terminal drought stress during grain filling period has recently become more common in the semiarid mediterranean regions, where wheat (triticum aestivum) is grown as an important winter cereal crop. the objective of this experiment was to study the effect of terminal drought stress on grain yield, gas exchange variables, and some physiological traits of nine bread wheat cultivars. an experimen...

Introduction The rate and extent of leaf thickness and area Leaves which develop at elevated CO2 concentrations are development are important determinants of whole often thicker than those on ambient 2 plants. In a plant photosynthetic capacity. The interactive effects study of four Populus clones, Radoglou and Jarvis (1990) of photon flux density (PFD), nitrogen supply and CO 2 found increases...

in order to investigate the effect of different ratios of ammonium: nitrate on the photosynthesis and fatty acid composition in canola (brassica napus l.) under different levels of salinity, an experiment was conducted as a factorial based on complete randomize design at agricultural research center in east azerbaijan in 2010. the first factor was different ratios of nitrogen sources to ammoniu...

Little is known about how exotics influence the ecophysiology of co-occurring native plants or how invader impact on plant physiology may be mediated by community diversity or resource levels. We measured the effect of the widespread invasive forb spotted knapweed (Centaurea maculosa) on leaf traits (leaf dry matter content, specific leaf area, leaf nitrogen percentage, leaf C:N ratios, and del...

A quantitative analysis was applied to the stomatal and biochemical limitations to light-saturated net photosynthesis under optimal field conditions in mature trees and seedlings of the co-occurring evergreen oak, Quercus ilex L., and the deciduous oak, Q. faginea Lam. Stomatal limitation to photosynthesis, maximal Rubisco activity and electron transport rate were determined from assimilation v...

Crop models are powerful tools to test hypotheses, synthesize and convey knowledge, describe and understand complex systems and compare different scenarios. Models may be used for prediction and planning of production, in decision support systems and control of the greenhouse climate, water supply and nutrient supply. The mechanistic simulation of tomato crop growth and development is described...

Declining net primary production (NPP) with forest age is often attributed to a corresponding decline in gross primary production (GPP). We tested two hypotheses explaining the decline of GPP in ageing stands (14-115 years old) of Pinus taeda L.: (1) increasing N limitation limits photosynthetic capacity and thus decreases GPP with increasing age; and (2) hydraulic limitations increasingly indu...

Sugar beets (Beta vulgaris L.) infected with the Beet Yellows Virus exhibit lower rates of net photosynthesis at light saturation than do healthy plants. These Pn reductions were correlated with increases in leaf resistance to water vapor loss. Theoretical analyses demonstrated that, although the leaf resistance to water vapor loss increases could account for a major part of the net photosynthe...