Effect of the roots pruning in the growth of the Eucalyptus seedlings

Abstract

O trabalho teve como objetivo avaliar o efeito das podas no sistema radicial de mudas de Eucalyptus camaldulensis , produzidas em blocos. No viveiro, foram testados tr\ueas tratamentos (T1: sem poda do sistema radicial; T2: 1 poda do sistema radicial; T3: duas podas do sistema radicial), disposto em DIC, com nove repeti\ue7\uf5es, sendo cada repeti\ue7\ue3o composta por 96 mudas. Parte dessas mudas foi levada para o campo para avalia\ue7\ue3o do efeito da poda das ra\uedzes ap\uf3s o plantio no campo. Foram dispostas em quatro blocos casualizados, com 49 mudas por parcela. O substrato utilizado para produ\ue7\ue3o de mudas foi a mistura de plantmax florestal (60%) e fibra de coco de granulometria mista (40%), sendo adicionados 8 g de osmocote (19-06-10) por quilo do substrato. As podas das ra\uedzes na fase de viveiro foram realizadas aos 80 e 90 dias ap\uf3s a semeadura, com auxilio de uma l\ue2mina afiada. As mudas foram avaliadas aos 100 dias ap\uf3s a semeadura, quanto \ue0 altura da parte a\ue9rea, di\ue2metro do colo, massa seca da parte a\ue9rea, comprimento e di\ue2metro das ra\uedzes. No campo as mudas foram avaliadas quanto a altura e di\ue2metro ao 1, 3, 5, 7 e 9 meses ap\uf3s plantio. No viveiro, mesmo n\ue3o havendo diferen\ue7a no crescimento em altura e di\ue2metro da parte a\ue9rea das mudas entre os tratamentos, aquelas que n\ue3o sofreram poda de suas ra\uedzes (T1) apresentaram menor produ\ue7\ue3o de massa seca da parte a\ue9rea, representada pelas folhas. J\ue1 para o sistema radicial, quando foram aplicadas duas podas durante o ciclo de produ\ue7\ue3o, as mudas apresentaram maior comprimento e di\ue2metro de ra\uedzes produzidas. N\ue3o houve diferen\ue7a no crescimento das mudas ap\uf3s plantio no campo, no entanto, a condi\ue7\ue3o clim\ue1tica na \ue9poca de implanta\ue7\ue3o e condu\ue7\ue3o do experimento, al\ue9m do s\uedtio favor\ue1vel ao desenvolvimento das mudas pode ter contribu\ueddo para esse resultado, sendo necess\ue1ria condu\ue7\ue3o de novo experimento, para avaliar o efeito das podas, em mudas plantadas em condi\ue7\uf5es adversas.The objective of this work was to evaluate the effect of the roots prunings of Eucalyptus camaldulensis seedlings produced in blocks. In the nursery, three treatments were tested (T1: without roots pruning; T2: one roots pruning; T3: two roots pruning), in Completely Randomized Design, with nine replicates (96 seedlings for replicate). Portion of those seedlings was taken for the field for evaluation of the pruning roots effect after the planting in the field. The substrate used for production of seedlings was the mixture of forest plantimax (60%) and fiber of the coconut (40%), 8g of osmocote were added (19-06-10) per kilo of the substrate. The prunings of the roots in the nursery were accomplished to the 80 and 90 days after sowing, with sharp sheet. The seedlings were evaluated 100 days after the sowing, for height, stem diameter, shoot dry matter, length and diameter roots. In the field the seedlings were evaluated as the height and diameter to the 1, 3, 5, 7 and 9 months after planting. In the nursery, there was no difference in the shoot height and diameter of the seedlings among the treatments, but the seedlings which did not receive any root pruning (T1) presented smaller production of shoot dry matter, acted by the leaves. When two prunings were applied during the production cycle, the seedlings presented larger length and diameter roots. There was not nay difference in the growth of the seedlings after planting in the field; however, the climatic condition in the implantation and conduction of experiment, besides the favorable site to the development of the seedlings might have contributed to that result, being necessary the conduction again experiment, to evaluate the effect of the prunings, in seedlings planted in adverse conditions