the production of oxygen radicals in plants under salinity stress conditions in an the important factor for a diminishing of a photosynthesis and a cause fir a decrease in later vegetative growth. in order to study the effects of antioxidants and salinity stress on photosynthetic characteristics and growth in olive, an experiment was conducted in the research greenhouse of tabriz university in ...

A normal appearing plant with a low rate of photorespiration (ratio of (14)CO(2) released light/dark = 1.6) was found in an unselected tobacco (Nicotiana tabacum) cultivar. The plant was self-pollinated, and further selections were made on several successive generations. Excised leaves from the progeny of the selections were examined for photorespiration and net CO(2) assimilation in normal air...

Wilt disease of watermelon caused by Fusarium oxysporum f. sp. niveum in long-term monoculture system has been much often found particularly in protected land cultivation system worldwide. Fusaric acid (FA), a fungal phytotoxin, was extracted from F. oxysporum f. sp. niveum isolated from diseased watermelon plant. The influence of FA on the biomass and leaves photosynthesis of watermelon seedli...

Asian grapevine rust (Phakopsora euvitis) is a serious disease, which causes severe leaf necrosis and early plant defoliation. These symptoms are unusual for a strict biotrophic pathogen. This work was performed to quantify the effects of P. euvitis on photosynthesis, carbohydrates, and biomass accumulation of grapevine. The reduction in photosynthetic efficiency of the green leaf tissue surrou...

The effects of P deficiency on growth, N(2)-fixation and photosynthesis in white clover (Trifolium repens L.) plants were investigated using three contrasting relative addition rates of P, or following abrupt withdrawal of the P supply. Responses to a constant below-optimum P supply rate consisted of a decline in N(2)-fixation per unit root weight and a small reduction in the efficiency with wh...

Terrestrial biosphere models (TBMs) are highly sensitive to model representation of photosynthesis, in particular the parameters maximum carboxylation rate and maximum electron transport rate at 25°C (Vc,max.25 and Jmax.25 , respectively). Many TBMs do not include representation of Arctic plants, and those that do rely on understanding and parameterization from temperate species. We measured ph...

Effects of leaf rolling (LR) on maize photosynthesis under severe drought stress were studied in two cultivars with opposite drought responses, Batem 56-55 (drought tolerant) and Batem 51-52 (drought sensitive). Drought stress and artifi cial prevention of leaf rolling (PLR) were applied at grain fi lling stage for 30 days. LR in Batem 56-55 occurred later than in Batem 51-52. Leaf water potent...

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...

Leaf internal, or mesophyll, conductance to CO(2) (g(m)) is a significant and variable limitation of photosynthesis that also affects leaf transpiration efficiency (TE). Genotypic variation in g(m) and the effect of g(m) on TE were assessed in six barley genotypes (four Hordeum vulgare and two H. bulbosum). Significant variation in g(m) was found between genotypes, and was correlated with photo...