Chlorophyll degradation is vital during leaf senescence and fruit ripening, as it allows for recycling of nitrogen and other nutrients and for protection from buildup of phototoxic chlorophyll intermediates (Hörtensteiner, 2006). The first steps in chlorophyll breakdown are the removal of the phytol tail (dephytylation) and the central Mg atom. It has been thought that dephytylation typically o...

Photosynthetic light acclimation of leaves can result from (i) changes in mass-based leaf nitrogen concentration, Nm, (ii) changes in leaf mass:area ratio, Ma, and (iii) partitioning of total leaf nitrogen among different pools of the photosynthetic machinery. We studied variations in Nm and Ma within the crowns of two peach (Prunus persica L. Batsch) trees grown in an orchard in Portugal, and ...

Treatment of maize seedlings with different concentrations of sorbitol decreased the rate of germination substantially. Root and shoot length was also reduced by sorbitol treatment, however, decrease in root length was lower than shoot length. Incubation of leaf segments from maize seedlings grown in continuous light with sorbitol decreased the fresh weight and increased the dry weight in a con...

Seedlings of Taxodium distichum L., Quercus lyrata Walt. and Q. falcata var. pagodaefolia Ell. were grown for 22 days in a rhizotron system providing two soil redox potential regimes, +170 mV (low Eh) and +560 mV (high Eh). Leaf chlorophyll concentration and gas exchange, root alcohol dehydrogenase (ADH) activity, root and leaf ethylene production, and growth and biomass partitioning were measu...

Intercropping is an ancient agricultural practice that provides a possible pathway for sustainable increases in crop yields. Here, we determine how competition with wheat affects nutrient uptake (nitrogen and phosphorus) and leaf traits, such as photosynthetic rate, in maize. In a field experiment, maize was planted as a sole crop, in three different intercrop configurations with wheat (a repla...

Effects of sodium naphthenates (NAs) on root hydraulic conductivity (Lp) and gas exchange processes were examined in aspen (Populus tremuloides Michx.) seedlings grown in solution culture. Exposure of roots to NAs for 3-5 weeks significantly decreased Lp and stomatal conductance. Root-absorbed NAs also decreased leaf chlorophyll concentration, net photosynthesis and leaf growth. Short-term (< o...

Estimating plant traits in herbaceous plant assemblages from spectral reflectance data requires aggregation of small scale trait variations to a canopy mean value that is ecologically meaningful and corresponds to the trait content that affects the canopy spectral signal. We investigated estimation capacities of plant traits in a herbaceous setting and how different trait-aggregation methods in...

Increasingly, photosynthetic electron transport rate is being calculated from chlorophyll fluorescence measurements. The fluorescence signal is a complex mixture of contributions from different depths within the mesophyll. One condition required for electron transport calculated from fluorescence to represent the rate accurately is that the ratio of photosynthetic capacity to light absorbed be ...

The ch4 mutant of sweetclover (Melilotus alba) has previously been demonstrated to be temperature- and photoperiod-sensitive for the accumulation of chlorophyll. Pigment content of ch4 mutant leaves was examined as a function of trifoliolate mass, an index of leaf development. Inhibition of chlorophyll accumulation caused by increased growth temperature or decreased photoperiod can be attenuate...

abstract study on photosynthetic and enzym activity changes in lettuce under cadmium stress has been done in greenhouse. of zhejang university in chine the experimental design was a crd factorial design organized in hydroponic system with 7 replications. cadmium was added to nutrient solution in cdcl2 in three concentrations (0, 2, 4 mg/l). stomatal photosynthetic factors (transpiration, stomat...