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  • Author or Editor: P. C. Lin x
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Variation in shelf life of greenhouse-grown `Mustang' cucumber (Cucumis sativus L.) fruit was enhanced by preharvest experimental treatments of fruit thinning and fruit shading. Treatments also affected the dynamics of fruit elongation, fruit color at harvest, and chlorophyll fluorescence of the pericarp. Fruit color (grey level) at harvest, as measured by image analysis, had the highest simple (positive) correlation with shelf life. Rapid elongation and high photochemical quenching of fluorescence also characterized fruit having longer shelf life. The ability to predict cucumber yellowing is improved using a multiple regression approach, but prediction achieved by the best subset model is still too low to segregate commercially fruit having a short shelf life.

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Authors: and

The importance of light intensity and spectral quality on fruit color and shelf life of long English cucumber (Cucumis sativus L.) was studied in four greenhouse experiments. The intensity of cucumber greenness was measured nondestructively by video imaging, and shelf life was measured by visual observation of incipient yellowing. In the summer, filters were used to cover individual fruit to reduce light intensity reaching the fruit surface. The lower the light intensity incident on a cucumber, the shorter its shelf life. The average shelf life was 8, 5, or 1 days for cucumbers receiving 100%, 66%, or 31% of natural daylight, respectively. The fruit that were covered with a filter transmitting red (R) light were greener (low grey level via video imaging) than those with a far-red (FR) filter. In the fall, fruit receiving spectral R lighting from fluorescence tubes were greener and had a longer shelf life than those receiving FR lighting from incandescent bulbs. In the winter, high-pressure sodium (HPS) lighting was necessary to supplement natural daylight for crop growth and production. Under HPS, R and FR lighting produced the same fruit greenness and shelf life. In the spring, R-lighted fruit had longer shelf life than FR-lighted ones, although fruit color at harvest was similar. In these four experiments, postharvest shelf life of long English cucumber was generally related to fruit greenness upon harvest. The data suggest the importance of an open canopy in improving fruit greenness and shelf life of greenhouse-grown cucumbers.

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Authors: and

Abstract

Response of cold-treated ‘Nellie White’ Easter lily bulbs to various degrees of scale removal, ranging from 0 to 100%, showed that scales can perform inhibitory and promotive roles at various times. The scales were not necessary for flower induction, but the number of leaves and flowers initiated was proportional to the number of scales retained. Daughter scale removal accelerated daughter sprouting by increasing internode elongation, but subsequently reduced the rate of organ formation and expansion. Daughter scale removal reduced the number of leaves and flowers initiated and anthesis was delayed because of the reduction in rate at which these organs expanded.

Open Access

Various stem-training systems were applied to greenhouse-grown `Mustang' cucumber (Cucumis sativus L.) plants at two production stages. Training systems determined the number of stems per plant, orientation of laterals, and leaf: fruit ratio. Training systems permitting high canopy light penetration resulted in darker fruit and a longer shelf life. Shelf life was positively related to rapid fruit growth in Expt. 1 but not in Expt. 2. Training systems to achieve a long shelf life of greenhouse-grown long English cucumber are described.

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Abstract

High temperature tended to aggravate injury caused to tomato plants by flooding. Based on plant responses such as chlorosis, epinasty, and wilting, less than 0.2% (8 of 4630 accessions) of the world collection of the garden tomato (Lycopersicon esculentum Mill.) and related Lycopersicon species exhibited some level of tolerance to a short period of flooding associated with high temperature. The level of flood tolerance in one of the 8 flood tolerant accessions, L-123, was found to be less than that of 7 other vegetables tested.

Open Access

Agrobacterium-mediated transformation (AMT) was compared with a particle bombardment (PB) for stable transformation of `Eden Gem', a melon with high embryogenic potential. Pretreated cotyledonary explants were either wounded via particle bombardment prior to Agrobacterium infection or were bombarded with plasmid-coated gold microparticles, using a modified particle inflow-type gun. Although similar numbers of embryos initially were obtained with each method, most produced via AMT became abnormal, possibly due to the growth-regulatory effects of the antibiotic mefoxine, which was used to inhibit Agrobacterium. Stably transformed plants and progeny were obtained only with PB, as determined by detection of the NPTII gene in R0 plant by Southern hybridization and, in progeny, by PCR amplification.

Free access

Low hormetic doses of ultraviolet light (UV-C) stress on exposed peaches (Prunus persica). reduced brown rot resulting from field and artificial inoculation from Monilinia fructicola. To test the hypothesis that UV-C induced resistance through host responses the following tests involving biochemical changes (phenlyalanine ammonia-lyase activity (PAL) and ethylene production (EP)), bioassay of antifungal activity of tissue extracts to the fungus, and latent infection of rot free peaches previously treated with and without UV-C were determined. Exposure of peaches to UV-C dose of 7.5×104 ergs/mm2 promoted an increase in PAL and EP compared to the control. As the PAL activity increased, percent storage rots decreased. Antifungal activity to the fungal conidia in UV-C treated peach extract showed that the percent conidia germination was reduced 3 folds. Preharvest infection of brown rot which indicated latent infection was significantly reduced. To test for the germicidal effect of UV-C on M. fructicola on the surface of peaches, an artificial epiphytic population of the fungus was deposited on the peaches. A negative relationship between UV-C dose of 1.3 to 40×104 ergs /mm2, colony forming units and number of decaying brown rot lesions were found.

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