Influence of growth regulators and media on asexual propagation of Lavandula x intermedia

Date

2021-05

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Abstract

Lavender (Lavandula spp.) is a Mediterranean crop prized for its therapeutic and medicinal properties. In the United States lavender, is grown for essential oil production or to generate agro-tourism. Lavender production is a growing field of interest with Texas growers. As an alternative crop in the Texas High Plains region, lavender could potentially increase crop selection, in addition to bringing new jobs and economic opportunities to the region. However, currently there are few replicated studies on lavender propagation available to interested growers. This study was divided into two trials to determine optimal and economically feasible conditions required to asexually propagate lavender tip cuttings. The first trial was conducted in 2018 and focused on three hybrid lavender (Lavandula x intermedia) cultivars: ‘Grosso’, ‘Provence’, and ‘Edelweiss’. Cuttings were taken from a local high plains lavender farm. Two different media were selected for trial one, SunGro metro-mix (bark (50.0%), peat moss (20.0%), vermiculite (20.0%), and perlite (10.0%)) and 100% perlite. In addition to cultivars and media, cuttings were exposed to plant growth regulator (PGR) in two different treatments and a control: a soak (Hortus Indole-3-butyric acid (IBA) water-soluble salts at 800 ppm), a dry talc (Rhizopon AA #3 at 8000 ppm), and control (no plant growth regulator). Cuttings were stuck after receiving one of the three treatments and placed on a mist bench for approximately six weeks. Upon completion of each experiment, percent rooting, number of roots, length of longest root, and visual root and shoot ratings were measured for each cutting. This experiment ran twice (Spring and Summer, 2018), and data from each experiment were pooled. Results indicated that of the three cultivars, ‘Provence’ had the greatest rooting percentage. The application of a PGR did not influence a cutting’s ability to produce roots. However, when a PGR was applied the number and length of roots greatly increased when compared to control cuttings. In addition, media did not influence rooting percentage, but cuttings placed in perlite had a greater number of roots when compared to cuttings rooted in SunGro metro-mix. However, data indicate perlite has a negative impact on root length.

The second trial was conducted Summer 2019, and again Spring 2020. Each experiment running approximately eight weeks. This trial observed three L. x intermedia cultivars: ‘Grosso’, ‘Provence’, and ‘Hidcote Giant’. Four different media were selected for propagation: peat moss, perlite, a peat moss perlite mixture (3:1 ratio by volume), and a peat moss sand mixture (2:1 ratio by volume). Seven PGR treatments were observed for this trial. Treatments were either Naphthaleneacetic acid (NAA), Indole-3-butyric acid (IBA), or an untreated control. Each PGR was applied as a soak at either 500, 1000, or 1500 ppm. Upon completion of each experiment, percent rooting, number of roots, length of longest root, and visual root and shoot ratings were measured for each cutting. Results indicate, with the exception of IBA at 500 ppm, the application of a PGR significantly increased rooting percentage of all cuttings when compared to control cuttings. Of the three cultivars, ‘Grosso’ had the greatest rooting percentage, number of roots, and root length. Applying a PGR at concentrations greater than 500 ppm (1000 or 1500 ppm) showed an increase in cutting root length and number of roots. Of experimental media, cuttings rooted in the peat moss sand mixture had greater results in all observed categories.

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Keywords

Lavender, Propagation, Lavender Propagation, Lavender Media, PGR, Lavandin, Lavandula, Hybrid Lavender

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