RESUMO As cucurbitáceas possuem grande importância econômica, nutricional e social no Semiárido brasileiro. Nesta região, diversos fatores podem acarretar em redução na produtividade dessas culturas, destacando-se as doenças fúngicas e viróticas, tornando-se necessário o conhecimento das mesmas para um adequado manejo. Assim, o objetivo desse trabalho foi identificar as principais doenças de cucurbitáceas produzidas em alguns municípios localizados no Sertão Pernambucano. Para tanto, foram coletadas amostras de plantas com sintomas em cultivos nos municípios de Salgueiro, Serra Talhada, Floresta, Petrolândia, Ibimirim, Custódia e Inajá. Também foi aplicado um questionário visando obter informações do perfil produtivo dos produtores. Identificou-se sete patógenos fúngicos infectando cucurbitáceas, Pseudoperonospora cubensis, Colletotrichum sp., Podosphaera xanthii, Rhizoctonia solani, Didymella bryoniae, Fusarium sp. e Alternaria sp., e três vírus, Papaya ringspot virus type watermelon (PRSV-W), Watermelon mosaic virus (WMV), Zucchini yellow mosaic virus (ZYMV). Verificou-se que nos pequenos cultivos, a busca por informações para cultura implantada ainda é limitada, sendo esses cultivos, em sua maioria, provenientes de sementes crioulas em contraste com médios e grandes produtores que utilizam cultivares melhoradas. A cultura do melão e da melancia são as mais exploradas comercialmente e as abóboras utilizadas na agricultura de subsistência. Quanto a problemas fitossanitários, a maior parte dos entrevistados relatou conhecer as principais doenças que ocorrem na cultura e realizam controle com base na experiência pessoal e/ou através do auxílio da assistência técnica fornecida por lojas agropecuárias. Em poucos casos, em propriedades de grande porte, havia um engenheiro agrônomo para auxiliar nesse tipo de controle. | ABSTRACT Cucurbits have great economic, nutritional and social importance in the Brazilian semiarid region. In this region, many factors can result in reduced productivity of these crops, especially fungal and viral diseases. Therefore, knowledge of cucurbits is crucial for proper disease management. The objective of this work was to identify the major diseases of cucurbits grown in some municipalities in the Hinterland of the state of Pernambuco. Thus, plant samples were collected with symptoms in crops in the municipalities of Salgueiro, Serra Talhada, Floresta, Petrolândia, Ibimirim, Custódia and Inajá. A questionnaire was also applied to gather information about the production profile of producers. Seven fungal pathogens infecting cucurbits were identified: Pseudoperonospora cubensis, Colletotrichum sp., Podosphaera xanthii, Rhizoctonia solani, Didymella bryoniae, Fusarium sp. e Alternaria sp., and three viruses as well: Papaya ringspot virus - watermelon strain (PRSV-W), Watermelon mosaic virus (WMV), Zucchini yellow mosaic virus (ZYMV). It was found that in small crops, there is limited search for technical information om cropping, and these crops originate mostly from native seeds, in contrast to medium and large producers, who use improved cultivars. The melon and watermelon crops are the most commercially exploited, while pumpkins are used in subsistence agriculture. As for plant health problems, most respondents reported knowing the main diseases that occur in crops and perform disease control based on personal experience and / or through the help of the technical assistance provided by agricultural stores. In a few cases, in large farms, there was an agronomist to assist in this type of control.

