PHYSIOLOGY OF VEGETATIVE REPRODUCTION

Within any of the numerous different types / systems of propagating trees, there are large numbers of factors that determine whether or not the propagule is in a good physiological condition, and will form a functional plant and grow. For example, when propagating from single-node, leafy cuttings from juvenile shoots, the factors that will determine the level of success are:- Stockplant environment x stockplant management x topophytic variables x node position x nursery management x post-severance treatments x propagation environment Each of these factors are themselves multi-faceted and influenced by the ambient environment (light quality and quantity, water, temperature, nutrients) of the stockplant garden, the nursery or the propagation bench. For example, in the stockplant garden the environment (light, water and nutrients) and the management of stockplants can have both short-term impacts on rooting ability by determining the levels of water or heat stress experienced by the tissues being propagated either before severance from the stockplant, or long-term impacts on rooting ability through their effects on the morphology or physiological condition of the shoots. Similarly once the cuttings have been severed from the stockplant the environment of the nursery and the handling of the severed cuttings before and after insertion in the propagation bed will also determine the levels of stress that the cuttings experience. In addition, the cuttings are also affected by the activities of the person doing the propagation and particularly the care taken by this person to minimise the levels of stress experienced by the cuttings (eg. maintenance in a cool, shady, moist environment; reduction of transpiration by leaf trimming, etc). The human element in this is what is commonly called having ‘Green fingers’ and reflects the person’s sensitivity to the needs of the plant material.