Effects of atmospheric humidity and soil moisture content on the relative intensity of chlorophyll fluorescence of cucumber (Cucumis sativus L.) exposed to high air temperatures were assessed as a measure of heat stress or injury. 1. After exposure to 25 •Ž (control) and 42•‹, 44•‹ and 46•Ž for two to three hours, the intensity of fluorescence decreased a little at 42•‹ and 44•Ž but markedly at...

Serious environmental degradation of aquatic ecosystems has been caused by eutrophication and by pollutants such as herbicides. Therefore, measurement of in situ algal photosynthetic activity is important for environmental monitoring. With ordinary nonimaging fluorometers, algal chlorophyll fluorescence can be measured easily, but heterogeneity within samples cannot be detected. Effects of a he...

In vivo chlorophyll fluorescence associated to Photosystem II is being used to evaluate photosynthetic activity of microalgae grown in different types of photobioreactors; however, controversy on methodology is usual. Several recommendations on the use of chlorophyll fluorescence to estimate electron transport rate and productivity of microalgae grown in thin-layer cascade cultivators and metha...

Jujube (Ziziphus jujuba Mill.) fruit is an important medicinal plant in Iran. The harvesting time is a crucial for jujube fruit quality. Several characteristics of jujube fruit when harvested at four development stages; white mature (light green), crisp mature (white-red), fully mature (red) and fully ripe (dehydrated brown) were evaluated. Fruit weight, diameter, volume, pulp to stone ratio, f...

To elucidate effect of chemical reagents addition on growth of aquatic plants in restoration of aquatic ecosystem, Spirodela polyrrhiza (L.) Schleid was used to evaluate its physiological responses to excess iron (Fe(3+)) and copper (Cu(2+)) in the study. Results showed that accumulation of iron and copper both reached maximum at 100 mg L(-1) iron or copper after 24 h short-term stress, but exc...

Non-photochemical chlorophyll fluorescence quenching (NPQ) plays a major role in the protection of the photosynthetic apparatus against damage by excess light, which is closely linked to the production of reactive oxygen species (ROS). The effect of a short heat treatment on NPQ and ROS production was studied with detached tobacco leaves by fluorescence imaging of chlorophyll and of the ROS sen...

The spatial heterogeneity of stomatal closure in response to rapid desiccation of excised well-watered Tradescantia virginiana leaves grown at moderate (55%) or high (90%) relative air humidity (RH) was studied using a chlorophyll fluorescence imaging system under non-photorespiratory conditions. Following rapid desiccation, excised leaves grown at high RH had both a greater heterogeneity and a...