Growth and Structural Development of Tectona grandis in Different Cultivation Systems in Brazil

The objective of the research was to assess the growth and structural changes of clonal and seed-origin teak trees in monoculture and agroforestry systems. The experiment was established in a randomized complete block design with six replicates. Eight treatments were etablished consisting of combinations of two propagation types (clonal and seed-origin), two types of cultivation systems until the age of 24 months (monoculture and taungya system with maize) and two types of cultivation system after 24 months of age (monoculture and silvopastoral systems). The data were analyzed by modeling the growth and yield, diameter distribution and diameter class ingrowth. The technical age of thinning was then determined by the percent entries method. Independent of the cultivation system, clonal trees presented greater tree height and diameter than seed-origin trees. Regarding the cultivation systems, systems ending in a monoculture phase presented greater tree height and diameter than systems ending in a silvopastoral phase. In terms of structure, represented by the evolution of diameter distribution, seed-origin trees and systems ending in a silvopastural phase resulted in flatter and broader distributions than clonal trees and final monoculture phase. Overall, the technical age of the first thinning varied from 6 to 9 years, being earlier for clonal trees in monoculture and later for seed-origin trees in systems ending in a silvopastoral phase. The slower growth and greater variability in silvopastoral systems with seed-origin teak tree can be attributed to the genetic variability of the trees associated competition with the brachiaria grass, which also made the plants more susceptible to the attack of pests.