Carbohydrate Concentrations in Honey Mesquite Roots in Relation to Phenological Development and Reproductive Condition

Abstract

Lower concentrations of total available carbohydrates were found throughout the growing season in roots of honey mesquite trees with many flowers and pods than in trees with a low reproductive potential. Following bud burst, during the period of pod elongation, mesquite trees with few reproductive organs replenished the root issue with carbohydrates faster than did trees bearing many reproductive organs. During the seed development phase of growth, a second decline in root carbohydrate concentrations occurred. This decline began approximately 1 week later in the heavily fruited trees compared to the trees with few pods. Variation in carbohydrate storage among trees differing in reproductive potential largely explains why it is difficult to consistently kill mesquite roots with growth regulating herbicides. When carbohydrates are no longer accumulating in the roots of trees with few flowers or seed pods, those trees with many reproductive organs may be accumulating carbohydrates. Since herbicides such as 2,4,5-T move to the roots when carbohydrates are accumulating, little herbicide would get to the roots in the one case. Optimum herbicide application dates for West Texas would generally occur from May 15 to June 15 and from July 1 to July 15.