PROPAGATION OF COMPACT MICRO-GRAFTED NURSERY TREES FOR DISTANT LOCATIONS

Micro-grafting can be used to accommodate grafting procedures to the restricted timing and reduced growth force associated with the specialized production of such trees. Two forms of micro-grafting are generally used: 1) shortly after germination, for those species which develop a thick enough stem at this stage and 2) high up on a relatively succulent stem. Both methods produce exceptionally healthy graft unions.

Air root-pruning techniques used for the creating of compact fibrous root systems tend to complicate grafting operations. The difficulty appears to be related to cessation of top growth correlated to sudden cessation of downward root growth; this condition will persist until lateral roots develop.

In the event that air-root pruning is practised both in a seed bed and in subsequent nursery growth, this condition can occur at two distinct periods of growth.

The method initiated at Avdat is primarily intended for use within a third world context. In intentionally avoids use of expensive equipment.

Seeds are mostly planted in shallow baskets supported on plastic pipes or stones, in order to obtain early lateral rooting. These seedlings, sometimes already grafted, are transplanted onto ridges before continuous hot weather sets in. The ridges are built on the contour of a 45° hillside underlaid with thick black polyethylene sheeting. This causes the roots to grow down at a slant; and on reaching the base of the ridge they burn off by exposure to sun and air, progressively developing the lateral fibrous rooting earlier initiated.

The ridges are covered on the northside by a moss-like ground cover which stabilizes the soil mixture, increases water absorption aerates, cools and permits inoculation and development of beneficial soil microorganisms. The ridges are protected against overheating on the upper south side by rocks.

Trees are extracted by simply pulling out of water-saturated ridges. Micrografting ensures that, even if trees are dispatched with

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