| Abstract: | Winter rye grain was vernalized, using the restricted moisturetechnique, at various temperatures and moisture levels and therelation between first-leaf blade length and the degree of vernalizationanalysed. There was an inverse relation between these two factors,but leaf length was influenced by both temperature and moisturelevel in a manner quite different from the effect on the vernalizationtemperatures and the major requirement for short-leaf productionproved to be the period of restricted germination normally imposedduring vernalization. Cell counts of the epidermis of the firstleaf blade showed that the reduction in length was due to inhibitionof the earliest phase of leaf extension growth. It is suggested that some growth-promoting substance in theembryo, possibly IAA, is broken down during the restricted germinationperiod. When grain is sown this shortage impedes early leafextension until the level is restored by synthesis or translocation. |
