Effect of temperature on seed germination parameters in Kalmegh (Andrographis paniculata Wall. ex Nees.)

Kalmegh (Andrographis paniculata Wall. ex Nees) is a medicinal herb of tropical south east Asia and native to India and Sri Lanka. It has been used herb for liver ailment in all prevailing systems of medicine viz. Ayurvedic, Unani, Homeopathic and modern throughout most of the south East Asian countries viz. China, India, Sri Lanka, Indonesia, Thailand, Burma, and Vietnam, etc. Commercially cultivation of Kalmegh is done through seeds. Optimal germination potential, temperature and first as well as final count day are three primary parameters for developing the seed quality standards. Germination of Kalmegh variety ‘CIM-Megha’ was carried out at six constant temperatures at an interval of every ‘5 °C’ from ‘15 to 40 °C’ temperatures coupled with 16 h light and 8 h dark photo period. The temperature of ‘25 °C’ was found optimally suitable with ‘94.6’ and ‘23.6’ percentage of germination and germination energy, respectively, while the temperature at ‘40 °C’ was deleterious with no germination. Significant decrease in percentage of germination and germination energy was observed at ‘15 °C’, ‘20 °C’, ‘30 °C’ and ‘35 °C’ of temperature in comparison to ‘25 °C’. The study further revealed that days 5-6 and days 7-9 after seed sowing were the ideal for first and final count, respectively for seed germination of Kalmegh.