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  • Author or Editor: C. M. Hansen x
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Abstract

Premature ripening, a physiological disorder of ‘Bartlett’ pears, was induced experimentally by use of temperature controlled limb cages. Exposure to 65° day and 45° F night temperatures for 3-31 days prior to harvest caused an early acceleration in ethylene production and occurrence of the climacteric rise in respiration. These changes were accompanied by fruit softening, increases in soluble pectin and protein N, a more rapid decline in malic acid as well as a decrease in the rate of citric acid accumulation. Treatments with gibberellic acid (GA3), 100 ppm, and succinic acid 2,2-dimethyl hydrazide (Alar), 1000 ppm, counteracted the effect of cool temperature exposure and retarded premature ripening. The disorder did not develop in fruit maintained at 75° day and 60° night temperatures during the experiment.

Open Access

Abstract

To study the effect of maturity on ethylene induced ripening, ‘Anjou’ pears were picked at 4 stages of development representing 57%, 71%, 86% and 100% of total growth period. Beginning of a distinct maturation stage in ‘Anjou’ pears was not evident from changes in wt, firmness, soluble pectin, soluble solids, protein N or malic acid. Respiration, ethylene production and softening were differentially affected by ethylene treatment, according to concn applied (0.05-2.0 ppm) and time required for stimulation. Threshold concn affecting these reactions decreased progressively during maturation. Ripening as measured by softening was not dependent on development of the respiratory climacteric. Maturation of the ‘Anjou’ pear appears to involve a reorganization of metabolism preparatory for ripening.

Open Access

Abstract

Radical pruning rejuvenated highbush blueberries (Vaccinium australe Small) which had become excessively large and unproductive. The method returned poorly productive bushes (less than 3,390 kg/ha or 1.5 tons/acre) to superior production (11,300 kg/ha or 5 tons/acre) in 2 years. After 4 years, yields were greater yet (18,080 kg/ha or 8 tons/acre).

Open Access

A natural product known as taxol has been approved by the FDA for treatment of ovarian and breast cancers. In addition, preliminary clinical studies have shown encouraging results when using taxol to treat melanomas, lung, head, and neck cancers. Ornamental yews have been identified as a potential renewable source of taxol and related taxanes. Commercial nurseries were surveyed during Summer and Fall 1991 as a basis for estimating populations of Taxus cultivars currently growing in the United States. Clippings of selected cultivars were sampled from nursery fields in Ohio and Michigan to estimate expected clippings yields as a function of cultivar and cultivar age. More than 30 million Taxus plants were reported to be grown by the 19 major nurseries that responded to the survey. About 88% of all Taxus plants reported in the survey were grown in the three-state area of Ohio, Michigan, and Pennsylvania. Taxus × media `Densiformis', `Hicksii', and `Brownii' were found to be grown by nearly all nurseries in the survey; more than half grew T. × media `Wardii' and T. cuspidata `Capitata', while other well-known cultivars seem to have been specialties of one or two nurseries. Annual clippings yields on a dry-weight basis (db) ranged from ≈20 g/plant to 140 g/plant. Expected yields were found to be very dependent upon plant age and cultivar. Taxus × media `Hicksii' appeared to be the most ideal ornamental yew that could provide a renewable source of taxol because of immediate availability and potential for mechanical harvesting of upright clippings. An estimated 3000 to 4000 ovarian cancer patients could be treated annually with the taxol currently available for extraction from T. × media `Hicksii' clippings.

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