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S.J. Li, T.J. Facteau, and P. Chen

Several characteristics of amylases involved in starch degradation were studied in extracts from immature (30 days before harvest) `d'Anjou' pears (Pyrus communis L.). Enzyme activity was not detected until after at least 60 minutes of incubation in frozen or lyophilized tissues. Activity increased significantly after 90 minutes and increased linearly after 2 to 12 hours of incubation. Activity was greater, however, in frozen than in lyophilized tissues. Three buffers (acetate, tris-HCl, and imidazole-HCl) were used at a range of pH levels (4.6-8.2) to ascertain the optimum assay system. Highest specific activity was recorded with acetate buffer at pH 5.6. The Km value in this system was 1.43 × 10-3g·ml-1. Specific activity increased as Ca concentration in the reaction mixture increased from 1 to 15 mm CaCl2 but did not change as Ca concentration increased from 15 to 25 mm CaCl2. The `d'Anjou' pear amylases were purified 5.7-fold using ammonium sulfate fractionation.

Open access

T. J. Facteau, S. Y. Wang, and K. E. Rowe

Abstract

Foliar uptake of fluoride (F) resulting from hydrogen fluoride (HF) fumigations was linear with dose (concentration F in μg/m3 × duration of exposure in hours) at F concentrations lower than 17.5 μg/m3. Above this level, duration of exposure was the only important factor and uptake was non-linear with time. Higher leaf N levels resulted in greater F uptake. Production of CO2 was increased more by high F concentration for short periods than by low concentration for longer periods where leaf N was optimal or supraoptimal. Amino nitrogen (AN) levels increased more at low F concentration for longer periods than high concentration for shorter periods. The response patterns were similar at optimal and supraoptimal leaf N. Protein nitrogen (PN) decreased with increasing In HF dose at optimal and very low leaf N levels. Changes in PN and AN were significantly correlated in leaf tissue with optimal, but not in tissues with deficient or supraoptimal N.

Open access

T. J. Facteau, K. E. Rowe, and N. E. Chestnut

Abstract

There was no reduction of surface pitting of sweet cherry (Prunus avium L.) or bruising in 7 trials over a 4-year period as a result of applications of CaCl2 from 950, 1400, or 3800 mg Ca/liter in single or multiple applications from 1 to 6 weeks before harvest. Cherry fruit firmness was increased and fruit size was decreased by increasing the amount of Ca applied in 3 out of 7 trials. The time of application, from shuck stage to 1 week before harvest, was not critical.

Open access

T. J. Facteau, S. Y. Wang, and K. E. Rowe

Abstract

Increased flouride (F) fumigation levels resulted in decrease in percent ‘Royal Ann’ pollen germination and pollen tube growth. As dose (hour x concentration in μgF/m3) increased, ‘Van’ pollen tube growth in vivo decreased. A linear relationship between increased dose and flouride residue in the flowers was shown.

Free access

T.J. Facteau, N.E. Chestnut, K.E. Rowe, and C. Payne

Gibberellic acid-treated `Napoleon' sweet cherry (Prunus avium L.) fruit were firmer but lost more weight during brining than nontreated fruit. GA treatment delayed fruit softening, thereby extending the harvest period. Mean fruit weight was increased by GA only in fruit harvested at a more mature state. GA delayed soluble solids accumulation in one of two years. In one orchard district, solution pockets were less frequent in GA -treated fruit in 1988 and in late-harvested GA -treated fruit in 1989. GA treatment did not alter the incidence of fruit with solution pockets in a second district in 1988 and increased levels of solution pockets in fruit harvested later in 1989. Incidence of fruit with solution pockets increased as maturity progressed in nontreated fruit in both years and both districts. Chemical name used: gibberellic acid (G A).

Open access

T. J. Facteau, K. E. Rowe, and N. E. Chestnut

Abstract

Multiple applications (1-3) of 10 and 50 ppm GA3 to ‘Bing’ and ‘Lambert’ (Prunus avium L.) sweet cherries increased fruit firmness and weight, and delayed harvest. Firmness was positively related to dose of GA3 (number of applications × concentration), soluble solids (SS), and In leaf/fruit ratio. GA3 interacted with SS so that the effect of GA3 dose on firmness was increased at higher SS levels. Fruit coloring was delayed by GA3. Chemical name used: gibberellic acid (GA3).

Open access

P. M. Chen, W. M. Mellenthin, S. B. Kelly, and T. J. Facteau

Abstract

‘Bing’ sweet cherries (Prunus avium L.) harvested at commercial maturity were commercially packed and stored in 6 low-02 and 1 high-C02 controlled atmospheres (CA) at −1.1°C for 35 days and in a second study were stored in either 1.5% 02 and 0.8% C02 or 12% 02 and 10% C02 at 5.6°, 3.3°, or 1.1°C for 23 days. Fruit stored at 0.5–2.0% 02 with 0.03% C02 maintained a higher percentage of very green stems, brighter fruit color, and higher levels of titratable acids than those stored in air at −1.1°C for 35 days. High C02 atmospheres conserved fruit brightness and TA level but did not prevent stem discoloration. The only effect of lowering temperature from 5.6° to 1.1° was a slight increase in fruit firmness after storage.