Efeitos de métodos de produção de mudas e equipes de plantadores na arquitetura do sistema radicular e no crescimento de Pinus taeda Linnaeus

Abstract

Despite the technological evolution on the forest tree seedlings production, there are several problems to be solved yet. Seedlings out of pre-established morphological standard and/or older than the age recommended for planting, seedlings grown in unsuitable containers are some of the problems which can result in unsatisfactory results on the field. This paper aimed to evaluate the effects of seedlings age, the effect of containers type and the planters team effects on the Pinus taeda trees growth and root system morphological architecture 46 months after their planting. Eight treatments were planted in a randomized block design distributed on a factorial design, with two planters team: 1. specially trained; 2. ordinary, and four seedling production methods: 1. plastic tubes of 55 cm3 (six months of age); 2. plastic tubes of 55 cm3 (ten months of age); 3. plastic tubes of 126 cm3 (six months of age); 4. bare root seedlings (nine months of age). The field trial was established on four blocks, with eight treats and 25 plants per plot. Treatments were randomized within blocks and data were collected only on the nine inner plants in each plot. A row of trees out of the blocks was planted as external border. Seedlings height was evaluated just after planted. Plot volume (survival, height, DBH-diameter at breast height), small root weight and root system architecture were evaluated at 46 months of age. A cylindrical sampler was used to collect small roots and a big tractor with special equipment used for digging was used to remove the whole root system. Architecture of each root system was classified based on the photograph analysis taken at three angles (front, side and from the top). When necessary, the data were transformed to attend the requirements of the analysis of variance (ANOVA) and analysis of covariance (ANCOVA). Spearman correlation was used to evaluate relations between traits. Based on the results observed, it was conclude that: the seedling production method affect the tree height and DBH growth (and volume per plot), but do not affect the small roots weight and the architecture of the root system of 46 months P. taeda trees; the method of production M3 (containers of 126 cm3, seedlings with 6 months of age) is better in terms of growth; trees originated from seedlings with six and ten months of age, grown in 55 cm3 containers, shown similar height and DBH at 46 months of age, but also shown different survival, which affect the total volume per plot; trees originated from six months of age seedlings grown in 126 cm3 containers shown better DBH and height growth, but similar volume per plot when compared with trees originated from same age seedlings grown in 55 cm3 containers; The training provided to teams of growers improves survival rate, therefore, the volume per plot. However, it should be emphasized that the excess of trampling can affect the development of the architecture of the root system of trees of P. taeda;DBH is highly correlated with individual tree volume and the mean DBH is medium correlated with mean plot volume at 46 months of age; the root system architecture of 46 months P. taeda trees can be evaluated by mean of excavation, with moderate accuracy, attributing it note to the view of top, without necessity removal the tree, reducing cost and time.