Effect of potash levels and topping on leaf potassium, yield and quality in flue cured tobacco

Potassium is the most important plant nutrient and is taken up by tobacco plant in large quantities. Pot culture experiments conducted using light soil with different K levels in combination with topping and no topping showed increased yield of green leaf, cured leaf and grade index. Green leaf yield was at par in 80 to 600 kg/ha K level and was significantly higher than 0 kg/ha and 800 kg/ha of K gave higher yield than others. Cured leaf yield was on par in 80 and 200kg/ha K, but significantly higher than 0 kg/ha and 400 kg/ha gave higher yield than at the lower three levels but was similar to that at 600 kg/ha K. 800 kg/ha K gave significantly higher yield than at 0, 80, 200 and 400 kg/ha but was equal to that at 600kg/ha K. Grade index was higher in 600 and 800 kg/ha K than other treatments. Topping increased yield more than the control. Interaction between K and topping was significant for grade index. Under both topping and control 600 and 800 kg/ha gave higher grade index than other treatments. K deficiency symptoms appeared especially more severely in untopped plants when K was withheld. Leaves from topped plants contained higher K than in untopped plants. Application of increasing levels of K increased K and decreased C a content in cured leaves. Higher levels of K gave higher leaf K content in leaves than in younger ones. On the other hand Mg content decreased with higher K content in general. Analysis of cured leaves showed that nicotine, reducing sugars and chlorides were not affected by K. Leaf burn was low in 0 kg/ha K but increased with increasing levels of K. Leaf thickness generally decreased with higher doses of potash and topping increased thickness as compared to no topping. It is concluded that potash application above 600 kg/ha improved yield characters and leaf potassium, calcium, leaf burn and thickness were significantly affected by potash levels and topping.