Desempenho silvicultural e fisiológico de clones de eucalyptus sp. Sob duas condições hídricas em campo.
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Data
2021-02-22
Autores
Fernandes, João Pedro Peixoto
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Universidade Estadual Paulista (Unesp)
Resumo
O Brasil é um dos países com a maior área de floresta plantada do mundo, e o gênero Eucalyptus no setor florestal brasileiro. Mesmo considerando a alta plasticidade fenotípica da maioria das espécies do gênero, há fatores que limitam seu bom desenvolvimento e produção, a exemplo do déficit hídrico, que acarreta diversas alterações morfológicas, bioquímicas e fisiológicas, comprometendo a produtividade. Estimativas de parâmetros genéticos dos principais caracteres fisiológicos envolvidos na tolerância à seca em eucalipto ainda são pouco conhecidos. Assim, o presente trabalho teve por objetivo avaliar a produtividade, estabilidade e adaptabilidade de clones de eucalipto sob duas condições de disponibilidade hídrica em campo. Dez clones de eucalipto foram submetidos a duas condições de cultivo em campo, sem e com restrição de 30% de redução hídrica, avaliando-se, no período chuvoso e seco, a atividade fotossintética máxima, condutância estomática, taxa de transpiração e os potenciais hídricos foliares antemanhã e ao meio-dia. Também, foram determinados o crescimento em altura, diâmetro á altura do peito e volume individual de madeira aos 32 meses após o transplante. Os dados foram analisados via modelos mistos e a estabilidade, adaptabilidade e produtividade estimados pelo método da média harmônica da performance relativa dos valores genotípicos (MHPRVG). A interação clones x condição hídrica foi não significativa para a maioria dos caracteres avaliados, mas há variabilidade genética entre os clones e bom controle genético sobre os caracteres de fisiológicos e de crescimento. Os clones C3, B2 e A1 foram os genótipos mais promissores nas condições dos experimentos por apresentarem alta estabilidade, adaptabilidade e produtividade.
Brazil is one of the countries with the largest area of planted forest in the world, and the genus Eucalyptus stands out for composing a significant portion in the production of the Brazilian forest sector. Even considering the high phenotypic plasticity of most species of the genus, factors that limit its good development and production, an example of the water deficit, which causes several morphological, biochemical and physiological changes, compromising productivity. Estimates of genetic parameters of the main physiological traits subject to drought tolerance in eucalyptus are still poorly understood. Thus, the present work aimed to evaluate the productivity, stability and adaptability of eucalyptus clones under two conditions of water availability in the field. Ten eucalyptus clones were obtained from two cultivation conditions in the field, without and with water restriction, evaluating, in the rainy and dry period, the maximum photosynthetic activity, stomatal conductance, transpiration rate and leaf water potentials at noon before dawn. Also, growth in height, diameter at chest height and individual volume of wood were determined. The data were realized through mixed models and the stability, adaptability and productivity estimated by the method of the harmonic mean of the relative performance of the genotypic values (MHPRVG). The interaction between clones x water condition was not expressed for most of the characteristic traits, but there is genetic variability between the clones and good genetic control over the physiological and growth traits. Clones C3, B2 and A1 are the most promising qualified for the selection of water stress tolerant eucalyptus genotypes because they present stability, adaptability and productivity
Brazil is one of the countries with the largest area of planted forest in the world, and the genus Eucalyptus stands out for composing a significant portion in the production of the Brazilian forest sector. Even considering the high phenotypic plasticity of most species of the genus, factors that limit its good development and production, an example of the water deficit, which causes several morphological, biochemical and physiological changes, compromising productivity. Estimates of genetic parameters of the main physiological traits subject to drought tolerance in eucalyptus are still poorly understood. Thus, the present work aimed to evaluate the productivity, stability and adaptability of eucalyptus clones under two conditions of water availability in the field. Ten eucalyptus clones were obtained from two cultivation conditions in the field, without and with water restriction, evaluating, in the rainy and dry period, the maximum photosynthetic activity, stomatal conductance, transpiration rate and leaf water potentials at noon before dawn. Also, growth in height, diameter at chest height and individual volume of wood were determined. The data were realized through mixed models and the stability, adaptability and productivity estimated by the method of the harmonic mean of the relative performance of the genotypic values (MHPRVG). The interaction between clones x water condition was not expressed for most of the characteristic traits, but there is genetic variability between the clones and good genetic control over the physiological and growth traits. Clones C3, B2 and A1 are the most promising qualified for the selection of water stress tolerant eucalyptus genotypes because they present stability, adaptability and productivity
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Palavras-chave
Déficit hídrico, Fotossíntese, Parâmetros genéticos, Adaptabilidade, Estabilidade