ABSTRACT. Black spot (Asperisporium caricae) is one of the main foliar fungal diseases of papaya crops. This disease acts directly on leaves and fruits causing leaf area reduction and fruit deterioration. The quantification of diseases is a fundamental part of the disease management and control process; therefore, a scale is required to help quantify black spot disease. The objective of this work was to propose a standardized methodology to quantify black spot severity in papaya leaves. A scale was developed considering the maximum and minimum values of the disease in the field that included eight levels of severity: 0.1, 0.3, 0.6, 1.0, 2.3, 5.0, 10.0, and 20.0%. Without the aid of a scale the disease is often overestimated, with absolute errors of approximately 75%. When the scale was used, 100% of the evaluators showed improved accuracy and precision, and absolute error was reduced to the 10% range. The scale also provided good repeatability and high reproducibility. The use of the scale provided an improvement in the R2 values, with mean values of 93 and 92 in the second and third evaluations, respectively, demonstrating that the scale is useful for different aspects of the pathosystem of A. caricae, such as for determining the efficiency of fungicides, characterization of varietal resistance, construction of the disease progression curve, and estimation of damage.

ABSTRACT The elephant grass (Cenchrus purpureus (Schumach.) Morrone) is one of the species with great prominence for energy production because of its favorable traits, such as high yield and short cycle, combined with several biomass quality characteristics. Therefore, this study intended to evaluate the morpho-agronomic traits of eight elephant grass genotypes under different cutting ages. A randomized block design with three replicates was applied to the experiment, and plots were composed of a 12 m long line divided into six subplots for each of the bimonthly cuts. Eight genotypes were evaluated in the plots, and the cutting ages (2, 4, 6, 8, 10, and 12-mo) were analyzed in the subplots. The following traits were assessed: DM yield, (DMY) percentage of DM, and average plant height (HEI). All genetic-statistical analyses were conducted using the Genes Program. The evaluated genotypes showed nonsignificant differences, indicating that, for the evaluated traits, these genotypes are genetically similar. Most genotypes presented linear effect of 2nd degree in the two assessment cuts, pointing they did not reach their maximum capacity of DMY in the time interval of the evaluated cuts. The maximum %DM achieved for the most genotypes occurred at about 9-mo age, while genotypes Vruckwona and BAG-86 at about 10-mo age. The maximum points for HEI trait were between 8 and 10-mo age. Increasing the cutting interval leads to increases in DM yield, with the 10-mo cutting age being the most efficient, resulting in higher yields.

O objetivo deste trabalho foi selecionar genótipos de capim-elefante com base na produção de matéria seca, utilizando a metodologia de modelos mistos (REML/BLUP). O experimento foi conduzido na Pesagro, RJ, Brasil. Foram obtidos 25 híbridos em esquema de dialelo parcial, 10 genitores e a cultivar Capim Cana D’África. Foram avaliadas as características largura da folha (LL), comprimento da folha (CF), diâmetro do colmo (DC) e número de perfilhos (NP) em seis semanas a partir da 5ª semana após o plantio. Na última semana foram avaliadas a porcentagem (%MS) e produção de matéria seca (PMS). Os componentes de variância e coeficientes de repetibilidade foram estimados pelo método da máxima verossimilhança restrita (REML) e a predição de valores genotípicos pela melhor predição linear não viciada (BLUP). Para análise das variáveis foi utilizado o software Selegen-REML/BLUP. Observou-se grande influência da variância ambiental na variância fenotípica para as características LL, CF, DC e NP. Foram obtidos valores de repetibilidade de média magnitude para a LL, CF e DC. Os genótipos que apresentaram potencial para maior produção de biomassa foram H16, H17, G, P1, H4, P4, H25 e H22.

