PHENOTYPIC PLASTICITY AND YIELD RESPONSE OF COMMON BEAN (Phaseolus vulgaris L.)VARIETIES UNDER DIFFERENT SOIL MOISTURE LEVELS AT HAWASSA, SOUTHERN ETHIOPIA

Abstract

Common bean (Phaseolus vulgaris L.) is an herbaceous annual leguminous plant grown worldwide for its edible dry seeds or green unripe pods. Bean is particularly suitable for food security due to its short growing cycle and adaptability to different cropping systems. However, the common bean productivity is commonly influenced by different biotic and abiotic factors. Soil moisture is one of the main environmental factors affecting growth and crop yield. A pot experiment was performed to study the effects of moisture stress on the morphological, physiological traits, and yield components of common bean varieties under shade house. The treatment comprised a factorial combination of five common bean Varieties (Hirna, kufanzik, Awash-1, Ado, Chercher) and three moisture levels (control, waterlogging stress, and drought stress) with three replication, totally 15 treatment combination was formed. The drought stress and waterlogging treatments were imposed at 20 days after planting, as soon as the commencement of trifoliate leaves. The result of this finding revealed that all growth parameters were significantly influenced by moisture levels; however, crop phenology influenced by the interaction effect of main factors. photosynthesis rate, transpiration rate, stomatal conductance, water use efficiency, relative water content, chlorophyll-a, chlorophyll-b, chlorophyll (a+b), chlorophyll fluorescence, pods per plant, seeds per plant, grain yield per plant and harvest index were significantly influenced by the interaction effect of varieties and moisture levels, but free proline content was increased similarly under control and drought stress. Stomata number, epidermal cell number, stomata width, and stomata length were only influenced by varieties. The result also indicated that the morphological and physiological reactions to drought stress and waterlogging stress were varies among varieties. Varieties exposed to water stress and waterlogging significantly reduced all tested parameters, except for crop phenology and proline concentration as compared to daily watering (control) treatment. Ado and Awash-1 were relatively susceptible to damage when drought stress and waterlogging stress occurred compared to Hirna, Chercher, and Kufanzik. From this study Hirna and Kufanzik Varieties were considered as tolerant as they were able to maintain their phenotypic plasticity and performed better yield compared to Chercher, Awash-1 and Ado, but Chercher variety was able to tolerate under logging stress than others, however, this study was conducted on a specific common bean variety in one season. Further research is hence needed under field condition to determine the water stress effects on a large number of common bean varieties before generalized conclusions can be drawn.