Rooting ability of leafy and leafless cuttings of 'Tainung 1' papaya (Carica papaya) trees

Papaya mainly propagates by seed, with the exception of China where cuttings and tissue culture are widely used. Seed propagation requires sexing for hermaphrodite plant that produces the fruit demanded by the market. Cuttings give 100% hermaphrodite plants. This study had the objective to develop a commercial protocol for 'Tainung 1' papaya cuttings that can be replicated by the farmers. Cutting thickness and leaf presence associated with the pre-conditioning of lateral shoots (source of cuttings) in the field grown bearing papaya trees were studied. Misting nursery under controlled condition with heated bed was used to root papaya cuttings. Randomized blocks with 20 replications for each thickness of cutting (length of 15 to 20 cm) - named thin/medium/thick - totaling 60 replicates per treatment were studied: T1 - cuttings with growing tips (GT) with leaves attached from decapitated trees (DT); T2 - cuttings without GT and leafless from DT were preconditioned (tips and/or leaves were detached one week before collection to promote healing of cuts); T3 - cuttings with GT and leafless from DT, preconditioned; and, T4 - cuttings with GT and leafless from non-decapitated trees, preconditioned. All cuttings were treated with auxin (gel solution containing indole butyric acid 3 g L-1), potted in coconut fiber, and kept for 30 days under misting with heated bed at 30°C. Rooting ability (RA) and root mass density (RM) were measured. Thickness of cuttings did not show any significant differences in all treatments. T1 with 91% RA gave the heaviest RM in contrast with T3 with 7% RA and the lightest RM. On the other hand, T2 and T4 gave 80 and 71% RA, respectively, not as many RM as T1 but enough for achieving good root system. Therefore, T2 and T4 cuttings, both leafless, were the most promising for mass production in the nursery since they allow higher density (double to triple) with less disease pressure when compared to T1.