ABSTRACT
Chambers were constructed to measure gas exchange of entire potted grapevines (Vitis vinifera L.). The plant enclosures were constructed from Mylar film, which is nearly transparent to photosynthetically active radiation. Maintaining a slight, positive, internal pressure allowed the Mylar chambers to inflate like balloons and required no other means of support. The whole-plant, gas-exchange chamber design and construction were simple and inexpensive. They were assembled easily, equilibrated quickly, and did not require cooling. They allowed for the measurement of any plants in a relatively short period. This system would enable the researcher to make replicated comparisons of treatment influences on whole-plant CO2 assimilation throughout the growing season. While CO2 measurement was the focus of this project, it would be possible to measure whole-plant transpiration with this system.
Subject(s)
Carbon Dioxide/metabolism , Photosynthesis , Plant Leaves/metabolism , Rosales/metabolism , Cell Respiration , Equipment Design , Evaluation Studies as Topic , Plant Leaves/growth & development , Polyethylene Terephthalates , Rosales/growth & developmentABSTRACT
The role of photoperiod and temperature in the cold acclimation of living Haralson apple (Pyrus malus L.) bark was studied in the autumn under field conditions in Minnesota. Whole trees, or different parts of the same tree, were exposed to either natural conditions, artifically lengthened days, or artificially warmed nights, or they were subjected to manual leaf removal. The results indicate that acclimation occurs in two stages which are induced by short days and frost (or low temperature), respectively. Leaves were stimulated by short days to produce translocatable substance(s) which promoted cold acclimation of the living bark. Leaves of plants grown under long days were the source of a translocatable substance(s) which inhibited acclimation. The second stage of hardiness, induced by frost (or low temperature), did not involve translocatable factors.Inductive short days could overcome the effect of high temperatures, and low temperatures could overcome the effect of noninductive long days in promoting the first stage of acclimation to -30 C. Frost was necessary for maximum hardiness to -55 C. Plants grown in a greenhouse, in the autumn, under long days and high temperatures acclimated slightly in spite of the noninductive conditions. Short days and frost (or low temperatures) appeared to regulate different and independent endogenous acclimation processes.
