尿素和缩二脲含量对作物的双重毒害作用

DOUBLE TOXIC ACTION OF BIURET AND UREA ON CROP GROWTH

采用培养和盆栽试验研究了施用缩二脲和不同缩二脲含量的尿素对水稻、玉米和烤烟生长的影响。结果表明,0～128mg/L缩二脲溶液对水稻、玉米和烤烟种子发芽均无明显影响,但对根系生长有明显毒害作用,水稻、玉米受害临界浓度为16mg/L,烤烟则为32mg/L。缩二脲与尿素共存时,其毒害临界浓度大大降低,二者呈双重毒害作用。当尿素中缩二脲含量为4.0％时,玉米和烤烟的尿素施用量应分别小于240和390kg/ha;当缩二脲含量为1.4％时,施用量应分别小于360和390kg/ha。

Solution culture and pot experiments were conducted to study the influence of biuret and biurct-containing urea on seed germination and seedling growth of rice, maize and tobacco. Seed germination of the three crops was not affected by seed treatment with biuret solution in the range of 0～128 mg/l. However, toxic symptoms caused by biuret were conspicuously manirested in the roots of the three crops after seed germination. The critical toxic concentration of biuret was 16 mg/l for rice and maize and 32 mg/l for tobacco. The critical toxic concentration of biuret was markedly lowered in the presence of urea. It is therefore, suggested that biuret and urea have a double toxic action on crop growth. The utilization of biuret-containing urea should be limited on different crops. The maximum rate of urea containing 4.0% or 1.4% biuret was found to be 240 and 390 kg/ha or 360 and 390 kg/ha for maize and tobacco, respectively.