Aluminum tolerance in triticale, wheat, and rye

Acid soils containing high levels of aluminum (Al) are known to severely li mit plant growth on over 1.6 billion hectares worldwide. In the United Stat es, a gradual decline in the pH of many soils both in the Great Plains as w ell as the Southeast, has caused many soils to become high in levels of fre e Al. This worldwide condition encouraged the analysis of wheat (Triticum a estivum L. em Thell.), triticale (X Triticosecale Wittmack), and rye ( Seca le cereale L.) germplasm from one of the major acid soil regions of the wor ld (Brazil) in order to evaluate and compare the genetic potential of Al ge nes for cereal improvement. The objectives were to compare Al-tolerance lev els in wheats, triticales, and ryes by measuring root elongation responses in Al-containing hydroponic nutrient solutions. Root elongation was impaire d for all species grown in 1 mg/L concentrations of Al. Rye had the longest root regrowth and Al-sensitive wheats had the shortest root regrowth. The triticales containing a 2D(2R) substitution developed in the mid-1970s had the poorest root regrowth of all triticale types. The newly developed advan ced triticale lines (AABBRR) yet to be released for commercial production s howed the highest degree of Al tolerance of all the triticale types and app roached or exceeded the levels observed in rye. This indicated that progres s is being made in improving Al-tolerance of triticale in Brazil. Of all th e old and new wheat varieties showing the highest degree of Al-tolerance, n one of them were better than 'BH 1146' a variety that is at least 50 years old. This indicated that over the past 50 years, although Brazilian wheat b reeders have made yield improvements in wheat production, they have not imp roved Al-tolerance. Rye showed a higher degree of Al-tolerance than the oth er cereals when tested in 1 mg/L of Al, but as expected, some variation was noted.