Effect of Chloride in Irrigation Water on Oriental (Sun-Cured) Tobacco

Abstract

ABSTRACT Responses of tobacco (Nicotiana tabacum L.) to chloride vary according to tobacco types, cultivars, and methods of fertilization, cultivation, and harvesting used. Until now, research has focused on types other than Oriental. In this work, the effect of chloride concentration (10 to 80 mg L−1) in irrigation water on growth and agronomic and chemical characteristics of Oriental tobacco was evaluated with a three-year (1999–2001) outdoor pot experiment. Whether Oriental tobacco cultivars, aromatic and neutral, respond differently to chloride was also investigated. The results showed that the influence of chloride on growth-development and total cured leaves yield on Oriental tobacco was inconsistent and substantial only in neutral cultivars. The increased cured leaves yield in neutral cultivars with 50 mg Cl L−1 was attributed mainly to the increased size of leaves. Leaf chloride concentration increased linearly with the increase of chloride level in irrigation water, but the leaf chloride concentration and the rate of linear increase were highest in the upper leaves of the plant, and decreased gradually from the upper to the lower leaves. Generally, the optimum chloride level in irrigation water was found to be below 20 mg L−1, whereas the 40 mg L−1 level was the critical upper threshold to avoid adverse effects on Oriental tobacco. The six cultivars showed different accumulation rates of chloride in leaves, and these rates were affected differently by the increased chloride in water. The changes in chemical characteristics examined concerning cured-leaf product quality were minor. The results indicate that one may choose among cultivars, either aromatic or neutral, in order to limit the adverse effects of irrigation with water containing increased chloride concentration.