Disponibilidade e demanda hídrica na produtividade da cultura do eucalipto

• Ano de defesa: 2009
• Autor(a) principal: Alves, Maria Emília Borges
• Orientador(a): Mantovani, Everardo Chartuni
• Banca de defesa: Drumond, Luis César Dias , Fernandes, André Luis Teixeira
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Meteorologia Agrícola
• Departamento: Agrometeorologia; Climatologia; Micrometeorologia
• País: BR
• Palavras-chave em Português: Hidrogel; Coeficiente de cultura; Irrigação; Florestas plantadas
• Palavras-chave em Inglês: Hydrogel; Crop coefficient; Irrigation; Planted forests
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::AGROMETEOROLOGIA
• Link de acesso: http://locus.ufv.br/handle/123456789/1496

The planted forest sector in Brazil plays a fundamental role in the socioeconomic scenario of the country, contributing to the production of goods and services, increased value of forestry product and the generation of jobs, foreign investments, taxes and revenue. Establishing relationships between water consumption of the eucalyptus crop and availability of water in the soil may contribute to predicting the production potential of the planted forests, taking into consideration the distinct climatic conditions to which the crop is exposed in the diverse regions in which eucalyptus is grown, influencing productivity and duration of the production cycle. Therefore, simulations performed for evaluation of the effects of greater water supplies on productivity obtained under these conditions may generate important information for management of the eucalyptus crop. However, there is little information available on the water demands of eucalyptus crops, requiring investigations to determine this demand. The use of irrigation in planted forests is highlighted, including the supply of water to the eucalyptus crop in the plating phase and the association of water retention polymers (hydrogel) in irrigation in order to elevate the retention of water and therefore reduce the number of irrigations and volume of water applied, where this resource is amply used by commercial eucalyptus producers. In light of the reported aspects, the objectives of the present study were: to study the relationships between the eucalyptus crop and the water supply, evaluate the use of hydrogel during eucalyptus planting, estimate the water needs of the eucalyptus crop based on an estimate of the crop coefficient (Kc) of eucalyptus and establish a relationship between productivity and water supply by means of simulations. Therefore, an initial experimentation sought to associate different doses of hydrogel to evapotranspiration of the crop with different soil types and two irrigation frequencies. In this study it was concluded that the use of hydrogel had a positive effect on survival and growth of the eucalyptus seedlings after planting. Reduction in evaporation by the addition of the hydrogel made a greater volume of water available to the plants, reducing mortality rates. Under the two studied conditions, benefits were observed for planting both in a green house and outside of the greenhouse. However, the establishment of ideal values for utilization of hydrogel is still premature. The second portion of this work was to estimate the crop coefficient (Kc) of eucalyptus using the dual crop coefficient (Kc dual) methodology, proposed by Allen et al. (1998). This estimate is based on observed climate and crop height data in an experiment conduced in the region of Rio Doce, MG, Brazil, considering a period of 1.5 years after planting, the initial and middle stages of crop development. Thus, the average values for the estimated crop coefficients are 0.57, 0.13 and 0.60 for Ke (soil water coefficient for evaporation), Kcb (basal crop coefficient) and Kc (single crop coefficient), respectfully in the initial phase of development, and 0.01, 0.81, and 0.82 for Ke, Kcb and Kc, respectfully in the middle stage of crop development. The estimated values should not be considered definite values since the estimates do not substitute values measured in the field. In the third portion of this work, an estimate of eucalyptus productivity under diverse conditions of water supply was established, using as a reference point data observed in an experiment conducted in the region of Rio Doce, MG, during a complete eucalyptus cycle between the years of 2001 and 2008. The IRRIPLUS software was used to simulate the recommended irrigation depth (IRRI-1) and based on this depth two scenarios of water availability were created (IRRI-2 and IRRI-3), to estimate the crop productivities by means of the 3-PG model, comparing the real observed values in dry conditions (NI) and those of real applied irrigation (IR). This real applied irrigation was inferior to that recommended by IRRIPLUS. Therefore, a close correlation was observed for the aerial biomass portion (BPA) in the IR and NI treatments, which permitted that the other variables, diameter at chest height (DAP), volume (V), plant height (Ht) and average annual growth (IMA) were accurately estimated, under the same conditions and under the influence of the irrigation depths recommended by the IRRIPLUS® software. The evaluated variables presented positive increase, responding linearly to the addition in water supply, presenting relative gains proportional to the increase in applied irrigation depths.