Relationship between seasonality, hedging and carbohydrates on growth of eucalypts in the vegetative propagation by minicuttings. / Relação entre sazonalidade, desrama e carboidratos no crescimento do eucalipto na propagação vegetativa por miniestaquia.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

The importance of the Eucalyptus in the current conjuncture of Brazilian forestry has stirred up significant investments in research, which has leaded to the development of the improved methods of vegetative propagation. The clonal propagation of Eucalyptus spp. allows the fast multiplication of selected genotypes, allowing high gains even with characteristics of low heritability (i.e., growth and cellulose content), immediate increase in productivity, in addition to success with the application of cutting techniques. There are evidences on the existence of correlation between carbohydrate concentration, rooting of cuttings and steckling survival. Although carbohydrates do not have regulatory role in the rooting process, they are an important source of carbon and energy for the synthesis of essential substances in the formation of plant body. The silvicultural and environmental management of the miniclonal garden can alter carbohydrate concentrations in the plant, thus, this management makes it possible the alteration of the endogenous content of sugars, resulting in increases of the survival of young plants. This research was carried out at the nursery of Aracruz Celulose S.A., which has the largest prodution of clonal eucalypt stecklings, located in Aracruz, Espírito Santo State, Brazil. The company is also the worldwide leader in the production of bleached eucalypt cellulose fiber. Two clones were evaluated in two seasons (winter and summer). Plants from stem cuttings were evaluated by several biometrical and biochemical parameteres. The biometrical parameters were survival rate, dry biomass and productivity. The biochemical parameteres were separation, characterization and quantification of several structural carbohydrates and their seasonal variation. It was not found significant statistical differences between the tested conditions through the t-Test for comparison of averages with 95% confidence. However, using another method of principal components analysis (PCA), it was demonstrated that are biological differences among treatments, evidencing an optimum season and periodicity of hedging of cuttings for each clone, which could be related to the endogenous content of carbohydrates. Among the main results obtained, it was observed a 9.10% increase in carbohydrates during summer in relation to winter. The gain in sugar content in the summer was 138.00% and 143.00%, respectively, for clones A and B, compared to winter. The increment in survival rate of stecklings was increased 2.60% and 1.69%, respectively, for clone A and B; also, productivity of harvested cuttings from stock plants increased 212.80% and 145.48%, respectively, clone A and B. In general, the summer is the most indicated season for collection of cuttings, for all the evaluated parameters, because it is the most productive season. In terms of periodicity of hedging of cuttings, the collection at each 9 days was shown to be the more indicated for all the evaluated parameters.

ASSUNTO(S)

eucalipto manejo florestal crescimento vegetal carbohydrates eucalyptus carboidratos fisiologia vegetal hedging. seasonality propagação vegetal. minicultings vegetative propagation estacas (plantas)

ACESSO AO ARTIGO

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