近来发现,有些新植龙眼幼树抽出第一次新梢尚未转绿时,梢芽就失水枯死。其主要原因是果农在果苗刚刚抽生新芽就急于施用尿素,由于施用不当,尿素中的杂质缩二脲或尿素水解过程中产生的氰酸铵、氨基甲酸铵对幼树新根引起了毒害作用,根系变黑坏死,导致新芽干枯死亡。龙眼定植后,抽出的新 Recently found that some new plants longan saplings out of the first green shoots have not yet turned green, the shoot bud on the water loss dead. The main reason is that the fruit growers are urgently required to apply urea when the seedlings are freshly sprouted. Due to improper application, the biuret in the urea or the ammonium cyanate generated in the urea hydrolysis process causes the poisoning effect of the ammonium carbamate on the new root of the young tree , The root becomes black necrosis, resulting in death of new shoots. Longan colonization, the new out