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  • Author or Editor: L.R. Parsons x
  • Journal of the American Society for Horticultural Science x
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Abstract

Water uptake and movement in Thuja occidentalis pyramidalis Hort, during periods when soil was frozen were examined by use of deuterium as a tracer. Plants in containers were buried to the soil line and electric heating cables were placed below the pots. Deuterated water was added through access tubes when the soil was warmed above 0°C. The amount of deuterium tracer in the foliage was analysed with a gas chromatograph-mass spectrometer (GC-MS). Using this technique, it was found that no water moved from the roots to the foliage when the soil was frozen. When the soil temperature was raised above 0°C, tissue deuterium content increased 7 to 10 fold.

Open Access

Abstract

Cut carnation flowers shipped from California by air occasionally arrive at eastern markets in a senescent condition with losses greater in the warm autumn months. CO2 and C2H4 production by the flowers has a pattern similar to that of climacteric-class fruits, with senescence correlated with a rise in release of the gases.

Cut carnation flowers show an enormous increase in respiratory heat with increasing temperature: 89 BTU/ton/hour at 0°C versus 14,718 at 50°C. In C2H4-free air, the flowers tolerate elevated temperatures but their vase life is reduced. Their sensitivity to C2H4 increases dramatically with increasing temperature, with the threshold concentration partially depending on prior stresses on the flowers.

Flowers in containers exposed to direct sunlight developed temperatures as high as 49.5°C. Air temperatures inside containers shipped via jet aircraft were as high as 35°C. The C2H4 concentrations in the containers may reach 10.5 ppm.

The remarkable resistance of cut carnation flowers to mechanical injury, combined with their low metabolic rates at low temperatures, makes refrigerated surface shipments feasible and perhaps economically desirable. Their resistance to injury seems related to their light weight, the damping action of the petals, and the lack of phenolase or readily oxidizable phenolic compounds in the petals.

Open Access