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Keywords: 油菜籽,次生休眠,光胁迫

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Oilseed rape seeds (Brassica napus L.) harvested from mature plants require only imbibition of water and a suitable temperature. Despite this absence of primary dormancy, there is evidence that rapeseeds, due to the induction of secondary dormancy, are able to persist in the field for up to 10 years, and thus can emerge as volunteer plants in later crops. In addition, volunteers originate from seeds shed before and during harvest. The level of seed losses is influenced by the timing and technique of harvest, and can reach several thousand seeds per m2. As a consequence of both these effects, problems from volunteer rape occur frequently in subsequent crops.   Volunteer rape has been particularly troublesome in broad-leaved crops. It is a highly competitive weed and due to its prolonged period of emergence, timing of herbicide application is sometimes a problem. Volunteer rape can contaminate the sown crop resulting in heterogenous mixtures of seeds. This not only affects breeding and the production of seed crops, but can also affect growers when they switch from one type or quality of rape to another, or if they grow different rape qualities in one rotation, e.g., rapeseed for human consumption in the normal rotation and rapeseed for industrial use on set-aside land. The problem will not disappear with the introduction of herbicide resistant oilseed rape, as there are no indications that seeds of these cultivars will not have the potential to persist. The ability of rapeseed to persist in the soil for a long time and at high percentages also has to be taken into account in risk assessment of genetically manipulated rape, as rape can escape in space by pollen transfer or in time via the soil seedbank. Although hybridization between oilseed rape and wild crucifers is infrequent, it does occur. Traits, such as herbicide resistance or pest and disease resistance, if transferred into wild plants have the potential to alter the agro-ecosystem significantly.……


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