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  • Author or Editor: Walter J. Kender x
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Abstract

Mature grapevines (Vitis labrusca L. cv. Concord) in a factorial experiment testing effects of nitrogen fertilization, rootstock, flower cluster thinning, weed control, and pruning severity were evaluated for oxidant injury in 1971, 1972, and 1973. Nitrogen at 56 and at 112 kg/ha, own-rooted vines, and flower-cluster thinning reduced the incidence of oxidant stipple over no nitrogen, vines grafted on Couderc 3309 rootstock, and no thinning, respectively. In 1971, a relatively dry growing season, vines in clean-cultivated plots showed less oxidant injury than vines in sod plots. Pruning severity and training system had no influence on oxidant stipple development. Total N concentration of tissue was negatively correlated to oxidant stipple severity. The interactions between flower cluster thinning and weed control, rootstock, and N fertilization were significant, where thinning moderated the deleterious effects of these factors.

Open Access

Abstract

Orchard and greenhouse experiments were conducted to determine the influence of foliar applications of 6-benzylamino purine (BA) on branching of young apple trees. BA at 100 and 500 ppm, applied to actively growing shoots stimulated lateral bud growth on these shoots during the current season. The presence of fruit, termination of shoot growth, and the localization and non-persistence of BA reduced its effectiveness in breaking apical dominance. For optimum response to BA, multiple spray applications to actively growing shoots in a non-fruiting condition were required. Spray applications of BA failed to induce lateral bud growth on previous season’s wood.

Open Access

Abstract

Calcium arsenate has been used to control the maggot in the lowbush blueberry fields of Maine since the late 1920's (6). The ability of arsenic to accumulate in the soil from repeated use to crops is known and has been reported by various researchers (1, 2, 3).

Open Access

Abstract

2-Chloroethylphosphonic acid (Ethrel), applied to grapevines as an aqueous spray at 100, 200, or 400 ppm, induced hard seed formation in 6 of 13 seedless cultivars studied. Viable seeds were produced in 2 of these cultivars.

Ethrel also promoted femaleness in the staminate flowers of the SO4 rootstock, resulting in fruit and hard seeds in this normally fruitless cultivar.

Open Access

Abstract

Lowbush blueberry fruit, exhibiting the characteristic double sigmoid growth pattern, were analyzed for endogenous gibberellin-like substances, auxins, and inhibitors on 10 sampling dates throughout their ontogeny. During the initial berry enlargement period (stage I) from 0 to 26 days after anthesis, gibberellin content was high and auxin and inhibitor contents low. Gibberellin-like substances reached a peak of 2.1 GA3 equivalents (ug/g dry weight) 26 days after anthesis. At the onset of growth stage II, gibberellin activity declined sharply and remained at a low level throughout the developmental period. During the stage of retarded berry growth, 26 to 48 days after anthesis, auxin activity increased markedly followed by a decrease prior to the start of growth stage III.

All 3 growth substances were at non-active levels during the ripening period. However, inhibitor activity increased sharply as berries developed blue coloration, 61 and 69 days after anthesis. The growth promoting substances were associated with the premature phases of blueberry fruit development and the inhibiting substances with senescence. Auxins and inhibitors were low in flower buds and open flowers while gibberellin-like substances exhibited slight activity in these tissues.

Open Access

Abstract

An effective and simple system for studying ethylene evolution from apple (Malus domestica Borkh.) shoots was devised and used to follow seasonal patterns of ethylene evolution, as well as changes in ethylene evolution following ethephon and shoot bending treatments. Field studies using intact two year wood of spur and non-spur strains of ‘Delicious’ and ‘McIntosh’ showed similarly high levels of ethylene early in the season which subsequently declined. The large differences in ethylene evolution between sampling dates may have been caused by climatic differences at the time of sampling. No differences in ethylene evolution were detected among strains or cultivars although differences in flowering were observed in the following season.

Open Access

Abstract

‘Miller Sturdeespur Delicious’ apple (Malus domestica Borkh.) trees made less extension growth than ‘Imperial Red Delicious’ (non-spur) under controlled conditions. No differences in extension growth were measured between ‘MacSpur’ and ‘Imperial McIntosh’ (non-spur) trees. Development of the spur-type morphology was determined by the number of lateral buds which grew into spurs during the second growing season. Application of (2-chloroethyl)phosphonic acid (ethephon) alone, or in combination with butanedioic acid mono-(2, 2-dimethylhydrazide) (daminozide) decreased extension growth and increased shoot ethylene evolution in growth chamber studies, and promoted flowering in the field. Application of daminozide plus ethephon was more effective than ethephon alone. Daminozide alone did not affect shoot ethylene. No change in ethylene evolution or shoot development was detected following applications of gibberellin 4/7 (GA) or 2, 3, 5-triiodo benzoic acid (TIBA) to spur or non-spur type trees. Bark scoring had no effect on shoot ethylene. However, this treatment also promoted flowering of young trees in the field. It is suggested that while some manipulations can increase shoot ethylene evolution and also promote flowering, the ethylene evolved following treatment operates indirectly by retarding growth, rather than by directly stimulating flower bud initiation.

Open Access