Influence of aluminum stress on shoot and root growth of contrasting genotypes of coleus

Abstract

Two cultivars of Coleus blumei Benth., found previously to differ in stress tolerance to UV-B radiation, water stress, and air pollutants-stress-tolerant 'Marty' ('M') and stress-sensitive 'Buckley Supreme' ('BS')-were grown in a greenhouse at Beltsville, MD in nutrient solutions containing 0 to 24 mg aluminum (Al) L -1 (Experiments I and II) and on an acid Al-toxic Tatum subsoil (clayey, mixed, thermic, Typic Hapludult) (Experiment III) at six lime levels, from 0 to 6,000 μg calcium carbonate (CaCO 3 ) g -1 (pH 4.47 to 7.30 and percent Al saturations from 60 to 0) to characterize their possible genotypic differences in response to Al toxicity. Significant inhibitory effects of Al stress on shoot growth were generally observed in solution culture at 8 mg Al L -1 or higher, while inhibition of root growth in solution culture was generally observed at 16 mg L -1 or higher. At 16 and 24 mg Al L -1 (Experiment II), the relative dry weights of shoots and roots were reduced to about 60% of the control values in both cultivars. Leaf tissue concentrations of phosphorus (P) and Al were increased and calcium (Ca) was decreased at 24 mg Al L -1 . Both cultivars of Coleus were extremely tolerant to Al stress, both in nutrient solution and in an acid Al-toxic Tatum subsoil. Thus, Coleus appears to be a 1045

Aluminium toxicity in plants: a review

“…They also indicated that most lines were sensitive to Al, but ninety lines showed intermediate tolerance. Krizek et al [124] tested two cultivars of Coleus blumei in nutrient solution containing 0 to 24 mg/l aluminium and on an acid Al-toxic Tatum subsoil under greenhouse conditions. Significant inhibitory effects of Al stress on shoot growth were generally observed in solution culture at 8 mg/l Al or higher concentration, while inhibition of root growth in solution culture was generally observed at 16 mg/l Al or higher levels.…”

Molecular Basis of Aluminium Toxicity in Plants: A Review

“…For the first time, they demonstrated that Al tolerant group of wheat was able to increase pH in nutrient solutions comparatively to Al sensitive cultivars, when both are tested with or without Al. [82] tested two cultivars of Coleus blumei in nutrient solution containing 0 -24 mg/L Al and in Al-toxic tatum subsoil under greenhouse conditions. Inhibitory effects of Al-toxicity were observed on shoot growth, that were cultured in nutrient solution having Al concentration 8 mg or above, while inhibition of root growth was observed in solution having Al concentration 16 mg/L or above.…”