Comparative agroenvironmental risks of pesticides in different cropping systems: application of the I-Phy indicator

The green revolution laid the foundations of modern agriculture, by using science and technology to produce more from same resources. The pesticides contributed to agricultural output in the last decades; however, their use has resulted in environmental pollution, health problems, soil and water contamination and negative impact on biota. The impacts of agricultural activities to the environment depended on the practices adopted during the production process. Measurement tools to assess the impacts of those practices are necessary to improve agricultural systems and must be evaluated in different ecosystems. Different soils, climates and crops impose many phytosanitary arrangements. This complex network and the fact that most of the indicators and measurement tools are developed for temperate climates makes it difficult to quantify the environmental impacts under subtropical regions. The I-Phy index is a predictive indicator that assesses the risks of pesticide usage in agriculture and identifies as to which practices generate the main environmental impacts of pesticides. The objective of this study was to test the suitability of the I-Phy index for subtropical conditions and, if suitable, compare the pesticide risk between two regions. Five crops were assessed under three different cropping systems: no-tillage, minimal tillage and conventional tillage. The I-Phy index was sensitive in both regions and capable of identifying that no-tillage generally presented risks of environmental pollution slightly lower than the other tillage systems. The results of I-Phy index showed that high environmental vulnerability of the fields and the numerous applications of active ingredients with high risks resulted in high risks of general contamination. The application of I-Phy on these two case studies showed the indicator can be useful as a support tool to farmers, research and extension institutions pursuing management practices with lower impact on the environment

Importance and correlations of characters for cowpea diversity in traditional varieties.

Cowpea is a legume with ample plasticity, versatility and nutritional potential. It is a species widely used as a source of income and subsistence for small farmers in several Brazilian states, among them Acre. Due to the different varieties found in the State, it is the target of studies aiming at its genetic improvement. Thus, as one of the first stages of its improvement, it was aimed to determine the importance and correlations of characters for diversity and selection in traditional varieties of cowpea. The experiment was carried in completely randomized design, with plots consisting of four vase with capacity to 15.7 L, with one plant each and two replicates. The characteristics evaluated were: days for emergence, flowering (days), plant vigor (note), number of main stem nodes, apical leaflet length (mm), apical leaflet width (mm), length of pod (cm) and width of the pod (cm). The correlation coefficients (phenotypic, genotypic and environmental) were obtained, and the principal components analysis and the importance of the characters by the method proposed by Singh were carried out. The Singh method and principal components analysis were partially concordant in the distinction of the evaluated characters. The days for emergence, width of the apical leaflet, flowering and length of the apical leaflet were the main determinants for quantification of the genotypes and those that contributed the most to the variability of cowpea. The least discriminant characteristic by principal component analysis and recommended for discarding was plant vigor. O feijão-caupi é uma leguminosa com ampla plasticidade, versatilidade e potencial nutritivo. Trata-se de uma espécie bastante utilizada como fonte de renda e subsistência para pequenos agricultores em vários estados brasileiros, entre estes, o do Acre. Devido as diferentes variedades encontradas no Estado, é alvo de estudos visando o seu melhoramento genético. Assim, como uma das primeiras etapas do seu melhoramento, objetivou-se determinar a importância e correlações de caracteres para a diversidade e seleção em variedades tradicionais de feijão-caupi. O experimento foi realizado em delineamento inteiramente casualizado, com parcelas constituídas por quatro vasos de volume igual a 15,7 L, com uma planta cada e duas repetições. As características avaliadas foram: dias para emergência, florescimento (dias), vigor da planta (nota), número de nós do caule principal, comprimento do folíolo apical (mm), largura do folíolo apical (mm), comprimento da vagem (cm) e largura da vagem (cm). Foram obtidos os coeficientes de correlações (fenotípicas, genotípicas e ambientais), realizada a análise de componentes principais e a importância dos caracteres pelo método proposto por Singh. O método de Singh e componentes principais foram parcialmente concordantes na distinção dos caracteres avaliados. Os caracteres dias para a emergência, largura do folíolo apical, florescimento e comprimento do folíolo apical foram os principais determinantes para quantificação dos genótipos, e os que mais contribuíram significativamente para a variabilidade de feijão-caupi. A característica menos discriminante pela análise de componentes principais e recomendada para descarte foi o vigor da planta

Produção de sementes de genótipos de Brachiaria humidicola em Rio Branco, Acre.

