抓紧进行第1次间苗,每次留3～4株。真叶4～5片时.要进行第2次间苗,每穴留2～3株。10片真叶左右即可定苗,每穴留壮苗1株。有的菜农为了卖商品小白菜,有意识地拖延(?)苗和定苗期,这样会导致病害发生,影响大白菜产量.
First, the seedling management Chinese cabbage seedling stage is from pulling the cross to the group of trees (1 leaf ring - the late-maturing varieties from the 8 leaves), when the average temperature of 20 ~ 22 ℃ average, if more than 25 ℃, Breathing strong, nutrition and more consumption, physiological weakness, prone to disease.While the cabbage seedlings need water, although not much, but this time the temperature is high, the soil moisture evaporates quickly, while the seedling roots into the soil shallow, the ground will affect the growth slightly, But also cause the virus disease. Therefore, seedling should be small water pouring, the best early and late pouring, watering can reduce the temperature of 6 ~ 8 ℃, favorable seedling robust growth. Cabbage seedlings pull the cross when the first step should be paid close attention to each time to stay 3 to 4 strains. True leaves 4 ~ 5. When the second seedlings to be carried out, leaving 2 to 3 per hole. About 10 pieces of true leaves can be fixed seedlings, leaving one seedling per hole. Some vegetable farmers in order to sell the product of Chinese cabbage, consciously delayed (?) Seedling and Dingmiao period, this will lead to disease occurs, affecting Chinese cabbage production.