Clonal micropropagation of rocket (Eruca sativa Mill.)

Abstract

Purpose. To optimize the method of clonal micropropagation of rocket (Eruca sativa Mill.). Methods. Seeds of rocket cultivars 'Znahar' and 'Lybid' were used for introduction into in vitro culture. Solutions of sodium hypochlorite (35%), ethanol (70%) and HgCl2 (0.2%) were used for sterilization. A 5% solution of chloramine served as a control. Sterile material was planted on liquid and solid agar nutrient media according to Murashige-Skoog (MS) and Hamborg-Eveleg (B5). A solid nutrient medium MS supplemented with 0.5 mg/l BAP was used as a control at all stages of reproduction. 6–benzylaminopurine (BAP), benzylaminopurine (BA), kinetin, IAA, NAA and IBA were added to media for reproduction and rooting. The control was IAA (0.5 mg/l). Results. Sterilization of seeds with HgCl2 resulted in obtaining 93 and 90% sterile material; however, no viable seeds were found. The highest indicators of material sterility in the studied rocket varieties were noted for the use of sodium hypochlorite solution: in 'Znahar' 93% and 'Lybid' 89%. In addition, viability in this treatment was at the level of 90 and 85%, respectively. Higher indicators of both the number of shoots (8 and 6) and their height (8 and 3 cm) of both studied varieties were obtained on the MS medium (medium B5 – 5 and 5 shoots, and 5 and 4 cm, respectively). The most intensive shoot formation occurred with the use of kinetin. In particular, on the MS medium, variety 'Znahar' formed 19 shoots, 'Lybid' 17 shoots; on B5 – 16 and 13 shoots, respectively. At a concentration of 0.8 mg/l, the length of the shoots of the studied varieties was with IAA 10 and 8 cm, with NAA 15 and 13 cm and with IBA 18 and 16 cm, respectively. The same tendency was observed when the concentration increased to 1.2 mg/l. The number of lateral roots varied from 3 to 7 in the control and from 4 to 11 in the experimental treatments. Most of the roots were formed at an IBA concentration of 1.2 mg/l. In the case of adding 0.8 mg/l of NAA, 7 roots were formed in 'Znahar' and 5 in 'Lybid'; when increasing the concentration to 1.2 mg/l the number was 10 and 9, respectively. Conclusions. The worst indicators of viable seed material were obtained after sterilization with a HgCl2 solution (93 and 90% of sterile and 0% of viable seeds) and the best with sodium hypochlorite solution (93 and 89% of sterile and 90 and 85% of viable seeds). On the liquid nutrient media according to different prescriptions, the smallest indicators of the height of shoots and their number were obtained. Also, in these treatments, the vitrification of plants, their slow growth and insignificant shoot formation were observed. The longest root system was formed in the studied rocket varieties with adding IBA to the nutrient medium. At the same time, under such conditions, regardless of the IBA concentration, plants formed too long root system that can be injured during planting; therefore, it is more appropriate to use IAA and NAA or their combination.