Doctoral Dissertations

Date of Award

6-1982

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Plant, Soil and Environmental Sciences

Major Professor

David L. Coffey

Committee Members

V. H. Reich, J. L. Collins, O. J. Schwarz, W. J. McLaurin

Abstract

The effects of black plastic mulch and methyl bromide-chloropicrin fumigation on yield of 'Flora-Dade' tomatoes (Lycopersicon esculentum Mill.) under Tennessee growing conditions were studied. Total marketable yield was increased by 15-18 percent with mulch or mulch plus fumigation, over no mulch or fumigation only. Combining mulch and fumigation appeared to delay early marketable yield by promoting vegetative growth. Improved soil moisture and nutrient regimes under plastic mulch seemed to be the primary factor in improving total yields. Mulch or mulch plus fumigation may be of questionable economic advantage in areas of Tennessee where soil pathogens and nematodes are not a serious problem. The influence of plastic mulch, fruit size, ethylene gas and storage time on fruit color, firmness, pH and soluble solids of 'Flora- Dade' tomato were also studied. Although significant differences due to the treatment inputs were found for firmness, pH and soluble solids, the magnitude of the differences may be too small to be of practical importance. Exterior and interior red color development of the fruit showed the most pronounced response to the treatment inputs. Red color development was significantly enhanced by the treatment inputs of no mulch, ethylene, and storage times of 8 and 11 days, respectively. Fruit of greater than 7.3 cm diameter had more color development than fruit of smaller diameter. Mulch appeared to exert its influence by generally optimizing growing conditions. Storage times of 8 and 11 days had the most profound effect on the quality attributes studied, while ethylene influenced mainly red color development. Sensory evaluation panelists could detect no differences in flavor (acidity) or color and appearance between vine ripe tomatoes or tomatoes picked mature green and ripened in storage with ethylene. They rated the vine ripe fruit as having significantly better texture and overall acceptability than the ethylene treated fruit.

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