SELECTION OF AVOCADO ROOTSTOCKS FOR SALINE CONDITIONS

Some observations and preliminary experiments have shown that the avocado, being heterozygous, shows much variability in the behaviour of the seedlings used as rootstocks under saline conditions, a characteristic which may serve as an excellent basis for selection of tolerant rootstocks to saline irrigation water. On the other hand, for commercial orchards, rootstocks with uniform genetic characteristics are needed, and this can be achieved only by means of vegetative propagation.

In order to find rootstocks for saline conditions, a long-range selection and testing programme has been carried out over the last 15 years, in three main stages.

In the first stage, selection was carried out among a large number of seedlings of the Mexican, Guatemalan, and West Indian types growing under saline conditions. At the end of this stage, only a few, outstanding tolerant seedlings were chosen. Some of them have been propagated vegetatively, and their offspring used for further experiments.

In the second stage, the behaviour of various grafted seedling rootstock under saline conditions was studied.

In the third, concluding stage, the two main avocado cultivars, Fuerte and Hass, grafted on vegetatively propagated rootstocks from the first stage selection, were tested for 7 years under saline conditions.

At present we possess selected resources of rootstocks, mainly of the West Indian types, with high relative tolerance to saline irrigation water, which enable us to grow avocado trees in regions with saline water that until recent years could not be used for this crop.

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