Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9473538 | Field Crops Research | 2005 | 14 Pages |
Abstract
One of the main sources of considerable amounts of chloride to soils is irrigation water. The responses of tobacco (Nicotianatabacum L.) to chloride are varied and inconsistent depending on the tobacco type, variety and methods of fertilization, cultivation and harvesting used. In this work, the impact of the interaction between four chloride levels (10, 20, 40, 80 mg Lâ1) in irrigation water and three nitrogen fertilizer forms (NO3-N 100%, NH4-N 100% and NO3-N 50%:NH4-N 50%) on growth, agronomic and chemical characteristics of Virginia tobacco was evaluated over 2 years (1999, 2000) in an outdoor pot experiment. The results showed that the adverse influence of chloride in irrigation water on plant height and number of leaves per plant was already substantial above 40 mg Lâ1, within 30 days after transplanting. In this period, visual toxicity symptoms of chloride appeared on the lower leaves of plants treated with ammonium nitrogen. In addition, the effect of chloride on flowering time, chlorophyll content of leaves, aboveground fresh weight of plant, total cured product yield and chemical characteristics, depended on the form of nitrogen, with nitrate nitrogen restricting the detrimental effects of chloride in irrigation water up to 40 mg Lâ1. The reduced yield of cured product at 80 mg Lâ1 was the result of the adverse effects of chloride on the leaves of the middle and upper stalk position. Leaf chloride concentration was highest in the upper leaves and increased linearly with the increase of chloride level in irrigation water at each leaf position on the stalk and this increase was more rapid as ammonium nitrogen percentage was increased. Chloride increased the concentration of reducing sugars in cured leaves at each leaf position, in all nitrogen forms and nicotine mainly in plants treated with nitrate nitrogen. The changes in total nitrogen and ash content are considered as minimal. We conclude that the optimum chloride level in irrigation water is below 20 mg Lâ1, whereas the level of 40 mg Lâ1 in combination with nitrate nitrogen fertilizers can be considered as the upper threshold to avoid adverse effects on Virginia tobacco.
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Authors
N.A. Karaivazoglou, D.K. Papakosta, S. Divanidis,