ABSTRACT Studies have shown that some plant species exhibit satisfactory production levels when grown under high salinity levels, whereas others exhibit decreased production due to sodium sensitivity even at low sodium concentrations. The castor bean is moderately sensitive to salinity. The aim of the present study was to evaluate the early growth of three castor bean varieties (BRS Energia, MPA 34 and MPB 01) grown in nutrient solution with increasing sodium concentrations (control, 25, 50, 75 and 100 mmol L-1). A completely randomized split-plot experimental design was used, with a 5x3 factorial scheme and three replicates per treatment. Salinity resulted in decreased dry weight of all castor bean varieties grown for 31 days under hydroponic conditions. The dry weight accumulation was less affected at the root than at the shoot level. Nevertheless, the shoot dry weight decreased with the increasing salinity. MPA 34 exhibited higher early growth than the remaining tested varieties. Salinity affected the early development of the tested castor bean varieties, and this effect was more pronounced at the shoot than at the root. Variety MPA 34 is promising for cultivation under moderate salinity levels. | RESUMO Pesquisas demonstram produções satisfatórias de espécies quando cultivadas em altos níveis de salinidade, enquanto outras reduzem a sua produção por apresentarem sensibilidade ao sódio, mesmo em baixas concentrações. A mamoneira é moderadamente sensível à salinidade e, neste sentido, este trabalho teve por objetivo avaliar o crescimento inicial de três cultivares de mamoneira (BRS Energia, MPA34 e MPB 01), cultivadas em solução nutritiva, com concentrações crescentes de sódio (controle; 25; 50; 75 e 100 mmol L -1). O delineamento experimental foi inteiramente casualizado, em fatorial 5x3 e parcela subdividida, com três repetições. A salinidade reduziu a matéria seca de todas as variedades de mamoneira cultivadas por 31 dias em sistema hidropônico. Entretanto, observou-se que o sistema radicular foi menos afetado quanto ao acúmulo de matéria seca, quando comparado ao acúmulo da parte aérea. Ainda assim, a matéria seca da parte aérea reduziu gradativamente a partir do aumento da salinidade. A variedade MPA 34 apresentou maior crescimento inicial, quando comparada as demais variedades. A salinidade afetou o desenvolvimento inicial das variedades de mamoneira, sendo a parte aérea mais afetada que o sistema radicular. O cultivo da variedade MPA 34 demonstrou-se promissor sob condições de moderados níveis de salinidade.

RESUMO O objetivo deste trabalho foi determinar o tamanho de amostra necessário para avaliar a severidade da brusone da folha no arroz irrigado em experimentos com diferentes tratamentos fungicidas. Foram utilizados dados de severidade da brusone e área abaixo da curva de progresso da doença de três experimentos utilizando o controle químico realizados no Rio Grande do Sul. Foi realizada a análise de variância, para verificar se a severidade da doença foi diferenciada entre os tratamentos. Também foi verificado se a dispersão da doença foi diferenciada entre os tratamentos e as avaliações, através da razão variância/média e do índice de Morisita. A dispersão da doença entre os tratamentos e ao longo das avaliações é importante para a escolha da fórmula utilizada no cálculo do tamanho da amostra. A dispersão da doença não foi a mesma ao longo dos experimentos, variando entre tratamentos e avaliações. Diante deste comportamento, optou-se por utilizar uma fórmula de cálculo que não estivesse associado a distribuições que indicassem a distribuição espacial da doença no campo (binomial negativa ou Poisson). O tamanho de amostra para a estimação da severidade média da brusone do arroz variou entre os tratamentos e as avaliações. Para avaliar a área abaixo da curva de progresso da doença é necessário avaliar menos folhas. Recomenda-se a avaliação de 293 folhas para estimar a severidade, e 63 para estimar a AUDPC, com 20% de erro. | ABSTRACT The aim of this study was to determine the sample size needed to assess the severity of leaf blast in rice in experiments with different fungicide treatments. The severity and the area under the disease progress curve data of three chemical disease control treatments carried out in Rio Grande do Sul, were used in the study. Analysis of variance was performed to verify whether the severity of the disease differed between treatments. The spread of disease was was also found to be different between treatments and assessments, using the variance/mean ratio and Morisita index. The spatial distribution of the disease among the treatments and during the evaluations is important for the choice of the equation used to calculate the sample size. The spatial distribution of the disease was not the same across the experiments, and it varied between treatments and evaluations. Thus, we decided to use a formula that was not associated with distributions to indicate the spatial distribution (negative binomial or Poisson) of the disease in the field. The sample size to estimate the average of rice leaf blast severity varied between treatments and evaluations. The area under the disease progress curve is necessary to be determined to reduce the number of samples needed. Thus, it is recommended to assess 293 sheets to estimate severity, and 63 to estimate AUDPC at 20% error.

