Thesis (Ph. D.)--University of Wisconsin--Madison, 1972. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Some effects of post-harvest treatments of abscisic acid (ABA) and kinetin on the maintenance of quality and consumer appeal were studied on young lettuce plants. The treatments employed two concentrations of abscisic acid (1 and 5 ppm), one concentration of kinetin (20 ppm) and a combination of 5 ppm abscisic acid and 20 ppm kinetin. The plants were sprayed to the run-off point and placed in a storage chamber at 3±1°C with relative humidity close to 100%. After 6 weeks of storage all lettuce including untreated controls were in good condition. The chemical treatments did not have any distinct effect on the quality of lettuce as evaluated by a panel of observers for visual quality rating. The 20 ppm kinetin retarded chlorophyll degradation when compared to the control or the ABA-only treatments. Considering chlorophylls A and B separately, the kinetin-treated plants showed a significantly higher chlorophyll A content than other treatments, including the control. The differences in chlorophyll B content followed the same trend but only approached the 5% level of significance. ABA in the 5 ppm + 20 ppm kinetin treatment had a mild antagonistic activity to kinetin, and hence reduced the effect of kinetin on both chlorophyll A and B. Measurement of chlorophyll contents and adjustment to the original fresh weight before the samples were put in storage, provided a common basis to make comparisons for the study of chlorophyll degradation as functions of storage time and chemical treatment. Means of chlorophyll contents reported on this basis showed a trend of degradation from the 5th week to the 7th week. Temperature at 3±1°C and high relative humidity in the storage appear to be favourable for keeping lettuce. Hygenic preparation of the storage chamber also resulted in disease-free product even at the end of 7 weeks in storage. / Land and Food Systems, Faculty of / Graduate

No description available.

No description available.

Thesis (Ph.D.) - University of Queensland, 2005. / Includes bibliography.

This report focuses upon our efforts to evaluate the effect of sustainable versus conventional fertilization practices on subsequent populations of soil-borne pathogens on lettuce roots. The different fertilization treatments included conventional fertilizer, composted cow manure, and a biological soil conditioner. Near plant maturity, lettuce roots were collected from the field and the populations of Pythium and Fusarium were determined. The lowest population of both of these pathogens was found in the plots fertilized with composted cow manure, while the highest levels of Pythium and Fusarium were detected in the plots treated with conventional fertilizer. Further field studies are planned to confirm these initial findings. Of the two pathogens assayed, Pythium is of greatest concern because of its ability to destroy roots and reduce plant growth and vigor. Species of Fusarium are commonly found in soil and on plant roots and usually do not cause damage to plants unless the plants are under stress.

No description available.

Thesis (MSc Plant Pathology)--University of Pretoria, 2005. / Summary in English. Includes bibliographical references. Available on the Internet via the World Wide Web.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

No description available.