Nitrogen concentration in plants is normally determined by expensive and time consuming chemical analyses. As an alternative, chlorophyll meter readings and N-NO(3) concentration determination in petiole sap were proposed, but these assays are not always satisfactory. Spectral reflectance values of tomato leaves obtained by visible-near infrared spectrophotometry are reported to be a powerful t...

Knowledge of foliar nitrogen (N) concentration is important in pecan [Carya illinoinensis (Wang.) K. Koch] management protocols. Lower cost and/or rapid methods to determine foliar N are desirable and may result in improved management strategies as well as enable precision agricultural practices to be deployed in pecan production. This study investigates using a portable chlorophyll meter and V...

Current technologies for measuring plant water status are limited, while recently remote sensing techniques for estimating N status have increased with limited research on the interaction between the two stresses. Because plant water status methods are time-consuming and require numerous observations to characterize a field, managers could benefit from remote sensing techniques to assist in irr...

Cells of the red alga Porphyridium cruentum (ATCC 50161) exposed to increasing growth irradiance exhibited up to a three-fold reduction in photosystems I and II (PSI and PSII) and phycobilisomes but little change in the relative numbers of these components. Batch cultures of P. cruentum were grown under four photon flux densities of continuous white light; 6 (low light, LL), 35 (medium light, M...

Spanish moss (Tillandsia usneoides L.) was collected in South Carolina, maintained in a greenhouse, then exposed to five levels of photosynthetic photon flux density (PPFD) for 3 weeks. Following this treatment, plants were sampled for chlorophyll concentrations, nocturnal acid accumulations, and photosynthetic responses to subsequent exposure at a range of PPFD. No acclimation to PPFD was obse...

knowledge of the physiological characteristic of tree and shrubs species and their adaptability to environmental factors is an important issue in species selecting for tree planting projects in water scarcity regions. therefore, this investigation try to examine the chlorophyll content and stomatal conductivity in various species of trees and shrubs. the effects of environmental factors are als...

The quantum yield of photosystem II, determined by chlorophyll fluorescence and the quantum yield of CO2 uptake, determined from gas exchange, are two physiologically important measurements in clarifying the response to environmental stress. Both measurements, however, require an accurate assessment of leaf light absorption in the photosynthetically active radiation wavelength range (400–700 nm...

Light-shade adaptation of the chlorophyll a/b containing procaryote Prochlorothrix hollandica was studied in semicontinuous cultures adapted to 8, 80 and 200 mumole quanta per square meter per second. Chlorophyll a contents based on dry weight differed by a factor of 6 and chlorophyll b by a factor of 2.5 between the two extreme light conditions. Light utilization efficiencies determined from p...

Twelve greenbug (Schizaphis graminum (Rondani)) biotype E-resistant synthetic hexaploid wheats synthesized by crossing Triticum dicoccum Schrank. and Aegilops tauschii (Coss.) Schmal. were evaluated for the three known insect resistance categories, including antibiosis, anti-xenosis, and tolerance. Different methods were evaluated for calculating antibiosis and tolerance. Calculating intrinsic ...

energy of a moving gas into rotational energy. At a given flow rate Q, the rotor of the turbine meter would spin at an angular velocity ωi as shown in Figure 1. With an idealized turbine meter, the rotational speed of the rotor would be directly proportional to the volumetric flow rate of the flowing medium. The relationship between flow rate Q and the angular velocity ωi can be expressed as fo...