We investigated the effect of intraspecific competition on growth parameters and photosynthesis of the salt marsh species Atriplex prostrata Boucher in order to distinguish the effects of densitydependent growth inhibition from salt stress. High plant density caused a reduction of 30% in height, 82% in stem dry mass, 80% in leaf dry mass, and 95% in root dry mass. High density also induced a pr...

The activity and extent of light activation of three photosynthetic enzymes, pyruvate,Pi dikinase, NADP-malate dehydrogenase (NADP-MDH), and fructose 1,6-bisphosphatase (FBPase), were examined in maize (Zea mays var Royal Crest) leaves relative to the rate of photosynthesis during induction and under varying light intensities. There was a strong light activation of NADP-MDH and pyruvate,Pi diki...

Mungbean (Vigna radiata (L.) Wilczek) or green gram as a dryland grain legume is exposed to varied timings and severity of drought stress, resulting in variability in photoassimilate production. In order to evaluate some physiological responses in one mungbean cultivar to timing and severity of drought stress, a 3-replicate RCBD (randomized complete block design) field experiment was carried ou...

1. An optical system is described which furnishes an intensity of 282,000 meter candles at the bottom of a Warburg manometric vessel. With such a high intensity available it was possible to measure the rate of photosynthesis of single fronds of Cabomba caroliniana over a large range of intensities and CO(2) concentrations. 2. The data obtained are described with high precision by the equation K...

Photosynthesis in Chlorella pyrenoidosa is inhibited by iodo-acetic acid and iodo-acetamide, both of which attack the Blackman reaction. Since acetamide is without effect, the iodo-acetyl radical must be responsible. The study of the action of the acid is complicated by the fact that its ions penetrate slowly, if at all, so that negative results with this agent are without significance unless p...

Whole-plant photosynthetic rate of rose (cv. Kardinal) was measured with an open system consisting of a computer-controlled data acquisition system and an infrared gas analyzer (IRGA). The system was used to monitor diurnal patterns of whole-plant gas exchange in response to environmental variables and a model to simulate this was constructed. A model for leaf photosynthesis was calibrated and ...

Salinity tolerance of four grape genotypes [GharaUzum, Hosseini, AghUzum and Keshmeshi] was studied under various salinity levels (25, 50 and 100 mM NaCl). As a result, growth indices were significantly (P<0.05) reduced by salinity, whereas Cl- and Na+ contents in the plant parts were increased. Cl- accumulation exceeded than that of Na+ in all treatments. Among the genotypes studied, GharaUzum...

The main objectives of this study were to elucidate the roles of silicon (Si) in alleviating the effects of 2 mM zinc (high Zn) stress on photosynthesis and its related gene expression levels in leaves of rice (Oryza sativa L.) grown hydroponically with high-Zn stress. The results showed that photosynthetic parameters, including net photosynthetic rate, transpiration rate, stomatal conductance,...

Effects of sulfur on photosynthesis in sugar beets (Beta vulgaris L. cv. F58-554H1) were studied by inducing sulfur deficiency and determining changes in the photosynthesis of whole attached leaves and of isolated chloroplasts. The rates of photosynthetic CO(2) uptake by intact leaves, photoreduction of ferricyanide, cyclic and noncyclic photophosphorylation of isolated chloroplasts, and the ra...