effect of topping height and timing on quantity and quality influe-cured tobacco (var.k326)

one of the most important practices in flue-cured tobacco farming is topping and sucker control at the right time. topping cause's development and root growth, drought tolerance, reduce deployment pests, increased synthesis of nicotine. this study was conducted in randomized complete block design (rcbd) with 10 treatments in 3 replications over two years (2008-2009) at tirtash research and education center. treatments consisted of three phases(button stage, early flowering and full flowering) and three levels of leaf removal (18, 20 and 22) with the control treatment without topping and sucker control.the results of combined analysis showed that there were significant differences between treatments for fresh weight, cured leaf weight, total income, net income, mean price, sugar and nicotine percent (α = 1%). according to results the highest and lowest cured-leaf yield belongs to topping at button stage with 22 leaves with 4546 kg/ha and control with 3054 kg/ha respectively.