EFFECT OF CULTURE CONDITIONS ON MULTIPLICATION AND GROWTH OF MALUS IN VITRO
A part of the differences in growth during the propagation of plants can be traced back to the physiological state of the stockplants (Cheng, 1978). Dormancy and bud position (Quoirin, Lepoivre, Boxus, 1977) can effect the growth and development of meristems in the first part of the culture.
But often growth differences are a result of unobserved changes in the composition of the culture medium or in the growth conditions. However, the effects appear in subsequent culture stages as elongation or rooting. Probably the inconsistant effect of phloroglucinol (Welander and Huntrieser, 1981, Zimmermann and Broome, 1981, Welander, 1983) are a result of this phenomenom.
The direct and indirect effects of growing conditions in subsequent cultures of apple are presented. Effects of growing media on multiplication and vitrification in M26 are described.
It is concluded that the importance of certain factors can only be confirmed after several replications during more than one subculture. Also the effects on following culture stages have to be taken into account to avoid problems during rooting or weaning. In this way a more universal propagation system can be defined, not only reliable under specific conditions and valid for only one cultivar.