Aluminium tolerance of four bean (Phaseolus vulgaris L.) varieties

Abstract

Four bean (Phaseolus vulgaris) varieties (‘Rosecoco'– GLP 2, ‘Mwitemania'– GLP X 92, ‘Mwezi Moja' – GLP 1004, and French bean – ‘Amy') locally obtained from seed merchants in Kenya were investigated for their aluminium tolerance under two techniques of screening, namely root elongation and staining. Using hydroponic system, 3-day old seedlings were subjected to aluminium treatments of 0, 3, 5, 10, 20 and 50 µM, followed by subsequent root elongation studies and staining by Eriochrome cyanine R. The two techniques in combination produced the following increasing order of aluminium tolerance: French bean < Mwezi moja < Mwitemania < Rosecoco. Root elongation produced superior differential rating in assessing for aluminium toxicity in the beans. On the other hand, Eriochrome cyanine R staining lacked clear differentiation especially where there were marginal differences of Al tolerance. It follows that, screening for aluminium tolerance in common beans can preferably be accomplished through the staining technique procedure and only be followed by root elongation method under circumstances of ambiguity or where difference in tolerance are inseparable through the former.