Comparisons between two economically valuable forest species (Eucalyptus grandis and Pinus taeda) in relation to seed behaviour under controlled deterioration

Abstract

-The objectives of this work were to analyze seed behaviour under controlled deterioration and estimate viability equations for forest species Eucalyptus grandis and Pinus taeda. Desired moisture content levels were achieved from initial values after either rehydration over water or drying over silica gel, both at 25 o C. Seed sub samples with 8 moisture contents each for E. grandis (1.2 to 18.1%, initial value of 11.3%) and P. taeda (1.5 to 19.5%, initial value of 12.9%) were sealed in laminate aluminium-foil packets and stored in incubators maintained at 40, 50 and 65 o C. The seeds from these species exhibited true orthodox and sub-orthodox storage behaviour, respectively, however E. grandis showed higher seed storability, probably due to a different seed chemical composition. Lowest moisture content limits estimated for application of the viability equations at 65 o C were 4.9 and 4.1 mc for E. grandis and P. taeda, on equilibrium with ±20% RH. The viability equation estimated quantified the response of seed longevity to storage environment well with K E = 9.661 and 8.838; C W = 6.467 and 5.981; C H = 0.03498 and 0.10340; C Q = 0.0002330 and 0.0005476, for E. grandis and P. taeda, respectively. . COMPARAÇÕES ENTRE DUAS ESPÉCIES FLORESTAIS DE VALOR ECONÔMICO (Eucalyptus grandis AND Pinus taeda) COM RELAÇÃO AO COMPORTAMENTO DAS SEMENTES SOB DETERIORAÇÃO CONTROLADA RESUMO -Os objetivos deste trabalho foram analisar o comportamento de sementes sob deterioração controlada e estimar as equações de viabilidade das espécies florestais