Rhizogenesis of rocket (Eruca sativa Mill.) and wall-rocket Diplotaxis tenuifolia (L.) DC.

Abstract

Purpose. To test the efficiency of the plant growth regulating substances at different concentrations for stimulating the rhizogenesis of rocket (E. sativa) and wall-rocket (D. tenuifolia). Methods. The experiment was carried out at the Biotechnology Laboratory of the Institute of Bioenergy Crops and Sugar Beet of the National Academy of Agrarian Sciences in 2020–2022. Rocket varieties ‘Znahar’, ‘Lybid’, ‘Zlat’, ‘Silvetta’ and wall-rocket variety ‘Liudmyla’ were used in the study. Seeds were examined for their quality indicators, sterilized with a solution of 35% laundry detergent and ethanol and seeded in vitro. Sterile seedlings were transferred to the Murashige-Skoog (MS) medium supplemented with benzylaminopurine (BAP) for propagation. Naphthylacetic acid (NAA), indolyl-3-acetic acid (IAA), indolyl-3-butyric acid (IBA) and gibberellic acid (GA) were added to the nutrient medium according to the MS prescription in different concentrations. Results. The introduction of IBA (0.8 mg/l) and GA into the nutrient medium, regardless of the concentration, resulted in the longest root system in all treatments. The studied modification made it possible to obtain root length on the 9th day of cultivation from 7 to 64 cm and on the 14th day from 10 to 70 cm. On the 14th day of cultivation, in the plants grown under the concentration of GA >1.0 mg/l, the root not only the elongated and browned, but reached 70 cm in length. For the introduction of IBA into the medium previously supplemented with GA, on the 9th day of cultivation, negative effect was noted in all treatments, namely the elongation of internodes and central root. On the 14th day, vitrification of shoots and significant elongation of both central and lateral roots occurred in all treatments. The central root reached 70 cm in length, which is not advisable during the adaptation period. The results of the experiment indicate that on the 21st day, the longest root system (12 cm and 42 cm) was obtained in the rocket variety ‘Zlat’ (0.1 mg/l GA and 1.5 mg/l GA, respectively) and the shortest root length (6 cm and 21 cm) in the wall-rocket variety ‘Liudmyla’ (0.1 mg/l GA and 1.5 mg/l GA, respectively). Importantly, the root length of ‘Zlat’ variety on the 21st day of cultivation, compared to the 14th day, at a concentration of 0.1 mg/l increased by only 3 cm, while in the 'Liudmyla' variety by 2 cm. Considering this, it is impractical to carry out cultivation up to 21 days. The lowest root length was obtained with the use of IBA and GA: rhizogenesis occurred more slowly than in previous treatments, and on the 14th day the root length was in the range from 3 to 20 cm. Conclusions. The longest root system in all studied treatments was obtained in variety ‘Zlat’, while shortest in ‘Liudmyla’. The optimal concentrations of NAA + IBA + GA for the cultivation of the studied rocket and wall-rocket varieties are 0.3 and 0.5 mg/l.