The number of glandular trichomes on the peduncles of true lavender inflorescences as an additional breeding trait for essential oil

The main receptacle of essential oil in true lavender is the peltate glandular trichomes of the calyxes in the whorls of the inflorescences. Their average size is 175 ± 25 pm, in some cases - up to 250 pm. For the extraction of lavender oil, not only the calyxes are used, but the whole inflorescences including the flowering shoots. The surface of the peduncles of lavender inflorescences is also covered with peltate glandular trichomes. However, their contribution to the total volume of essential oil in the inflorescence has almost never been determined. The aim of this research was to study the distribution density of glandular trichomes within the inflorescence and to determine the proportion of the contribution of flowering trichomes to the formation of essential oil in the inflorescence. The research was carried out in 2021 on the basis of the V.S. Pustovoit All-Russian Research Institute of Oil Crops in two ecological and geographical points of the Krasnodar region. The object of the study was the true lavender varieties Voznesenskaya 34, Rannyaya, Yuzhanka and Voznesenskaya Aroma. It was found that the size of glandular trichomes on peduncles of true lavender is 90 ± 15 pm. Their number on peduncles, depending on the variety, varies from 2141 to 3003 pcs. The density of distribution of glandular trichomes on the surface of peduncles is equal to 8.60-14.93 pcs/mm3. The total volume of essential oil in all glandular trichomes of peduncles is 0.41-0.57 mm3. The total volume of essential oil in the inflorescences varied from 2.28 to 5.15 mm3. The share of essential oil in the glandular trichomes of the peduncles in relation to the entire inflorescence ranged from 9.33 to 19.56%. It is concluded that peltate glandular trichomes on flower-bearing axes make a significant contribution to the essential oil content of lavender inflorescences. For the selection of true lavender to increase the essential oil content and the yield of essential oil, an additional selection trait is proposed - the amount of glandular trichomes on the surface of peduncles, which can be regulated by changing their distribution density on the surface of peduncles, or increasing the length of inflorescences.