Influence of daylength on vernalization of winter rye.

Abstract

In 1958-61, germinating seeds, seedlings and young plants (10-14 days old) of winter rye cv. Petkuser were subjected to cold treatment (+6 degrees C) for varying periods, and to natural (winter), continuous or 8 hr photoperiod before, during and after cold treatment. Growth (fresh-and dry-weight) and development stage were periodically determined and plotted, and heading times (from end of cold treatment) recorded. In continuous photo-period treatments, growth was more pronounced and heading earlier with incandescent bulbs than with fluorescent tubes used for additional illumination. Inherent growth depressions (at the end of the vegetative phase and after the final spikelet number was reached) were found to interact with the treatments. The results as a whole led to the following conclusions for winter rye. Short-day treatment retards heading (R) by a direct depression of growth, but also accelerates it indirectly (A) by accelerating differentiation of flower primordia when plants are subsequently exposed to continuous photoperiod. (A) reaches a limit, but (R) goes on increasing; hence the net effect of prolonged short-day treatment is to retard heading. In plant vernalization, heading is earliest when cold and short-day treatments are combined. After optimum vernalization of seeds by prolonged cold treatment, short-day treatment will only retard heading, since the limit of (A) has already been reached; after a shorter cold treatment of seeds, short-day treatment, if not too prolonged, will accelerate heading.-W.M.S.R. (Abstract retrieved from CAB Abstracts by CABI’s permission)