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The influence of mulch types (black polyethylene, red polyethylene, and straw-vetch in raised bed hill culture) on the chemical composition of `Northeaster' and `Primetime' strawberry (Fragaria ×ananassa Duch.) fruit and plant parts was evaluated. Ascorbic acid (AA), malic acid, citric acid, and ellagic acid levels were higher in `Primetime' than in `Northeaster' fruits, while `Northeaster' had a higher soluble solids content (SSC). Fruit grown on straw-vetch had lower SSC than did those grown on the polyethylene mulches. The AA content in the fruit of either cultivar was not affected by the mulch treatment. Fruit grown on the straw-vetch mulch had less red surface and flesh color but higher pigment intensity than fruit grown on the polyethylene mulches. Strawberry plants grown on straw-vetch mulch had the largest leaf area and the highest chlorophyll content, while plants grown on red polyethylene mulch had the smallest leaf area and lowest chlorophyll content. There were significant mulch × cultivar interactions in fruit titratable acid (TA) and AA levels, sugars, citric and ellagic acid contents, leaf area and chlorophyll levels, and soluble carbohydrate and starch contents in leaves, petioles, crowns, crown-roots, and roots. TA was highest in `Northeaster' fruit when grown on red polyethylene, whereas TA was highest in `Primetime' fruit when grown on straw-vetch. The highest fruit citric acid levels were found in straw-vetch mulched plots of `Northeaster', and in black polyethylene mulched plots of `Primetime'. Ellagic acid accumulation was highest in `Northeaster' fruit grown on black polyethylene, and in `Primetime' fruit grown on red polyethylene or straw-vetch mulches. Fruit glucose content was highest in `Northeaster', but lowest in `Primetime', when grown on the straw-vetch mulch. There was a general tendency for soluble carbohydrate and starch levels in plant tissues to be lowest when the plants were grown in red polyethylene mulch and highest when grown in black polyethylene mulch. `Primetime' contained higher total carbohydrate levels than did `Northeaster' in all tissues tested.

Tomato fruit firmness is a key quality component of tomatoes produced for processing applications. Fruit firmness is generally considered a quantitatively inherited trait. Pericarp firmness of modern tomato cultivars is believed to be derived from a fairly narrow genetic background and is the result of the cumulative effort of numerous breeders over many years. Despite inferior phenotypes, wild species contain loci that can substantially increase tomato fruit quality. In the current study, inheritance of fruit firmness in firm and ultra-firm processing tomato germplasm developed from transgressive segregants of interspecific Lycopersicon esculentum × L. hirsutum and intraspecific L. esculentum crosses was characterized. Large-fruited breeding lines that varied in fruit firmness from soft to firm were identified for genetic analyses. A six-parent diallel of these advanced breeding lines was developed for field trials over multiple locations. Fruit firmness in the resulting 36 lines was determined by measuring fruit elastic properties during fruit puncture and compression. Following loading for compression, stress relaxation was recorded for 15 s. A three-parameter model was used to fit the relaxation curves. There was little correlation between firmness (maximum force) and the three relaxation parameters, i.e., firmness measured the elastic component and the relaxation parameters measured the viscous portions of the texture. General and specific combining ability for firmness derived from the respective genetic backgrounds was determined. Genetic variance components for fruit firmness were estimated using a diallel analysis and narrow sense heritability was measured using parent-offspring regression.

Experiments were conducted to compare changes in quality of slices of red tomato (Lycopersicon esculentum Mill., cv. Sunbeam) fruit from plants grown using black polyethylene or hairy vetch mulches under various foliar disease management systems including: no fungicide applications (NF), a disease forecasting model (Tom-Cast), and weekly fungicide applications (WF), during storage at 5 °C under a modified atmosphere. In this study, we used the fourth uniform slice from the stem end and analyzed for firmness, soluble solids content (SSC), titratable acidity (TA), pH, electrolyte leakage, molds, yeasts and occurrence of water-soaked areas. With both NF and Tom-Cast fungicide treatments, slices from tomato fruit grown with hairy vetch mulch showed greater firmness than those from tomato fruit grown with black polyethylene mulch after 12 d of storage. Ethylene production of slices from tomato fruit grown using hairy vetch mulch under Tom-Cast was about 1.5- and 5-fold higher than that of slices from tomato fruit grown under the WF and NF fungicide treatments after 12 d, respectively. Within each fungicide treatment, slices from tomato fruit grown using hairy vetch mulch showed less chilling injury (water-soaked areas) than those from tomatoes grown using black polyethylene mulch. The percentage of water-soaked areas for slices from tomato fruit grown using black polyethylene mulch under NF was over 7-fold that of slices from tomato fruit grown using hairy vetch under Tom-Cast. These results suggest that, under our conditions, fruit from plants grown using hairy vetch mulch may be more suitable for fresh-cut slices than those grown using black polyethylene mulch.