Search results for "Far-red"

Über den Ureidstoffwechsel beim Laubmoosprotonema von Funaria hygrometrica L. (Sibth.)

1973

Summary 1. Allantoin and allantoic acid were about 6 % of the total nitrogen content of moss protonema (Funaria hygrornetica L.). 2. The level of endogenous allantoin depends on the spectrum colour of the irradiation. The peaks coincide with the peaks of a chlorophyll absorption spectrum from a methanolic extract of moss protonema. 3. The total amount of allan to in consists of two parts. One part is supplied by metabolism in darkness but the main one depends on light. Green- and far red light are “physiological dark conditions” for the moss protonema. In the dark ureide degradation comes to an end with allantoic acid. There are only traces of urea. 4. The coinciding correlations between th…

2021

Abstract Remote sensing-based measurements of solar-induced chlorophyll fluorescence (SIF) are useful for assessing plant functioning at different spatial and temporal scales. SIF is the most direct measure of photosynthesis and is therefore considered important to advance capacity for the monitoring of gross primary production (GPP) while it has also been suggested that its yield facilitates the early detection of vegetation stress. However, due to the influence of different confounding effects, the apparent SIF signal measured at canopy level differs from the fluorescence emitted at leaf level, which makes its physiological interpretation challenging. One of these effects is the scatterin…

The 2013 FLEX—US Airborne Campaign at the Parker Tract Loblolly Pine Plantation in North Carolina, USA

2017

The first European Space Agency (ESA) and NASA collaboration in an airborne campaign to support ESA’s FLuorescence EXplorer (FLEX) mission was conducted in North Carolina, USA during September–October 2013 (FLEX-US 2013) at the Parker Tract Loblolly Pine (LP) Plantation (Plymouth, NC, USA). This campaign combined two unique airborne instrument packages to obtain simultaneous observations of solar-induced fluorescence (SIF), LiDAR-based canopy structural information, visible through shortwave infrared (VSWIR) reflectance spectra, and surface temperature, to advance vegetation studies of carbon cycle dynamics and ecosystem health. We obtained statistically significant results for fluorescence…

Red and far-red sun-induced chlorophyll fluorescence as a measure of plant photosynthesis

2015

Remote estimation of Sun-induced chlorophyll fluorescence emitted by terrestrial vegetation can provide an unparalleled opportunity to track spatiotemporal variations of photosynthetic efficiency. Here we provide the first direct experimental evidence that the two peaks of the chlorophyll fluorescence spectrum can be accurately mapped from high-resolution radiance spectra and that the signal is linked to variations in actual photosynthetic efficiency. Red and far red fluorescence measured using a novel airborne imaging spectrometer over a grass carpet treated with an herbicide known to inhibit photosynthesis was significantly higher than the corresponding signal from an equivalent untreated…

Über die wirkung des phytochroms beim laubmooskallus II. Sauerstoffmetabolismus und acetylcholinwirkung

1974

Summary The oxygen metabolism is a good parameter for the determination of rapid responses of green moss callus to light. We measured the oxygen uptake with the Warburg method and polarographically with a Clark electrode and the YSI-oxygen monitor. The exposure of dark grown moss callus to red light (5–20 min) induced a rapid increase in O2-uptake after switching off the light. The respiration change depends on the exposure duration and the light intensity. During the first 2 or 3 h after irradiation with red light and with red-far red light, the rates of the O2-uptake show no differences but after this lag-phase the 2 curves are splitting. The respiration of the red irradiated cells remain…

Influence of Light on the Bioelectric Potential of the Bean (Phaseolus vulgaris) Hypocotyl Hook

1975

By use of surface electrodes electropotenlial measurements were carried out on hypocotyl hooks of Phaseolus vulgaris seedlings. The hooks were illuminated with a small spot of white, blue, red or far red light. The potential changes in bean hypocotyl hooks do not show the red-far red reversible characteristics of phytochrome-mediated processes. By experimenting with inhibitors of photosynthesis we could demonstrate that the light-triggered potential changes in green bean hooks are correlated to photosynthetic electron transport phenomena. The red-light-induced transient is a depolarization, whereas blue light induces a hyperpolarization. Etiolated beans exhibit no bioelectric potential chan…

Red : far-red light ratio and UV-B radiation: their effects on leaf phenolics and growth of silver birch seedlings

2004

The natural variation in quantity and quality of light modifies plant morphology, growth rate and concentration of biochemicals. The aim of two growth-room experiments was to study the combined effects of red (R) and far-red (FR) light and ultraviolet-B (UV-B) radiation on the concentrations of leaf phenolics and growth and morphology of silver birch (Betula pendula Roth) seedlings. Analysis by high-performance liquid chromatography showed that the leaves exposed to supplemental FR relative to R contained higher concentrations of total chlorogenic acids and a cinnamic acid derivative than the leaves treated with supplemental R relative to FR. In contrast, concentration of a flavonoid, querc…

The Effect of Light on the Growth of Pea Plants and the Subsequent Influence in Shikimate Oxidoreductase (EC 1.1.1.25) Activity

1981

Summary Pea plants were cultured in white light, red and far red light, and in the dark during a period of three weeks. At several states of development we investigated the activity of the enzyme shikimate oxidoreductase, the amount of fresh and dry matter, and the contents of protein in stem, leaves, cotyledons, and roots. The enzyme activity was found to be distributed organ-specifically and uninfluenced by the phytochrome system, but it was significantly depressed in plants grown in the dark compared to plants grown in white light. Enzyme activity occurred also in non photosynthetic plants. Regarding the different light conditions the activity of shikimate oxidoreductase was found to cor…