Influence of in vitro preconditioning of citrus microshoots with paclobutrazol on ex vitro survival

The influence of the in vitro conditioning and rooting of the microcuttings in different basal media viz., Murashige and Skoog and Gamborg supplemented with various concen­ trations of paclobutrazol (0.25^1.0 mg/1) on their in vivo establishment and growth was in­ vestigated using four citrus species viz., C. reticulata Blanco (Khasi Mandarin), C. volkameriana Ten, and Pasq, C. reshni Tanaka (Cleopatra Mandarin), and C. nobilis X C. deliciosa Tenure (Kinnow). The inclusion of paclobutrazol in the medium had a signifi­ cant influence on in vivo growth especially in relation to height. Paclobutrazol reduced the stem and root growth but at 0.75 and 1.0 mg/1 more persistent leaves and new leaves on es­ tablished plants were recorded. Stomata of leaves cultured in medium supplemented with paclobutrazol showed smaller stomatal apertures. Among the species, Kinnow and C. vol­ kameriana showed the maximum leaf area. The optimum concentration of paclobutrazol for maximum establishment was found to be 1 mg/1 paclobutrazol (94.6% to 97.2 %) in all the species.