Effects of variation in seed sources and pre-sowing treatments on seed germination of Tamarindus indica: a multi-purpose tree species in Bangladesh

Abstract

We investigated the morphology and germination of Tamarindus indica seeds in order to discover the effects of variation in seed sources and pre-sowing treatments on germination. The experiment was carried out in the nursery of the Forestry and Wood Technology Discipline, Khulna University, Bangladesh. Seeds were collected from different but healthy trees from various locations in Bangladesh and subjected to four pre-sowing treatments, i.e., control, immersion in cold water (4°C for 24 h), immersion in hot water (80°C for 10 min) and scarification with sand paper. Seed germination was carried out in poly-bags with a mixture of topsoil and cow dung in the ratio of 3:1. The average length of the fresh seeds was 1.35 ± 0.26 cm, their width 1.07 ± 0.20 cm and thickness 0.69 ± 0.11 cm. The results revealed that pre-sowing treatments affected the germination process of seeds, which significantly increased the germination percentage with the cold water (81.67%) and scarification with sand paper (82.33%) treatments, compared with those in the control (58.33%) and hot water treatment (59.00%). In all treatments germination started on average within 5 to 7 days after the start of the treatments and were completed from 13 to 19 days later. The greatest success in germination (82.33%) was found in scarification with sand paper, followed with 81.67% in the cold water treatment. The results of analyses of variance (ANOVA) showed significant differences (p < 0.05) in germination closing dates, seed germination periods and germination percentages among the treatments but no significant difference among seed sources. However, the effect of the interaction between seed source variation and pre-treatment differed significantly in seed germination closing dates and germination percentages. We recommend cold water treatment (submersion of seed at a temperature of 4°C for a 24-h period) for seed germination of T. indica in rural Bangladesh.