Induction of Defense-Related Physiological and Antioxidant Enzyme Response against Powdery Mildew Disease in Okra (Abelmoschus esculentus L.) Plant by Using Chitosan and Potassium Salts

Foliar sprays of three plant resistance inducers, including chitosan (CH), potassium sorbate (PS) (C₆H₇kO₂), and potassium bicarbonates (PB) (KHCO₃), were used for resistance inducing against Erysiphe cichoracearum DC (powdery mildew) infecting okra plants. Experiments under green house and field conditions showed that, the powdery mildew disease severity was significantly reduced with all tested treatments of CH, PS, and PB in comparison with untreated control. CH at 0.5% and 0.75% (w/v) plus PS at 1.0% and 2.0% and/or PB at 2.0% or 3.0% recorded as the most effective treatments. Moreover, the highest values of vegetative studies and yield were observed with such treatments. CH and potassium salts treatments reflected many compounds of defense singles which leading to the activation power defense system in okra plant. The highest records of reduction in powdery mildew were accompanied with increasing in total phenolic, protein content and increased the activity of polyphenol oxidase, peroxidase, chitinase, and β-1,3-glucanase in okra plants. Meanwhile, single treatments of CH, PS, and PB at high concentration (0.75%, 2.0%, and/or 3.0%) caused considerable effects. Therefore, application of CH and potassium salts as natural and chemical inducers by foliar methods can be used to control of powdery mildew disease at early stages of growth and led to a maximum fruit yield in okra plants.

Allelopathic potentiality of lupinus seed extract on yield and chemical composition of soybean seeds

The allelopathic effect of aqueous extract of lupin [Lupinus terms cv. Giza 1] seeds at 5 percent, 15 percent and 25 percent concentration [w/v] on soybean after 30 days of seedling establishment could be effective in enhancing the production. The data illustrated that soybean seed yield was stimulated by lupin extract at 5 percent concentration, no appreciable changes with 15 percent level whereas the highest concentration [25 percent] showed an inhibitory effect .The promotion or reduction of soybean yield, caused by lupin extract treatments was paralleled with increased or decreased total protein and oil constituent of the seeds. The biochemical interference of lupin extract may afford greater possibilities for mechanism of allelopathic action that depends upon physiological response, capacity of soybean. This is reflected mostly on the primary and secondary metabolic products. So the 5 percent lupin extract has a positive allelopathic effect due to its ability to increase plant growth and to stimulate soybean yield production. This finding suggests that the potential beneficial involvement of lupin seed aqueous extract as crop-crop stimulator, by its application at lower concentrations after soybean emergence, should be effective in enhancing crop production

Effect of different concentrations of lupin seed extract on the growth criteria and pigmentation of soybean plant at different growth stages

This long-term greenhouse pot experiment study indicated that the application of lupin [Lupinus termis cv. Giza 1] extracts after 30 days of soybean seedling establishment could be effective in enhancing soybean production. Data revealed that soybean growth was stimulated by lupin extract of 5% concentration and no appreciable changes with 15% level, whereas the highest concentration [25%] showed an inhibitory effect. The extent of growth stimulation or inhibition by lupin extracts varied with the measured growth parameters. Regarding the pigments, the shoot of plants treated with lupin extracts contained less chlorophylls and carotenoids than the untreated plants. The magnitude of reduction increased with raising the lupin extract concentration and was greater in older than younger plants