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  • Author or Editor: J. T. A. Proctor x
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Abstract

The growth and cropping of apple trees, as with other crops, is dependent largely upon environment. The environment consists of two distinct components, the soil and the atmosphere, which, while sharply divided by the surface of the earth, interact with each other. The aerial component’s influence on production can be considered on three scales. The macro scale and hence macro climate is a regional climate, e.g. the Okanagan Valley of British Columbia. The next scale is the individual farm, or less, where the macroclimate can be modified by factors such as exposure, altitude, slope and aspect. The resultant local climate is the mesoclimate. Microclimate, the third scale, includes detailed studies close to the earth’s surface, and within the orchard and tree.

Open Access

Abstract

‘Summerland’ (regular-bearing) and ‘Macspur’ (spur-bearing) apple trees (Malus domestica Borkh.) on Mailing (M) 26 rootstock were grown in pots under 4 shade treatments (100%, 88%, 50% and 12% full sun) and with grass, bare soil, and white plastic ground covers. ‘Macspur’ trees grew and flowered more than ‘Summerland’ trees. The 2 strains responded similarly to shade, but responded differently to ground covers. The greatest increase in fresh weight, number of shoots, and blossom clusters for ‘Macspur’ resulted with white plastic, while the least response was with grass; the reverse held for ‘Summerland’.

Open Access

Abstract

Eleven-year-old ‘Golden Delicious’/M. 26 apple (Malus domestica Borkh.) trees were left unthinned (483 fruit/tree), thinned to one fruit/spur (370 fruit/tree), or completely defruited. Leaf water potential, leaf stomatal conductance, and leaf water content were monitored during the growing season. From 3 weeks after thinning and continuing to harvest, trees with an average of 483 or 370 fruit had significantly lower leaf water potentials than defruited trees. Trees thinned to 370 fruit had consistently higher leaf water potentials than unthinned trees with 483 fruit. Leaves on unthinned or one fruit/spur trees had higher stomatal conductances than leaves on completely defruited trees, although these differences were detected later in the season than those for leaf water potentials. No treatment differences in leaf water content were observed. Defruited trees had higher specific leaf weights, longer shoot extension, and greater increases in trunk cross-sectional area than those not defruited. Fruit size was greatest on trees thinned to one fruit/spur.

Open Access

Abstract

Albedo of plantings of strawberry (Fragaria × Ananassa Duch.) and bare soil is a major factor determining the amount of radiation absorbed and used by the crop in various energy exchanges. It varied diurnally and had a mean daily value of about 22% for 7 days in a one-month period during the major plant-growth and fruit-bearing periods. Exposing moist soil, or soil wetting, reduced albedo by about 20%; this reduction was greatest in the 700 to 1350 nm region. Spectral distribution of reflected radiation from strawberry leaves had broad peaks in the 700 to 1300 nm range and was greater than that from soil in the same range.

Open Access
Authors: and

The development of a complete and healthy early season canopy of spur leaves, and later addition of bourse leaves, is essential for fruit set, fruit growth and quality in apple. The present study was undertaken to evaluate the temporal role of spur leaves and bourse shoots on fruit set, growth and return bloom in three apple cultivars and fruit Ca Level at harvest in two cultivars.

Individual flowering spurs on mature wood of “Cox's Orange Pippin”, “Golden Delicious” and “Crispin” apple trees were modified by removing the spur leaves, the bourse shoot, or both, at full bloom and two, four and eight weeks afterwards. Leaf removal reduced fruit set, yield (as fruit number and not size), fruit calcium level at harvest, and return bloom. Defoliationhad its greatest effect on fruit calcium level when done early in the season and plots of this against treatment time suggested a curvilinear relationship. Return bloom was dependent on the presence of the bourse shoots on the spur but not on spur leaves. Return bloom of all three cultivars declined with the number of fruitlets per spur four weeks after full bloom.

Free access

Abstract

Plants of 8 cultivars of celery (Apium graveolens L. var. dulce) exposed to ozone under controlled conditions, or grown in the field under ambient conditions, had comparable injury symptoms but varied in relative susceptibility to injury in the 2 different environments.

Open Access

Abstract

Covering apples with foil bags about 1 month after bloom to harvest had no effect on fruit size or starch content, had inconsistent effects on fruit firmness, and reduced soluble solids, anthocyanin and chlorophyll. Uncovering fruits at various times before harvest allowed formation of anthocyanin, maximum amounts being dependent on cultivar and time of exposure.

Open Access

Abstract

Simulated pest injury to expanding or fully expanded apple leaves (Malus domestica Borkh. ‘McIntosh’) by midrib cutting, lamina pricking, or heat injury from ironing reduced net photosynthesis (Pn). Only cutting of the basal half of the midrib of fully expanded leaves reduced transpiration (Tr). Application of gibberellic acid (GA3), and particularly of 6 benzylamino purine (BA), to lamina lesions damaged by pricking, stimulated Pn. This Pn compensation of injured apple leaves mediated by phytohormones may overcome otherwise damaging levels of some pests.

Open Access

Abstract

Leaflet length and width were used to calculate leaflet area, leaf area and total leaf area per plant for 3-year-old American ginseng, Panax quinquefolius L. grown in growth chambers. On the basis of correlation and regression analyses the product of leaflet length and width (LW) was chosen as the independent variable, but leaflet width squared (W2) also proved satisfactory. Although leaflet shape varied somewhat with position, one regression equation was found suitable. Assuming that the Y-intercept was equal to zero had little effect on the coefficient of determination (R2) or the standard error of estimation so the following equations were chosen to determine leaflet, leaf and total leaf area, respectively: A = 0.66 LW (R2 = 98.92%, ± 0.75 cm2); A = Σ0.67 LW (R2 = 98.36%, ± 2.49 cm2); A = Σ0 .67 LW (R2 = 97.36%, ± 7.83 cm2). The relationship between leaflet LW and total leaf area per plant was used to determine leaf area per plant and LAI for commercial ginseng crops 1, 2, 3, and 4 years old.

Open Access

Abstract

Defoliation (0%, 25%, 50%, 75%, or 100% leaves removed) of apple trees (Malus domestica Borkh.) to simulate loss in photosynthetic area caused by spotted tentiform leafminer (Phyllonorycter blancardella F.) reduced trunk cross-sectional area, yield, and fruiting the following year. Shoot growth responded the year of injury and the following year. Fruit size and maturity also were affected. Punching holes (0, 2, 4, 8 simulated mines of 0.56. cm2) into leaves of mature fruiting trees had no effect on vegetative growth. Fruiting may have been reduced. Leaf punching reduced rootstock growth of small potted apple trees.

Open Access