ABSTRACT
This chapter reviews the carbohydrate physiology and biochemistry of Allium species. The nonstructural carbohydrates in Alliumspp. include glucose, fructose, and sucrose together with a series of oligosaccharides, the fructans. Under controlled conditions Steer examined the influence of day/night temperature on the accumulation of nonstructural carbohydrates within a cultivar. Carbohydrates accumulated in the leaf blades and leaf bases only when both phytochrome photoequilibrium and photoperiod were suitable for bulbing. Very little information is available for comparing the nonstructural carbohydrate content of different Allium species. Additional comparisons between species and cultivars with respect to nonstructural carbohydrates are required. Relationships between the fructan content and the geographic origin of Allium species may suggest why Allium species contain different amounts of nonstructural carbohydrates although they have similar enzyme systems. The activities of the enzymes and the flux rate of carbon through the carbohydrate pools should be measured in individual leaf bases from the stage of bulb initiation until maturity.
