Superação de dormência de sementes e desenvolvimento de mudas de jatobazeiro em substratos alternativos

The propagation of the jatoba (Hymenaea courbarilL.) by seeds is highly promising in the recovery of degraded areas. Thus, the present research aimed to compare methods forjatoba plant seeds dormancy overcomingand to evaluate the development of seedlings of this species in alternative substrates. In the first experiment, in screened nursery, a completely randomized design was used, with four replications and seven seed treatments: scarification with sandpaper(SS), SS and immersion in water for 24 h, SS and immersion in water for 48 h, intact seed, seed immersed in water for 48 h and seed immersed in water for 96 h. The seedlings that emergency were counted every other days, from 13 to 51days after sowing, quantifying the emergence percentage, the emergence speed index and the emergence average time.The second experiment, in greenhouse,was composed ofthree replicates, in randomized blocks, being seven substrates were used:commercial substrate (CS); 40% SC + 60% forest humus (FH); 40% SC + 60% charcoal rice husk (CRH); 40% SC + 60% bovine manure (BM); 40% CRH + 60% BM; 40% CRH + 60% FH; e 40% FH + 60% BM. At 50, 70 and 120 days after sowing were evaluated the parameters: seedlingheight, leafsnumber, stem diameter, fresh matterand dry matter of aerial partand roots, and leaf area.At 120 DAS, the chlorophyll index was also evaluated. The scarification with sandpaper and immersion of seeds in water for 24 hours presented a greater emergence (96.4% and IVE = 0.697).The mixture containing 40% FHand 60% BMresulted seedlings with a larger leaf area, chlorophyll index and roots and aerial part dry matter, at 120 days after sowing.

Topsoil acidity of forested mineral lands in Estonia

The active acidity (pH) of forested mineral lands’ topsoil, its relationships with alternative soil acidity characteristics and the influence of soil acidity on forest soils’ profile fabric and functioning are analysed in the pedo-ecological conditions of northeastern Europe. The active acidity of the forest floor (O-horizon) was taken as the baseline for this analysis. The acidity of the forest floor was studied in accordance with the underlying soil horizons, which are humus and/or raw-humus horizons in the more fertile soils, whereas in less fertile soils, they are podzolized horizons. The data on soil acidity are presented by main soil types, forest site types, forest humus cover types (pro humus forms) and forest stand groups. In this work, the influences of forest floor acidity on mineral topsoil fabric, soil processes and peculiarities of carbon sequestration are explained. The active acidity of the forest floor provides a great indicative value in elucidating the regularities of the forest soil cover, as a whole, formation and functioning. For evaluating the normality of soil functioning, or the absence of disturbances in ecosystem functioning, the intervals of soil type specific reference pH levels have been established.