Exposure of winter brassicas to periods of low temperature decreases the transition required from vegetative to reproductive growth. This low-temperature exposure also results in the acquisition of freezing tolerance. To investigate the relationship between vernalization and freezing tolerance, homozygous microspore-derived (DH) lines were developed from reciprocal crosses between two winter cultivars of Brassica napus L., cv. Cascade and cv. Rebel. A resulting line, termed Vern-, expressed a high degree of freezing tolerance and was selected for study. Analysis of growth and development revealed that Vern- is a true spring type, having completely lost the vernalization requirement. Using markers previously mapped in B. rapa, it was concluded that Vern- inherited freezing-tolerance alleles from Cascade. With regard to vernalization and flowering time, Rebel, although traditionally classified as a winter type, carries spring alleles at the major and some of the minor loci. Vern- inherited these alleles from Rebel, in addition to one spring allele from Cascade. Thus, spring alleles from both parents were critical in establishing the spring phenotype observed in Vern-.

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The ability to produce ferric acetate in house has provided a new mordant source for use in Newcomer's fluid (6:3:1:1:1 isopropanol, propionic acid, acetone, petroleum ether, 1,4-dioxane) for species with small chromosomes. This method improves on one first published in 1970.