Propagation of the Fruit Crop Artocarpus altilis by Root Cuttings of Various Lengths and Diameters

Artocarpus altilis is tropical fruit crop of increasing importance in Puerto Rico. The plant is commonly propagated by root cuttings, but little research has been conducted in the island to determine the influence of root cutting length and diameter for A. altilis transplant production. Experiments were conducted in Mayaguez, Puerto Rico, to evaluate various lengths (10, 15, 20, 25, 30, and 40 cm) and diameters (1.25, 2.50. 3.75, and 5.00 cm) of root cuttings from two selections from Puerto Rico (PR 1 and PR 2) on sprouting and growth for transplant production in the nursery. Roots were separated from the mother trees, cut to the desired length and separated by diameter. The resulting root cuttings were placed horizontally in plastic containers filled with a sphagnum-based growing medium and irrigated daily. Sprouting, shoot height, and leaf number were determined every two weeks for 6 months. There were no significant differences in the results between A. altilis selections. Root cuttings 1.25 cm in diameter and 10 or 15 cm in length generated very few plants that did not survive in the nursery long enough to produce transplants. Root cuttings 40 cm-long tended to sprout faster but produced several shoots that competed among themselves slowing their vertical growth. Root cuttings 2.5 to 5 cm in diameter and 15 to 20 cm in length tended to sprout fast and to have greater shoot length and leaf number, with the highest rate of success in producing transplants for orchards.