AVOCADO SELECTIONS WITH POTENTIAL USE AS ROOTSTOCKS. I. GRAFTING AND SCION GROWTH

Abstract

This research was conducted in a 50 % shaded nursery in order to evaluate grafting success and scion growth of 39 avocado (Persea americana Mill.) selections, from which 19 are tolerant to drought, 11 tolerant to salinity, and nine tolerant to avocado root rot (Phytophthora cinnamomi Rands), as well as two chinini (Persea schiedeana Nees) salinity tolerant selections. The seedling rootstocks probably were hybrids of the West Indian x Guatemalan races, and were grown in 6 L containers filled with a good fertility sandy clay loam
soil. Plants were watered during the dry season. Using the lateral tongue technique, avocado selections were grafted onto seedling rootstocks in June 1999. A total of 1549 grafts were done: 747 were tolerant to drought, 392 tolerant to salinity, and 410 tolerant to P. cinnamomi. Global grafing success was 96 %. In P. cinnamomi tolerant selections, it ranged from 92 to 100 %, from 40 to 100 % in drought
tolerant selections, and from 50 to 100 % in salinity tolerant selections. Grafting success for P. schiedeana selections, S-44 and S-88, were 100 and 50 %, respectively. Rootstock stem diameter had no effect on grafting success. Scion stem elongation was different between avocado selections, but for clonal propagation in the nursery, all selections reached an appropriate height (15 a 20 cm) in less than 90 d after grafting.