Studies on the Persistence of Rape Seeds (Brassica napus L.), Emphasizing their Response to Light

Abstract

Rape seed showed a range of responses to light. When tested under standard germination conditions, they were unresponsive to light but under unfavourable germination conditions they tended to be inhibited by light. After prolonged exposure to sub-optimal germination conditions in darkness rape seed exhibited light sensitivity. Their germinability in darkness was considerably reduced, whilst their germinability in light was high. This light sensitivity was subsequently lost. Seeds being transferred from darkness to light during the germination test were not able to react to light any more. So, during germination tests in darkness seeds developed skotodormancy. Generally, there was no change of germinability when rape seed were imbibed under sub-optimal germination conditions in light. In one cultivar light inhibition was imposed but seeds of this cultivar remained highly germinable in darkness as well. So, after imbibition in light rape seed were never dormant in darkness. A pot experiment carried out to test the conclusions of the previous laboratory experiments under a more natural environment confirmed the strong impact of the light environment on the ability of rape seed to persist in darkness. It also confirmed genotypic differences identified in the laboratory studies.