This paper presents spectroscopic investigations of IsiA, a chlorophyll a-binding membrane protein produced by cyanobacteria grown in iron-deficient environments. IsiA, if associated with photosystem I, supports photosystem I in light harvesting by efficiently transferring excitation energy. However, if separated from photosystem I, IsiA exhibits considerable excitation quenching observed as a ...

The present investigation envisages the in vivo measured laser induced chlorophyll florescence spectra of EMS (Ethyl methane sulphonate) treated safflower leaves. Seeds of safflower were treated with 0.5% EMS for three treatment durations (3h, 5h and 7h) to raise the populations. The effect of EMS treatment on chlorophyll content in the leaves was assessed using laser induced chlorophyll fluore...

The photosystem II (PS-II) reaction center is composed of several polypeptides which contain carotenoids and chlorophyll. Three pigment-free extrinsic proteins, with masses 33, 24, 18 kDa, are involved in the oxygen evolving system [1]. One of the extrinsic proteins, a 33 kDa polypeptide, accelerates a dark step in the oxygen-evolving reaction [2] and preserves the binding of the Mn atoms to th...

1. The percent inhibition of oxygen evolution by a given herbicide concentration is the same at various light intensities except at very low intensities where the percent inhibition becomes larger. The same results are obtained with the herbicide DCMU. 2. The concentration of DCMU causing 50% inhibition of oxygen evolution decreases with de­ creasing chloroplast (and thus of chlorophyll) concen...

Many plant tissues fluoresce due to the natural fluorophores present in cell walls or within the cell protoplast or lumen. While lignin and chlorophyll are well-known fluorophores, other components are less well characterized. Confocal fluorescence microscopy of fresh or fixed vibratome-cut sections of radiata pine needles revealed the presence of suberin, lignin, ferulate, and flavonoids assoc...

This study pursues the detection of bruised areas caused by mechanical impact on Golden Delicious apples using chlorophyll fluorescence imagery. When a fruit is impacted by a mechanical force and a bruise occurs, the chlorophyll nuclei inside the peel are damaged, which causes a reduction in fluorescence excitation compared to non-impacted areas. This difference allows automated detection of br...

A phytoplankton bloom occurred in Ardley Cove, King George Island in January 2016, during which maximum chlorophyll-a reached 9.87 mg/m3. Records show that blooms have previously not occurred in this area prior to 2010 and the average chlorophyll-a concentration between 1991 and 2009 was less than 2 mg/m3. Given the lack of in situ measurements and the poor performance of satellite algorithms i...

The Stepanov equation, relating the intensity of emission, f(e)(v), at a given frequency, and that of absorption, k(v), at the same frequency, is applied, in its modified form (see equation 3 in text) to suspensions of Chlorella, Porphyridium, and Anacystis and to chlorophyll solutions. This application can reveal whether the yield of fluorescence, Phi(v), is constant, or changes with frequency...

In the present study, we investigated changes in chlorophyll fluorescence, photosynthetic parameters and fruit yields, as well as fruit phytochemical accumulation of strawberry (Fragaria ananassa Duch.) that had been cultivated in a greenhouse under different combinations of light intensity and temperature. In plants grown with low light (LL) photosystem II chlorophyll fluorescence was found to...