Photosynthetic efficiency is a critical determinant of crop yield potential, although it remains below the theoretical optimum in modern crop varieties. Enhancing mesophyll conductance (i.e. the rate of carbon dioxide diffusion from substomatal cavities to the sites of carboxylation) may increase photosynthetic and water use efficiencies. To improve water use efficiency, mesophyll conductance s...

Suboptimal levels of phosphorus (P) strongly inhibited leaf expansion in young cotton (Gossypium hirsutum L.) plants during the daytime, but had little effect at night. The effect of P was primarily on cell expansion. Compared to plants grown on high P, plants grown on low P had lower leaf water potentials and transpiration rates, and greater diurnal fluctuations in leaf water potential. Hydrau...

The hydraulic conductance of the leaf lamina ( K lamina ) substantially constrains whole-plant water transport, but little is known of its association with leaf structure and function. K lamina was measured for sun and shade leaves of six woody temperate species growing in moist soil, and tested for correlation with the prevailing leaf irradiance, and with 22 other leaf traits. K lamina varied ...

We studied the effect of scion donor-tree age on the physiology and growth of 6- to 7-year-old grafted Scots pine (Pinus sylvestris L.) trees (4 and 5 years after grafting). Physiological measurements included photosynthethetic rate, stomatal conductance, transpiration, whole plant hydraulic conductance, needle nitrogen concentration and carbon isotope composition. Growth measurements included ...

Responses of stomata to environment have been intensively studied, but little is known of genetic effects on stomatal conductance or their consequences. In Pima cotton (Gossypium barbadense L.), a crop that is bred for irrigated production in very hot environments, stomatal conductance varies genetically over a wide range and has increased with each release of new higher-yielding cultivars. A c...

The role of plasma membrane aquaporins (PIPs) in water relations of Arabidopsis was studied by examining plants with reduced expression of PIP1 and PIP2 aquaporins, produced by crossing two different antisense lines. Compared with controls, the double antisense (dAS) plants had reduced amounts of PIP1 and PIP2 aquaporins, and the osmotic hydraulic conductivity of isolated root and leaf protopla...

because of slow growth rates caused by an inefficient transport system and low leaf photosynthetic capacity, gymnosperm seedlings are weak competitors with angiosperms in productive habitats. We measured component (shoot, leaf, and root) and whole-plant hydraulic conductances of sapling-sized tropical plants growing on nitrogen-poor white sand in Borneo. After accounting for size effects, there...

We investigated how leaf hydraulic conductance (K(leaf)) of loblolly pine trees is influenced by soil nitrogen amendment (N) in stands subjected to ambient or elevated CO(2) concentrations (CO(2)(a) and CO(2)(e), respectively). We also examined how K(leaf) varies with changes in reference leaf water potential (Psi(leaf-ref)) and stomatal conductance (g(s-ref)) calculated at vapour pressure defi...

A reduction in leaf stomatal conductance (g) with increasing leaf-to-air difference in water vapour pressure (D) is nearly ubiquitous. Ecological comparisons of sensitivity have led to the hypothesis that the reduction in g with increasing D serves to maintain leaf water potentials above those that would cause loss of hydraulic conductance. A reduction in leaf water potential is commonly hypoth...

This paper reports how water stress correlates with changes in hydraulic conductivity of stems, leaf midrib, and whole leaves of Prunus laurocerasus. Water stress caused cavitation-induced dysfunction in vessels of P. laurocerasus. Cavitation was detected acoustically by counts of ultrasonic acoustic emissions and by the loss of hydraulic conductivity measured by a vacuum chamber method. Stems ...