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为确定整治烟田无机氮肥的最佳施氮量,优化氮肥管理措施,通过设置不同梯度施氮量试验,研究了无机氮肥施用量对烤烟生长、烟株氮素累积分配的影响,分析了不同施氮量下,整治烟田的氮素平衡和施氮经济效益,提出了采用便携式叶绿素仪指导氮肥管理的关键施肥时期叶部SPAD阈值。结果表明:随着施氮量的增加,整治烟田烤烟的长势、氮素累积分配、氮素利用率、烤烟经济性状均呈“先升高、后降低”的变化规律;烤烟的偏生产力、农学效率随施氮量增加呈现“报酬递减”规律。综合施氮量对烤烟氮素利用状况、经济性状以及烟田氮素平衡的影响,认为整治烟田推荐施氮量为90 kg/hm2。根据最佳施氮量下移栽时间与烟株不同叶位的SPAD值间的关系,认为烤烟移栽后21、51 d第3叶位叶片的SPAD值正常范围分别为(28.8±3.5)、(26.4±4.7);移栽后81 d第9、15叶位叶片SPAD值正常范围分别为(35.3±3.6)、(40.8±3.7),可用以指导整治烟田的氮素养分管理。
In order to determine the optimum amount of nitrogen fertilizer for remediation of inorganic nitrogen fertilizer in tobacco fields and optimize the management measures of nitrogen fertilizer, the effects of different amount of inorganic nitrogen fertilizer on the growth of tobacco and the nitrogen distribution of tobacco plants were studied by setting different nitrogen application rates. Under nitrogen application rate, nitrogen balance and economic benefits of nitrogen application in tobacco field were improved. The leaf SPAD threshold of the key fertilization period using portable chlorophyll meter was proposed. The results showed that with the increase of nitrogen application, the growth of flue-cured tobacco in flue-cured tobacco increased with the increasing of nitrogen content, the nitrogen utilization efficiency and economic characteristics of flue-cured tobacco, Productivity, agronomic efficiency with the increase of nitrogen rate showed “return diminishing ” law. Based on the effects of N rates on nitrogen utilization, economic traits and nitrogen balance in tobacco fields, the nitrogen application rate of 90 kg / hm2 in tobacco fields was considered. According to the relationship between the transplanting time and the SPAD value of different leaf positions under the optimal nitrogen application rate, the SPAD values of the leaves at the third leaf position 21 and 51 d after transplanting were 28.8 ± 3.5, (26.4 ± 4.7). The SPAD values of the leaves at the 9th and 15th leaves 81 days after transplanting were (35.3 ± 3.6) and (40.8 ± 3.7), respectively, which could be used to guide the nitrogen management of tobacco fields.