Effect of chloride in irrigation water on three tobacco types
One of the main sources of considerable amounts of chloride to soils is the irrigation water. Responses of tobacco (Nicotiana tabacum L.) to chloride have been varied and are inconsistent according to various tobacco types, varieties, and methods of fertilization, cultivation and harvesting used. In this work, the effect of chloride concentration (10 to 80 mg L-1) in irrigation water on growth, agronomic and chemical characteristics of Oriental (sun-cured), Virginia (flue-cured) and burley (air-cured) tobacco was evaluated with a three year (1999, 2000, 2001) outdoor pot experiment. In addition, it was investigated whether varieties of Oriental (six varieties), Virginia (four varieties) and burley (two varieties) tobacco types, respond differently to chloride. 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 Virginia and burley tobacco types, as well as in neutral varieties of Oriental tobacco type. Leaf chloride concentration in three tobacco types was increased linearly with the increase of chloride level in irrigation water, but the leaf chloride concentration and the rate of linear increase were lowest in burley tobacco type comparably to Virginia and Oriental types. Generally, the optimum chloride level in irrigation water was found to be below 20 mg L-1. The varieties from three tobacco types tested, showed different accumulation rates of chloride in leaves and these rates were affected in a different way by the increased chloride in water. The results of the varieties evaluation indicate that there is ability of choice among varieties, either Oriental or Virginia and burley tobacco types, in order to limit the adverse effects of irrigation with water containing increased chloride concentration.