O potencial de produção de sementes de híbridos de Brachiara humidicola é ainda desconhecido e poucas informações sobre a produção de sementes de Brachiaria na Amazônia são encontradas na literatura. O objetivo deste estudo foi estimar a produtividade de sementes puras em híbridos e cultivares de B. humidicola em Rio Branco, AC. Foram avaliados 4 híbridos apomíticos, além das cultivares Comum e BRS Tupi. O delineamento experimental foi em blocos ao acaso com 4 repetições. Foram avaliadas a produtividade total de sementes, produtividade de sementes puras e porcentagem de sementes vazias. Foram realizadas análises de variância, estimação das correlações genotípicas e agrupamento de médias por Scott-Knott. Ao analisar a produtividade de sementes puras, houve destaque para a cultivar Comum (53,29 kg ha-1), seguida pela BRS Tupi (29,96 kg ha-1). Os híbridos apresentaram média inferior às cultivares para esta característica, sendo a menor produtividade observada para PL193 (2,86 kg ha-1). Conclui-se que os híbridos de B. humidicola possuem baixa produtividade de sementes puras, quando comparados ao seu genitor masculino, a cv. BRS Tupi, e que as cultivares de B. humidicola apresentam potencial de produção de sementes em Rio Branco, AC. Estudos adicionais sobre a qualidade das sementes colhidas são necessários, visando a determinação da produtividade de sementes puras viáveis

Seleção genotípica de variedades de milho via metodologia de modelos mistos.

Uma das técnicas utilizadas que tem evoluído em programas de melhoramento vegetal trata-se da análise via modelos mistos. A seleção de cultivares utilizando esta metodologia permite inferências mais precisas e realista acerca da avaliação genotípica dos genótipos superiores para de seleção. O objetivo deste trabalho foi selecionar genótipos de milho (Zea mays L.) de quatro safras do programa de melhoramento da Embrapa Acre, utilizando a metodologia de modelos mistos - REML/BLUP. Os experimentos foram conduzidos no campo Experimental da Embrapa Acre. O delineamento utilizado foi em látice retangular 5x6, com duas repetições. Utilizaram-se dados de produtividade de grãos de 78 variedades testadas no ensaio Nacional de milho nos anos 2013/2014, 2014/2015, 2015/2016, 2017/2018. Utilizou-se o modelo MHVG para estimar a estabilidade genotípica. Utilizou-se o software Selegem REML/BLUP para as análises estatístico-genéticas. Nos quatro anos verificou-se que as variedades não superaram as médias de produção dos híbridos. O ordenamento dos genótipos coincidiu nos quatro anos de avaliação indicando comportamento amplo das cultivares. A metodologia de modelos mistos foi eficiente na avaliação dos ensaios de valor de cultivo e uso, auxiliando na seleção e descarte de cultivares a cada ano agrícola. Os genótipos BRS 1055 e HTCMS-SP1 são os selecionados. One of the techniques used that has advanced in breeding programs is the analysis using mixed models. The selection of cultivars using this methodology allows for more accurate and realistic inferences about the genotypic evaluation of the superior genotypes for selection. The objective of this work was to select corn genotypes from four harvests of the Embrapa Acre breeding program, using the mixed model methodology - REML / BLUP. The experiments were conducted in the Experimental field of Embrapa Acre. The design used was in a 5x6 rectangular lattice, with two replications. Grain yield data from 78 varieties tested in the years 2013/2014, 2014/2015, 2015/2016, 2017/2018 were used. The MHVG model was used to estimate the genotypic stability. The Selegem REML / BLUP software was used for statistical-genetic analysis. In the four years it was found that the varieties did not exceed the average production of the hybrids. The ordering of the genotypes coincided in the four years of evaluation, indicating broad behavior of the cultivars. The mixed model methodology was efficient in evaluating the cultivation and use value tests, assisting in the selection and disposal of cultivars each agricultural year. The genotypes BRS 1055 and HTCMS-SP1 are selected

Understanding the chronology and occupation dynamics of oversized pit houses in the southern Brazilian highlands

A long held view about the occupation of southern proto-Je pit house villages of the southern Brazilian highlands is that these sites represent cycles of long-term abandonment and reoccupation. However, this assumption is based on an insufficient number of radiocarbon dates for individual pit houses. To address this problem, we conducted a programme of comprehensive AMS radiocarbon dating and Bayesian modelling at the deeply stratified oversized pit Houe 1, Baggio 1 site (Cal. A.D. 1395-1650), Campo Belo do Sul, Santa Catarina, Brazil. The straigraphy of House 1 revealed an unparalleled sequence of twelve well preserved floors evidencing a major change in occupation dynamics including five completely burnt collapsed roofs. The results of the radiocarbon dating allowed us to understand for the first time the occupation dynamics of an oversized pit house in the southern Brazilian highlands. The Bayesian model demonstrates that House 1 was occupied for over two centuries with no evidence of major periods of abandonment, calling into question previous models of long-term abandonment. In addition, the House 1 sequence allowed us to tie transformations in ceramic style and lithic technology to an absolute chronology. Finally, we can provide new evidence that the emergence of oversized domestic structures is a relatively recent phenomenon among the southern proto-Je. As monumental pit houses start to be bulit, small pit houses continue to be inhabited, evidencing emerging disparities in domestic architecture after AD 1000. Our research shows the importance of programmes of intensive dating of individual structures to understand occupation dynamcis and site permanence, and challenges long held assumptions that the southern Brazilian highlands were home to marginal cultures in the context of lowland South America