整治烟田无机氮肥管理对烤烟氮素综合利用的影响

Effects of Inorganic Nitrogen Management on Nitrogen Use Efficiency of Tobacco in Renovated Farmland

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 and optimize the best application rate of inorganic nitrogen and nitrogen management of renovated field planted tobacco,a series of trial with treatments of different inorganic nitrogen rates were conducted,the effects of different inorganic nitrogen rates on growth of tobacco and accumulation and distribution of nitrogen were studied,and the nitrogen balance and economic benefits were investigated,and the critical threshold of guiding nitrogen management with chlorophyll meter was carried out. The results showed that ： with the increasing application rates of inorganic nitrogen fertilizer,the growth of tobacco,distribution and accumulation of nitrogen,nitrogen use efficiency and the economic characteristics of tobacco all presented an increasing trend at the initial stage and then decreased at end. Meanwhile,the partial productivity and agronomic efficiency of tobacco were fitted to laws of‘diminishing returns＇ with the increasing application rates of inorganic nitrogen fertilizer. Considering the effects of application inorganic nitrogen fertilizer on tobacco nitrogen use efficiency and nitrogen balance,the recommendation application rate of inorganic nitrogen fertilizer was 90 kg / hm2. According to the relationship between transplanting period and SPAD value of leaves,the normal range of 3rd position leaves were（ 28. 8 ± 3. 5） and（ 26. 4 ± 4. 7） after transplanting 21 and 51 days,respectively. The normal range of 9thand 15 thposition leaves were（ 35. 3 ± 3. 6） and（ 40. 8 ± 3. 7） after transplanting 81 days,respectively. The tobacco SPAD value by portable instruments could guide the management of renovated tobacco field.