Interception of photosynthetically active radiation (PAR) was evaluated relative to greenness and normalized difference [MSS (7 5)/(7 + 5)] for five planting dates of wheat for 1978-79 and 1979-80 at Phoenix, Arizona. Intercepted PAR was calculated from leaf area index and stage of growth. Linear relationships were found with greenness and normalized difference with separate relationships descr...

Different applications dealing with plant physiology, biomass production and natural illumination in greenhouses require knowledge of the photosynthetically active radiation. In absence of measurements of this flux, one must rely on parametric approaches. In this way, the radiant energy is computed using available atmospheric parameters. In the present work, we have developed a comparison among...

C4 plants have a biochemical carbon-concentrating mechanism that increases CO2 concentration around Rubisco in the bundle sheath. Under low light, the activity of the carbon-concentrating mechanism generally decreases, associated with an increase in leakiness (ϕ), the ratio of CO2 retrodiffusing from the bundle sheath relative to C4 carboxylation. This increase in ϕ had been theoretically assoc...

Title of Dissertation: MAPPING PHOTOSYNTHETICALLY ACTIVE RADIATION (PAR) USING MULTIPLE REMOTE SENSING DATA Tao Zheng, Doctor of Philosophy, 2007 Dissertation directed by: Dr. Shunlin Liang, Professor Department of Geography Incident Photosynthetically Active Radiation (PAR) is an important parameter for terrestrial ecosystem models. Presently, deriving PAR using remotely sensed data is the onl...

Knowledge of the photosynthetically active radiation is necessary in different applications dealing with plant physiology, biomass production and natural illumination in greenhouses. Nevertheless, as a result of the absence of widespread measurements of this radiometric flux, it is often calculated as a constant ratio of the broadband solar radiation. This ratio is affected by many parameters. ...

Understanding processes of maize (Zea mays L.) growth and production of grain in highyielding, irrigated conditions offers hope to understand yield potential in many other environments. In this study we investigated such processes at the plant level, and attempted to simulate maize yields at the field level and county level in the high yielding region of the High Plains of Texas. In addition, w...