Growth and quality of australian cedar saplings originated from different multiclonal minigarden systems

Abstract

Forestry researchers often evaluate minicutting vegetative propagation of Australian cedar (Toona ciliata) as a viable technique for this species. However, the adoption of minigarden systems for commercial propagation still requires viability and quality testing of saplings produced after multiple harvests. In the present work, we evaluate survival, growth, and quality of Australian cedar saplings grown from minicuttings originating from multiple harvests of ministumps planted in gutter or tube systems. Experiments were conducted in a greenhouse using a completely randomized design with a 2 × 4 factorial treatment structure (two minigarden systems and four minicutting harvests). For the gutter system, six minicutting harvests were performed 50, 86, 115, 149, 177 and 212 days after planting ministumps, whereas for the tube system, four harvests were performed 115, 149, 177 and 212 days after planting ministumps. At the end of each sapling production cycle (105 days after each minicutting harvest), saplings were evaluated for survival, foliar area, dry mass of aerial parts, number and length of adventitious roots, dry mass of the root system, height to diameter ratio, ratio between the dry mass of aerial parts and dry mass of root system, and Dickson’s Quality Index. Sapling survival was not affected by minigarden system, except for a reduction observed in fourth cycle saplings from the tube system. Sapling quality was also similar between systems. However, sapling growth potential decreased with production cycle, indicating that ministumps lose vigor with multiple harvests.