Effect of mini-cutting size on adventitious rooting and morphophysiological quality of Ilex paraguariensis plantlets

Abstract

As the energizing and therapeutic effects of infusions of mate (Ilex paraguariensis A.St.-Hil) leaves are increasingly recognized, rising global consumption is also increasing the demand for plantlets with high genetic and morphological qualities. Mini-cuttings are an alternative for clonal plantlets; however, more details are needed on factors that affect the success of this technique. Here, toward maximizing production, we evaluated adventitious rooting competence of mini-cuttings of different sizes and the morphophysiological quality of the resultant plantlets. Small (one bud; length up to 2.5 cm), medium (multiple buds; length 2.6–5.0 cm), and large (multiple buds; length 5.1–10.0 cm) mini-cuttings were planted in a mixture of commercial substrate, vermiculite, and coarse sand (1:1:1 v:v:v), grown in a humidity chamber, then evaluated after 45, 60, 75, and 90 days for survival, percentage of callus and shoot formation, number and length of shoots, percentage of rooted cuttings, and number and length of roots. Any rooted mini-cuttings were then cultivated in commercial substrate and subsurface soil (2:1 v:v) and evaluated after 30, 60, 90 and 120 days of cultivation for morphophysiology of the plantlets, percentage of survival, number of leaves, shoot height, stem diameter, and ratio of shoot height to stem diameter. After 120 days, the plantlets were evaluated for the ratio of shoot and root dry mass, total length, surface area, total volume, and mean diameter of roots and Dickson quality index. Adventitious rooting of the mini-cuttings and the morphophysiological quality of the plantlets were not influenced by the size of the vegetative propagule. Therefore, single-bud mini-cuttings have similar adventitious rooting competence, and result in plantlets with adequate morphophysiological quality, based upon leaf development, shoot height, stem diameter and length, and surface area, volume and diameter of roots. Single-bud mini-cuttings up to 2.5 cm long can thus be used to maximize production of mate plantlets by mini-cuttings.