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- Author or Editor: M. W. Williams x
Abstract
(2-Chloroethyl)phosphonic acid (ethephon) applied to ‘Delicious’ apples before harvest to improve fruit quality can change fruit shape (length/diameter ratio) the next year. The change is magnified when ethephon follows a summer application of succinic acid-2,2-dhnethylhydrazide (SADH) and is most evident on low vigor trees.
Abstract
Limb units and whole trees of ‘Delicious’ and ‘Golden Delicious’ sprayed in the fall with 250 ppm, 500 ppm and 1000 ppm Ethrel significantly decreased fruit set and vegetative growth the following season.
Abstract
Fruit color and quality of ‘Golden Delicious’ apples was directly related to the nitrogen content of the tree. When leaf-nitrogen (N) levels were above 2.2% dry weight, the fruit tended to be large and green. Maximum yields of high-quality fruit were obtained when leaf-N levels were from 1.9 to 2.1% dry weight.
Abstract
In 3 different seasons watercore began to develop in ‘Delicious’ fruit as the minimum temperatures dropped to near 4°C. In 1970 and 1971 watercore started to appear just before a sharp rise in sorbitol level occurred in the limb sap. In 1972 considerable watercore developed in the fruit before a significant increase in sorbitol was observed in the sap.
Abstract
The application of cytokinins and gibberellins alone and in combination to ‘Delicious’ apples just after full bloom affected fruit shape by increasing the length-to-diameter ratio of the fruits. Cytokinins caused fruits to be longer with prominent well-developed calyx lobes. The treated fruit had the appearance of fruits grown where early season temperatures are cool. Gibberellin A4 + A7 caused fruits to be longer but did not appreciably affect the development of the calyx lobes.
Abstract
Lanolin bands containing 2, 3, 5-triiodobenzoic acid (TIBA) applied to the pedicel of apple fruits 2 to 3 weeks after bloom caused the fruits to drop. Naphthaleneacetic acid (NAA) applied to the cut end of defruited pedicels prevented pedicel abscission, but a band of lanolin containing TIBA at mid-pedicel caused most of them to abscise. Cytokinins did not prevent pedicel abscission. Indole-3-acetic acid (IAA) and gibberellins A3 and A4,7 more effectively prevented pedicel abscission of ‘Delicious’ than ‘Golden Delicious’.
Nursery stock of plum (Prunus salicina Lindel., `Casselman') was planted 1 Apr. 1988 in an experimental orchard at the Kearney Agricultural Center, Univ. of California, near Fresno. The trees were enclosed in open-top fumigation chambers on 1 May 1989 and exposed to three atmospheric ozone partial pressures (charcoal-filtered air, ambient air, and ambient air + ozone) from 8 May to 15 Nov. 1989 and from 9 Apr. to 9 Nov. 1990. Trees grown outside of chambers were used to assess chamber effects on tree performance. The mean 12-hour (0800-2000 hr Pacific Daylight Time) ozone partial pressures during the 2-year experimental period in the charcoal-filtered, ambient, ambient + ozone, and nonchamber treatments were 0.044, 0.059, 0.111, and 0.064 μPa·Pa-1 in 1989 and 0.038, 0.050, 0.090, and 0.050 pPa·Pa-1 in 1990, respectively. Leaf net CO2 assimilation rate of `Casselman' plum decreased with increasing atmospheric ozone partial pressure from the charcoal-filtered to ambient + ozone treatment. There was no difference in plum leaf net CO2 assimilation rate between the ambient chamber and nonchamber plots. Trees in the ambient + ozone treatment had greater leaf fall earlier in the growing season than those of the other treatments. Cross-sectional area growth of the trunk decreased with increasing atmospheric ozone partial pressures from the charcoal-filtered to ambient + ozone treatment. Yield of plum trees in 1990 was 8.8, 6.3, 5.5, and 5.5 kg/tree in the charcoal-filtered, ambient, ambient + ozone, and nonchamber treatments, respectively. Average fruit weight (grams/fruit) was not affected by atmospheric ozone partial pressure. Fruit count per tree decreased as atmospheric ozone partial pressure increased from the charcoal-filtered to ambient + ozone treatment. Decreases in leaf gas exchange and loss of leaf surface area were probable contributors to decreases in trunk cross-sectional area growth and yield of young `Casselman' plum trees during orchard establishment.
Abstract
Combination sprays of the growth regulators succinic acid-2-2-dimethylhydrazide (SADH), (2-chloroethyl)phosphonic acid (ethephon), and 2-(2,4,5-trichlorophenoxy)propionic acid (fenoprop) or naphthaleneacetic acid (NAA), applied on ‘Tydeman's Red’ apple trees 4 weeks before the estimated normal harvest date, advanced red coloration and maturity of the fruit sufficiently to permit harvest of approx ¾ of the fruit 2 weeks ahead of the normal harvest date. Of die materials tested the combination of SADH (2,000 ppm), ethephon (500 ppm) and fenoprop (20 ppm) produced the most pronounced effects.
Abstract
A method is described for introducing small quantities of chemicals by gravity flow into terminal shoots of young apple trees. The destruction of acid fuchsin and 14C labelled growth regulators by this method was down the main stem, out to the lateral branches, and into the leaves.
Abstract
‘Delicious’ apples treated with a 1,000 ppm spray of succinic acid-2,2-dimethylhydrazide (SADH) at 70 to 80 days after full bloom were firmer than control fruit at harvest and remained firmer throughout the 9-month storage period.