Stimulating Effect of Ash from Sorghum on the Growth of Lemnaceae—A New Source of Energy Biomass

The multifunctional use of macrophytes including production of biofuels, reduction of post-industrial waste, animal feed, phytoremediation and bioindication of toxicity, are developing directions that support the energy industry, including RES. The ash from Sorghum contains large amounts of macroelements, including phosphorus, nitrogen, potassium, calcium, as well as many micronutrients. The aim of the research was to determine the possibility of using ash from Sorghum as a media supplement for the cultivation of aquatic macrophytes. Plant cultivation was carried out in a phytotron room at 24 °C, 40 W light on a liquid medium supplemented with various concentrations of ash coming from the Sorghum combustion and control series. For all experimental series, Lemna minor L. plant growth analysis was performed by counting the number of fronds, determination of chlorophyll index, gas exchange (net photosynthesis, transpiration, stomatal conductivity of the cells and intercellular CO2 concentration), chlorophyll fluorescence, fresh and dry mass of plants as well as of important physical and chemical parameters of the medium i.e. COD, PO43− phosphates, NO3− nitrates. The energy value for L. minor L. biomass was determined. The experiments showed high sensitivity of plants grown on a medium supplemented with different concentrations of Sorghum ash compared to the control series, and depending on the concentration, the plant biomass increased proportionally. The medium supplemented with ashes was characterized by high physico-chemical parameters. The above studies indicate the possibility of using waste ashes and their management in supplementation of breeding media for macrophytes Lemnaceae, which constitute a new source of energy biomass.