MITIGATING LIPID PEROXIDATION IN LEAVES OF PRUNUS SP. ROOTSTOCKS USING EXOGENOUSLY APPLIED AUXINS

The effect of exogenously applied auxins on mechanical injury induced oxidative stress was studied in 6 promising rootstock selections of Prunus cerasus L., P. mahaleb L., and P. fruticosa Pall. Investigated selections were included in low-vigorous rootstock breeding programme for sweet and sour cherries. The standard rootstock PHL-A was used as a control, due to successful rooting. Leaves of investigated rootstocks were collected on: 0, 1st, 3rd and 7th day of inserting softwood cuttings into the rooting substrate under a fogging system with 95-99% average relative humidity. Exogenously applied auxin mixture consisted of 0.8% α-naphthylacetic acid (NAA) and 0.5% indolebutyric acid (IBA). Mechanical injuries during rooting period represent one of the factors that induce stress in softwood cuttings. Intensity of LP is used as a valuable biomarker of plant response to various abiotic factors. Differences in intensity of LP between auxin-treated and -untreated cuttings were examined. Almost all of investigated selections had lower LP intensity after auxin application (11.4-47.2%) between 1st and 3rd day. However, the most prominent change was in leaves of PHL-A (49.2%). The best LP-lowering effect were recorded in leaves of P. fruticosa, SV4 selection (56.9%) on 7th day and in P. mahaleb, M4 selection, on 1st and 3rd day (5.9, 5.8%), in comparison to untreated softwood cuttings. As for OV21 selection, LP intensity significantly increased in both treated and untreated cuttings on the 1st, 3rd and 7th day, but auxin-treated cuttings showed lower LP values, except on 7th day, reaching 221.3 nmol MDA equivalents g-1 fresh weight. Intensity of LP during vegetative propagation of selected genotypes could be used as one of the biochemical parameters in further rootstock selection for sweet and sour cherries.