Semester

Spring

Date of Graduation

2000

Document Type

Dissertation

Degree Type

PhD

College

Davis College of Agriculture, Natural Resources and Design

Department

Horticulture

Committee Chair

Bradford C. Bearce.

Abstract

Commercial production of strawberry fruit during the off season offers greenhouse operators an alternative crop. Quality of such fruit may be influenced by production system. A series of studies evaluated various aspects of greenhouse production of strawberry fruit. In a study of commercially available strawberry seed rate of germination for cv. 'Sweetheart', was enhanced by cutting the seed coat. Total germinated after 20 days was equal for the cut, the 4x and 8x sand paper scarification treatments. For cv. 'Fresca' the germination percentage was higher in plugs with Sunshine plug mix and Grodan Orchid Greenmix when compared to rockwool (RW) and rockwool plus coal bottom ash (CBA). In a nutriculture study of cv. 'Fresca' strawberries, vegetative growth was enhanced in CBA compared to RW. The next study of nutriculture grown cv. 'Fresca' found no significant differences in production measurements (days to first flower, days to first fruit, total number of flowers, and primary fruit fresh weight) due to substrate or nutrient solution strength. This study also found that color characteristics, internal/external chroma and hue, were responsive to both substrate and nutrient solution strength. The cv. 'Fresca' leaf and petiole tissue analysis showed above the recommended levels for calcium, boron, iron, manganese. Boron increased significantly in the Ft. Martin CBA grown plants. Repeating the nutriculture study with Ft. Martin CBA and RW control with commercially available cultivars (Cardinal, Crimson King, Earliglow, Honeoye, Surecrop, and Ozark Beauty) the number of crowns, number of leaves per plant, and fruit color measurements were determined by cultivar. Leaf area, leaf fresh weight, and leaf dry weight were reduced by the CBA. Leaf and petiole tissue analysis found supra-optimal levels of boron in all samples except 'Earliglow' in rockwool which had reduced boron. Gas chromatography flavor analysis for cv. 'Fresca' found the Pleasants and Ft. Martin CBA grown strawberries to be completely different from those grown in Albright CBA and the RW control. Cultivars, Cardinal and Honeoye, exhibited interaction with the media for flavor profiles. These studies show strawberry plant responses to varied cultural conditions and indicate the need for further nutrient/media studies and their link with flavor compound production.

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