in order to study the role of photosynthetic tissues on grain filling and remobilization of stem reserves under terminal drought, a pot experiment as semi-field was conducted as two-factor factorial in complete randomized design with three replicates at research farm of agriculture college of vali – e – asr university of rafsanjan during january to june 2012 . first factor was source strength r...

Seedlings of several species of gymnosperm trees, angiosperm trees, and angiosperm lianas were grown under tropical field conditions in the Republic of Panama; physiological processes controlling plant C and water fluxes were assessed across this functionally diverse range of species. Relative growth rate, r, was primarily controlled by the ratio of leaf area to plant mass, of which specific le...

In this study the sensitivity of peach tree (Prunus persica L.) to three water stress levels from mid-pit hardening until harvest was assessed. Seasonal patterns of shoot and fruit growth, gas exchange (leaf photosynthesis, stomatal conductance and transpiration) as well as carbon (C) storage/mobilization were evaluated in relation to plant water status. A simple C balance model was also develo...

In the first side-by-side large-scale trials of these two C(4) crops in the U.S. Corn Belt, Miscanthus (Miscanthus x giganteus) was 59% more productive than grain maize (Zea mays). Total productivity is the product of the total solar radiation incident per unit land area and the efficiencies of light interception (epsilon(i)) and its conversion into aboveground biomass (epsilon(ca)). Averaged o...

Tobacco is a salt-sensitive glycophyte crop species. In this work effect of silicone (Si) supplementation (1 mM as Na2SiO3) was studied in Nicotiana rustica L. cv. Basmas grown hydroponically in growth chamber under control, low (25 mM) and high (75 mM) NaCl concentration for two weeks. Dry matter production of leaves was depressed by salinity level as low as 25 mM and higher salt concentration...

Optimal allocation of leaf nitrogen maximizes daily CO(2) assimilation for a given leaf nitrogen concentration. According to the hypothesis of optimization, this condition occurs when the partial derivative of assimilation rate with respect to leaf nitrogen concentration is constant. This hypothesis predicts a linear increase of assimilation rate with leaf nitrogen concentration under constant ...

Significant differenoes in CO2 compensation concentration measured in the field among varieties of the species Zea mays L. are reported for the first time. CO2 compensation concentrations were signifioantly (P< 0.01) and negatively oorrelated with apparent photosynthesis at 300 pl C02/liter air. The Michaelis constant (as defined) for a leaf was significantly (P< 0.01) and positively correlated...

Accurate estimation of terrestrial gross primary productivity (GPP) remains a challenge despite its importance in the global carbon cycle. Chlorophyll fluorescence (ChlF) has been recently adopted to understand photosynthesis and its response to the environment, particularly with remote sensing data. However, it remains unclear how ChlF and photosynthesis are linked at different spatial scales ...

[1] This study evaluates the potential impact of clouds on ecosystem CO2 and CO2 isotope fluxes (‘‘isofluxes’’) in two contrasting ecosystems (a broadleaf deciduous forest and a C4 grassland) in a region for which cloud cover, meteorological, and isotope data are available for driving the isotope-enabled land surface model (ISOLSM). Our model results indicate a large impact of clouds on ecosyst...

The impacts of Dust and Sand Storms (DSS) on people, crops, livestock, infrastructure and health are well documented. Data have accumulated on the deleterious effects of dust aerosols when they settle on plants. Sand blasting of low growing plants is a common cause of failure in reforestation efforts. Burial of plants by moving sands are also a cause of much damage. The physics of moving sand a...