RESUMO Objetivou-se com este trabalho avaliar a eficiência de recuperação de nitrogênio (N), fósforo (P) e potássio (K) pela cultura da cenoura. Foram implantados dois experimentos em área de cultivo localizada em Rio Paranaíba - MG. A cultivar "Juliana" foi semeada no período de verão e a cultivar "Nayarit" no período do inverno. Os tratamentos consistiram de seis combinações de fertilizações N-P2O5-K2O (kg ha-1): sem N (0-500-450), sem P (100-0-450), sem K (100-500-0), padrão (100-500-450), maior que o padrão (100-700-600) e menor que a padrão (100-300-300). A colheita foi realizada quando a maior parte das raízes apresentavam-se dentro do padrão comercial mais aceito pelos consumidores. Quantificaram-se as matérias fresca e seca das raízes e das folhas e com base na matéria fresca de raízes calculou-se a produtividade. Determinaram-se os teores de N, P e K em folhas e raízes por ocasião da colheita e com bases nesses teores e na matéria seca de raízes e de folhas determinaram-se a absorção e a exportação de nutrientes. As fertilizações testadas influenciaram a produtividade comercial de ambas as cultivares. A omissão da fertilização com N, com P ou com K reduziu a produtividade da cultivar "Juliana". Para a cultivar "Nayarit" apenas a omissão de P reduziu a produtividade. Para essa cultivar o incremento de P e K aumentou a produtividade. A cultivar "Nayarit", mais produtiva que "Juliana", absorveu maiores quantidades de N, P e K. As eficiências de recuperação desses nutrientes por ambas cultivares de cenoura foram baixas. | ABSTRACT The objective of this work was to evaluate the carrot crop recovery efficiency of nitrogen, phosphorus and potassium from fertilizers. Two experiments were conducted in an experimental area in Rio Paranaiba - MG. The cultivar ("Juliana‟) was sown during the summer period and the cultivar "Nayarit‟ during the winter period. In both experiments, the treatments consisted of six fertilization combinations of N, P2O, K2O (kg ha-1): fertilization without N (0-500-450), without P (100-0-450), without K (100-500-0), standard (100-500-450), higher than standard (100-700-600) and lower than standard (100-300-300). The harvest was carried out when most of the roots presented commercial standard well accepted by the consumers. The fresh and dry matter of roots and leaves were quantified, and the yield was calculated based on the fresh matter. The analysis of N, P and K contents in leaves and roots were carried out by harvest time, and the nutrients absorption and exportation were determined based on these contents and on the dry matter of roots and leaves. N, P and K omissions reduced the yield of the cultivar "Juliana‟. For the cultivar "Nayarit‟, only P omission reduced and P and K fertilizations increased the yield. The cultivar "Nayarity‟, which is more productive than "Juliana", absorbed more quantities of N, P and K. Carrot recovery efficiency of nitrogen, phosphorus and potassium is low.

ABSTRACT Weed control is essential to reduce or eliminate the interference of weeds on crops. Chemical control with the application of herbicides consists of the most used method, with this aim in grain producing areas. Information about the selectivity of herbicides to C. spectabilis (showy crotalaria) are scarce, which are critical for the management of this species as a crop. One field experiment was performed to evaluate the selectivity of herbicides applied in post-emergence of showy crotalaria. The herbicides bentazon (720 and 576 g ha-1), imazethapyr (106 and 79.5 g ha-1), pyrithiobac-sodium (84 g ha-1), flumiclorac (60 g ha-1), flumiclorac in sequential application (30 / 30 g ha-1), imazethapyr + bentazon (106 + 480 g ha-1), and clethodim + quizalofop (96 + 100 g ha-1) were applied in plants with four true leaves, also using a control without herbicide application. Pyrithiobac-sodium and flumiclorac isolated and the tankmix of imazethapyr + bentazon provided greater injuries to showy crotalaria, also affecting the final plant height. Pyrithiobac-sodium (84 g ha-1) was not selective to showy crotalaria. The herbicides imazethapyr (79.5 g ha-1), flumiclorac (sequential application), and bentazon (576 g ha-1), despite the association between clethodim + quizalofop, can be used for weed management in showy crotalaria crop. | RESUMO O manejo de plantas daninhas é prática fundamental para reduzir ou eliminar a interferência da comunidade infestante sobre a espécie cultivada. O método de controle químico, por meio da aplicação de herbicidas, consiste no mais utilizado com esta finalidade em áreas de produção de larga escala. Informações de seletividade de herbicidas para C. spectabilis (crotalária) são escassas, sendo estas de suma importância para o manejo desta espécie como cultura. Um experimento de campo foi realizado para avaliar a seletividade de herbicidas aplicados em pós-emergência na crotalária. Os herbicidas bentazon (720 e 576 g ha-1), imazethapyr (106 e 79,5 g ha-1), pyrithiobac-sodium (84 g ha-1), flumiclorac (60 g ha-1), flumiclorac em aplicação sequencial (30 / 30 g ha-1), imazethapyr + bentazon (106 + 480 g ha-1), clethodim + quizalofop (96 + 100 g ha-1) foram aplicados sob plantas com quatro folhas verdadeiras, constando também entre os tratamentos testemunha sem aplicação de herbicidas. Pyrithiobac-sodium e flumiclorac isolados e a mistura entre imazethapyr + bentazon proporcionaram maiores injúrias a crotalária, afetando também a altura final das plantas. O pyrithiobac -sodium (84 g ha-1) não foi seletivo para a crotalária. Os herbicidas imazethapyr (79,5 g ha-1), flumiclorac (em aplicação sequencial), bentazon (576 g ha-1), além da associação entre clethodim + quizalofop podem ser utilizados para o manejo de plantas daninhas na cultura da crotalária.