The objective of this work was to select elephant grass genotypes based on dry matter production, using the mixed model methodology (REML/BLUP). The experiment was conducted at Pesagro, RJ, Brazil. Twenty five hybrids were obtained in partial diallel scheme, 10 parents and the cultivar Capim Cana D'Africa. We evaluated the characteristics sheet width (LL), leaf length (CF), stem diameter (DC) and number of tillers (NP) in six weeks from the fifth week after planting. The percentage (% MS) and dry matter production (PMS) was evaluated in the last week. The components of variance and repeatability coefficients were estimated by restricted maximum likelihood (REML) and the prediction of phenotypic and genotypic values for the best linear unbiased prediction (BLUP). The Selegen-REML/BLUP software was used for analysis of the variables. There was great influence of environmental variance in phenotypic variance for traits, CF, DC and NP. Average magnitude of repeatability values were obtained for the LL, CF and DC. The genotypes that presented potential for greater production of biomass were H16, H17, G, P1, H4, P4, H25 and H22.

Conduziu-se uma experiência não irrigada com um delineamento de blocos casualizados, num esquema de parcelas sub-sub-divididas sob cinco doses de Azoto, quatro de Fósforo e três repetições para cada tratamento, em Alegre (ES), para estimar níveis de adubação das cultivares. Utilizou-se a função de produção para obter o máximo físico e óptimo económico. As cultivares constituíram as parcelas, o fósforo as sub-parcelas e o azoto as sub-sub-parcelas. Observou-se a ausência de significância para o fósforo e para as suas interações. E significância para os outros fatores. Realizou-se uma análise envolvendo os fatores Genótipo e Azoto por meio do modelo estatístico de parcela sub-sub-dividida. A estimativa da produtividade (t ha-1) obteve um ajuste estatístico significativo (p < 0,05) ao modelo de segunda ordem. Os resultados indicaram respostas positivas na produtividade física em função da adubação azotada. A receita líquida operacional foi positiva para cvs. Guaçu/IZ.2, Cameroon-Piracicaba e Cana D’África, com os respectivos valores R$ 326,80; R$ 219,54 e R$ 281,49 sem utilização do azoto, devido ao baixo preço da tonelada do capim (R$ 41,82) e elevado preço da tonelada do azoto (R$ 2.670,00). Conclui-se que há possibilidade de manipular a produção de capim-elefante para fins energéticos sem a utilização da adubação azotada.

An experiment was conducted without irrigation in randomized block design, in a split-split plot design under five levels of nitrogenand four levels of phosphorus with three replicates for each treatment, in Alegre (ES), to estimate fertilization levels of cultivars. A function of production was used to obtain the levels of physical maximun and optimal economics. The cultivars were integrated in the plots, phosphorus in the subplots and nitrogen were integrated in the subsubplots. There was no significance for phosphorus and their interactions. The other factors showed significance. Therefore, we performed another analysis involving Genotype and Nitrogen factors through statistical model split split plot in space. The estimated productivity (t ha-1) obtained a significant statistical adjustment (p < 0,05) to the second-order model for the surveyed cultivars. The results indicated positive responses to physical productivity depending on nitrogen fertilization.The net operating revenue was positive for Guaçu/IZ.2, Cameroon-Piracicaba and Cana D’África, whose values were 326.80 R$; 219.54 R$ and 281.49 R$, respectively, without nitrogen fertilization, because of the low grass price (41.82 R$ per ton) and the high nitrogen quote (2,670.00 R$ per ton). Thus, it can be concluded that there is a possibility to manage the production of elephant grass for energy purposes without the use of nitrogen fertilization.

Abstract The elephant grass (Pennisetum purpureum) is a tropical perennial forage plant with high biomass production that adapts to various soil and climatic conditions in Brazil. Stability is defined as the consistency in performance of genotypes in different environments. The aim of the present study was to estimate stability parameters by the Eberhart and Russel method, and to select elephant grass genotypes with forage production stability and high-yield in Campos dos Goytacazes, RJ, Brazil. Five harvests were made for evaluation in two years. The experimental design was arranged as randomized blocks design, with 80 treatments and two replicates. After the individual analysis of variance for dry matter yield, a combined split-plot analysis was performed. Mean values from each harvest as well as overall means of the genotypes in the five harvests were grouped using the Scott-Knott test (p≤0.05). To obtain the estimates of stability over time, the method of Eberhart and Russell was used, considering the genotypes and successive harvests as environments. Genotypes Pasto Panamá, IJ 7136 cv. EMPASC 307, CAC-262, 02 AD IRI, 08 AD IRI, and Gigante de Pinda showed high forage production and phenotypic stability over the five harvests.

