The effects of salicylic acid, oxalic acid and chitosan on damping-off control and growth in Scots pine in a forest nursery

Abstract: Modern forestry in the European Union and in Poland is in constant search of environment-friendly technological solutions. These also relate to nursery production, in which attempts are made to apply non-chemical plant-protection products. The objective of this study was to assess the effects of salicylic acid, oxalic acid and chitosan (applied in the form of Beta-chikol®) in controlling damping-off and promoting the growth of Scots pine seedlings under nursery conditions. All the substances were used in seed treatment and in the form of foliar spray, 4 times during the growing season, in the following concentrations: salicylic acid 1% and 2%, oxalic acid 0.5% and 1%, and chitosan 2%. Seedlings were inventoried three times: 3 and 6 weeks after seed sowing, and at the end of the growing season. All seedlings were counted in 1-metre segments of individual rows of the seedbed. At the end of the growing season, parameters of seedling growth like shoot length, root-collar diameter, root length and the dry mass of above-ground parts were determined. The growth of pine seedlings was found to be stimulated by both chitosan and oxalic acid, while salicylic acid proved inhibitory to growth when present at 2% concentration, and showed no detectable influence on biometric parameters at 1% concentration. Numbers of seedlings germinating per 1-metre segment were significantly greater than in the (unprotected) control, where chitosan was applied. Likewise, oxalic acid applied at both concentrations was associated with greater numbers of germinating pine seedlings than in the control, albeit the statistical significance of this difference was achieved only 6 weeks after seed sowing, and only with the 0.5% concentration. Numbers of seedlings per metre-long segment were significantly lower in response to both concentrations of salicylic acid applied. Both chitosan (applied as Beta-chikol®) and 0.5% oxalic acid resulted in seedling protection against damping-off and enhanced growth, whereas the applied concentrations of salicylic acid were presumably excessive, hence the negative impact on both germination and growth.