Effect of temperature and water potential on germination of medicinal pumpkin (Cucurbita pepo. convar. pepo var. styriaca), black cumin (Nigella sativa L.) and borago (Borago officinalis L.)

There is a little information about the effects of temperature and water potential on germination of medicinal pumpkin, black cumin and borago. The factors include 9 levels of temperatures (5, 10, 15, 20, 25, 30, 35, 40 and 45oC) and 6 levels of water potentials. Results showed that temperature and water potential have significant effect on germination percentage (GP) and rate (GR). GP and GR decresed in three plants with decresing in water potential in all temperatures. Also, GP and GR increased with temperature increasing up to optimum temperature and decreased after it. Sensitivity of GR to temperature and water potential was more than GP. Also, sensitivity of GP and GR to water potential was more than temperature. Sensivity of black cumin germination to temperature and water potential was more than borago, and this was more than medicinal pumpkin germination.