In Vitro Multiplication of Swingle Citrumelo Rootstock with Coumarin

Abstract

Young Swingle citrumelo [ Citrus paradisi Macf. × Poncirus trifoliata (L.) Raf.] seedlings were sectioned into 0.5-cm and 1.0-cm nodal and internodal segments and plated on an agar-solidified basal medium containing different levels of coumarin as the only growth regulatory substance. The frequency of whole-plant recovery from stem segments was positively correlated with the concentration of coumarin in the medium. Recovery of whole plants from 0.5-cm segments required coumarin, which induced both root and shoot formation. An optimum concentration of coumarin (90–150 μ m ), increased the number of whole plants recovered per seedling ≈5-fold. Resulting plants were acclimated to soil efficiently and rapidly in humidity tents that received a continuous supply of moist air. This procedure could be used commercially to increase the availability of Swingle citrumelo rootstock.