Potential of some explants for callus inductionand plantlet regeneration in Solanum lycopersicum L.under treatment of different plant growth regulators

Plant growth regulators (PGRs) control signaling networks and developmental processes involved in plant responses to various biotic and abiotic stresses, making it crucial to study PGRs <i>in vitro</i>. The protocol for micropropagation of <i>Solanum lycopersicum</i> L., following callus induction and regeneration through explants such as internodal segments, leaves, and nodal segments, was established during the present study. Explants were inoculated on Murashige and Skoog (MS) medium supplemented with different plant growth regulators like BA (6-benzylaminopurine), 2,4-D (2,4-dichlorophenoxyacetic acid), BA + 2,4-D, IAA (Indoleacetic acid), IBA (Indolebutyric acid), and NAA (Naphthaleneacetic acid). It was observed that among all explants, the nodal segment showed maximum callus induction (83.33%) and multiplication (86.67%) at 0.25 mg/l of 2,4-D; the highest shoot number (3.33) at 0.5 mg/l of IAA + 0.5 mg/l of BA; the greatest shoot length (7.57 cm) at 0.75 mg/l of BA; root induction (80.95%), root number (21.88), and root length (10.62 cm) at 1 mg/l of IAA. Additionally, the maximum fresh weight (2.448 g) was observed at 0.5 mg/l of BA, while the highest dry weight (0.172 g) and dry matter content (14.25%) were noted at 1 mg/l of BA + 1 mg/l of 2,4-D for the internodal segment. Results of the present study revealed that among different explants, the best response was given by nodal segments, followed by internodal segments. Among the different PGRs, 2,4-D resulted in the highest callus induction and multiplication percentage.