INFLUENCE OF WATER DEFICIT AND SEASON ON BIOMASS YIELD FROM CLONAL STANDS OF EUCALYPTUS

Abstract

This study aimed to analyze the influence of different levels of water deficit (DH) on initial seedling development of six clonal stands of hybrid Eucalyptus grandis x E. urophylla in two seasons of the year. The experiment was conducted in the experimental site of UFES, in the municipality of Jerônimo Monteiro (ES), over two seasons: from February 9, 2009 to June 9, 2009 (season 1) and from July 11, 2009 to November 7, 2009 (season 2). In all experimental treatments, the first 30 days consisted of acclimating seedlings to the soils, which were thus irrigated. DH levels used in the experiment included: D0 – no water deficit; D1 - 90 days of water deficit; D2 - 60 days of water deficit followed by resumed irrigation for 30 days; D3 – 30 days of irrigation and 60 days of water deficit. The experiment was laid out in a completely randomized design, in subdivided plots (2x4), with four (4) levels of water deficit in the plot and two (2) seasons in the subplots, using three replications. Data on total dry matter of leaves, stem and branches, and root were subjected to analysis of variance and, if found significant, means were compared by the Tukey test at the 5% probability level. The environmental conditions of season 1 favored dry matter yield from both clonal stands, while season 2, having milder climate conditions, failed to favor potential growth of seedlings, even with irrigation conditions being satisfactory. Different levels of water deficit gradually reduced dry matter yield, yet without following a pattern of reduction.