Effect of foliar products on the inflorescence yield of lavender and essential oil

English. The topic of the effect of foliar fertilization on the productivity and oil content oflavender is relevant, but not sufficiently studied. The present study aims to establish the effect offoliar products on the growth, development and productivity of lavender. The field experimentwas carried out at the Agricultural University - Plovdiv with lavender of ‘Jubileina’ variety during2019–2020. The following variants were included in the study: 1. Untreated control; 2. Treatmentwith Fertileader Gold (FG) - 3 L ha-1; 3. Treatment with Fertiactyl Trium + Fertileader Vital(FT + FVital) - 1.5 + 1.5 L ha-1; 4. Treatment with Fertileader Viti (FViti) - 3 L ha-1; 5. Treatmentwith Fertileader Vital (FV) - 3 L ha-1; 6. Treatment with Fertileader Alpha (FA) - 3 L ha-1. Thosepreparations are bio stimulants for foliar application. The treatments were made in twoconsecutive lavender vegetation seasons. The first application was carried out in the secondgrowing season (2019) and the second in the next, third growing season (2020). The foliarapplication of all tested products increased the photosynthetic activity, but it was better expressedwhen using the plant nutrition products FV, FViti and FT + FVital. A positive effect was alsoobserved in the height and diameter of the bush, but during the third vegetation period. Thenumber of flowering stems increased by 62.9%; 59.4%; 53.3% and 8.4%, respectively, whenapplying the fertilizers FG, FT + FVital, FViti and FV. The application of FG and FT + FVitalincreased the yield of fresh inflorescences by 6.1% and 3.7%. The application of the differentproducts affected the oil yield in different ways; the application of FG, FT + FVital and FVitiincreased it, while FV and FA decreased it by 27 kg ha-1 and 16 kg ha-1, respectively, for the firstvegetation and by 43.4 kg ha-1and 33.1 kg ha-1 for the second vegetation. The boron containingproducts FG, FT + FVital and FViti led to a significant increase in the essential oil yield, whilethe application of the foliar fertilizers FV and FA reduced it. Based on those results, the first threeproducts are recommended.

English. Received: January 25th, 2022 ; Accepted: May 1st, 2022 ; Published: May 23rd, 2022 ; Correspondence: [email protected]