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  • Author or Editor: Kay Ryugo x
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‘Elliot’ pear is resistant, but not immune, to the fire blight-inciting bacterium, Erwinia amylovora. ‘Elliot’ fruit has the shape and coloration similar to those of ‘Doyenne du Comice’ and ‘Tyson’ (Hedrick, 1921).

Open Access
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The endosperm-nucellus of the almond increased in percentage dry weight as the volume decreased; the increase was accompanied by a textural change. Free GA increased from the time the embryo was microscopic in late April to a maximum when the embryo was partially developed, a period of approximately 3 weeks. GA decreased slightly from mid-May to early June when only the remnants of the nutritive tissues remained. GA-glucosides decreased while embryo development was occurring. Injection of 2-14C-mevalonic acid into the endosperm-nucellus resulted in rapid incorporation of label into presumptive GA precursors, suggesting that some gibberellins are synthesized in situ.

Open Access
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Aqueous and ethanolic extracts of the Prunus endocarp were found to delay germination and subsequent growth of peach, almond, cucumber and plantago embryos. Constituents in the extracts were partially purified by chromatographic separation on paper and thin-layer plates. While there are several components in the inhibitor complex, one has been identified tentatively as abscisic acid by its Rf values in different solvent systems, reactions with chromogenic reagents and absorption of ultraviolet light. Most of the inhibitors in the endocarp were fixed on anion exchange resins but not on nylon or hide powder. Mild acid hydrolysis of the endocarp yielded no HCN which eliminates cyanoglucosides as having a role in the inhibition. The extractives induced a marked reduction in oxygen uptake by germinating pea seedlings and growth inhibition in cucumbers. The latter was reversible with gibberellic acid (GA).

Open Access
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Abstract

Thirteen-year-old scions of ‘Bing’, ‘Black Tartarian’ and ‘Royal Ann’ on Vladimir (Prunus cerasus L.) grew to heights of 3 to 4 m while the same cultivars grafted about the same time on seedlings of P. avium L. or P. mahaleb L. or cuttings of Stockton Morello (P. cerasus L.) were 2 to 3 times as large. The trees on Vladimir tended to be willowy and were anchored poorly. Scions grafted on 2-year-old root suckers of dwarfing stock, when left unpruned, have borne crops continuously since the 2nd leaf. A training system utilizing these dwarfing and fruiting characteristics to advantage is described.

Open Access
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Analyses conducted on acetone powder and extracts prepared from ‘Golden Delicious’ apples collected from late July to early September revealed that the polyphenoloxidase (PPO) activity increased during the maturation period while the substrate level decreased. Protein content decreased initially and then increased as the apple approached full maturity. Similar analyses on other cultivars revealed wide variations; ‘Tohoku #3’ had low PPO activity and substrate level which may make this cultivar a good candidate for mechanical harvesting provided it possesses other acceptable horticultural characteristics.

Open Access
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Abstract

Heading back of 2nd flush growth to basal buds on vigorous young trees at different times of the year indicated that buds were converted from a vegetative to a reproductive state within 4 weeks after they were formed at the shoot apex. Defoliation or defoliation plus etiolation of 7 terminal nodes in July did not deter the buds at these nodes from differentiating pistillate flowers for the next season. Pruning greatly accelerated the differentiation processes.

Open Access
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Abstract

Yuzuhada is a Japanese term given to a fruit disorder which often occurs when certain cultivars of the oriental pear, Pyrus serotina are grafted onto seedlings of that species or of P. betulaefolia. A literal translation of the name, yuzuhada, is pomelo (citrus) skin disease because in severe cases, fruits of some varieties develop surface depressions similar to thick citrus rind. The disorder was described in 1928 by Mizuno (3), but it is practically unknown to American horticulturists. According to Hayashi (1), and Hayashi and Wakisaka (2), the symptoms of yuzuhada are similar to those of hard-end and black-end of Bartlett pear in that the fruits fail to soften normally and often manifest some darkening of the distal end near the calyx lobes. That these two disorders occur on the same rootstock species and that some of their manifestations appear to be similar suggest that a relationship might exist between the two disorders. This investigation dealing with stock influence on the scion variety was, therefore, undertaken to ascertain if there were any correlations between the potential of a rootstock to produce black- or hard-end of Bartlett and yuzuhada symptoms in varieties of P. serotina and two interspecific hybrids.

Open Access
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Abstract

Levels of incident photosynthetic photon flux density (PPFD), net photosynthetic rate (Pn), and stomatal conductance (g) were monitored on individual intact kiwifruit (Actinidia chinensis Planch.) leaves at well-exposed and densely shaded canopy positions. Diurnal fluctuations of Pn and g closely paralleled changes in PPFD for exposed leaves. PPFD reaching shaded leaves were extremely low throughout the day; Pn and g were correspondingly low. Pn ranged between 10 and 12 µmol CO2·m-2s-1 when exposed leaves were light-saturated at PPFD between 500 and 700 µmol·m-2s -1. Exposed and shaded leaves had similar chlorophyll concentrations, though the former had significantly higher chlorophyll a:b ratios. Implications relative to leaf canopy design and management are discussed.

Open Access
Authors: and

Abstract

Levels of incident photosynthetic photon flux density (PPFD), net photosynthetic rate (Pn), and stomatal conductance (g) were monitored on individual intact kiwifruit (Actinidia chinensis Planch.) leaves at well-exposed and densely shaded canopy positions. Diurnal fluctuations of Pn and g closely paralleled changes in PPFD for exposed leaves. PPFD reaching shaded leaves were extremely low throughout the day; Pn and g were correspondingly low. Pn ranged between 10 and 12 µmol CO2·m-2s-1 when exposed leaves were light-saturated at PPFD between 500 and 700 µmol·m-2s -1. Exposed and shaded leaves had similar chlorophyll concentrations, though the former had significantly higher chlorophyll a:b ratios. Implications relative to leaf canopy design and management are discussed.

Open Access
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Abstract

‘Hayward’ kiwi fruit (Actinidia chinensis Planch.) samples collected at 20-day intervals after full bloom, May 18, until harvest in late October, were analyzed for carbohydrates, protein, organic acids including ascorbic and dehydroascorbic acids, tannins and polyphenolic substances, and cytokinin-like compounds. Starch is a predominant carbohydrate stored in the carpellary tissue which becomes hydrolyzed as the fruit approach maturity. Quinic acid was the main organic acid in young fruit which disappeared concurrently with the appearance of ascorbic acid. Mature fruit has low concentrations of tannins and polyphenolic substances but many raphides. Types of cytokinins changed as the fruit developed.

Open Access