Seasonal Changes in the Carbohydrate Concentration in Pecan Shoots and Their Relationship to Flowering

Abstract

Vegetative and fruiting shoots were tagged in Oct. 1982 and 1983 on ‘Squirrel’, ‘Stuart’, and ‘Cape Fear’ pecan trees [ Carya illinoensis (Wangenh) C. Koch], and flowering was determined the following years. One-year-old shoots were sampled from vegetative and fruiting shoots of each cultivar on 14 Oct. 1982, 9 Feb., 11 Apr., 14 Oct., and 24 Nov. 1983, and 6 Jan. and 17 Apr. 1984 and analyzed for reducing and nonreducing sugars and starch concentrations. Fruiting reduced return bloom of ‘Cape Fear’ in 1983 and 1984, and ‘Stuart’ in 1983. Sugar and starch concentrations varied inversely. Sugar concentrations were increased in November, January, and February, and starch concentrations were greatest during October and April. The total carbohydrate concentration in fruiting shoots of each cultivar was greater or equal to that of vegetative shoots in all but one instance. The degree of return fruiting was positively associated with cultivars with early fruit ripening dates.