Illuminating shoots stimulates nitrate uptake by wheat (Triticum aestivum L. cv. ‘EM18’) roots. A method with a high time resolution (minutes), non-invasive technique, has enabled to measure the nitrate uptake time coarsely. The nitrate uptake by wheat roots increases in the light and decreases in the dark. The mechanism is thought to be via a signal carried in phloem, probably a sugar.
The aim of this study was to evaluate the influence of light on the production of carotenoids by Phaffia rhodozyma CBS 5626 yeast. The fed-cultures at different illuminance were conducted: in the dark, at constant illuminance of 400 lux and 600 lux, at variable illuminance. It was found that illuminance and time had a significant effect on the level of carotenoids synthesized by Phaffia rhodozyma CBS 5626. But these agents had no a significant effect on yeast dry matter yield. Light stimulated carotenogenesis in cells of the tested yeast; the highest yields of carotenoids were obtained in cultures run at illuminance of 400 lux, while the lowest in cultures run in the dark.
Germination responses of Galium cracoviense Ehrend. (Rubiaceae), a narrow endemic species from southern Poland, were tested in light and dark conditions at three constant temperatures (5, 10, or 22°C), before and after cold-wet stratification. Additionally, seeds were germinated under different calcium carbonate (CaCO3) concentrations (1, 5, 10, 15, 20, or 25 mM/L CaCO3) at 22°C in light. The high germination capacity of seeds incubated at different temperatures, shortly after collection, already suggested the absence of dormancy in this species. Thus, the seeds are ready to germinate immediately in the field when water resources are available and the temperature is adequate. Light was a significant factor for G. cracoviense; more seeds germinated in light than in darkness at all temperatures tested. Cold stratification decreased germination especially at higher temperatures. The light requirement for G. cracoviense germination ensures their successful germination on or near the soil surface, and in cracks and crevices in limestone, when temperature and edaphic conditions are favourable. Seeds of this species show temperature enforced dormancy throughout the winter. Germination was significantly affected by calcium carbonate. Non-germinated seeds germinated well after being transferred from higher CaCO3 concentrations to distilled water. The results indicate that the seeds of this species can endure CaCO3 stress without losing their viability and start germination once CaCO3 concentration is reduced. It can be concluded that the seeds of this species require lower Ca2+ ion concentration, moderate temperatures and the presence of light to germinate.
Two inoculums: Effective Microorganisms (EM) specimen available on the market and microbiological BAF1 inoculum, were applied in the experiment. The plants were cultivated in the growth chamber equipped with shelves with fluorescent or LED lamps. The highest number of inflorescences was under the influence of white color of light emitted by fluorescent lamps and blue color of light emitted by LED lamps, especially after application of BAF1 inoculum. Irrespective of microbiological inoculum, no significant effect of the color of light and type of lamps on such traits as height of leaves layer, number of leaves, greening index of leaves (SPAD) and length of inflorescences, was found. The white color light emitted by fluorescent lamps stimulated actinobacteria multiplication, especially after EM application. Regardless of the inoculum application, it was the blue color light emitted by LED lamps that stimulated the multiplication of moldy fungi. After the use of fluorescent lamps, the increase in dehydrogenase activity was observed, especially after the application of BAF1 inoculum. The activity of acid phosphatase was stimulated by blue and white+blue light emitted by LED lamps. The increase in the activity of urease was observed under fluorescent lamps emitting the green, blue and white color of light, after the application of EM.
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