Pre-illumination of cucumber leaf discs at a chilling temperature in low-irradiance white light resulted in accelerated re-reduction of P700(+) [the special Chl pair in the photosystem I (PSI) reaction centre] when the far-red measuring light was turned off. Measurements (in +/- methyl viologen or +/- DCMU conditions) of the re-reduction half time suggest that accelerated re-reduction of P700(+...

Herbicide application incurs water contamination and thus effective herbicide detection methods are needed. In this research, a kinetic model was developed to describe the processes of herbicide diffusion into plant tissues and binding to the active sites. DCMU [3-(3,4-dichlorophenyl)-1,1-dimethylurea], a commonly used herbicide, was used as a test chemical and its diffusion into plant leaves a...

TI1vwo basically differenlt svstemlls have been described by which chloroplast preparations are able to synthesize ATP in the light: cyclic and nioncyclic photophosphorylation (2, 3). Other systems producing ATP in the light. e.g. pseudocyclic (or aerobic) anid oxidative photoplhosphorylatioins might only be variations of the 2 basic types (26. 27). A main feature of true cyclic photophosphoryl...

Using high-intensity actinic light, the chlorophyll a fluorescence transient from HC0,-depleted chloroplasts shows a rapid initial rise (0 + 1) followed by a slow phase ( I + P). In the presence of HC0,-, the 0 -+ I rise is delayed but the I + P phase is much more rapid. Using lowintensity actinic light, the chlorophyll a fluorescence transient from 3-(3.4-dichlorophenyI)I , I dimethylurea (DCM...

The effects of salinity on the primary processes of photosynthesis were studied in the red alga Porphyra perforata. The results show that there are at least three sites in the photosynthetic apparatus of this alga that were affected by increased salinity. The first site, photoactivation and dark-inactivation of electron flow on the reducing side of photosystem I, was completely inhibited at hig...

Transport of pesticides by surface runoff during rainfall events is a major process contributing to pesticide contamination in rivers. This study presents an empirical regression model that relates pesticide loading over time in the Sacramento River with the precipitation and pesticide use in the Sacramento River watershed. The model closely simulated loading dynamics of diazinon, simazine, and...