The Behavior of StomataCarnegie Institution of Washington, 1921 - 104 pagina's |
Overige edities - Alles bekijken
Veelvoorkomende woorden en zinsdelen
11 NOON 80 per cent afternoon amount appearance atmometer August average barley become behavior caused cells cent open changes clear closure compared complete continued curve cut stems decrease determine difference effect epiderm evaporation experiments factors favorable field plants functioning greater guard-cells Hence hour humidity increased intensity June leaf leaves less light loss lower stomata manner maximum measured method mid-day closure midnight minute morning movement in upper nearly night opening normal observed occurred onion period plot potato potometers potted probably produce reached reduced relation relative humidity remained rise rose showing movement showing stomatal shown similar slowly soil species starch started stomata closed stomata of alfalfa stomata opened stomatal movement strip sufficient sugar-beet sunlight surfaces temperature throughout transpiration upper and lower upper stomata usually water-content water-loss weather wide open wind
Populaire passages
Pagina 104 - When the stomata are wide open or nearly wide open, transpiration is the result of the action of the factors of evaporation alone, since the stomata in nowise interfere with the action. As the stomata close, the influence of the factors is lessened, but until closure has reduced the apertures to fifty per cent, or less, stomatal regulation is still largely overshadowed by the control exerted by them.
Pagina 71 - ... stomatal aperture is not reduced by slight water deficiency in the leaf, but is very sensitive to light changes. On the whole, his results support LIVINGSTON'S contention of the regulatory importance of "incipient wilting," and are directly opposed to DARWIN'S theory that stomatal aperture plays the primary role in the regulation of transpiration.
Pagina 85 - The stomatal movement of the field plants, watered and unwatered, did not in any manner resemble that of the cut stems, and the transpiration from the potometers in turn showed no relationship to the changes in stomatal opening of these plants. For both these reasons, in the case of alfalfa at least, potometers can not be used to represent the transpiration of rooted plants.
Pagina 77 - Reduction of light to less than half of normal is usually necessary to produce any effect upon the stomata of plants growing in the open.
Pagina 71 - The decrease of water in the leaf occurs during the opening of the stomata. These organs are, therefore, not closely regulatory of the loss of water from the leaf and are ineffectual in maintaining a constant supply of leaf-water.
Pagina 49 - The third variation of this form of movement occurs in onion, where the stomata are wide open at night under conditions of high water-content and low evaporation. If watercontent alone becomes low, the stomata close at night, but if the evaporation increases instead, the stomata tend to close during the day.
Pagina 71 - The stomatal aperture is not reduced by slight water deficiency in the leaf ; hence the ordinary view that stomata, by their response to incipient drying, are the chief factors in maintaining the water-content of the leaf is not tenable.
Pagina 19 - Too much emphasis can not be placed on the importance of having a competent manager.