CHARACTERIZATION OF THE Hedera helix L. LEAVES GEOMETRY BASED ON SOME DIMENSIONAL PARAMETERS AND CALCULATED RATIOS

Abstract

The study analyzed leaves of ivy, Hedera helix L., in order to characterize the geometry of the leaves. The leaf samples were taken from the Protected Area "Padurea Cenad", Timis County, Romania. The dimensions of the leaves (L, w) were determined by measurement, with a precision of 0.5 mm. The leaves were scanned, 1:1 ratio. From the analysis of the leaf images, the perimeter (Per) and scanned leaf area (SLA) were determined. The correction factor (CF), specific to ivy leaves, was found (CF=0.69) for the purpose of use in non-destructive methods of measuring the leaf area (MLA) based on a general formula of the type MLA=L·w·CF. The fitting relationship between MLA and SLA was described by a linear equation, under statistical safety conditions (p<0.001). Different ratios between leaf parameters were calculated in order to characterize the leaf geometry (L/w, Per/L, Per/w, SLA/L, SLA/w, SLA/Per, MLA/L, MLA/w). Different levels of correlation between basic leaf parameters, leaf surface and the calculated ratios were identified, with statistical certainty for most cases (p<0.001). Both from the correlation analysis and from the regression analysis, a tighter relationship of MLA with foliar parameters (L, w) was found than in the case of SLA (based on r, R2, F test, and RMSEP values). From the analysis of the values obtained for the coefficient of variation (CV), the highest variability was found in the case of SLA (CVSLA=38.6726), followed by MLA (CVMLA=36.8300), and the lowest variability in the case of the ratio Per/w (CVPer/w=10.1515). The regression analysis facilitated the finding of some equations that described the variation of SLA and MLA with leaf parameters (L, w, Per) in conditions of statistical safety (p<0.001). 3D graphic models and in the form of isoquants were also generated, which represented the MLA variation in relation to the dimensional parameters of the ivy leaves studied.