The results of the essential-oil-bearing rose multi-year studies in the Crimea submountain region

Essential-oil-bearing rose is one of the most precious and valuable essential-oil-bearing plants cultivated in many countries. If management and care are good, the essential-oil-bearing rose plantations can be operated as long as for 20-30 years. However, in the literature there is no clear mention of the plantation productivity pattern in the context of the plantation age. The present paper is the first to report the findings of the analysis of four essential-oil-bearing rose varieties in terms of their productivity indicators which evidence the efficiency of operating commercial plantations for extended 14-year period in the Crimea submountain region. The research had as its goal carrying out a benchmarking analysis of the essential-oil-bearing rose varieties in terms of the basic commercially valuable indicators taking into account the plantation age in the Crimea submountain region context. The following essential-oil-bearing rose varieties were the subject of research: Lan (Belaya variety [Rosa alba L.] × Michurinka variety [R. damascena Mill. × R. gallica L.]), Lada (Belaya variety [Rosa alba L.] × Michurinka variety [R. damascena Mill. × R. gallica L.]), Legrina (Belaya variety [Rosa alba L.] × Michurinka variety [R. damascena Mill. × R. gallica L.]) and Zolushka (Vesna variety [Rosa damascеna Mill. × R. gallica subsp. еryosyla Kell. var. аustriaca Grantz f. рanonica Br.] × Krymskaya krasnaya variety [R. galica L.]). All the varieties were of hybrid parentage and clone reproduction. The research was carried out during 14 years (2010-2023) at the experimental station of the essential-oil-bearing crops selection and seed centre (Research Institute of Agriculture of Crimea) located in the Crimea submountain region (Krymskaya Roza village, Belogorsk District). The experimental station soil is southern carbonate-rich heavy loamy chernozem, on eluvial and deluvial deposits of dense carbonate rocks of cloddy structure. The nursery housing all the varieties was laid out in 2008. Root seedlings of Lan and Lada varieties and selection numbers Г-122 and 2030 which had successfully passed a competitive variety testing and in 2017 were registered as varieties under the trade names of Legrina and Zolushka were used for planting. One-row plots had 10 plants each, the planting pattern was 2,5×1,0 m, the registration plot space was 25 m2. Package of appropriate soil management and plant care measures recommended for the region was implemented in the nursery every year. Phenological observations, recording and analysis as provided for by the essential-oil-bearing rose breeding guidelines were carried out starting from the second vegetation year (the first harvest was in 2010). Each variety under study was evaluated for the flower weight and full-blossom condition, winter hardiness, bud forming capacity, overall plant condition, flower yield, decanted essential oil content and yield, weight content and yield of concrete. Recording, observations and analyses were carried out in accordance with the guidelines for the essential-oil-bearing crops selection and biochemical study. Winter hardiness of all the varieties is high and reaches 4.5-4.9 points (on a five-point scale). The maximum number of petals in a Zolushka variety flower is 69.7±2.1 pcs. Lan and Legrina varieties do not differ much in number of petals in a flower, 63.9±1.9 pcs and 64,5±1,6 pcs, respectively. Lada variety outstands with the lowest flower full-blossom condition (49.5±0.7 petals). The Lan variety has the least flower weight 3.29±0.10 g while the maximum flower weight 4.43±0.08 g is observed in the Legrina variety. Productivity of the varieties increased as the plants aged and there is evidence to suggest that the varieties productivity did not reach the maximum value over the project years. By the 14th flower harvest the yield of Lan, Lada, Legrina and Zolushka varieties increased 5.0, 3.8, 12.3 and 7.8 times as much as compared to the first flower harvest. The essential oil weight content in flowers of all the varieties changes little, if at all, irrespective of differences in weather conditions and reaches by an average 0.025±0.001 % in Lan, Lada and Legrina varieties and 0.011±0.001 % in the Zolushka variety. The research findings suggest that the yield of decanted essential oil in Legrina variety implicitly reaches 18.37 kg/ha for 14 flower harvests with the average of 1.31±0.18 kg/ha and is 1.9, 1.7 and 2.8 times as high as that in Lan, Lada and Zolushka varieties. In terms of the yield of concrete Legrina and Zolushka varieties (9.63±1.92 kg/ha and 9.31±1.41 kg/ha respectively) surpass Lan and Lada varieties 1.5 times as much. Thus, all the essential-oil-bearing rose varieties considered can be implicitly used in agricultural industry over extended periods without impairment of their commercially valuable properties.