Search Results

You are looking at 1 - 3 of 3 items for

  • Author or Editor: John V. Carter x
Clear All Modify Search
Author:

Abstract

To consider whether the land-grant system is appropriate to our current environment, it is necessary to step back and recall how the land-grant system came to be. This retrospection, in turn, requires a wider focus and a consideration of the history of American higher education in general.

Open Access

Hardened and nonhardened whole plants of three potato species, Solanum tuberosum L., S. acaule Bitt., and S. commersonii Dun., and one interspecific cross, `Alaska Frostless' (S. tuberosum x S. acaule) were placed in a low-temperature chamber capable of maintaining -4 ± 0.5C for 6 or 12 hours. The chamber was designed to control the root temperature independently from the rest of the plant. Cold acclimation did not affect the ability of any of the potatoes tested to undercool (supercool). Solanum tuberosum and `Alaska Frostless' did not undercool for the times and temperatures tested and in all cases were killed. Whole plants of S. acaule and S. commersonii undercooled, in some cases, for up to 12 hours. When plants of S. acaule froze, they were severely injured, although their hardiness levels were reported to be lower than the temperature to which they were exposed in this study. Whenever leaves and stems of S. commersonii were frozen they were not injured. Once the soil was allowed to freeze, all plants, in all cases, were frozen.

Free access

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