Effects Of Potassium And Zinc Foliar Application On The Growth And Potassium,Zinc Transport In Nicotiana Tabacum L.

Flue-cured tobacco is an important economic crop in China.Foliar spraying of potassium or zinc fertilizer to alleviate the lack of potassium or zinc deficiency symptoms,improve tobacco yield is of great significance.In this study,tobacco(Nicotiana tabacum L.)cultivar K326 was used as the experimental material,mainly using hydroponics,the effects of different K or Zn levels on tobacco growth and physiological indexes were studied.As well as foliar spraying different types and different concentrations of K or Zn fertilizer to alleviate tobacco deficiency symptoms.The transport and redistribution of K or Zn at different leaf positions after the application of K or Zn fertilizer were studied,for which lack of K or Zn.The results of the study have a certain practical significance for rational application of foliar fertilizer and improving leaf nutrition of tobacco plants.The growth of tobacco was more appropriate when the nutrient solution for the K level was 4-10 mmol L"1,while the other nutrient supplied under normal conditions.K concentration was 6 mmol L'1 in normal Hoagland nutrient solution.The best content of tobacco K range was 11.5%-14.0%.When the concentration of Zn in nutrient solution was less than 0.4 ?mol L-1,the growth of tobacco plants was affected.The critical value of Zn deficiency in tobacco leaves was 14.2 mg kg-1.The dry weight and K content of tobacco leaves increased after spraying with 1%-4%(w/v)KNO3,K2SO4 and KH2PO4,when the tobacco was lack of K and K content was 0.7%,compared with spraying water(control)treatment.3%KNO3 had better effects which leaf K content reached 1.8%after spraying,but was still significantly lower than the whole nutrient treatment(5.8%).The dry weight and Zn content of tobacco leaves increased with 0.1%-0.5%(w/v)Zn-EDTA and ZnSO4,when the tobacco was lack of Zn and Zn content was less than 14.2 mg kg-1,compared with spraying water(control)treatment.0.3%ZnSO4 had better effects which Zn content reached 226.63 mg kg-1,it was significantly higher than the whole nutrient solution(28.07 mg kg-1).The results also showed that 3%KNO3 or 0.3%ZnSO4 spraying had the best mitigation effect on the symptoms of deficiency,by the experiment which tobacco plants were cultured with sand.If the tobacco is seriously deficient in K,it is recommended to use 3%KNO3 spray several times every 4 days.And for the lack of Zn tobacco leaves,spraying 0.3%ZnSO4 once had a significant effect on the addition of Zn.3%(w/v)KNO3 or 0.3%(w/v)ZnSO4 foliar fertilizer was applied on the medial leaf(top third leaf)of K or Zn deficient tobacco plants.K or Zn can be transported to the superior and inferior leaf of the treatment leaf.After treatment,K was preferred to transport to the superior leaf,but Zn was preferentially transported to the inferior leaf.And the increase of K or Zn content was detected after one hour,indicating that the transport of K or Zn in the leaves was very fast.After treatment,the K content was treatment leaf>superior leaf>inferior leaf,zinc content was treatment leaf>inferior leaf>superior leaf.We investigated the X-ray energy spectrum analysis of the K content and scanning electron micrograph of transverse section in the vein of tobacco leaves.The results showed that the K in tobacco leaves was mainly distributed in the parenchyma.After foliar spraying on medial leaves of potassium deficiency tobacco,the content of K in adaxial epidermis,adaxial parenchyma,vascular tissue,abaxial parenchyma and abaxial epidermis of superior leaves,treatment leaves and inferior leaves increased.In the process of transport to the leaves,K will largely transfer to the superior leaves primarily.