Modification and Use of an Electric Hygrometer for Estimating Relative Stomatal Apertures

Wallihan, E. F.

doi:10.1104/pp.39.1.86

Cited by 58 publications

(16 citation statements)

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“…By studying r v atmospheric humidity, and other environmental features, it is possible to determine the time of day and year when most transpiration occurs and to understand better the mechanism by which transpiration is regulated in natural ecosystems. Until recently rL has been a difficult parameter to measure, but new instruments now permit field studies (Wallihan 1964, Van Bavel et al 1965, Turner et al 1969, Waggoner and Turner 1971 . In this paper I report on ( 1) the diurnal and seasonal rL patterns of lodgepole pine (Pinus contorta spp.…”

Section: Introductionmentioning

confidence: 99%

Patterns of Leaf Resistance to Lodgepole Pine Transpiration in Wyoming

Fetcher¹

1976

Ecology

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Leaf resistance (r_L) of lodgepole pine (Pinus contorta ssp. latifolia [Engelm. ex Wats] Critchfield) was measured with an aspirated porometer at three sites in the Medicine Bow Mountains, Wyoming. In the early part of the growing season all the sites had low leaf resistances (3—5 s/cm) and few significant changes in r_L during the day. Towards the end of the growing season, in August, significant increases in midday leaf resistance occurred at all sites. The greatest increase (to 57 s/cm) was found on the driest site. Smaller increases (to 10—14 s/cm) were measured at a dry—mesic site and a mesic site. The results indicate that stomatal control of transpiration is more important towards the end of the growing season and that the degree of control varies with the soil water regime of the site. The response of r_L to soil H_2O status appears to be nonlinear. When based pressure potential readings were above an upper threshold ( ‐9 bars) r_L did not increase during the day. Below a lower threshold ( ‐17 bars) r_L increased significantly. Between the two thresholds, changes in r_L under high light conditions are explained more readily by the interaction between vapor pressure deficit and soil H_2O status than by either factor alone.

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Section: Introductionmentioning

confidence: 99%

Patterns of Leaf Resistance to Lodgepole Pine Transpiration in Wyoming

Fetcher¹

1976

Ecology

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“…The stomatal resistance can be found when the boundarv layer resistance is low from leaf energy balance, water vapor and temperature gradient measurements. The diffusion porometer nmeasures the stomatal diffusion resistanice directly (10,11); other indirect methods are described by Slatyer (8) and Barrs (1).…”

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confidence: 99%

Design Calibration and Field Use of a Stomatal Diffusion Porometer

1969

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Abstract. Modifications of the design and calibration procedure of a diffusion porometer permit determinations of stomatal resistance which agree well with results obtained bv leaf energy balance. The energy balance and the diffusion porometer measurements indicate that the boundary layer resistances of leaves in the field are substantially less than those predicted from hcat transport formulas based on wind flow and leaf size.

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“…A recently develouped leaf resistance meter permits a convenient and rapid measutrement Olf RL (8,9). Provided cuticular water loss is low, RI, 'is dete,rmined primarily by stomaltal widlth and den,sity, buit al,so by their length and depth (1, 2,5,6).…”

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confidence: 99%