BORON AND ZINC NUTRITION OF TOBACCO GROWN IN PRINCE EDWARD ISLAND

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Abstract
Field experiments were conducted at various locations in Prince Edward Island to determine the effect of applied Zn and B on tobacco (Nicotiana tabacum L.) yield, grade index, and tissue B and Zn concentrations. Addition of B at 1.1 kg ha−1 did not increase tobacco yield. Rates of B at 8.8 kg ha−1 and higher proved toxic and resulted in yield reductions. At these higher rates there was more than 3 μg g−1 hot-water-soluble (HWS) B in the soil and 113–169 μg B g−1 in the various primings. Tissue B levels as low as 31 μg g−1 in the third priming and the HWS B as low as 0.3 μg g−1 soil did not give B deficiency symptoms. Additions of Zn tended to increase yields but not significantly. Tissue Zn levels as low as 17 μg g−1 in the 3rd priming did not result in Zn deficiency symptoms. No yield reductions occurred when the tissue Zn levels were as high as 115 in the first and 57 μg g−1 in the fourth priming. The grade index of tobacco was not affected by Zn applications but B applications of 8.8 kg ha−1 significantly decreased the index. Tissue Zn and B were higher in the 1st and 2nd than in the 3rd, 4th, or 5th primings. Key words: Tobacco yields, tissue boron, tissue zinc, boron toxicity