Effects Of Difference Varieties And Shoot Apex Regulation On Tobacco Potassium Efficiency

Therefore the question how to improve the potassium content of tobacco leaves has beenpaid attention to generally by the tobacco circle. This article is directed against the currentsituation that the shortage of potassium resource and the potassium content of tobacco leaves islower in our country, proceeded with the difference of potassium efficiency of different tobaccovarieties, so we combined nutrient soil culture and field test in order to compare the differenceof potassium efficiency between 20 relatively typical tobacco varieties and have chosen fiverepresentative varieties from it for further studied in the aspects, such as the absorption,transportation, accumulation and loss of the potassium, separately. We have studied themechanism of the difference of potassium efficiency of different tobacco varieties. The mainresults of study are as followed:1. In the field culture experiment, the potassium content of 20 different tobacco varietiesranged from 0.85ï¼…to 2.61ï¼…, the weight of single leaf ranged from 1.8g to 5.15g. Thepotassium content above 2.0g K/100g was consider as a high accumulation efficiency ofpotassium; while the weight of single leaf above 4.5g was consider as a high utilizationefficiency of potassium. As results that combination these two parameters, G28 was apotassium-efficiency variety and TI245 was a potassium-inefficiency variety.2. The potassium content of the potassium-efficiency variety G28 was significantly higherthan the potassium-inefficiency variety TI245 in every period of duration. The potassiumcontent of tobacco leaves decreased from early growing stage to late growing stage in potassiumtreatment, but from late growing stage to ripening stage, the potassium content of G28 increasedfrom 3.48ï¼…to 6.43ï¼…, it indicated that the difference in potassium absorption and accumulationof different tobacco potassium-efficiency variety mainly present in late growing stage.3. Effects of decapitation on plant growth, potassium absorption and distribution withinplant, as well as potassium (K) absorption dynamic and kinetics in tobacco plants wereexamined. A root nutrients absorption kinetic method was applied under hydroponic culture. Inthe decapitation and decapitation+NAA plants, the majority of the net increases in dry matterand potassium were allocated into the upper leaves and roots. The studies on the K uptakekinetics showed that K uptake activity and affinity were the highest in the control plant, and thelowest in the decapitated plant. It also found that potassium content could be improved ifoverground of tobacco was mainly growing part and the senedcing of tobacco leaves wasdelayed through the experiments of decapitation and spraying exdogenous hormone in the latergrowing stage of tobacco. These results indicated, the shoot apex is the strongest sink for drymatter and nutrients, and can regulate not only the dry matter and nutrients allocation among thedifferent organs, but also the nutrients absorption activity by the auxin synthesized in andtransported from the apex. Exogenous application of NAA after removal of the shoot apex canpartly replace the role of the shoot apex to stimulate the root nutrients uptake activity. The aredifferent reaction to the decapitation and spraying exdogenous hormone in the tobacco varietiesthat have different potassium efficiency.