| Abstract: | Summary In Canada, seeding of agronomically important crops takes place during the early months of spring when temperatures are well below the optimum. Low temperature reduces the rate and success of germination. This in turn can result in slow asynchronous emergence from the soil and poor stand establishment. As emergence is a function of both germination and early seedling growth, the effect of low temperature on these developmental processes is of great interest. This review examines how low temperature affects germination and early seedling growth in relation to biochemical and molecular processes. As Brassica napus L. cv. Westar, canola, does not exhibit primary or secondary dormancy, it serves as an ideal species in which to study low temperature emergence. First, emergence is reviewed by independent sections covering germination and early seedling growth. Germination is dissected into the three phases of germination. Early seedling growth is broken into sections covering storage reserve mobilization, the expression of gene sets related to developmental stages, and the role of ABA. Next, comparisons between chilling injury in seeds and chilling injury in plants, oxidative stress, and seed priming are discussed. Finally, the current state of experimental evidence and results are used to resynthesize low temperature emergence in Brassica napus with final thoughts on future directions. |
