evaluating the germination indices of two bean species (phaseolus vulgaris l. and pachyrhizus erosus (l.) urban) under drought stress and fertilizer treatments

The quality of seeds plays a fundamental role in advancing agriculture and enhancing crop yields. however, drought remains a major constraint, severely limiting crop growth and productivity. to assess how drought stress and different fertilizer treatments influence the germination performance of two bean species, i.e., common bean (phaseolus vulgaris cv. ‘goli’) and jicama bean (pachyrhizus erosus (l.) urban), a study was conducted at shahrekord university during the 2022–2023 growing season. the experiment followed a completely randomized design with three replications, incorporating four levels of drought stress (0, -6, -9, and -12 bars) and four fertilizer treatments: (1) no fertilizer (control), (2) biofertilizer at the recommended level, (3) vinasse organic fertilizer, and (4) a combination of biofertilizer and organic fertilizer at the recommended level. biochemical markers such as seed proline content, malondialdehyde concentration, and catalase enzyme activity varied significantly across treatments (p < 0.01). jicama bean demonstrated superior germination performance under favorable conditions. when grown without drought stress and treated with the combined fertilizer application, it achieved the highest germination percentage (100%), germination rate (42.48 seeds/day), seedling vigor index (8.55), shoot length (5.66 cm), shoot fresh weight (0.694 g), shoot dry weight (0.125 g), root fresh weight (0.772 g), and root dry weight (0.109 g). notably, moderate drought stress led to the longest root length (6.333 cm) in this species. under severe drought conditions, jicama bean exhibited the highest proline accumulation (0.317 μg/g fresh weight) and catalase activity (0.373 enzyme units/mg protein), indicating enhanced stress tolerance. severe drought stress without fertilizer caused the highest malondialdehyde content (65.89 nmol/g fresh weight). fertilizer applications mitigated the negative impacts of drought stress on seed germination. jicama bean consistently outperformed common bean in germination and early seedling growth, highlighting its resilience and adaptability under varying environmental conditions.