The gravitational component of water potential contributes a standing 0.01 MPa m-1 to the xylem tension gradient in plants. In tall trees, this contribution can significantly reduce the water potential near the tree tops. The turgor (of cells in buds and leaves is expected to decrease in direct proportion with leaf water potential along a height gradient unless osmotic adjustment occurs. The pr...

Stomatal characteristics affecting gas exchange were compared in two sweet corn hybrids (var. Bonanza and Monarch Advance) which differ in foliar ozone sensitivity. No significant differences were observed in stomatal frequencies, guard cell lengths, or conductances to water vapor diffusion.When plant water status was compared, leaf-water potentials for the ozone-resistant cultivar, Bonanza, we...

Leaf veins supply the mesophyll with water that evaporates when stomata are open to allow CO2 uptake for photosynthesis. Theoretical analyses suggest that water is optimally distributed in the mesophyll when the lateral distance between veins (dx) is equal to the distance from these veins to the epidermis (dy), expressed as dx:dy ≈ 1. Although this theory is supported by observations of many de...

The resistances to liquid water transport in the soil and plant were determined directly and simultaneously from measurements of soil, root, and leaf water potentials and the flux of water through the soil-plant system to the sites of evaporation in the leaf. For soybean (Merr.) transporting water at a steady rate, water potential differences between soil and root were smaller than between root...

Across plant species, leaves vary enormously in their size and their venation architecture, of which one major function is to replace water lost to transpiration. The leaf hydraulic conductance (K(leaf)) represents the capacity of the transport system to deliver water, allowing stomata to remain open for photosynthesis. Previous studies showed that K(leaf) relates to vein density (vein length p...

We examined open-grown Acer mono Maxim. trees of different sizes to test the hypotheses that (1) hydraulic limitation increases with tree size, thereby reducing photosynthesis, and (2) photosynthetic water- and nitrogen-use efficiencies change with tree size. Maximum net assimilation rate per unit dry mass was significantly lower in large trees than in small trees, whereas leaf nitrogen concent...

in order to study the effects of conventional and conservation tillage with management residue on wheat physiological properties, a field experiment was conducted in 2013-2014 at mashhad agricultural and natural resources research center of razavi khorasan province. this experiment was carried out as split plot design based on a randomized complete block design with three replications. main plo...

The different leaf water parameters, Le., totalleaf water potential (\}Jt), leaf osmotic potential at full turgor ('P S100) leaf osmotic potential at zero turgor (\PSO), relative water content at zero turgor (RWCO) and relative dry weight of the leaf (RDW) were studied during four growth stages in five varieties of sweet sorghum under various soil moisture regimes. In all the varieties, severel...

Stomatal guard cells regulate plant photosynthesis and transpiration. Central to the control of seed plant stomatal movement is the phytohormone abscisic acid (ABA); however, differences in the sensitivity of guard cells to this ubiquitous chemical have been reported across land plant lineages. Using a phylogenetic approach to investigate guard cell control, we examined the diversity of stomata...

Nocturnal fluxes may be a significant factor in the annual water budget of forested ecosystems. Here, we assessed sap flow in two co-occurring evergreen species (Eucalyptus parramattensis and Angophora bakeri) in a temperate woodland for 2 years in order to quantify the magnitude of seasonal nocturnal sap flow (E(n)) under different environmental conditions. The two species showed different diu...