Introduction Leaf senescence involves degradation of proteins, The activities of chlorophyllase, contents of pigments chlorophylls, nucleic acids, membranes, and subsequent including chlorophyll a and b, chlorophyllide a and b, transport of some of the degradation products to other and phaeophorbide a during leaf senescence under parts of the plant (Buchanan-Wollaston, 1997; Noodén, low oxygen ...

In oligotrophic lakes and oceans, the deep chlorophyll maximum may form independently of a maximum of phytoplankton biomass, because the ratio of chlorophyll to phytoplankton biomass (in units of carbon) increases with acclimation to reduced light and increased nutrient supply at depth. Optical data (beam attenuation as proxy for phytoplankton biomass and chlorophyll fluorescence and absorption...

Marine primary productivity is an important agent in the global cycling of carbon dioxide, a major 'greenhouse gas', and variations in the concentration of the ocean's phytoplankton biomass can therefore explain trends in the global carbon budget. Since the launch of satellite-mounted sensors globe-wide monitoring of chlorophyll, a phytoplankton biomass proxy, became feasible. Just as satellite...

The interconversion of chlorophyll a and chlorophyll b, referred to as the chlorophyll cycle, plays a crucial role in the processes of greening, acclimation to light intensity, and senescence. The chlorophyll cycle consists of three reactions: the conversions of chlorophyll a to chlorophyll b by chlorophyllide a oxygenase, chlorophyll b to 7-hydroxymethyl chlorophyll a by chlorophyll b reductas...

Effect of gibberellic acid on marigold (Calendula Officinalis L.) was evaluated in a pot culture experiment. A factorial experiment based on completely randomized design including 12 treatments and four replications was carried out. Main factor was foliar application stages (first, second and third) and sub factor included different concentrations of GA3 (0, 50, 150 and 250 mg L...

nickel and cadmium are heavy metals with some hazards for plant metabolism. the impacts of nickel chloride (0, 400 and 800 μm) in the presence of vitamin b complex (0, 30 and 60 ml from pharmacy commercial stock) and the impacts of cadmium chloride (0, 100, 200, 300, 400, 500 and 600 μl from 100 µm stock) in pot and cadmium nitrate (0, 100, 200, 400, 800, 1600 and 3200 μl from 100 µm stock) in ...

The objective of this study was to evaluate the stenting (grafted cutting) propagation of commercial pomegranate cultivars as scions on drought tolerant genotypes as rootstocks. The effect of drought stress on nine pomegranate rootstocks was analyzed. Cultivars including ‘Daneshgah 13’, ‘Daneshgah 32’ and ‘Daneshgah 8’ that were used as rootstocks showed the maximum drought tolerance among the ...

The photosynthetic apparatus is reorganized during acclimation to various light environments. During adaptation of plants grown under a low-light to high-light environment, the light-harvesting chlorophyll a/b-protein complexes decompose concomitantly with an increase in the core complex of photosystem II. To study the mechanisms for reorganization of photosystems, the assembly of chlorophyll w...

Effect of gibberellic acid on marigold (Calendula Officinalis L.) was evaluated in a pot culture experiment. A factorial experiment based on completely randomized design including 12 treatments and four replications was carried out. Main factor was foliar application stages (first, second and third) and sub factor included different concentrations of GA3 (0, 50, 150 and 250 mg L...