Vernalization

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vernalization The treatment of germinating seeds with low temperatures to induce flowering at a particular preferred time. For example, winter varieties of wheat can be sown in the spring and then be exposed to a temperature just above 0°C for a few weeks. The result of this is that they behave like spring varieties and flower in the same year (otherwise they would continue to grow vegetatively and would not flower until the following year). The stimulus is perceived by the apical meristem (either in the embryo or as an apical bud), and some plant hormones such as gibberellin can be used to achieve the same effect. Compare STRATIFICATION.

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vernalization The promotion of flowering by exposure of a plant to low temperatures. For example, winter cereals will not flower unless subjected to a period of chilling early in their development. Winter cereals are therefore sown in the autumn for flowering the following year. However, if germinating seeds are artificially vernalized they can be sown in the spring for flowering the same year. Biennial plants, such as carrot (Daucus carota), will remain in their nonflowering rosette form until subjected to cold treatment. For vernalization to be effective, the plant tissue must be actively metabolizing and supplied with carbohydrate (i.e. energy) and oxygen. In biennials, perception of the cold stimulus is confined to the shoot apex, and cold treatment of other parts of the plant is ineffective. Some studies have suggested that plant growth substances, including gibberellins and a hypothetical substance called ‘vernalin’, might be involved in the vernalization mechanism, but no conclusive picture has so far emerged.

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vernalization The treatment of germinating seeds with low temperatures to induce flowering at a particular preferred time. For example, winter varieties of wheat can be sown in the spring and then be exposed to a temperature just above 0°C for a few weeks. The result of this is that they behave like spring varieties and flower in the same year (otherwise they would continue to grow vegetatively and would not flower until the following year). The stimulus is perceived by the apical meristem (either in the embryo or as an apical bud), and some plant hormones such as gibberellin can be used to achieve the same effect. Compare stratification.

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ver·nal·i·za·tion / ˌvərnl-əˈzāshən/ • n. the cooling of seed during germination in order to accelerate flowering when it is planted. DERIVATIVES: ver·nal·ize / ˈvərnlˌīz/ v.