Air layering in Caryocar brasiliense - effect of stem diameter

Abstract

Seed propagation of pequizeiro (Caryocar brasiliense) has many disadvantages, including low germination rates and high genetic variability of the resulting plants. Therefore, vegetative propagation techniques, such as the air layering process, are potentially important for this species. This study evaluated the effects of stem diameter and parental plant on the air layering efficacy of pequizeiro. The air layering process was carried out in mid-December 2019, in the following stem diameters: less than 15 mm; 15-19 mm; 20-24 mm; 25-29 mm and above 29 mm. The treatments comprised four replicates of 10 air layers. After 3 months, the percentages of survival, callus formation and rooting were evaluated, in addition to the rooting vigor. The percentages of survival and callus formation observed in the air layering, regardless the parental plant, were higher than 85%, showing the high potential of this technique in the propagation of pequizeiro. The callus differentiation rate in roots varied between the parental plants. Considering the evaluated parameters, stem diameters ranging from 20 to 24 mm are the most suitable ones for the air layering process in pequizeiro. These results indicated the high potential of the air layering technique for the commercial propagation of pequizeiro.

Chemical composition of substrates on the rooting vigor of Caryocar brasiliense air layering

“…Air layering was performed on healthy, lignified stems with a diameter of 20-30 mm using pliers adapted for air layering, resulting in a 3 cm-wide girdling (Carmona et al, 2022).…”

“…The rooting vigor of each air layer was visually estimated using a scale that ranged from 0 -Presence of calluses, but no root formation; 1less than 20% of the calluses emitted roots; 2 between 21 and 40% of the calluses emitted roots; 3between 41 and 60% of the calluses emitted roots; 4between 61 and 80% of the calluses emitted roots; 5more than 80% of the calluses emitted roots (Carmona et al, 2022). The root lignification was evaluated by the following visual scale, according to the percentage of darkened roots in the air layering: 0 -0%; 1 -1 to 20%; 2 -21 to 40%; 3 -41 to 60%; 4 -61 to 80%; 5 -81 to 100%.…”

“…Therefore, the establishment of vegetative propagation protocols for Caryocar brasiliensis is crucial for the production of seedlings for use in commercial orchards and livestock-forest integration systems. Given the reported low efficiency of propagation via cuttings (Guimarães et al, 2019), air layering may be a viable option for obtaining clonal seedlings of this species (Carmona et al, 2022).…”