Relationship of Pre-anthesis Fructan Metabolism to Grain Numbers in Winter Wheat ( Triticum aestivum L.)

Four cultivars of winter wheat were analysed for non-structural carbohydrates at four harvest dates starting at inflorescence initiation and ending at anthesis. Grain number was determined from comparable plants harvested at maturity. Fructose, glucose, sucrose, and fructans were quantified in extracts of stems and inflorescences. In stems the content of the four carbohydrates increased until about a week before anthesis. During the week before anthesis the trend for the sugars was variable, but fructan content continued to increase. In inflorescences, trends for sugars were similar to those in stems; however, fructan content peaked 7-10 days before anthesis. Peak quantities of fructans in inflorescences and the quantities degraded after the peak were both correlated with grain numbers. The average degree of polymerisation of fructans from stems was 5 with most being in the range from 3 to 7. The degree of polymerisation in inflorescences ranged from 3 to 56. All of these data indicate that inflorescences differ from stems in their control of fructan metabolism.