Abstract
Rheum emodi Wall. ex Meissn (Polygonaceae) is a plant of Garhwal Himalaya reported to be endangered due to over-exploitation for medicinal use and poor seed germination and seedling survival in nature. To determine the optimum germination conditions for this Himalayan medicinal herb, seeds were hot-water pre-treated (80°C then cooling overnight), cold-water pre-treated (10°C left overnight) or placed in a range of gibberellic acid (GA3) concentrations (0.3, 0.6, 0.9 μM) for 24 h. Control seeds were untreated. The seeds were subjected to two light regimes (16:8 h alternate light:dark and continuous dark) at three temperatures (15, 20, 25°C). The highest germination (83.3%) occurred following hot-water pre-treatment and incubation under 16:8 h alternate light:dark conditions at 15°C, with a reduced mean germination time (MGT) of 8 d. The second highest germination (80%) was recorded under dark conditions at 15°C with cold-water pre-treatment with MGT of 11.3 d. The present study indicates a low germination temperature (≥ 15°C), which is the normal temperature in the study area, and light for improved seed germination of R. emodi. Farmers can also use hot-water pre-treatment prior to sowing the seeds.