Effects of Thermal and Salt Treatments during Imbibition on Germination and Seedling Growth of Sorghum at 42/19 °C

This investigation tested the influence of thermal treatment of seeds at various stages of imbibition on the germination percentage, speed and growth response of seeds and seedlings. Seeds of sorghum ( Sorghum bicolor L Moench) were treated in 2, 4 or 6 g NaCl l −1 solutions and exposed for 2 h to 45 °C during the first, second or third days of imbibition. Thereafter, the seeds were dried and germinated at 42/19 °C (day/night temperature). Salt treatments did not improve the final germination percentage but increased germination speed over untreated seeds. The higher the salt concentration used, the greater the dry weights of plumules and radicles. Thermal treatment on the third day of imbibition yielded higher germination percentages than untreated seeds, while thermal treatment on the second day gave faster germination. Both the second and third day thermal treatments gave superior germination indices and higher plumule‐to‐radicle ratios. It is concluded that thermal treatment may assist in acclimating seeds to heat stress.