[Basal bacteriosis of wheat and influence of agrotechnical methods on its spread].

Monitoring of bacterial diseases of wheat was conducted allowing for different doses of mineral fertilizers and crops predecessors. It is shown that symptoms of development of the basic disease of wheat, which is caused by Pseudomonas syringae pv. atrofaciens, varied depending on agrotechnical methods, stages of plant growth and environmental factors. Introduction of different doses of nitrogen, phosphate and potassium fertilizers, especially high ones, increases the damage of wheat by the agent of basal bacteriosis P. syringae pv. atrofaciens. Strains of this pathogen, isolated from the infected wheat plants, affect in the experiment such weeds as sow thistle, field horsetail, and couch grass.

[Chemical signaling in plant microspore cells].

Chemical signal transduction from the cell surface to organelles was studied in unicellular vegetative (Equisetum arvense) and generative (Hippeastrum hybridum pollen) microspores of plants. Neurotransmitters acetylcholine, dopamine, and serotonin, their agonists and antagonists, Na+, K+, and Ca2+ channel blockers, as well as forskolin and theophylline (agents increasing the intracellular level of cyclic adenosine monophosphate) were used as chemical signals. Both types of microspores exposed to neurotransmitters, their agonists, forskolin, and theophylline demonstrated growth activation, while neurotransmitter antagonists and ion channel blockers inhibited this process. No stimulating effects of neurotransmitters were observed for cells pretreated with the antagonists and ion channel blockers. Pretreatment with ion channel blockers and then by anticontractile agents (cytochalasin B or colchicine) either had no effect or increased the inhibition of microspore growth. Pathways of chemical signal transduction from the cell surface to organelles are discussed.

[Physiological metabolism and protective enzyme activity of Equisetum ramosissimum under Cu stress].

The study with pot culture experiment showed that Equisetum ramosissirmunm did not appear obvious poisoning symptoms when treated with low concentration Cu (500 mg x kg(-1)), while serious injuries were found when treated with high concentration Cu (1000 to approximately 3000 mg x kg(-1)), which reflected in the severe damage of cell membrane and cytoarchitecture as well as the structure and function of main organelles, and the significant decrease of the contents of leaf chlorophyll a and b and stem soluble monosaccharose. The cell membrane osmolarity and the average MDA content of the plant exposed to heavy copper pollution was 1 to approximately 2 and 1 to approximately 3 times greater than the control, respectively. It could be concluded that high concentration Cu disturbed the physiological metabolism, and critically threatened the normal growth of E. ramosissimum. The activities of protective enzyme, especially of SOD and POD, were enhanced with increasing Cu concentration, and had a positive correlation with Cu concentration (rPOD = 0.978, rSOD = 0.926, P < 0.05).

Use of imazapyr against Equisetum arvense on Swedish railway tracks.

Since glyphosate has been used extensively for weed control in Swedish railway tracks, common horsetail (Equisetum arvense L), previously relatively rare, has become very common. Glyphosate, although effective against most other weeds found on railway tracks, gives poor control of E. arvense, so that heavy infestation with this weed is now common. Imazapyr (applied as a 250g AE litre(-1) SL, Arsenal) has controlled E. arvense, but is known to be very mobile. Adequate control of the weed requires application of > or = 4 litres ha(-1) of imazapyr SL but environmental factors preclude the use of > 2 litres ha(-1). A suitable strategy was found to be one application of imazapyr SL at 2 litres ha(-1) in each of two successive years but best weed control was obtained by supplementing imazapyr in the first year with glyphosate 360 g AE litre(-1) SL (RoundUp Bio) at 3 litres ha(-1).