A rapid method of inducing root formation in West Indian (WI) germplasm is needed to evaluate them for tolerance or resistance to Phytophtora cinnamomi. WI germplasm have shown a considerable natural resistance to the disease when compared with proven rootstocks. Three experiments were conducted to evaluate rooting of WI avocado by stem cuttings, air layering, arid etiolation. Five concentrations of Indole-3-butyric acid (IBA) were employed to initiate rooting in mature stem cuttings. The same five concentrations of IBA in conjunction with 12 rooting factors;' were used to stimulate root initiation via air layering. Stem cuttings of etiolated avocado seedlings and etiolated shoots from a juvenile sucker of a mature WI avocado tree were also evaluated. Fifty percent of the etiolated stem cutting from the seedling plants rooted in 5 weeks; whereas 33% of the juvenile sucker of the mature tree rooted after 17 weeks. A single root arised from the air layer control treatment after 10 weeks. Callus formation was achieved in all air layer treatments and in the stem cuttings. Further research needs to be conducted to understand the limiting factor(s) affecting rooting. Once these limitation(s) are surpassed; the rooted clones will be used for testing for resistance to Phytophthora cinnamomi.


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