Aluminum Toxicity Effects on Growth and Nutrient Composition in Wheat1

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Abstract
Aluminum toxicity is frequently the limiting factor to crop production in acid soils. The diagnosis of Al toxicity for a specific wheat (Triticum aestivumL.) cultivar could be simplified by tissue analysis. Greenhouse studies were undertaken to determine the critical Al toxicity level for the cultivar ‘Stacy’ and tissue nutrients affected by Al status. Wheat plants were grown in 10 levels of Al (0, 1.9, 3.7, 9.3, 18.5, 37.1, 74.1, 148, 222, and 297 µMAl) in nutrient solution for 28 days. Aluminum toxicity reduced top dry weight, root dry weight, plant height, tiller numbers, and top/root dry weight ratio. Aluminum concentrations in the blade and stem tissues were low (maximum of 0.3 mmol kg−1in Blade 1, the most recently developed leaf with a developed ligule) and were linearly related to Al in nutrient solution. Aluminum is not readily accumulated in Stacy wheat. The critical Al toxicity levels, defined as the Al concentration in the tissue associated with a 10% decrease from maximum top dry weight due to toxicity, were 0.12 mmol kg−1in Blade 1 and 0.08 mmol kg−1in the whole plant. Knowing these tissue values, one may be able to detect Al toxicity from similar uncontaminated tissue from the Stacy cultivar sampled in the field. Using washed Blade 1 would be preferable to using the whole plant because soil contamination would be minimized. Aluminum toxicity decreased all elemental concentrations in Blade 1 and whole plants. With the exception of P and K in Blade 1, the decreases in elemental concentrations were related by either a linear or quadratic regression.