Extratos aquosos vegetais no controle de Bidens pilosa L.

Compostos secundários têm ação alelopática sobre a germinação, crescimento e desenvolvimento inicial de plântulas, e a Bidens pilosa pode ter sua germinação e crescimento afetados pela ação dos extratos alelopáticos. Nesse sentido, objetivou-se avaliar o potencial alelopático de extratos de braquiária (Brachiaria brizantha), girassol (Helianthus annus) e sorgo (Sorghum bicolor) na germinabilidade e no crescimento inicial de picão-preto (Bidens pilosa). Para isso foi instalado um experimento no delineamento inteiramente casualizado, com quatro tratamentos e seis repetições, sendo eles extrato de braquiária, girassol, sorgo e o controle (água destilada). Os extratos foram obtidos utilizando 200 g de material vegetal fresco para 1.000 mL de água destilada. As sementes foram distribuídas em caixa gerbox contendo duas folhas de papel germitest umedecidas com os tratamentos e levadas para a câmara de germinação. Foi acompanhada diariamente a germinação e, após 10 dias, foi avaliado o crescimento inicial. Os extratos não causaram prejuízos à germinação, porém, provocaram demora em seu tempo de eclosão, sendo o extrato de braquiária o mais prejudicial. As plântulas submetidas aos extratos de braquiária e sorgo apresentaram menor crescimento. Os extratos de braquiária e sorgo não apresentaram ação sobre a porcentagem de germinação das sementes de picão-preto, mas controlaram o crescimento inicial das plântulas e podem ser indicados para possíveis herbicidas naturais.Secondary compounds have allelopathic action on germination and growth, and initial development of seedlings and beggar tick can have its germination and growth affected by the action of allelopathic extracts. Thus, this work aimed to evaluate the allelopathic potential of Brachiaria (Brachiaria brizantha), sunflower (Helianthus annuus) and sorghum extracts (Sorghum bicolor) on germination and initial growth of beggar ticks (Bidens pilosa). For this, an experiment was conducted in a completely randomized design with four treatments and six replicates and brachiaria, sunflower and sorghum extracts and control (distilled water) treatments. Extracts were obtained using 200 g of plant material and 1,000 mL of distilled water. Seeds were distributed in gerbox containing two sheets of germitest paper moistened with treatments and taken to germination chamber. Germination was daily monitored, and ten days after, initial growth was evaluated. Extracts did not reduce germination. However, they caused increase in germination time, mainly by brachiaria extract. Seedlings submitted to brachiaria and sorghum extracts showed lower growth. Brachiaria and sorghum extracts showed no action on germination, but controlled the initial growth of beggar tick, being potential natural herbicides

Análise de trilha em caracteres agromorfológicos de genótipos de amendoinzeiro do grupo botânico Valência / Analysis of path in agromorphological characters of peanut genotypes of Valencia type

A identificação de caracteres que auxiliam na seleção indireta para produtividade torna-se necessária nas etapas iniciais de um programa de melhoramento de amendoim. Principalmente, quando for possível selecionar outra característica, de fácil medição e alta herdabilidade, que apresenta alta correlação com o caráter desejado visando a obtenção de cultivares mais produtivos. Objetivou-se decompor as correlações genotípicas por meio de efeitos diretos e indiretos das características morfológicas e agronômicas sobre a produtividade de sementes de genótipos de amendoinzeiro. Foram avaliados 60 genótipos do grupo ‘Valência’ no delineamento em blocos casualizados com quatro repetições. A hierarquia e a natureza das associações dos caracteres corroboraram para a submissão da análise de trilha em cadeia dupla, sendo a primeira cadeia constituída pelo número de vagem por planta, número de semente por vagem e peso de cem sementes, a segunda composta por altura da planta, número de haste, comprimento e diâmetro da vagem sobre o rendimento total de sementes. O coeficiente de determinação obtido estimou que 94,74% das variações registradas nos rendimentos de sementes são explicadas pelas variáveis primárias. Os componentes secundários não apresentaram equivalência e simultaneidade sobre os primários, uma vez que a altura da planta e o número de haste registraram associação positiva com o número de vagem por planta, ortogonalmente, com mesmo sinal de associação o diâmetro e o comprimento da vagem se relacionaram com o peso de cem sementes. Plantas mais altas e com mais hastes sustentam maior quantidade de vagens, sugerindo critério simultâneo para seleção indireta de genótipos mais promissores de rendimento de sementes. Esta decisão pode ser considerada muito relevante uma vez que ambas variáveis são não destrutivas e podem ser avaliadas facilmente antes da colheita

Ácido giberélico no crescimento inicial de plantas de pinhão manso / Giberelic acid in initial growth of jatropha plants

