1. We have obtained an action spectrum for chlorophyll formation in Euglena gracilis. This action spectrum is similar to the absorption spectrum of protochlorophyll. However, efforts to isolate and identify this pigment have been unsuccessful. 2. Porphyrins have been extracted from both the normal and dark-adapted Euglena and a chlorophyll-free mutant. 3. The "action" spectra for chlorophyll an...

Characteristics and quantum efficiencies of photocurrents at monolayer, mixed monolayers, and multilayers of chlorophyll a deposited on semiconducting SnOz electrodes and/or metal electrodes were surveyed. The quantum efficiency of photocurrent depends on the surface concentration of chlorophyll a as well as the thickness of layers. The photocurrent behavior of chlorophyll a multilayers is comp...

In a previous paper (l), studies were made of chlorophyll degradation products frequently to be found in leaf extracts. The solation of spectroscopically pure chlorophylls a and b was then considered (2). The logical outcome of these studies is the application of the data to the determination of chlorophyll in extracts. It is complicated by the suggestion that chlorophyll as known to Willstatte...

In a previous paper (l), studies were made of chlorophyll degradation products frequently to be found in leaf extracts. The solation of spectroscopically pure chlorophylls a and b was then considered (2). The logical outcome of these studies is the application of the data to the determination of chlorophyll in extracts. It is complicated by the suggestion that chlorophyll as known to Willstatte...

* Corresponding author. E-mail addresses: [email protected] (M. Fang). 1537-5110/$ – see front matter a 2009 IAgrE doi:10.1016/j.biosystemseng.2009.12.008 Heavy metal stress in soils results in subtle changes in leaf chlorophyll concentration, which are related to crop growth and crop yield. Accurate estimation of the chlorophyll concentration of a crop under heavy metal stress is essential...

A comparative study of polypeptide composition and freeze-fracture morphology of chloroplast membranes isolated from different, but photosynthetically active, regions of a romaine lettuce shoot is presented. Chloroplasts prepared from outer dark-green leaves possess a fully developed light-harvesting chlorophyll-protein complex, have low chlorophyll a:b ratios and display fracture faces similar...

Photosystem I (PSI) from Chroococcidiopsis thermalis PCC 7203 grown under far-red light (FRL; >725 nm) contains both chlorophyll a and a small proportion of chlorophyll f. Here, we investigated excitation energy transfer and charge separation using this FRL-grown form of PSI (FRL-PSI). We compared femtosecond transient visible absorption changes of normal, white-light (WL)-grown PSI (WL-PSI) wi...

This work introduces a new vision-based approach for estimating chlorophyll contents in a plant leaf using reflectance and transmittance as base parameters. Images of the top and underside of the leaf are captured. To estimate the base parameters (reflectance/transmittance), a novel optical arrangement is proposed. The chlorophyll content is then estimated by using linear regression where the i...

The SeaWiFS ocean colour sensor on board the SeaStar (Orbview 2) satellite is able to derive the chlorophyll concentration in the surface sea water. The chlorophyll algorithm employed is based on the ratio of radiance or reflectance measured in the blue and green spectral bands. Regression between the band ratio and the in-situ measurements of chlorophyll values gives the coefficients for the r...

The room temperature absorption bandshape for the Q transition region of chlorophyll a is calculated using the vibrational frequency modes and Franck-Condon (FC) factors obtained by line-narrowing spectroscopies of chlorophyll a in a glassy (Rebane and Avarmaa, Chem. Phys. 1982; 68:191-200) and in a native environment (Gillie et al., J. Phys. Chem. 1989; 93:1620-1627) at low temperatures. The c...