Resumen El pasto elefante (Pennisetum purpureum) es una planta forrajera perenne tropical con producción alta de biomasa que se adapta a diferentes condiciones edafoclimáticas en Brasil. La estabilidad se define como la consistencia en el rendimiento de los genotipos en ambientes diferentes. El objetivo del presente estudio fue estimar parámetros de estabilidad por el método de Eberhart y Russell, y seleccionar genotipos de pasto elefante con la estabilidad de la producción de forraje y de rendimiento alto en Campos dos Goytacazes, RJ, Brasil. Cinco cosechas se realizaron en dos años de evaluación. El diseño experimental fue de bloques al azar, con 80 tratamientos y dos repeticiones. Después del análisis individual de la varianza del rendimiento de materia seca, se aplicó análisis de parcelas divididas. Los valores medios de cada cosecha y las medias de rendimento de los genotipos en cinco cosechas se agruparon con la prueba de Scott-Knott (p≤0.05). Para obtener las estimaciones de la estabilidad en el tiempo se usó el método de Eberhart y Russell y los genotipos y cosechas sucesivas se consideraron como ambientes. Los genotipos Pasto Panamá, IJ 7136 cv. EMPASC 307, CAC-262, 02 AD IRI, 08 AD IRI y Gigante de Pinda mostraron producción alta de forraje y estabilidad fenotípica en las cinco cosechas.

Na busca da diminuição do efeito-estufa é necessário utilizar energia renovável através da biomassa do capim-elefante. Objetivou-se avaliar as características morfoagronómicas de cultivares numa experiência não irrigada em área cultivável num delineamentos de blocos casualizados num esquema de parcelas subdivididas com 12 repetições. As cultivares ‘Guaçu/IZ.2’, ‘Cameroon-Piracicaba’ e ‘Cana D’África’, constituíram as parcelas, e nas subparcelas as doses de 500 e 1000 kg ha-1 de N, estas fracionadas em cinco aplicações durante o cultivo no período chuvoso. Retiraram-se amostras da área útil de 2,25 m² nas subparcelas, em três cortes, medidas, pesadas e secas. Submeteram-se os dados à análise de variância conjunta pelo teste F. Utilizou-se teste de Tukey a 5% de probabilidade. Conclui-se que as cultivares, em geral, não diferiram entre si na produção de matéria seca, mesmo sob condições ambientais contrastantes, porém houve decréscimo na matéria seca e na altura, em virtude dos stresses hídricos ocorridos no terceiro corte. Entretanto, Cameroon-Piracicaba apresentou um menor perfilhamento, maior diâmetro do colmo e maior largura da lâmina em relação às demais. A cv. ‘Guaçu/IZ.2’ manifestou tendência a apresentar valores próximos à ‘Cameroon-Piracicaba’; e a cv. ‘Cana D’África’ apresentou esta tendência apenas em relação à largura da lâmina nas doses elevadas de adubação azotada.

In order to reduce the greenhouse effect, we propose the use of renewable energy from the biomass of elephant grass. This study aimed to evaluate the agronomic characteristics of cultivars in non-irrigated cropland experience in a randomized complete block designed in a split plot design with 12 repetitions. ‘Guaçu/IZ.2’, ‘Cameroon- Piracicaba’ and ‘Cana D’África’ cultivars were integrated into the plots and the doses of 500 and 1000 kg ha-1 of N were added into the subplots in fractions with five applications during cultivation in the rainy season. Samples were taken from the useful area of 2.25 m² in the subplots, in three cuts, measured, weighed and dried. Data were subjected to analysis of variance by F-test, and then comparisons were made using the average of the Tukey test at 5% of probability. It was concluded that cultivars, in general, did not differ in terms of dry matter, even under contrasting ambient conditions. However it was detected a decrease in the latter parameter and in height, due to water stress that occurred during the third cut. However, ‘Cameroon-Piracicaba’ showed lower tilling, larger stem diameter and width of the blades relative to the other. The cv. ‘Guaçu/IZ.2’ tended to show values near ‘Cameroon-Piracicaba’, while ‘Cana D’África’ showed this trend only in relation to the width of the blade at higher doses high of nitrogen fertilization.