Objetivou-se avaliar a ação do GA3 no crescimento inicial de plantas de pinhão manso, via pré-embebição de sementes e em pulverizações foliares. O delineamento experimental utilizado no primeiro experimento foi inteiramente casualizado, com seis tratamentos (concentrações de GA3) e quatro repetições. No segundo ensaio o delineamento foi em blocos casualizados em esquema fatorial 6 × 6 (seis concentrações de GA3 × seis avaliações no tempo) com quatro repetições. As sementes foram pré-embebidas por oito horas, submetidas aos seguintes tratamentos: controle em água destilada (0,0) e as concentrações de giberelina líquida 0,8; 1,6; 2,4; 3,2 e 4,0 mL do produto L-1 de solução, as quais correspondem a 32,0; 64,0; 96,0; 128,0 e 160 mg de GA3 L-1 de solução, respectivamente. Após isso, as sementes foram semeadas em sacos de polietileno preto, previamente preenchidos com substratos distintos para cada experimento, os quais foram mantidos em casa de vegetação a temperatura ambiente para germinação das sementes. No primeiro experimento, além dos tratamentos com as sementes foram realizadas pulverizações das plantas de pinhão manso, com as mesmas concentrações de GA3 utilizadas na embebição das sementes. Aos 40 dias após a semeadura foram avaliadas as características agronômicas em cinco plantas uniformes. No segundo experimento, as plantas foram avaliadas em seis fases de crescimento: 21, 31, 41, 51, 61 e 71 dias após a semeadura. De posse dos dados de massa da matéria seca total da planta e da área foliar foi possível calcular os índices fisiológicos taxa de crescimento relativo e taxa assimilatória líquida.  Os dados foram submetidos à análise de variância e as médias comparadas pelo teste de regressão, as quais foram ajustados a equações de regressão polinomial. O GA3 favorece a obtenção de plantas de pinhão manso mais altas, com maior número de folhas, menor diâmetro do caule, menor acúmulo de massa de matéria seca de raízes e folhas, além de antecipar as máximas taxa de crescimento relativo e taxa assimilatória líquida, acelerando o crescimento e desenvolvimento de mudas de pinhão manso

Estimating the global conservation status of more than 15,000 Amazonian tree species

Estimates of extinction risk for Amazonian plant and animal species are rare and not often incorporated into land-use policy and conservation planning. We overlay spatial distribution models with historical and projected deforestation to show that at least 36% and up to 57% of all Amazonian tree species are likely to qualify as globally threatened under International Union for Conservation of Nature (IUCN) Red List criteria. If confirmed, these results would increase the number of threatened plant species on Earth by 22%. We show that the trends observed in Amazonia apply to trees throughout the tropics, and we predict thatmost of the world’s >40,000 tropical tree species now qualify as globally threatened. A gap analysis suggests that existing Amazonian protected areas and indigenous territories will protect viable populations of most threatened species if these areas suffer no further degradation, highlighting the key roles that protected areas, indigenous peoples, and improved governance can play in preventing large-scale extinctions in the tropics in this century

Mapping density, diversity and species-richness of the Amazon tree flora

Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by forest type, as predictor, our spatial model, to the best of our knowledge, provides the most accurate map of tree diversity in Amazonia to date, explaining approximately 70% of the tree diversity and species-richness. Large soil-forest combinations determine a significant percentage of the variation in tree species-richness and tree alpha-diversity in Amazonian forest-plots. We suggest that the size and fragmentation of these systems drive their large-scale diversity patterns and hence local diversity. A model not using location but cumulative water deficit, tree density, and temperature seasonality explains 47% of the tree species-richness in the terra-firme forest in Amazonia. Over large areas across Amazonia, residuals of this relationship are small and poorly spatially structured, suggesting that much of the residual variation may be local. The Guyana Shield area has consistently negative residuals, showing that this area has lower tree species-richness than expected by our models. We provide extensive plot meta-data, including tree density, tree alpha-diversity and tree species-richness results and gridded maps at 0.1-degree resolution

Geographic patterns of tree dispersal modes in Amazonia and their ecological correlates

