Rodrigo Favreto

Banco de sementes do solo em área agrícola sob diferentes sistemas de manejo estabelecida sobre campo natural

Knowledge of the ecology of soil seed banks (SSB) contributes to improving integrated weed SSB management systems in croplands established in natural grassland areas. The aim of this study was to evaluate the effect of different cropping systems, established in a natural grassland field (Depressao Central of Rio Grande do Sul, 30o05´S, 51o40´O, altude 46m, rainfall 1398mm), on the SSB. Three different tillage-crop rotation systems were imposed (no-tillage - NT, reduced tillage - RT, and conventional tillage - CT) in three plots arranged in seven blocks. Two SSB evaluations were carried out in each tillage system, one in May and the other in October/ 2002. The SSB was evaluated by sampling soil cores, which were germinated in a glasshouse, and seedlings were counted and identified. Edaphic variables were registered to relate with collected data. The results indicated that different tillage systems affected the SSB composition, and that certain species responded differently to these influences. The NT system resulted in higher BSS wealth, a lower number of Brachiaria plantaginea seeds, a higher number of Sida rhombifolia seeds, but inverse values were recorded for RT and CT systems. The spatial soil seed bank distribution presented high heterogeneity among cropping systems. Edaphic variables, specially organic matter, pH and phosphorous, showed associations with the variation in SSB composition.

Banco de sementes do solo de margem viária dominada por capim-annoni-2 e sujeito ao controle com distúrbios no solo e introdução de gramíneas

The impacts of the anthropic actions in roadsides promotes a differenciated ecosystem in its surroundings facilitating the establishment of opportunist species like annoni-2-grass (Eragrostis plana Nees). The roadsides of Rio Grande do Sul state, in southern Brazil, are invaded by this weed specie forming dispersion centers. The objective of this study was to evaluate the soil seed bank (SSB) size and composition in these roadsides, and demonstrate its potential to regenerate the original grassland of these degraded and invaded areas. The trial was established on roadside next to the Sao Lucas Farm headquarters, in Rio Pardo county RS, from January 2005 to may 2006. The experimental design was a split-plot type in complete blocks, with tree replications. The plots were submitted to two treatments: deep sub-soil tillage and deep sub-soil tillage plus light soil disking