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  • Author or Editor: Jorge B. Retamales x
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`Bluecrop' highbush blueberries (Vaccinium corymbosum L.) received various N fertilizer treatments for 5 years. Treatments were evaluated by measuring berry yields and leaf N levels annually and bush size after 5 years. Nitrogen fertilizers increased yields and leaf N levels compared with nonfertilized controls. Split applications of urea (half applied at budbreak, half at petal fall) resulted in 10% higher yields than the same amount in a single application at budbreak. Urea and two controlled-release fertilizers (CRF) with different dissolution rates (3 to 4 months, 8 to 9 months) resulted in similar yields and leaf N levels when compared at the same rate of N. The dissolution rate of the CRF materials did not affect yields or leaf N levels.

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Bitter pit is the most important physiological disorders for apples in Chile. During the 1995–96 season, the predictive capacity of bitter pit through magnesium infiltration of the fruit in commercial orchards of three locations in South Central Chile: San Fernando (SF), Curico (CU), and San Javier (SJ) was established. Three orchards were chosen in each location and for each cultivar; fruit were collected 60, 40, and 20 days before commercial harvest. Fruit were infiltrated for 2 min with magnesium chloride at 0.05 M using vacuum levels of 500 or 100 mm Hg for `Granny Smith' and `Braeburn', respectively. The predictive capacity (correlation between predicted and effective bitter pit—after 90 days at 2°C + 10 days at 18°C) increased closer to harvest; with regards to location: SF > CU > SJ. Bitter pit-like symptoms, caused by Mg infiltration stabilized 16 days after infiltration. Bitter pit incidence was better predicted than severity. Bitter pit was better predicted for `Granny Smith' than for `Braeburn'.

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Abstract

AC 94377 (alone and in combination with an auxin), GA3, and BA were evaluated for induction of parthenocarpy and subsequent retention of sour cherry (Prunus cerasus L. ‘Montmorency’) fruit. The persistence of AC 94377-treated fruit was enhanced by addition of CFPA or NAA, persistence and growth being greatest with AC 94377 (3.0 × 10−3 m) + CFPA (7.5 × 10−5 m). CFPA alone (7.5 × 10−5 m) often prevented abscission of flowers, but failed to induce significant fruit growth. Parthenocarpic fruit weighed 30-40% less than seeded fruit. Abscission of parthenocarpic fruit occurred primarily during June drop, and was reduced by an additional application of AC 94377 + CFPA with or without GA3 3 weeks after bloom. AC 94377 and NAA sprayed 2 and 3 weeks after full bloom did not affect the magnitude of June drop of open-pollinated fruit. The rate of fruit abscission was related to time after application, presence or absence of seeds, and relative position between seeded and parthenocarpic fruit. When AC 94377, GA3, and CFPA were applied in lanolin paste to defruited pedicels, only mixtures including CFPA reduced the abscission rate significantly. Chemical names used: l-(3-chlorophthalimido)-cyclohexanecarboxamide (AC 94377); 2-chloro,4-fluorophenoxyacetie acid (CFPA); N-(phenylmethyl)-lH-purin-6-amine (BA); gibberellic acid (GA3); 1-naphthaleneacetic acid (NAA).

Open Access

Bitter pit (BP) is the main physiological disorder of apples in Chile. Its incidence affects pre- and postharvest handling of the fruit and the profitability of this species. Since 1991, its control and prediction have been studied by this research team through field and laboratory trials. The BP incidence is linked to the fruit Ca concentration; however, fruit Ca analysis has not adequately predicted BP incidence in postharvest. Several authors have proposed Ca/Mg antagonism, which has been the basis to develop a predictive method through fruit Mg infiltration (IMG) 40 days before harvest. IMG has been massively used for two seasons in Chile, with 375 samples processed in 1997 and 1170 in 1998. The industry has been increasing its proportion of the samples processed, from 22% in 1997 to 71% in 1998. The most prominent varieties are `Granny Smith' (GS) > `Braeburn' (BR) > `Royal Gala' (RG) > `Red King Oregon' (RKO). The massive use of IMG has obtained predictive capacities (r 2 between BP predicted and BP after 3 months regular cold storage) of 0.8 for `Fuji'; 0.7 for GS, BR, and RG; and 0.58 for RKO. (This reduction in the predictive capacity with regards to the previous research under controlled conditions would, in part, be due to problems in obtaining fruit samples: non-uniform fruit size, inadequate sampling dates, diverse fruit numbers, etc.) Developments are underway to increase the geographical coverage of the service, the predictive capacity of the method for certain cultivars and productive areas and the number of samples processed.

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Abstract

To study the efficiency of fertilizer use by highbush blueberry (Vaccinium corymbosum L.), four mature ‘Bluecrop’ plants were treated before budbreak (21 Apr.) with soil applications of 15N-enriched urea at a rate equivalent to 40 kg N/ha. Leaf samples were collected at 1- to 4-week intervals during the season and whole plants were harvested at the end of the growing season (22 Sept.). Different plant components were separated, dried, weighed, and analyzed by mass spectrometry. Fertilizer-derived N was observed in leaves 2 weeks after application. The percentage of N from the fertilizer peaked 3 weeks after application (16.5%) and declined to ≈11% shortly thereafter. Plants recovered 32% of applied N by the end of the growing season. Leaves accounted for 32% of this total. Shoot tissue also accounted for 32% of fertilizer-derived N in the plant, with the highest percentage accumulating in young shoots. Less than 15% of fertilizer N remained in the soil at the end of the season.

Open Access

We assessed the influence of fruit maturity (percent blue coloration), shipping mode [plane (air) vs. boat (sea)], and storage method [refrigerated air (RA) vs. controlled-atmosphere (CA)] on highbush blueberry (Vaccinium corymbosum L.) quality. Fruit picked when 60% blue had lower soluble solids (SS), higher titratable acidity (TA), and a lower SS: TA ratio than 100% blue fruit both before and after 15 days of storage at 2 °C. They were also firmer and had better internal condition. Fruit shipped by sea to North America had poorer internal condition, were less firm, had fewer sound fruit, and lost more water than those arriving by air and stored for the duration of the sea shipment. CA storage (2 kPa O2 and 8 kPa CO2, 0 °C, 21 days) of fruit shipped by air did not enhance fruit quality in comparison with RA storage (ambient O2 and CO2, 0 °C, 21 days) except by minimizing mass loss. After an additional holding period (20 °C, 3 days) to simulate nonrefrigerated retail conditions, CA-stored fruit had less decay than RA-stored fruit. Maintaining low temperature during the holding period after CA or RA storage was critical in preventing decay, especially for the `Ivanhoe', which was more susceptible to decay, softening, and internal breakdown than `Bluecrop' across all treatments.

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