VARIATION OF SOME PHYSIOLOGICAL INDICES IN Tagetes erecta L. ACCORDING TO GROWTH SUBSTRATE

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The study evaluated the influence of some growing substrates with variable content of compost from biodegradable waste on some physiological indices and growth parameters in the Tagetes erecta L. species. Different components were used to prepare the growth substrates, and depending on the weight of participation, the experimental variants resulted: V1 – garden soil 100%; V2 – compost 100%; V3 – compost 20% + peat 70% + vermiculite 10%; V4 – compost 30% + peat 60% + vermiculite 10%; V5 – compost 40% + peat 50% + vermiculite 10% (each variant in four repetitions). The biological material was represented by the Tagetes erecta L. species. The genotype "Tagetes erecta F1 Discovery Orange" was cultivated. Physiological indices and biometric parameters were evaluated, considered representative to quantify the plants response to growth substrates: plant height (Ph), shoots number (Sn), plant diameter (Pd) and shoots diameter (Sd). Several determinations were made during the vegetation period, at different times: April 22 (T1), May 22 (T2), June 18 (T3), July 21 (T4) and August 27 (T5). A strong, positive correlation was recorded between plant height (Ph) and shoot diameter (Sd), r=0.881***. Moderate correlations were recorded between plant height (Ph) and shoot number (Sn), r=0.715***, between plant height (Ph) and plant diameter (Pd), r=0.754***, between shoot number (Sn ) and shoot diameter (Sd), r=0.700***, and between plant diameter (Pd) and shoot diameter (Sd), r=0.781***. Weak correlation was recorded between shoot number (Sn) and plant diameter (Pd), r=0.669*** (*** p < .001). In the PCA evaluation, PC1 explained 83.581% of variance, and PC2 explained 10.035% of variance. The cluster analysis, in relation to the important parameters considered (Ph, Pd) facilitated obtaining a dendrogram of association of the variants (Coph.corr.=0.881). The dynamics of the plants main parameters (Pd, Ph) on the experimental variants in relation to time, was described by polynomial equations of the 2nd degree under differentiated conditions of statistical certainty. A variable increase (D) in the evaluated parameters (positive and negative values) was recorded in the experimental variants (V2 – V5) in relation to the control variant (V1) and the moments of determination during the study period.