The cultivation of Khasi Mandarin (Citrus reticulata L. Blanco), an important commercial fruit, is faced with the problem of insects, pests and diseases. In order to overcome the hurdles of field cultivation of this species, in vitro approaches became necessary for selection of genotypes. The present study was undertaken to study the amenability of cotyledonary explants of C. reticulata for direct shoot regeneration without an intervening callus phase. A highly efficient, rapid and reproducible protocol was developed for in vitro shoot regeneration of C. reticulata from cotyledons of 12 day old germinated seeds. Explants were cultured on Murashige and Skoog medium (MS) supplemented with different concentrations and combinations of 6-Benzylaminopurine (BAP), α-naphthaleneacetic acid (NAA) and kinetin. The best response for multiple shoot formation after four weeks of culture was observed on media supplemented with 5 mg/l BAP where 84% of the explants responded producing an average of 6.5 buds per explant. In vitro rooting of the microshoots was tried on Murashige and Skoog medium incorporated with various concentrations and combinations of BAP, NAA and indole-3-butyric acid (IBA). IBA was found to be superior than other auxins for in vitro root induction. Eighty eight percent of the regenerated shoots developed roots when transferred to MS medium with 2 mg/l IBA. Thereafter, the in vitro regenerated plantlets were successfully acclimatized and established in soil with a survival percentage of 93.33%.
