MICROPROPAGATION OF TROPICAL FRUITS: BENEFICIAL EFFECTS OF NON-IONIC SURFACTANTS

Abstract

The effects have been investigated of the non-ionic surfactant, Pluronic® F-68, on bud induction/shoot regeneration in epicotyl and cotyledon explants of Citrus depressa and on shoot regeneration from leaf segments of 4-6 week-old axenic plants of Passiflora edulis var. flavicarpa, P. giberti and P. mollissima. Supplementation of agar-solidified MS-based bud induction/shoot regeneration medium with 0.5% (w/v) Pluronic® F-68, significantly (P < 0.05) increased mean fresh weight gain of cultured epicotyls of C. depressa, the percentage of explants giving shoots and number of shoots regenerated per explant. This Pluronic® concentration also enhanced the mean percentage of cotyledons which developed buds and the number of buds per cotyledon. Fresh weight gain was not affected in the range 0.001 - 0.5% (w/v) of Pluronic® F-68 evaluated for cotyledon explants. Supplementation of NN-based medium with 3 mg l -1 6-benzyladenine (6-BAP), 2.0 mg l -1 kinetin and 0.001-0.5% (w/v) Pluronic® F-68, significantly (P < 0.05) increased mean (±SE) biomass gain of leaf explants of P. mollissima by a maximum of 2.7±0.1 g f.wt. over control. The same concentration range of Pluronic® F-68 in MS-based medium, containing 1.0 mg l -1 6-BAP and 0.5 mg l -1 kinetin, also significantly (P < 0.05) increased the mean fresh weight gain of P. edulis leaf explants and the mean percentage of leaf explants of P. giberti undergoing shoot regeneration.