Performance of ginger grass (Lippia alba) for traits related to the production of essential oil

Abstract

Lippia alba (Verbenaceae) is a shrub whose essential oil has important biological, pharmacological, and aromatizing properties. To reach the sustained cultivation of new species with economic potential, the present study aimed to evaluate L. alba performance for fresh leaf matter (FM), leaf dry matter (DM), virus symptoms (VS -Cucumber mosaic virus, CMV), oil yield (OY), and oil chemical composition (OC), and to evaluate DM stability and adaptability. Ten genotypes of four chemical groups (chemotypes) were evaluated in six experiments designed as randomized blocks with two plants per plot, over the whole State of São Paulo, Brazil. A 2.0 × 0.4 × 1.6 m spacing was used in Monte Alegre do Sul and Pindorama, while a 1.0 × 0.4 × 0.6 m spacing was used in Campinas, where four experiments were established under different irrigation and fertilization conditions. The genotype effect was significant (p < 0.05) for all traits evaluated, with high leaf productivity of IAC-16 (citral chemotype), best OY means in the linalool and limonene/carvone chemotypes, and susceptibility of the latter chemotype to CMV. The genotype performance oscillations in the six environments were significant for FM and DM, and despite their significance for phytochemical traits (OY and OC), they were of low magnitude. No qualitative variation was detected for OC. The IAC-2 (linalool) and IAC-13 (limonene/carvone) genotypes showed high stability and wide adaptability, and are recommended to establish initial cultivations of this species. This research also indicated genetic sources to start Lippia alba genetic breeding programs. IAC-1 to IAC-4 (linalool), IAC-9 to IAC-11 (myrcene/ camphor), IAC-13 and IAC-14 (limonene/carvone), and IAC-16 (citral). Plants were selected based on differences in plant morphology, oil yield, and the relative proportions of substances in the oil. Six experiments were carried out in three regions of the State of São Paulo (SP), Brazil, in a randomized block design, with four replicates and two plants (clones) per plot. Four experiments were installed in Campinas (22°31' S, 47°02' W, 680 m), representing four environments (E1 -with both fertilization and irrigation; E2 -with fertilization but no irrigation; E3 -no fertilization but with irrigation; E4 -no fertilization nor irrigation). As to fertilization, two sidedressing applications of the 04-14-08 (N, P 2 O 5 , K 2 O) fertilizer were made, and a drip irrigation system was used. A row spacing of 1.0 m was adopted in these four experiments (environments), with 0.4 m between clones and 0.6 m between plots. The other two experiments were carried out in Monte Alegre do Sul (22°24' S, 46°24' W, 760 m) (E5) and Pindorama (21°06' S, 48°32' W, 534 m) (E6), with a row spacing of 2 m, 0.4 m between clones, and 1.6 m between plots, under a sprinkler irrigation system.

Heterogeneity of linalool chemotypes of Lippia alba (Mill.) N.E.Br., based on clonal half-sib progenies

“…Since low values (significant for the T-test) are usually obtained in correlation studies, we used the classification criteria proposed by Shimakura and Ribeiro Júnior (2009). Significant but low correlation values were obtained by Yamamoto et al (2008) in L. alba.…”

“…In Monte Alegre do Sul, the superiority of the harvest by comparison with the Campinas site can be explained by the better soil and climate conditions in the region. Yamamoto et al (2008) also observed that clones were superior when grown on this site.…”

“…We first obtained a recombinant population (or base population) from the aggregate fruits of eight L. alba (linalool chemotype) genotypes (IAC-1 to IAC-8) studied by Yamamoto et al (2008), who studied 20 clones representative of five chemotypes: linalool (eight genotypes), myrcene/camphor (three genotypes), limonene/carvone (four genotypes), citral (four genotypes) and myrcene (one genotype). Since the species is outcrossing and self-incompatible, these chemotypes randomly recombined.…”

“…Since the species is outcrossing and self-incompatible, these chemotypes randomly recombined. Fruits of L. alba are schizocarpic, round, dry and indehiscent, measuring about 3.0 mm and composed of two mericarps, each containing a seed of around 0.4 mm (Yamamoto et al, 2008). Since the seeds are very small, delicate and remain inside the mericarps, obtaining large quantities is not viable.…”

“…Since the seeds are very small, delicate and remain inside the mericarps, obtaining large quantities is not viable. Thus, for practical reasons, the fruits are planted rather than the seeds (Yamamoto, 2008). A total of 8,000 fruits were planted.…”