叶面喷施硫酸钾镁肥对不同部位烟叶镁、钾、钙吸收的影响

目的]在云南省曲靖市植烟土壤交换性钙镁比超过20的缺镁烟区，通过土壤镁肥施用和叶面喷施进行钙镁比调控，了解其对烤烟钾、钙、镁吸收的影响，为曲靖市缺镁烟区烤烟的平衡施肥技术提供理论依据和生产指导。方法]通过田间小区试验，采用完全随机区组设计，以不施镁肥作为对照，分别设3个叶面喷施硫酸钾镁肥处理和2个根层施镁＋叶面喷施处理。采集根、茎、上部叶、中部叶和下部叶5个部位进行烘干称重，并且粉碎制样，测定钾、钙、镁含量；每个小区从初烤烟叶中选取上部（B2F）、中部（C3F）、下部（X2F）样品，分析烟叶全钾、钙、镁含量。结果]从不同部位来看，叶面喷施及土壤施用和叶面喷施配合调控钙镁比提高了中、下部烟叶对镁、钾的吸收以及下部烟叶对钙的吸收，但降低了上部烟叶对镁、钾、钙的吸收以及中部烟叶对钙的吸收。烟叶不同部位镁、钾、钙的累积分配量比较表现为中部叶〉下部叶〉上部叶；从不同部位来看，中、上部烟叶钙镁比、钾镁比降低，下部烟叶钙镁比增加，而下部烟叶钾镁比处理之间没有差异。结论]叶面喷施及土壤施用和叶面喷施配合调控对烟叶钙镁比、钾镁比的影响，主要是通过影响镁的吸收。

Effects of Potash Magnesium Sulphate Foliar Application on Absorption of Magnesium,Potassium and Calcium of Different Flue- cured Tobacco Leaf Position

Objective] Soil exchangeable Ca/Mg in tobacco area of magnesium deficiency in Qujing, Yunnan was more than 20. For understanding their effects on tobacco potassium, calcium and magnesium, soil application of magnesium fertilizer and foliar spraying were used. The final goal was to provide theoretical basis and guidance for balanced fertilization technology of Qujing flue-cured tobacco production in magnesium deficiency area. Method ] Using field plot test with completely randomized block design, no application of Mg fertilizer as control, 3 treatments of foliar fertilizer of potassium and magnesium sulfate and 2 root layer application of Mg2＋ foliar treatment were arranged. Root, stem, the upper leaves, middle leaves and lower leaves were collected, oven dried, crushed and sampled. And potassium, calclum, magnesi- um contents were determined. Each cell from baking selection in upper leaves （B2F） , middle （C3F）and lower （X2F） samples was chosen, and total potassium, calcium, magnesium content of tobacco were analyzed. Result ] Potash magnesium sulphate foliar application and soil application with foliar application increased absorption of magnesium, potassium in middle and bottom leaves. And it increased the absorption of calcium in bottom leaves. But potash magnesium sulphate foliar application and soil application with foliar application reduced absorption of magnesium, potassium and calcium in upper leaves. And it reduced the absorption of calcium in middle leaves. The accumulation amount of magnesium, potassium and calcium in different flue-cured tobacco leaves position was middle leaves 〉 bottom leaves 〉 upper leaves. From different flue-cured tobacco leaf position, Ca/Mg and K/Mg in middle and upper leaves decreased, Ca/Mg in bottom leaves increased. There was no difference between K/Mg treatments in bottom leaves. Conclusion]Regulation K/Mg and Ca/Mg by potash magnesium sulphate foliar application and soil application with foliar application was mainly affected by the absorption of magnesium.