梨枣幼树生长发育对底施氮肥反应的研究初报

Preliminary study on responses of pear jujube saplings growth to nitrogen fertilizer

对不施氮肥、根围无氮肥和混匀施氮肥三种情况下盆栽梨枣幼树地上部和根系的生长状况、土壤速效氮含量以及氨挥发速率进行了测定,探讨梨枣幼树生长发育对氮肥的反应及其原因。结果表明:不施肥时,梨枣幼树地上部生长量及根系数目与鲜重显著大于其他两个处理,生长状况良好;根围无肥的梨枣幼树在栽植早期阶段生长状况良好,后期长势缓慢甚至出现枯枝落叶现象;混匀施肥的梨枣幼树在发芽不久后就停止生长,甚至枯死。其原因在于过量集中施氮导致土壤氨挥发增大,毒害根系;同时,因土壤氮素浓度过大,也使土壤水分有效性降低。

The growth condition of shoot and root, the content of soil available nitrogen and the rate of ammonia volatilization of potted pear jujube saplings on the cases of no N fertilizer, no N fertilizer around roots and N fertilized uniformly were investigated to explore the responses of the potted pear jujube tree saplings growth to nitrogen fertilizer and the reasons. The results showed that the shoot and root number and the fresh weight of jujube tree saplings on the case of no N fertilizer was significantly greater than the other two treatments, and the growth was in a good condition; The jujube saplings on the case of no N fertilizer around roots were growing well in the early stage of planting, but the growth became slowly and even appeared dead branches deciduous phenomenon in the later stage; The jujube saplings on the case of N fertilized uniformly stopped growth shortly after germination, or even died. The reason for these was that the excessive concentration of nitrogen led to the increase of soil ammonia volatilization, and finally made the roots be poisoned, meanwhile, the effectiveness of soil moisture were reduced because of the excessive concentration of soil nitrogen.