Effect of some pre-sowing treatments on seed germination and seedling growth of Melia azedarach l. and Tamarindus indica l. trees

Abstract

The present study was conducted during two successive seasons of 2020 and 2021 to determine the effect of some pre-germination treatments on germination and seedling growth of Tamarindus indica and Melia azedarach . In this study, seeds of the two species were subjected to seven treatments i.e. soaking seeds in GA3 at 1000, 2000 and 3000 ppm for 24 h.; immersing seeds in concentrated sulphuric acid for 10 and 20 min.; seed scarification by steel file and untreated (control) seeds. Seeds were sown in poly ethylene pots (25 x 30 cm) under normal environmental condition for germination. The highest germination percentage was recorded in seeds of the two species treated by mechanical scarification, followed by immersion in concentrated sulphuric acid (98%) for 20 and 10 minutes. Meanwhile, the lowest values of germination percentage were obtained with the control, followed by soaking seeds in GA3 at 1000 ppm compared to other treatments. Mechanical scarification, followed by concentrated H 2 SO 4 for 20 and 10 min. led to highly significant reduction in time to attain 50% germination as well as the highest values of vigor index for the tested species in the 1st and 2nd seasons compared to other treatments. Also, the results showed that the pre-germination treatments have a significant effect on the growth performance (shoot and root length, number of leaves, fresh and dry weight of shoots and roots as well as chlorophyll content) of M. azedarach and T. indica . The highest values of the growth parameters were obtained from applying scarification and concentrated sulphuric acid for 20 and 10 min., respectively. The study recommended mechanical scarification and sulphuric acid for 20 minutes for the best seed germination and seedling growth of these tree species.