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. 相似文献
Abstract The synthetic activity of protein and changes in the activity profiles of enzymes during cold acclimation were studied in leaves, stems, and crowns of a hardy winter wheat cultivar ( Triticum aestivum L. cv. Horoshirikomugi) and a less hardy winter wheat cultivar (Triticum aestivum L. cv. Norin 61). The results showed that one of the genetic differences between the two cuitivars is found in the activities of protein synthesis under low temperatures. The profiles of the changes in enzymatic activities showed that the adjustment of enzymatic activities was a tissue-specific event to accommodate environmental changes. The synthesis of the enzymes involved in a peroxide scavenging system such as hexokinase, glucose-6-phosphate dehydrogenase, dehydroascorbate reductase, ascorbate peroxidase, and so on started at the acclimation stage, while the phosphoglucose isomerase, which appears to be a maintenance-type enzyme in the wintering wheat, showed a small increase in the activity at later stages of acclimation period in their stems of both cuitivars. When the field was covered with snow, the catalase activity in the leaves started to decrease abruptly, while catalase activities in the stems and crowns did not exhibit appreciable changes during the life under snow. The life-cycle dependent changes in enzymatic activities appear to occur in late March or early April under snow. 相似文献