Study of chitosan as a seed treatment

Abstract

Chitosan extracted from chitin is soluble in weak acids and forms gels and films [1]. The antifungal activity of chitosan in agriculture is supported by several factors: the molecular activity of chitosan, the type of micromycetes and the interaction of environmental factors with chitosan [2]. These properties encourage the study of chitosan further in the field of seed treatment because micromycetes cause significant crop losses. In this study, chitosan with different molecular weights (high, medium, and low molecular weight) and in different concentrations were tested as a substance that can inhibit the growth of micromycetes on natural, non-sterilised seeds of spring wheat 'Koksa' and spring barley 'Podarek'. The fungicidal activity of chitosan usually increases with increasing concentration, but there are also cases when a strong fungicidal efficiency is seen when using higher concentration chitosan preparations, which is suppressed and the growth of micromycetes begins [3]. This may be due to the ability of some micromycete enzymes to break chitosan down to glucosamine units and turn it into an energy source. Therefore, three different concentrations of each molecular weight of the chitosan were used: 0.5 g·l-1, 1 g·l-1, and 2 g·l-1, in the study to identify the effect of concentration. Chitosan gels were obtained by dissolving chitosan powder in weak acetic acid (1%). Summer cereal seeds were coated with chitosan gels by dipping the seeds into the prepared gels and pulling them out. After coating seeds were sown on potato agar in Petri dishes. Micromycete colonies were identified and counted five days later. Fungi of Bipolaris spp. Alternaria spp., Penicillium spp., Ulocladium spp., Mycelia sterilia, Saccharomyces spp. and Mucor spp. – were detected on the seeds of spring wheat 'Koksa'; whereas Bipolaris spp., Aspergillus spp., Alternaria spp., Penicillium spp., Ulocladium spp., Mycelia sterilia, Saccharomyces spp. and Mucor spp. Were defined on the seeds of spring barley 'Podarek'. In conclusion, the effect of low molecular weight chitosan on Bipolaris spp. Alternaria spp. and Saccharomyces spp. was defined. The fungicidal effect of high molecular weight chitosan on Bipolaris spp. Penicillium spp. and Mycelia sterilia micromycetes was also determined. A correlation by concentration was observed: solutions with higher concentrations have a greater negative effect on the amount of all identified micromycete genera. Further studies are required to determine the interaction between molecular weight and concentration of chitosan and the impact on fungicidal efficacy.