Simple Improvement of In Vitro Shoot Elongation and Rooting of Sida cordifolia L. from Nodal Segments

Efficient in vitro propagation of Sida cordifolia L. from nodal explants is often limited by poor shoot and root elongation. This study aimed to improve elongation of shoots and roots from two-node explants through simple modifications of the Murashige and Skoog (MS) culture medium. Explants were cultured on full- and half-strength MS media. Half-strength MS (1/2MS) significantly increased shoot (3.9-fold) and root (4.2-fold) elongation compared to full-strength MS. Therefore, subsequent experiments were conducted using 1/2MS. Further modifications included supplementation of 1/2MS medium with KH2PO4, plant growth regulators (TDZ, BAP, 2iP, GA3), and pretreatment of nodal segments with Norit buffer before cultivation. KH2PO4 did not further affect shoot elongation but significantly enhanced root elongation, with the greatest effect at 170 mg L−1. Pretreatment of nodal segments in Norit buffer had almost the same effect as KH2PO4, both on shoots and roots. In contrast, cytokinins and GA3 inhibited both shoot and root elongation compared to hormone-free 1/2MS medium. The results indicate that 1/2MS medium alone is most suitable for improving shoot and root elongation in vitro in S. cordifolia. Supplementation of the 1/2MS medium with 170 mg L−1 KH2PO4 further enhances root elongation. The use of cytokinins and GA3 should be avoided.