Impacts of high temperature on embryonic growth and seed germination of dill (Anethum graveolens)

Temperature is the main exogenous factor that determines the growth, development and productivity of agricultural plants, including seed germination. In this work, we studied the thermosensitivity of heterogeneous dill seeds (Anethum graveolens). The study aimed to study the short-term (1-5 days) effect of high temperature (40 degrees C) on the growth of the embryo and germination of dill seeds formed on different umbels of the mother plant. The growth of the embryo had a significant effect on seed germination (r = 0.976; P < 0.001). Seeds collected from primary umbels have a more developed embryo and can overcome the effects of thermal stress. We also found that the duration of heat exposure at 40 degrees C, leading to a decrease in viability, can vary from 1-5 days for seeds from primary umbels, to 1-2 days for seeds from secondary umbels, which, in our opinion, is due to the heteromorphism. The influence of the place of seed formation on the mother plant and the high temperature during germination is critical for embryo growth and dill seeds' germination.