胡萝卜苗期生长缓慢,从播种到5—6叶,需要1个多月时间,这段时间必须防除杂草,否则,在严重的杂草竞争下,将减产30—60％。Blanco,H. G.认为胡萝卜全生育期中前三分之一段时间是杂草竞争的临界期。北京地区7月中下旬播种胡萝卜,正值高温多雨季节,杂草生长迅速。再加上许多胡萝卜采用密植方式栽培,除草就更加困难。针对这些问题,我们自1977年来断续地 Slow growth of carrot seedling stage, from sowing to 5-6 leaves, takes more than 1 month, during this time weeds must be controlled, otherwise, in the serious weed competition, will cut 30-60%. Blanco, H. G., believes that the first third of the carrot’s whole growth period is the critical period for weed competition. In mid-to-late July, Beijing saw sowing carrots, a period of high temperature and rainy weather, and the weeds grew rapidly. Coupled with the cultivation of many carrots using close planting, weeding is even more difficult. In response to these questions, we have been intermittent since 1977