Aim: To investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser-availability hypothesis) and/or the availability of resources for constructing zoochorous fruits (resource-availability hypothesis). Time period: Tree-inventory plots established between 1934 and 2019. Major taxa studied: Trees with a diameter at breast height (DBH) ≥ 9.55 cm. Location: Amazonia, here defined as the lowland rain forests of the Amazon River basin and the Guiana Shield. Methods: We assigned dispersal modes to a total of 5433 species and morphospecies within 1877 tree-inventory plots across terra-firme, seasonally flooded, and permanently flooded forests. We investigated geographic patterns in the proportional abundance of dispersal modes. We performed an abundance-weighted mean pairwise distance (MPD) test and fit generalized linear models (GLMs) to explain the geographic distribution of dispersal modes. Results: Anemochory was significantly, positively associated with mean annual wind speed, and hydrochory was significantly higher in flooded forests. Dispersal modes did not consistently show significant associations with the availability of resources for constructing zoochorous fruits. A lower dissimilarity in dispersal modes, resulting from a higher dominance of endozoochory, occurred in terra-firme forests (excluding podzols) compared to flooded forests. Main conclusions: The disperser-availability hypothesis was well supported for abiotic dispersal modes (anemochory and hydrochory). The availability of resources for constructing zoochorous fruits seems an unlikely explanation for the distribution of dispersal modes in Amazonia. The association between frugivores and the proportional abundance of zoochory requires further research, as tree recruitment not only depends on dispersal vectors but also on conditions that favour or limit seedling recruitment across forest types

Geography and ecology shape the phylogenetic composition of Amazonian tree communities

AimAmazonia hosts more tree species from numerous evolutionary lineages, both young and ancient, than any other biogeographic region. Previous studies have shown that tree lineages colonized multiple edaphic environments and dispersed widely across Amazonia, leading to a hypothesis, which we test, that lineages should not be strongly associated with either geographic regions or edaphic forest types.LocationAmazonia.TaxonAngiosperms (Magnoliids; Monocots; Eudicots).MethodsData for the abundance of 5082 tree species in 1989 plots were combined with a mega-phylogeny. We applied evolutionary ordination to assess how phylogenetic composition varies across Amazonia. We used variation partitioning and Moran's eigenvector maps (MEM) to test and quantify the separate and joint contributions of spatial and environmental variables to explain the phylogenetic composition of plots. We tested the indicator value of lineages for geographic regions and edaphic forest types and mapped associations onto the phylogeny.ResultsIn the terra firme and várzea forest types, the phylogenetic composition varies by geographic region, but the igapó and white-sand forest types retain a unique evolutionary signature regardless of region. Overall, we find that soil chemistry, climate and topography explain 24% of the variation in phylogenetic composition, with 79% of that variation being spatially structured (R2 = 19% overall for combined spatial/environmental effects). The phylogenetic composition also shows substantial spatial patterns not related to the environmental variables we quantified (R2 = 28%). A greater number of lineages were significant indicators of geographic regions than forest types.Main ConclusionNumerous tree lineages, including some ancient ones (>66 Ma), show strong associations with geographic regions and edaphic forest types of Amazonia. This shows that specialization in specific edaphic environments has played a long-standing role in the evolutionary assembly of Amazonian forests. Furthermore, many lineages, even those that have dispersed across Amazonia, dominate within a specific region, likely because of phylogenetically conserved niches for environmental conditions that are prevalent within regions

Geography and ecology shape the phylogenetic composition of Amazonian tree communities

Aim: Amazonia hosts more tree species from numerous evolutionary lineages, both young and ancient, than any other biogeographic region. Previous studies have shown that tree lineages colonized multiple edaphic environments and dispersed widely across Amazonia, leading to a hypothesis, which we test, that lineages should not be strongly associated with either geographic regions or edaphic forest types. Location: Amazonia. Taxon: Angiosperms (Magnoliids; Monocots; Eudicots). Methods: Data for the abundance of 5082 tree species in 1989 plots were combined with a mega-phylogeny. We applied evolutionary ordination to assess how phylogenetic composition varies across Amazonia. We used variation partitioning and Moran\u27s eigenvector maps (MEM) to test and quantify the separate and joint contributions of spatial and environmental variables to explain the phylogenetic composition of plots. We tested the indicator value of lineages for geographic regions and edaphic forest types and mapped associations onto the phylogeny. Results: In the terra firme and várzea forest types, the phylogenetic composition varies by geographic region, but the igapó and white-sand forest types retain a unique evolutionary signature regardless of region. Overall, we find that soil chemistry, climate and topography explain 24% of the variation in phylogenetic composition, with 79% of that variation being spatially structured (R$^{2}$ = 19% overall for combined spatial/environmental effects). The phylogenetic composition also shows substantial spatial patterns not related to the environmental variables we quantified (R$^{2}$ = 28%). A greater number of lineages were significant indicators of geographic regions than forest types. Main Conclusion: Numerous tree lineages, including some ancient ones (>66 Ma), show strong associations with geographic regions and edaphic forest types of Amazonia. This shows that specialization in specific edaphic environments has played a long-standing role in the evolutionary assembly of Amazonian forests. Furthermore, many lineages, even those that have dispersed across Amazonia, dominate within a specific region, likely because of phylogenetically conserved niches for environmental conditions that are prevalent within regions