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- Author or Editor: P. L. Ager x
- Journal of the American Society for Horticultural Science x
Abstract
Nitrogen and K were applied to 26-year-old ‘Western’ pecan [Carya illinoensis (Wangenh.) C. Koch] trees at 0, 56, 112, or 224 kg ha−1, and 0, 93, or 186 kg ha−1, respectively, for 6 consecutive years (1978–1983). There was a positive relationship between N rate and leaf N concentration and shoot growth. The number of new shoots per 1-year-old shoot was increased by N application. Yield was greater using 56, 112, or 224 kg N ha−1 than no N. Nitrogen rate was negatively related to leaf K concentration and curvilinearly related to leaf Mn concentration, but did not affect leaf Ca or Mg. Leaf P and Zn concentrations were reduced during some years by N application. Potassium application increased leaf K concentration in 1980, 1982, and 1983, but did not affect leaf K concentration in other years. Surface applied K moved to the 30–45 cm depth by 1980 and to the 45–60 cm depth by 1982. Potassium rate was positively related to leaf Mn concentration, but not leaf N, P, Ca, Mg, or Fe concentration. Annual yield was increased by K rate only in 1979, but cumulative yield was positively related to K rate.
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.