Concurrent Comparisons of Stomatal Behavior, Water Status, and Evaporation of Maize in Soil at High or Low Water Potential

Abstract

Concurrent measurements of evaporation, leaf conductance, irradiance, leaf water potential, and osmotic potential of maize (Zea mays L. cv. Pa6O2A) in soil at either high or low soil water potential were compared at several hours on two consecutive days in July. Hourly evaporation, measured on two weighing lysimeters, was similar until 1000 hours Eastern Standard Time, but thereafter evaporation from the maize in the dry soil was always less than that in the wet soil; before noon it was 62 % and by midafternoon, only 35 % of that in the wet soil. The leaf water potential, measured with a pressure chamber, was between -1.2 and -2.5 bars and between -6.8 and -8 bars at sunrise (about 0530 hours Eastern Standard Time) in the plants in the wet and dry soil, respectively, but decreased quickly to between -8 and -13 bars in the plants in the wet soil and to less than -15 bars in the plants in the dry soil by 1100 to 1230 hours Eastern Standard Time. At this time, the leaf conductance of all leaves was less than 0.1 cm sec in the maize in the dry soil, whereas the conductance was 0.3 to 0.4 cm sec-' in the leaves near (15), and previous stress history (10). Also, the development of plant water stress is influenced by aerial environment as well as the soil water status. Thus the development of stress and stomatal behavior in a species at high and low soil water potentials, using the data presented in the previous studies, is not a rigorous comparison since the data at the two soil potentials were obtained on different dates and even in different years.In the present study, the stomatal behavior, plant water stress and E of maize in soil at low and high water potentials have been compared over the same period of time and under the same meteorological conditions on plants at the same stage of development. The direct comparison of stomatal behavior and development of plant water stress of plants in moist and dry soil enabled the role of leaf turgor on stomatal behavior to be assessed and the concurrent measurement of E enabled the role of stomatal conductance on E to be evaluated.

Effects of water stress on gas exchange of field grown Zea mays L. in Southern Italy: an analysis at canopy and leaf level

“…3e;4e). In a study carried out on field grown maize, Turner (1975) observed a stomatal closure when leaf water potential dropped to values lower than -1.50 MPa. In our case, midday w l measured on 54 DAS, dropped to -1.88 MPa, thus indicating that a stomatal closure was occurred limiting ecosystem gas exchange.…”

Morphological and architectural development of root systems in sorghum and maize

“…Prior to each harvest, the area of each leaf blade on every plant was estimated in situ from the measured length and width, multiplied by a scaling factor of 0.69 for sorghum (Lafarge and Hammer 2002) and 0.75 for maize (Turner 1975). At harvest, the shoot of each plant was cut at the base of the stem, and separated into stem (including leaf sheath) and leaf blade fractions.…”

Different strategies of drought resistance in three Mediterranean sclerophyllous trees growing in the same environmental conditions

“…Diurnal osmotic adjustment has been reported in some higher plants (Turner, 1975;Cutler & Raines, 1978;Wenkert, Lemon & Sinclair, 1978;Cutler, Shahan & Steponkus, 1980) but it has been found to be insignificant in others (Hinckley et al, 1980). Rapid changes in plant water potential due to a drop in turgor pressure in response to a small water loss are known to occur in leaves with relatively inelastic cell walls (Tyree, 1976;Tyree & Karamanos, 1980;Salleo & Lo Gullo, 1985;Lo Gullo et al, 1986) and are likely to be useful in plants subjected to shortterm water stress (changing in intensity, for instanee, with a nictemeral rhythm).…”