Adaptation To Soil Acidity By Common Beans (Phaseolus Vulgaris L.) is Associated With Root Morphological Traits and Structures

Abstract Aims Common bean is an important source of food and fodder and is used to improve soil fertility when integrated in cropping systems through intercropping or rotation. Although widely grown by smallholders in Ethiopia, its productivity is constrained by several factors including soil acidity, which limits nutrient availability and uptake. The negative effects of soil acidity may be mediated by root system morphology and structure. Therefore, the aim of this study was to determine if root traits in common bean are associated with tolerance to soil acidity. Methodology The study was laid out in a split-plot design, whereby soil amendment practices with phosphorus (+P or -P) and liming (+lime or –lime) and their combinations were assigned to main plots and varieties to subplots. Two improved varieties (Nasir and Deme) and two farmers’ varieties (Polpole and Pantarkin) of common bean were evaluated under each soil amendment practice. Results Farmers’ variety Polpole produced significantly (p< 0.05) more hypocotyl roots (14.17) with a wider hypocotyls angle (5.87°) than other varieties. In addition, Polpole had a larger tap root diameter (2.57 mm) and length (34.10 cm) in plots amended with P. The improved variety Deme showed a higher number of basal roots (14.0) and basal root whorls (4.20) as well as lower basal root angle (0-15°) in plots amended with P and lime. Analyses demonstrate that common bean varieties differ in their ability to tolerate soil acidity due to differences in their root morphological and structural traits. Conclusion The results suggest an opportunity to identify and further develop acid tolerant varieties for low input farming systems to improve and enhance bean productivity and efficiency of the agro ecosystem at large.