In this study, explants tolerated a higher concentration of PGRs without showing any
abnormality in morphology and also without any increase in proliferation rate. Although
some proliferation was observed on media containing BA alone, a low level of auxin was
also necessary for optimum proliferation. In apple, a related woody species, only BA was
required for initial growth and development of shoot tip explants, which very frequently
produced proliferated cultures (Lane, 1978). Shoot orientation did not influence shoot
multiplication rate as was shown by Lane (1979) for ‘Bartlett’ pear..