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  • Author or Editor: Harry Janes x
  • Journal of the American Society for Horticultural Science x
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Abstract

Poinsettias (Euphorbia pulcherrima Willd. cvs. Annette Hegg Supreme, V-10, and Brilliant Annette Hegg) were grown on heated benches and exposed to root zone temperatures between 18° and 29° C. Increasing media temperatures affected bract size and development, internode length, fresh and dry weight of stems, leaves, and bracts, as well as the number of axillary shoots of cultivars differentially. In general, plants grown at higher temperatures were shorter, had more prominent axillary shoots, and developed anthocyanin sooner than unheated controls.

Open Access

Abstract

Various concentrations of salicylhydroxamic acid and alpha, alpha-dipyridyl (reported inhibitors of cyanide-insensitive respiration) applied to fruit of ‘Bose’ pear (Pyrus communis L.) reduced fruit softening. The application of silver ions, reported to inhibit ethylene action, delayed ripening.

Open Access

Abstract

Acetaldehyde is produced in fruit of pear (Pyrus communis L.) and can stimulate ripening. The action of selective inhibitors indicates that acetaldehyde operates independently of ethylene.

Open Access

Abstract

Tomato plants (Lycopersicon esculentum Mill. cv. Laura), pruned to a single-flower truss, were exposed to 90 μmol·s−1·m−2 supplemental photosynthetic lighting (0400 to 2200 hr) during the developmental period: a) anthesis to initial fruit set, b) anthesis to mature-green fruit, or c) anthesis to red-ripe fruit. The yield response was compared to plants receiving d) no supplemental photosynthetic lighting after incipient anthesis. The greatest increase in average fruit weight was produced with continued supplemental lighting during the developmental-period initial fruit set to the mature-green stage. Net photosynthetic activity, μmol CO2/min per dm2, was the greatest in the canopy during early anthesis and then steadily declined as the canopy aged. Net whole plant photosynthetic activity, μmol CO2/min per plant, increased steadily after the early anthesis stage of development to a peak rate during the rapid fruit development stage. Net whole plant photosynthetic activity then declined as the plant approached the mature-green and then finally the red-ripe stage of fruit development.

Open Access

Abstract

Cyanide-resistant respiration in carnation (Dianthus caryophyllus L.) petal tissue increased daily until 3 days after flowers were harvested. Mitochondria from petals exhibited only cyanide-resistant respiration when malate and pyruvate were provided as substrate. Although intact petals from freshly harvested flowers exhibited little cyanide-resistant respiration, mitochondria isolated from them were highly cyanide-resistant in their respiration if malate and pyruvate were provided as substrate. Pyruvate, in mitochondria, was capable of releasing mitochondria inhibited by cyanide in the presence of malate. Pentose-phosphate pathway activity was significant throughout the postharvest period, but was maximum 5 days after flowers were harvested. The gas exchange quotient (GEQ) was 1 for the first 3 days after harvest, declining on days 4 and 5 and dramatically increasing on day 6 as a result of a climacteric increase in CO2 evolution accompanying flower wilting.

Open Access

Abstract

The accuracy of a computer planning model for the management of a single-truss tomato (Lycopersicon esculentum Mill.) production system was tested in the greenhouse. The model was used to generate a production schedule for 24 successive crops during a 15-month study. The time, in days, required for an emerging seedling to reach anthesis and the total fresh weight fruit yield were predicted for each of the 24 crops by the planning model. Correlation analysis, used to compare the expected crop response (i.e., data generated by the planning model) to the actual crop response, indicated that both the number of days from emergence to anthesis and fresh weight fruit yield were accurately forecast, r 2 = 0.76 and 0.83, respectively. More important, the cropping schedule that was generated by the planning model successfully produced a continuous harvest of tomatoes from sequential crops.

Open Access