Seed viability constants for Eucalyptus grandis

Abstract

-This work aimed to analyse Eucalyptus grandis W.Hill ex Maiden seed behaviour, under controlled deterioration, and to estimate viability equation constants for the species. Seeds were harvested in the growing season of 1999, and the moisture contents were adjusted from 11.3% to a range between 1.2 and 18.1% at 25ºC. The subsamples were sealed into laminate aluminium-foil packets, for storage in incubators at 40, 50 and 65±0.5ºC. The seeds presented orthodox performance, in which the constants for predicting seed longevity of E. grandis were K E = 9.661, C W = 6.467, C H = 0.03498 and C Q = 0.0002330. The usual and inverse relationship between water content and seed longevity was also observed. The lowest moisture content limit for application of the viability equation at 65ºC was 4.9%, estimated under hygroscopic equilibrium with 23% of relative humidity in the storage environment.Index terms: seed deterioration, storage, seed longevity. Constantes de viabilidade para sementes de Eucalyptus grandisResumo -Este trabalho teve como objetivos verificar o desempenho de sementes de Eucalyptus grandis W.Hill ex Maiden, após a deterioração em condições controladas, e obter as constantes da equação de viabilidade. As sementes foram colhidas na safra de 1999, e a umidade foi ajustada de 11,3% para valores entre 1,2 e 18,1% a 25ºC As subamostras foram acondicionadas em embalagens de alumínio termossoldadas, armazenadas a 40, 50 e 65±0,5ºC. As sementes apresentaram um desempenho ortodoxo em relação ao armazenamento. As constantes para a predição da longevidade foram K E = 9,661, C W = 6,467, C H = 0,03498 e C Q = 0,0002330. Foi observada a relação inversa entre teor de água e longevidade. O limite inferior de grau de umidade, calculado para aplicação da equação a 65ºC, foi de 4,9%, estimativa obtida sob equilíbrio higroscópico com umidade relativa de 23% no ambiente de armazenamento.Termos para indexação: deterioração de sementes, armazenamento, longevidade de sementes.

Seed controlled deterioration of three interspecific elephant grass × pearl millet hybrids

“…Considering a controlled one-year-storage at 50% RH, 25°C and initial seed viability of 70%, the sigma values estimated for Eucalyptus grandis W.Hill (Fantinatti & Usberti, 2007) and Brachiaria brizantha (Usberti, 2006) were 295 and 714 days, respectively, while in this research, the interspecific hybrids would require 396 days for the viability drop by one probit. The final seed viabilities estimated would be 24.2, 51.1 and 34.5% for Cutting-type, Original and Grazing-type hybrids, respectively and the variations observed were probably due to the different chemical compositions among species, which influence significantly their seed storability.…”