EFFECT OF ALUMINUM ON RELATIVE YIELD AND PLANT-CHEMICAL CONCENTRATIONS OF CEREALS GROWN IN SOLUTION CULTURE AT LOW IONIC-STRENGTH

The effects of aluminum (Al) on yield and plant chemical concentrations were determined for 5 cereal species (18 cultivars) using a low ionic strength solution culture technique. The relationship between relative yield and solution Al activity was determined using polynomial exponential splines, and the Al activity (mu-M) at which yields were reduced by 50% (Al(RY50)) determined. Based on the yields of plant tops, the wheat (Triticum aestivum) cultivars Warigal, Sonora-63 and Scout were sensitive to Al (Al(RY50) < 0.5), and Cardinal, Waalt, BH1146, Atlas-66 and Carazinho were tolerant (Al(RY50) 1.4-3.3). Avena byzantina cv Acacia (Al(RY50) 0.9) was more sensitive and A. stigosa cv Saia (Al(RY50) 2.5) more tolerant to Al than the common oats (A. sativa) (Al(RY50) mean 1.8, range 1,4-2.4). Both barley (Hordeum vulgare) cultivars, Kearney and Dayton, were sensitive to Al (Al(RY50) 0.3 and 0.8 respectively). The most consistent effect of increasing solution Al on the plant nutrient concentrations in the cereals was to decrease Mg and Ca concentrations in the tops by an average of 37% and 11% respectively, and decrease Mg concentrations in the roots by an average of 47%.