Reliable spatiotemporal crop data are vital for sustainable agricultural management. However, efficient algorithms that can be automatically applied to large regions scarce, especially cash crops, since it is hard distinguish their uniqueness merely from temporal profiles of traditional vegetation indices. The efficiency knowledge-based features and red-edge pigment indices in characterizing gr...

Photosynthetic pigments from etiolated cucumber (Cucumis sativus var. Beit Alpha improved, Hazera Co., Gedera) cotyledons were extracted by direct immersion of the intact cotyledons into the solvent N,N-dimethylformamide (DMF). The solvent is especially efficient when pigment concentration is low; time and tools are saved and the loss of pigment that usually occurs in more complicated extractio...

NPQ (non-photochemical quenching) is a fundamental photosynthetic mechanism by which plants protect themselves against excess excitation energy and the resulting photodamage. A discussed molecular mechanism of the so-called feedback de-excitation component (qE) of NPQ involves the formation of a quenching complex. Recently, we have studied the influence of formation of a zeaxanthin-chlorophyll ...

In evergreen conifers, where the foliage amount changes little with season, accurate detection of the underlying "photosynthetic phenology" from satellite remote sensing has been difficult, presenting challenges for global models of ecosystem carbon uptake. Here, we report a close correspondence between seasonally changing foliar pigment levels, expressed as chlorophyll/carotenoid ratios, and e...

Note: When Robert Emerson was killed in a plane accident on February 4, 1959, much of the experimental material accumulated in his two years work on the action spectrumn of photosynthesis in the far-red region, remained uinpublished. He was to present these resuilts to the Botanical Congress in Montreal in August, 1959. Instead, the following paper was presented, prepared on the basis of Emerso...

As the world strives to create a more sustainable environment, green chemistry has come to the fore in attempts to minimize the use of hazardous materials and shift the focus towards renewable sources. Chlorophylls, being the definitive "green" chemical are rarely used for such purposes and this article focuses on the exploitation of this natural resource, the current applications of chlorophyl...

Introduction Porphyrins are the extroverts of chemistry. Bright purple and fluorescent, they are used biologically in the processes of energy capture and utilization. Porphyrins are the key to life. It has been suggested that abiotic formation of porphyrins, in particular uroporphyrinogen would have provided the first pigments necessary for the eventual synthesis of the chlorophylls. This would...

The evolutionary developments that led to the ability of photosynthetic organisms to oxidize water to molecular oxygen are discussed. Two major changes from a more primitive non-oxygen-evolving reaction center are required: a charge-accumulating system and a reaction center pigment with a greater oxidizing potential. Intermediate stages are proposed in which hydrogen peroxide was oxidized by th...

In contrast to what happens in higher plants and eukaryotic algae, a nitrogen deficiency during growth causes a change in pigment composition but no significant changes in whole cell lipid and fatty acid composition of the two Cyanobacteria, Pseudanabaena sp. (strain M2) and Oscillatoria splendida (strain L3). Nitrogen deficiency does not affect the cellular content in chlorophyll a, but it cau...

background:  stresses such as heat shock, starvation, or osmotic is essential to lead isolated microspores towards embryogenesis. despite the effectiveness of stresses in embryogenesis, they exert adverse effects on metabolism and growth of the regenerated plants.objectives: the effects of heat shock and 2,4-d treatment on total protein content of treated microspores, morphological and physiolo...