in order to compare photosynthetic features of triticale, bread wheat, and barley under water deficit conditions, this experiment was carried out in kurdistan province in western iran. four genotypes of triticale, three cultivars of bread wheat, and a new variety of barley were compared under well watered (ψsoil= -3 bars) and soil water deficit (ψsoil= -12 bars) conditions in a randomized compl...

Despite the optimism of some molecular biologists, natural selection among the wild ancestors of crops is unlikely to have missed simple genetic improvements that would consistently have enhanced individual fitness. Tradeoff-free opportunities for further improvement of crop traits like photosynthetic efficiency or drought tolerance may therefore be elusive. Opportunities linked to acceptable t...

Plant biodiversity can enhance primary production in terrestrial ecosystems, but biodiversity effects are largely unstudied in the ocean. We conducted a series of field and mesocosm experiments to measure the relative effects of macroalgal identity and richness on primary productivity (net photosynthetic rate) and biomass accumulation in hard substratum subtidal communities in North Carolina, U...

To assess the influence of stream water on leaf gas exchange and water potential in different sized boxelder trees (Acer negundo L.), we compared these characteristics in trees growing beside a perennial stream and a nearby ephemeral stream in a montane-riparian forest in northern Arizona. Patterns of tree water use were quantified by stable isotope analysis (delta(18)O). Physiological characte...

BACKGROUND AND AIMS The light availability on a temperate, deciduous-forest floor varies greatly, reflecting the seasonal leaf dynamics of the canopy trees. The growth and/or reproductive activity of understorey plants should be influenced by the length of the high-irradiance period from snowmelt to canopy closure. The aim of the present study was to clarify how spring-blooming species regulate...

Gamma-aminobutyric acid (GABA) is important in plant responses to environmental stresses. We wished to clarify the role of GABA in maintenance of photosynthesis in muskmelon seedlings (Cucumis melo L., cv. Yipintianxia) during saline-alkaline stress. To this end, we assessed the effect of GABA on the structure and function of the photosynthetic apparatus in muskmelon seedlings grown under salin...

Elevated [CO2] reduced phenolic contents during the seedling, tillering, elongation and flowering stages. At maturity, however, a significant or trend of increase was observed (Fig.1). Leaf gas exchange parameters showed that acclimation of photosynthesis to CO2 could have led to that change in response. Indeed, plants grown at elevated [CO2] exhibited higher net photosynthetic rate (A) values ...

Invasion by the exotic annual grass Bromus tectorum has increased the cover and connectivity of fine litter in the sagebrush steppes of western North America. This litter tends to cover biological soil crusts, which could affect their metabolism and growth. To investigate this possible phenomenon, biological soil crusts dominated by either the moss Bryum argenteum or the lichen Diploschistes mu...

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...