Rooting induction of different Lavandula angustifolia accessions by auxin application

Resumo

Lavandula angustifolia Miller (lavender), considered a hard to root species, is comprised of many varieties and horticultural forms, and genotypes from different provenances may present variance in rooting capacity. The objective of this experiment was to test different concentrations of indol-3-butyric acid (IBA) on rooting of eight (G1 to G8) L. angustifolia genotypes from different provenances. Cuttings were treated with different doses (0 to 2000 mg L^-1) of IBA. Rooting percentage (RP), root number (RN), and length of the longest root (RL) were evaluated. The different accessions presented very diverse response to IBA application. IBA did not exert influence on rooting of G1, G2, and G7; was benefic to G3 until 700 mg L^-1; was benefic to G4 and G6; and was prejudicial to G5 and G8; the same IBA dose which promoted better rooting on G3 (700 mg L^-1) was toxic to G5; 1500 mg L^-1 of IBA promoted better rooting, greater root number and length on G6 but was completely and significantly detrimental to G8. G1 and G3 presented high rooting percentages, in spite of L. angustifolia being considered a hard to root species. G4, G5 and G6, however, presented very poor rooting, compared to the other genotypes. Necessity of auxin application and adequate dose may not be generalized to L. angustifolia different accessions. Its use should be incentivized when the genotype is recalcitrant to root and auxin concentration should be adjusted to it.