Differential Tolerances of Triticale, Wheat, Rye, and Barley to Aluminum in Nutrient Solution

Aluminum toxicity to cereals is an important consideration when adapting a new crop to the acid soils of the Southeast. The objective of this study was to evaluate the relative tolerances of different cultivars of triticale (X Triticosecale) a new crop, wheat (Triticum aestivum L.), rye (Secale cereale L.), and barley (Hordeum vulgare L.) to A1 in nutrient solution with a pH of 4.8 at the time of transplanting. Plant induced pH change in the nutrient solution and dry matter produced were used as criteria for evaluating A1 tolerance. Triticale resembled the other three species in increasing the pH of the solution during growth when no A1 was added to the nutrient solution. When 6 ppm A1 was added, triticale ‘6TA 131’ and ‘6TA 298,’ A1-tolerant ‘Thorne’ and ‘Seneca’ wheats, and ‘Vitagraze’ rye increased the nutrient solution pH to values higher than 5.0. However, triticales ‘6TA 385,’ ‘6TA 203,’ and 6TA 522,’ the different barley cultivars, and ‘Abruzzi’ rye either decreased or had no effect on solution pH. ‘Atlas 66’ wheat induced significantly higher pH at 6 ppm A1 added to the medium than all the other cultivars tested. The addition of 6 ppm A1 to the nutrient solution reduced the shoot growth of the different cultivars generally in a similar manner. However, reductions in root dry matter by A1 indicated that, on the average, A1 tolerances were: A1-tolerant wheat and rye > triticale and A1-tolerant barley > A1-sensitive barley and A1-sensitive wheat. The pH changes induced by the plants in the solution with 6 ppm A1 generally confirmed the same order of tolerance as obtained from reductions in root dry matter. Increasing A1 in solution significantly increased A1 but decreased Ca and P in triticale, wheat, and rye. Aluminum-sensitive wheat contained higher A1 in roots than A1-tolerant wheat. The roots of triticale and rye cultivars significantly differed in A1 concentration.