The ascorbate system during the early stage of germination in Pinus laricio seeds treated with extracts from two different sources of humus

The ascorbate system plays an important role during the early stage of seed germination, utilizing high quantities of ascorbic acid (AA) to eliminate the H2O2 produced by oxidative metabolism. The ascorbate/dehydroascorbate (AA/DHA) ratio is considered a good indicator of the ability of seeds to germinate. Extracts from humus were obtained from two different forestry sites, one of which had Fagus sylvatica L. (Fs) as the principal type of vegetation and the other which had Abies alba Miller (Aba) as the principal type of vegetation. These extracts had high molecular weight (>3500) and their influence on the AA system during the early stage of Pinus laricio P. spp. calabrica seed germination was tested, Enzyme activities (AA peroxidase (APX), ascorbate free radical (AFR) reductase and DHA reductase) and the AA and DHA seed contents were determined. Both humus fractions used inhibited AA peroxidase and AFR reductase activities and decreased the AA/DHA ratio. These negative effects on the ascorbate system and consequently on seed germination were more evident with the Aba humus fraction, probably due to its higher content of peptidic-C and carbohydratic-C groups