RESUMO A palma tem grande importância para a pecuária da região semiárida do Brasil. Essa planta vem apresentando elevada produtividade de forragem, influenciada por vários fatores de manejo. Objetivou-se avaliar o efeito de doses de adubação orgânica (20, 40 e 80 t/ha de esterco bovino/ha/dois anos) e densidades de plantio (20, 40, 80 e 160 mil plantas/ha) sobre a produtividade da palma forrageira Clone IPA-20 (Opuntia ficus indica Mill). O experimento foi conduzido na Estação Experimental de Caruaru, pertencente ao Instituto Agronômico de Pernambuco - IPA. O delineamento experimental foi em blocos casualizados, com arranjo de parcelas subdivididas. Verificou-se maior produtividade de parte aérea com o aumento da densidade populacional e aplicação de 80 t de esterco/ha/dois anos, com valores de 61; 90; 117 e 139 t MS/ha/dois anos, nas densidades de 20, 40, 80 e 160.000 plantas/ha. A produtividade do cladódio-planta e peso seco da raiz foram influenciados pela densidade de plantio, apresentando respostas exponenciais, tendendo a apresentar maior peso do cladódio planta e raízes por área com a elevação da densidade de plantio. A eficiência da adubação orgânica diminuiu com a elevação das doses de esterco. Recomenda-se para plantios com 160.000 plantas/ha aplicação de, no mínimo, 40 t de esterco bovino/ha/dois anos para incremento na produtividade da palma. | ABSTRACT Cactus is crucial for the livestock of semi-arid regions in Brazil. This plant has shown the high productivity of forage, which is influenced by several management factors. This study aimed to evaluate the effect of organic fertilization doses (20, 40 and 80 t/ ha of bovine manure/ha/two years) and planting densities (20, 40, 80 and 160 thousand plants/ha) on the productivity of cactus pear Clone IPA-20 (Opuntia ficus-indica Mill). At the Experimental Station of Caruaru at the Agronomic Institute of Pernambuco, IPA has conducted the experiment. The experimental design was randomized blocks, with split plot arrangements. Higher shoot productivity was observed with increased population density and the application of manure at 80 t ha-1 two years-1 with values of 61, 90, 117 and 139 t DM ha-1 two years-1 at densities of 20, 40, 80 and 160,000 plants ha-1. The planting density influenced the productivity of cladode-plant and root dry weight, showing exponential responses, with higher cladode-plant and roots weight by area observed with increased plant density. The efficiency of organic fertilization decreased with the increase in manure doses. For increase cactus productivity, 40 t of bovine manure ha-1 two years-1 for plantations with 160,000 plants/ha is recommended.

Seven biochemical descriptors were used to estimate the genotypic variability of peanut in response to moderate water stress. Six genotypes, constituted by four lines and two cultivars, were grown in pots, each containing two plants. At 15 days after emergence (DAE), the treatment differentiation was carried out: Control-plants maintained with daily watering, and Stress-plants submitted to water stress by complete suspension of watering for 15 days. The experimental design was completely randomized with factorial scheme 6 x 2 (genotype x water treatments), with five replications. The biochemical variables evaluated were: catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), free proline, total carbohydrates, soluble proteins, and amino acids. Results obtained by biochemical analysis and estimation of genotypic variability indicated that proline is the most appropriate descriptor for selecting genotypes tolerant to water stress, which led to identification of L81V and L108V as promising lines for drought tolerance breeding program.

