BORON AND ZINC NUTRITION OF TOBACCO GROWN IN PRINCE EDWARD ISLAND

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