Abstract
The aim of experiments was to investigate a maximal efficiency of PSII, as a marker indicating growth, vigor, energetic value and physiological activity of sorghum fertilized with wastes from a biomass biodigestion to methane in a distillery integrated with a biogas plant using corn grains as substrate. The sorghum plants grown outdoor in different climate and in pots and in field were fertilized with different doses of the waste or Apol-humus – a soil improver and Stymjod – a nano-organic-mineral fertilizer. The maximal efficiency of PSII, in comparison with plant growth and health, chlorophyll content, gas exchange, activity of selected enzymes, element content in leaves and energetic value were studied. The wastes applied to soil resulted in increased maximal efficiency of PSII and the doses of 30 m3 ha-1 and 40–50 m3 ha-1 of the non-centrifuged and centrifuged ones, respectively, were most efficient. This enhancement was associated with the increased kinetics of plant growth, their health, fresh and dry biomass and physiological activity of plants as evidenced by activity of acid and alkaline phosphatase, RNase and dehydrogenase, as well as by gas exchange: net photosynthesis, transpiration, stomatal conductance, intercellular CO2 concentration and index of chlorophyll content in leaves. The fertilization with Apol-humus and Stymjod additionally increased maximal photochemical efficiency of PSII and plant development, biomass yield and physiological activity. The results indicate that waste from a biomass biodigestion to methane can be used as a natural fertilizer in sorghum crops and this ensures their recycling and environmental protection. The measurement values of maximal efficiency of PSII were proportionally to the vigor, growth and physiological activity of the plants. The obtained results indicate that the maximal efficiency of PSII in sorghum plants is a non-destructive method for defining the degree of growth and may be used as a marker of plant vigor and health, development and physiological activity expressed by gas exchange and activity of selected enzymes.
Highlights
Management of waste from a biomass biodigestion to methane and its ecological use in plant production as fertilizers are among important issues in the world agriculture
The purpose of this work was to investigate the suitability of maximal efficiency of photosystem II (PSII), as the marker indicating growth, vigor, energetic value and physiological activity of sorghum fertilized with wastes from a corn grain biodigestion to methane, supplemented with new generation biostimulators, Apol-humus and Stymjod, and its usefulness in monitoring of waste applicability in sorghum crops
The noncentrifuged waste applied to soil at the dose of 10–40 m3 ha−1 and the centrifuged one at 20–60 m3 ha−1 significantly increased the maximal efficiency of PSII, which showed that the most profitable were their doses of 40 m3 and 40–50 m3, respectively
Summary
Management of waste from a biomass biodigestion to methane and its ecological use in plant production as fertilizers are among important issues in the world agriculture. The problem in the waste application in agriculture is a quick and reliable assessment of the effects of plant fertilization that would enable rational management of this treatment For this reason, technologists are looking for physiological methods that immediately show the reaction of the plants to different treatments, which enables quick cultivation decisions to be made in the growing season without waiting for the completing plant growth in autumn. Strasser et al (2000) suggested six parameters which can be used in screening tests: F0/Fm, (dV/dt)0, VJ, VI, tFmax and Sm. By measuring the intensity and nature of this fluorescence, plant ecophysiology can be investigated (Lichtenthaler et al, 1986; Zebrowska and Michałek, 2014). The Fv/Fm is calculated as (Fm − Fo)/Fm when Fo means a (minimal) fluorescence level of dark-adapted sample when all reaction centers of the photosystem II are open and Fm is a (maximal) fluorescence level of dark-adapted sample when a high intensity pulse has been applied and the all reaction centers of the photosystem II are closed (Kitajima and Butler, 1975)
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