Flue-cured tobacco and Cl rates : implications on yield, quality, and nutrient concentration

Abstract

The increase in flue-cured tobacco (Nicotiana tabacumL.) yields in recent decadesdue to genetic improvements of new cultivars and management technologies mayincrease the plant demand for Cl, and the increased dry mass may dilute Cl concentra-tion, thereby reducing negative effects. This study evaluated the effect of increasingdoses of Cl on tobacco production, quality, and chemical composition of leaves, infour growing environments located at research stations where flue-cured tobacco isproduced in North Carolina. The treatments consisted of 11 rates of Cl (0, 11, 22,34, 45, 56, 67, 78, 90, 101, and 112 kg ha−1) in each growing environment, with fourreplications in a randomized complete block design. The yield and visual quality,total alkaloids, and reducing sugars concentrations of cured leaf were determined.In addition, the concentration of selected nutrients (N, P, K, Ca, Mg, S, and Cl) andnitrate (NO3−) in tobacco leaves was measured in five different periods. Rates of Clup to 112 kg ha−1did not reduce the productivity or quality of flue-cured tobaccoin any environment. The Cl rate required to reach the threshold of 1.0% Cl contentin cured leaf was site-specific, being surpassed even in the control treatment at onelocation, or with Cl rates higher than 34 and 90 kg ha−1in two environments. Inone environment, the Cl rates increased tobacco yield, probably due the direct effectof Cl as a nutrient. Although the increasing Cl rates increased the reducing sugarsconcentration, visual quality was not attenuated.