A FAST AND RELIABLE METHOD FOR MEASURING pH CHANGES AT THE RHIZOSPHERE OF Fe-EFFICIENT AND Fe-INEFFICIENT BEAN GENOTYPES

Abstract

The present research was conducted in order to evaluate five common bean (Phaseolus vulgaris L.) genotypes Fe-efficient and Fe-inefficient on their capacity to decrease the pH of the rhizosphere when subjected to Fe-stress. Seeds were germinated in glass test tubes with nutrient solution (pH of 6.8), agar and a pH indicator (bromocresol purple). A completely random design with six replications was utilized. Bean genotypes showed variation in their capacity to decrease the pH of the rhizosphere; AN-22 and Pinto Mexicano 80 were capable of decreasing the rhizosphere pH as low as 3.0; while Durango 222 and Lagunero 87 did not decrease the rhizosphere pH below 6.0. The methodology used to measure rhizosphere pH was suitable to detect differences among bean genotypes in their capacity to decrease rhizosphere pH.