The northern region of Piauí state is an important center of irrigated organic fruit farming, wherein sandy soils with low organic matter content are predominant, besides climate with high temperatures, long periods of water deficit and constant wind. Given this situation, it becomes necessary to investigate alternative management options able to meet the challenges of agricultural productivity. In this context, green manuring becomes an important practice, mainly when using fast - growing species and with great potential for biomass production. Thus, a study was carried out at Embrapa Meio - Norte to measure Crotalaria juncea biomass yield after thinning and at various sowing densities. The evaluated parameters were plant height, stem diameter, number of branches per plant, fresh and dry weight of shoots and roots. The results showed that sowing density had no influence on plant height; however, unthinned plants reached greater heights, which might have been due to reduced competition for light. Thinning had no effect on diameters of plant stem base; on the other hand, lower planting densities promoted larger diameters also due to less competition. Likewise, the number of branches per plant was not affected by thinning, being greater at lower planting densities on account of less competition. Thinned plants achieved higher averages of fresh shoot weight. Nevertheless, shoot dry biomass was greater at higher planting densities. Furthermore, both fresh and dry weight of roots were not influenced by any of the adopted treatments.

The aim of this study was to evaluate the performance of progenies from Citrullus lanatus var. lanatus (cultivated watermelons) when crossed with progenies from C. lanatus var. citroides (fodder watermelon with a historic of resistance to the nematode Meloidogyne enterolobii). The parents and their F1s were evaluated for resistance to this nematode. In the initial stages of eleven treatments, watermelon seedlings plantlets were transplanted to plastic bags of six kilograms once the first leaves developed. Ten inoculated plants with 5,200 eggs in the soil near the stem of the plant and four non-inoculated ones were used in each treatment, in a complete block design. Sixty-two days after sowing, the following characteristics were evaluated: the length of the aerial part of the plant (LAP, in m), fresh mass of the aerial part (FMAP, in g), root fresh mass (RFM, in g), egg number (EN) and reproduction factor (RF). A comparison between the averages of inoculated and non-inoculated plants was performed using Scott-Knott test at 5% and the diallelic analysis was performed using the GENES program. The morphological characteristics did not allow for the identification of the parent plants or the F1s with respect to nematode resistance, but the variables EN and RF were useful for such identification. The analyses of the general and specific combining abilities indicate highly significant effects with respect to this resistance, showing additive gene effects as well as dominance and epistatic gene effects, allowing for identification of parents and F1s that can be used in watermelon breeding programs to improve resistance to the M. enterolobii.

The aim of the study was to evaluate the morphological and productive characteristics of five genotypes of Desmanthus spp. submitted to two cutting intensities (20 and 40 cm), in the semi-arid region of Pernambuco. Of the genotypes studied, three were derived from ecotypes collected in municipalities of Pernambuco (7G, 31D and 50J) and two were from the state of Sergipe, coming from Australia (10AU and 13AU). Four cuttings were made with a frequency of 60 days. The treatments were randomized in blocks, with split plots and three replications. The variables studied were plant height, stem diameter, canopy diameter, the number of leaves per branch, LAI, leaf yield, stem yield, pod yield and forage yield, and leaf stem-1 ratio and pod stem-1 ratio. Genotypes 7G and 31D had higher forage yield and a larger number of leaves per branch. Forage yield was higher in the intensity of 20 cm. The cuttings reduced the total yield, stem yield, pods yield and forage yield, of the different genotypes studied. For leaf stem-1 ratio, the genotype 13AU was higher than genotypes 7G and 50J in the cutting intensity of 40 cm. Genotype 10AU had the highest pod stem-1 ratios in the three cuttings. The differences shown between genotypes of Desmanthus spp., especially 7G and 31D, in the intensity of 20 cm, indicate the possibility of selecting promising materials for cultivation in the semi-arid region of Pernambuco, with desirable morphological and productive characteristics to the forage plants.