SUCROSE SYNTHASE, INVERTASES, AND SUGARS IN GROWING ASPARAGUS SPEARS

Asparagus (Asparagus officinalis L.) spear tips lose sucrose rapidly after harvest and this probably contributes to spears' short postharvest life. As the first step towards controlling this loss of sucrose and possibly improving postharvest life, the activities of sucrose-cleaving enzymes, and levels of sugars were measured in tips and 3 cm sections of spears from tip to butt. Sucrose was the major sugar in tips but not in the rest of the spear. Glucose and fructose were almost equimolar throughout the spear and increased fivefold from tip to butt. Fructose was always slightly more abundant than glucose. Sucrose synthase, bound acid invertase, and neutral invertase activities were similar in both tips and spear sections. Soluble acid invertase activity in the middle section of the spear was 4-5 times that of tips and butts. Sugar composition and enzyme activities in spear sections and tips were not closely correlated.