The aim of this study was to investigate variation in mating system among three Brazilian Amazon populations of the tree Bertholletia excelsa with different levels of anthropogenic interventions. We collected open-pollinated seeds from one natural population, remnant trees dispersed in a pasture, and trees from a plantation. Outcrossing rate not varied among the populations and indicates that all seeds were originated from outcrossing (tm=1.0). Mating among relatives was significant higher in the plantation than forest and pasture populations, probably due the fact that many trees are related in the plantation. Correlated mating was significantly higher in pasture (rp=0.47) and plantation (rp=0.51) than in the natural population (rp=0.22), suggesting that trees in natural population are pollinated by a higher number of pollen donors. The paternity correlation was significantly higher within (rp(w)=0.41) than among fruits (rp(a)=0.18), showing a higher probability to find full-sibs within than among fruits. The fixation index was generally lower in seed trees than in their seedlings, suggesting selection for heterozygous individuals from seedling to adult stages. Progeny arrays collected from the natural population had a lower proportion of pairwise full-sibs than in pasture and plantation and higher variance effective size (2.75) than trees in pasture (2.15) and plantations (2.22). Results highlight that seed collections for conservation, breeding and reforestation programs preferentially should be carried out in natural populations due low proportion highest variance effective size within progeny.

ABSTRACT. Due to the nutritional content and commercial value of its seeds, Bertholletia excelsa is one of the most important species exploited in the Amazon region. The species is hermaphroditic, insect pollinated, and its seeds are dispersed by barochory and animals. Because the fruit set is dependent on natural pollinator activity, gene flow plays a key role in fruit production. However, to date, there have been no studies on pollen and seed flow in natural populations of B. excelsa. Herein, we used microsatellite loci and parentage analysis to investigate the spatial genetic structure (SGS), realized pollen and seed dispersal, and effective pollen dispersal for two B. excelsa populations in the Brazilian Amazon forest. Two plots were established in natural forests from which adults, juveniles, and seeds were sampled. Realized and effective pollen flow was greater than realized seed flow. The distance of realized pollen dispersal ranged from 36 to 2060 m, and the distance of realized seed dispersal ranged from 30 to 1742 m. Both pollen and seeds showed a dispersal pattern of isolation by distance, indicating a high frequency of mating among near-neighbor trees and seed dispersal near to mother trees. Both populations present SGS up to 175 m, which can be explained by isolation by distance pollen and seed dispersal patterns. Our results suggested that fragmentation of these forest populations may result in a significant decrease in gene flow, due to the isolation by distance pollen and seed dispersal patterns.

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A inoculação é a prática mais importante na cultura da soja. O objetivo do trabalho foi verificar o efeito de diferentes doses, formas (líquida e turfosa) e vias (semente e sulco) de aplicação do inoculante Bradyrhizobium japonicum em duas cultivares de soja (TMG 1188 RR e TMG 133 RR). O delineamento experimental foi em blocos ao acaso (DBC) com quatro repetições. O esquema experimental predominante foi em fatorial 8 x 2. O primeiro fator foi os tratamentos com inoculantes: testemunha (semente pura); 200 Kg de N.ha-1 (ureia), 200 e 800 mL.ha-1 de inoculante líquido aplicado via jato dirigido, no sulco de semeadura (200 e mL liq/sulco e 800 mL liq/sulco); 200 e 800 mL de inoculante líquido.100 kg-1 de sementes (200 mLliq/sem e 800 mL Liq/sem); 100 e 400 g de inoculante turfoso.50 Kg-1 de sementes (100 g turf/sem e 400 g tur/sem). O outro fator foi as duas cultivares, em que Bradyrhizobium japonicum não altera os teores de clorofila da soja em "primeiro ano" de cultivo. As doses de 200 e 800 mL.ha-1 líq/sulco são as que produzem mais nódulos e grãos. Em "primeiro ano", a cultivar TMG 1188 RR é mais produtiva que a TMG 133 RR.