Collection, sterilization, excision and culture

Abstract

The success or failure of micropropagation of tree species often depends on the condition of the plant material at the time of collection. This is particularly true when expiants are obtained from trees grown in the field. The physiological condition of tissues varies with season, position within the tree and climatic factors. For example, the nitrogen content of foliage is influenced by rainfall patterns (Miller et al. 1977). Light has an effect on the accumulation of reserves and stress modifies ABA and other hormone levels in tissues (Johnson 1988). Each of these conditions can affect the manner in which tissue responds in culture. In addition, environmental factors influence the level of microbial contamination of the tissues (see section 4.3.).