Seedling root response of some Kenyan bread wheat cultivars grown in acid nutrient culture solution containing aluminum

The objective of this study was to determine whether a series of Kenyan bread wheat cultivars differed in tolerance to aluminum toxicity. Fourteen Kenyan wheat cultivars representing current and former widely grown cultivars of diverse pedigree origin, and two control cultivars, Maringa (Al-tolerant) and Siete Cerros (Al-susceptible), were tested in solution cultures with 0 (control), 148, 593, and 2370 M Al at pH 4.6. Highly significant (p0.01) differences in seedling growth were observed among cultivars for root mass, root length and root tolerance index (RTI). Significant (p0.05) cultivar × treatment interactions were observed for root mass and RTI. All characters were negatively affected by increased Al concentration, with root length and root mass being affected the most. RTI is a commonly used index which measures the relative performance of individual cultivars with and without aluminum stress. High levels of tolerance to Al were identified in the Kenyan cultivars by evaluating RTI with this simple nutrient solution technique. Romany and Kenya Nyumbu had RTI values approaching those of the Al tolerant Brazilian cultivar Maringa, a spring wheat standard that has been used for high Al tolerance.