Neste trabalho caracterizou-se a qualidade dos frutos em diferentes pontos de colheita para armazenamento das cultivares de maracujá: BRS Gigante Amarelo, BRS Ouro Vermelho e BRS Sol do Cerrado. Foram avaliados as características físicas dos frutos (aparência, perda de massa, coloração da casca) e os parâmetros químicos do suco (conteúdo de acidez, pH, ácido ascórbico, sólidos solúveis totais, açúcares solúveis totais e açúcares redutores). Utilizou-se uma Amostragem Simples ao Acaso (ASA), com 0,05 de significância e as médias foram comparadas pelo Teste "t" por Intervalo de Confiança. Os frutos colhidos nos estádios iniciais de amadurecimento apresentaram maior perda de massa e alteração da qualidade do suco. Conclui-se que os frutos das diferentes cultivares colhidos na safra de verão (novembro/dezembro) devem ter pelo menos 55% de casca com coloração amarela para proporcionar menor perda de massa, manter a qualidade do suco e aumentar a sua vida útil.

In this study the fruit quality was characterized at different harvest points for storage of varieties of passion fruits: BRS Gigante Amarelo, BRS Ouro Vermelho and BRS Sol do Cerrado. The physical characteristics of fruits (appearance, mass loss and peel color) and chemical parameters of juice (content of acidity, pH, ascorbic acid, total soluble solids, total soluble sugars and reducing sugars) were characterized. The method of Simple Random Sampling (SRS) was applied, with 0.05 level of significance, and means were compared using the "t" Test for Confidence Intervals. Fruits harvested in the early ripening stages showed a higher mass loss as well as the worst juice quality. It was concluded that fruits of different cultivars harvested in summer seasons must present at least 55% of yellow peel color to render the lower mass loss, the best quality of juice and to extend the storage time.

O objetivo deste trabalho foi avaliar o efeito da concentração de soluções de sacarose, sucralose e açúcar invertido sobre a cinética da desidratação osmótica de pedaços de goiaba. Frações de 1/12 do fruto foram imersas em soluções de sacarose a 0,5 e 0,4 g mL-1; de sacarose a 0,3 g mL-1 + sucralose a 0,2 g L-1 e em xarope de açúcar invertido, a 50 ºC, por 2 h, sob agitação de 60 min. A solução de açúcar invertido promoveu maior perda de água e redução de massa nas amostras de goiaba submetidas à desidratação osmótica. O melhor desempenho foi obtido para o tratamento em solução de sacarose a 0,4 g mL-1; com perda de água e redução de massa semelhantes aos valores obtidos na imersão em solução de sacarose a 0,5 g mL-1 e ganho de sólidos similar ao observado em solução de sacarose a 0,3 g mL-1.

The present work aimed at investigating the effect of sucrose, sucralose and inverted sugar solutions on the kinetics of osmotic dehydration of guava pieces. The fruits were cut in twelfths and immersed in sucrose solutions at 0.5 and 0.4 g mL-1; of sucrose at 0.3 g mL-1 + sucralose at 0.2 g L-1 and in inverted sugar syrup for 2 h at 50 ºC, under agitation of 60 min. The undiluted inverted sugar solution promoted the highest levels of water loss and weight reduction in osmo-dehydrated guava pieces. The best overall performance was achieved by immersing guava pieces in sucrose solutions at 0.4 g mL-1 which led to water loss and mass reduction of similar values attained with sucrose solutions at 0.5 g mL-1; whereas maintaining the same level of solids gain achieved with sucrose solutions at 0.3 g mL-1.