Allelopathic effects of Rumex azoricus on lettuce: impacts on seed germination and early growth

Abstract: Members of the Rumex genus possess allelochemical compounds that vary depending on the plant part and extract concentrations. Therefore, this study aimed to investigate the allelopathic effects of extracts from the roots, stems, and leaves of Rumex azoricus at concentrations of 0%, 25%, 50%, and 100% on the seed germination of a lettuce plant in a laboratory setting. The results indicated that stem extract was most effective for enhancing germination percentage (68.67%), germination speed (5.12 seeds/time interval), and subsequent traits related to germination percentage (50%), germination speed (3.6 seeds/time interval), as well as subsequent traits in control seeds. The 25% extract concentration improved germination percentage (68%) and germination speed (5.05 seeds/time interval), along with subsequent traits compared to control (0%), which exhibited the lowest germination percentage (50%), germination speed (3.6 seeds/time interval), and related traits. The combined results also demonstrated that 25% stem extract significantly increased germination percentage (80%), speed (5.85 seeds/time interval), root length (1.2 cm), root fresh weight (0.032 mg), shoot length (2.2 cm), and shoot fresh weight (0.06 mg) in contrast to control seeds, which showed the minimum germination percentage (50%), speed (3.6 seeds/time interval), root length (0.17 cm), root fresh weight (0.006 mg), shoot length (0.95 cm), and shoot fresh weight (0.03 mg). The allelopathic effects of R. azoricus extract varied depending on the plant part and concentration; both stem and leaf extracts at low concentrations were the most effective, whereas root extracts at all concentrations produced results similar to those of control seeds.