Thesis (MscAgric (Horticulture))--University of Stellenbosch, 2008. / Commercial production of sweet cherries has recently increased in South Africa, with more than 400 ha planted by 2006. Cherry, a high chilling fruit variety, is however not suited for the mild winter climate of South Africa. This was recognizable through common observed symptoms of delayed foliation and poor fruit set. In addition, cherry is exposed to long and hot summers in the postharvest period. The objective of this study was to evaluate cherry cultural practices that can manipulate (reduce) the trees chilling requirement under South African conditions. Cultural practices where aimed at increasing reserves (nitrogen, cytokinin and carbohydrates) in the tree. In addition, bud dormancy progression of cherry buds was quantified to determine the bud dormancy progression pattern under mild winter conditions. This was achieved through sampling of cherry shoots from different cherry production areas which was then forced in the growth cabinets. A model was developed to identify possible factors and groupings that can explain the cherry bud dormancy pattern. A model, comprising two joined straight lines, was fitted in order to characterize bud dormancy behaviour for sweet cherry cultivars under mild winter conditions. All cherry cultivars followed the expected pattern of entrance and exit from dormancy. Factor analysis showed that factors related to the entrance into dormancy primarily characterize bud dormancy behaviour. Bud dormancy patterns were also a function of environmental conditions within a year as shown by cluster analysis. In addition, buds entered dormancy in mid-summer and remained dormant until chilling accumulation commenced. Bud dormancy release was generally extended over a three to five-month period for all cultivars. Prior to spring budburst exit of both lateral and terminal buds occurred rapidly. Data indicate that there is no ecodormant phase for cherry under the prevalent climatic conditions in South Africa. Further experimentation was aimed at increasing reserves within the trees through cultural practices. In the nitrogen trials, fertilization in the postharvest period had no significant effect on field budburst or bud dormancy progression in one-year-old shoots. Time of flowering was advanced in N treatments during 2007 only. Yield was not significantly increased. Therefore, in this trial, N fertilization in the postharvest period did not significantly reduce the chilling requirement of mature sweet cherry trees under mild winter conditions. Application of particle films (Surround® and Raynox®) or ethylene inhibitors (Retain®) in the summer did not reduce the heat stress the trees experienced. Treatments had no significant effect on carbon assimilation, stomatal conductance, leaf surface temperature, fluorescence, bud dormancy, budburst, flowering and fruit set. Cytokinins sprays (benzyladenine) in autumn did not affect bud dormancy progression, spring budburst or flowering. Hydrogen cyanamide application in spring significantly advanced budburst, time to full bloom and increased yield. Promalin® and Retain®, however, had no significant effect on budburst, flowering or yield. It is therefore evident that cherry, due to its unexpected bud dormancy behaviour and its inability to be significantly influenced by several cultural practices, adapts poorly to South African climatic conditions through not reducing its chilling requirement significantly.

The tart cherry (Prunus cerasus) is the most significant fruit tree crop in Utah, accounting for roughly 51% of the total statewide commercial fruit acreage. In order to accommodate harvesting equipment, tart cherries are grown in conventional orchards with large trees spaced up to 5.5 meters apart. New methods of harvest are adapted to smaller trees in tighter spaced high density (HD) orchards. HD orchards bear fruit earlier in the orchard life than conventional orchards, but likely require different pruning and management strategies, which have not yet been determined for tart cherry. Experimental HD orchards were used to determine the type of renewal pruning cuts to maintain orchard productivity, and to determine whether mechanical pruning (hedging) could be used to maintain tree size. It was found that when removing branches during pruning, leaving the branch stub at least 10 cm long greatly increases the likelihood of getting adequate renewal growth. Mechanical hedging at bloom or 45 days after bloom did not change yields or fruit quality when applied to a well-pruned and maintained orchard. Spray pattern analysis in these canopies suggested that hedging creates a more consistent canopy density than unhedged HD canopies. This research provides distinct guidelines on renewal pruning of tart cherry to maintain productivity, and shows that mechanical hedging strategies can be a viable option for maintaining tree size in HD plantings without increasing pruning costs.

A positive relationship between foliar copper levels and fruit firmness in apricots was established in the late 1980’s. A review of the literature and discussions with both national and international researchers led to research upon the influence of foliar applied copper on fruit quality. Studies were initiated using cherries, which in addition to being a soft fruit also suffer from rain induced fruit cracking. Results of initial studies suggested that the treatment should be applied to other fruit crops to determine if similar responses occur in these. To this end two further experiments were conducted on apples. As a result of this research, a practical means of reducing rain induced damage to cherries was developed. This finding has major ramifications for all cherry growing regions of the world. / Doctor of Philosophy (PhD)

Bibliography: leaves 169-185.

Die Broschüre fasst die Ergebnisse von Untersuchungen zum Süßkirschenanbau mit Regenschutzüberdachung zusammen. Unter der Überdachung ist der Anteil an geplatzten Früchten bedeutend geringer. Um den Anbau wirtschaftlich zu gestalten, sollte die Pflanzung nur mit ertragreichen Sorten mit großen, festen Früchten an geeigneten, nicht spätfrostgefährdeten Standorten erfolgen. Notwendig ist ein intensives Anbausystem mit schwach wachsenden Unterlagen sowie eine bedarfsgerechte Bewässerung und Düngung. Ebenso wichtig ist eine ausreichende Befruchtung. Bei einer Standzeit der Anlage von 20 Jahren, einem mittlerem Ertrag von 100 dt/ha und einem durchschnittlichem Erlös von 2,25 €/kg ist der Anbau von Süßkirschen unter einer Regenschutzüberdachung wirtschaftlich.

Thesis (M.S. in horticulture)--Washington State University, December 2008. / Title from PDF title page (viewed on Apr. 17, 2009). "Department of Horticulture and Landscape Architecture." Includes bibliographical references.

Thesis (D. Min.)--Gordon-Conwell Theological Seminary, 2006. / Abstract and vita. Includes bibliographical references (leaves 127-130).

Thesis (D. Min.)--Gordon-Conwell Theological Seminary, 2006. / Abstract and vita. Includes bibliographical references (leaves 127-130).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1957. / Typescript. Abstracted in Dissertation abstracts, v. 17 (1957) no. 11, p. 2359-2360. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 71-72).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1923. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 262-263).