The mangrove habitat exhibits many unique physical features, one of the most important of which is a salinity gradient. Photosynthetic rates, as measured by leaf stomatal conductance and leaf chlorophyll fluorescence induction, were tested as indicators of salinity stress in seedlings of the red mangrove, Rhizophora mangle, grown under five different salinity levels: 0, 15, 30, 45, and 60 parts...

Barley (Hordeum vulgare) leaf segments unroll and green when illuminated. Illuminated segments also have an increased capacity for RNA synthesis. Part of this increased RNA synthesis may be attributed to an increased RNA polymerase activity. In addition, following illumination there is an increased formation of polysomes.Analyses of RNA synthesized during illumination showed that the radioactiv...

Spectral reflectance of plant canopies provides an accurate indication of ground cover fraction, which is highly correlated with radiation capture. If nutrients and water do not limit growth, radiation capture is highly correlated with daily growth rate and ultimate yield. However, if nutrients and water limit growth, none of the common spectral indices are able to separate a more developed, st...

Ascorbic acid (Asc) is a major antioxidant in plants that detoxifies reactive oxygen species (ROS) and maintains photosynthetic function. Expression of dehydroascorbate reductase (DHAR), responsible for regenerating Asc from an oxidized state, regulates the cellular Asc redox state, which in turn affects cell responsiveness and tolerance to environmental ROS. Because of its role in Asc recyclin...

It has been known since Herlitzka's work in 1912 that it is possible to prepare colloidal solutions of chlorophyll by grinding plant tissue. Lubimenko (1927) found that some leaves (Funkia and Aspidistra genuses) gave on extraction with water clear stable green solutions which contained all the chlorophyll of the original leaf in combination with a protein. Other leaves gave extracts which cont...

Because the timing and amount of N fertilizer applications are important in producing high yield in cotton (Gossypium hirsutum L.), determining changes in plant N status is a valuable management tool. This study evaluated the Spectrum Technologies CM-1000 chlorophyll meter as compared with the GER model 1500 spectroradiometer for remote estimation of leaf chlorophyll concentration (Chl) under N...

We have extended a conventional photosynthesis model to simulate field and laboratory measurements of chlorophyll fluorescence at the leaf scale. The fluorescence paramaterization is based on a close nonlinear relationship between the relative light saturation of photosynthesis and nonradiative energy dissipation in plants of different species. This relationship diverged only among examined dat...

The ambient mass spectrometry technique, desorption electrospray ionization mass spectrometry (DESI-MS), is applied for the rapid identification and spatially resolved relative quantification of chlorophyll degradation products in complex senescent plant tissue matrixes. Polyfunctionalized nonfluorescent chlorophyll catabolites (NCCs), the "final" products of the chlorophyll degradation pathway...