HOSTING CAPACITY OF HORTICULTURAL PLANTS FOR INSECT PESTS IN BRAZIL

Factors such as fertilization, allelochemicals, trichomes, weather, and natural enemies can influence pest populations. Thus, it is necessary to understand the factors that predispose vegetable species to pests and the role of polyculture, crop rotation, and neighboring plants. The objective of this research was to study the hosting capacity for pests of Abelmoschus esculentus (L.), Brassica oleracea L. vars. acephala and capitata, Capsicum annuum L., Cucurbita moschata (Duchesne), Cucurbita maxima Duchesne and Cucumis sativus L., Lycopersicon esculentum Mill., Solanum gilo Raddi and Solanum melongena L., and Phaseolus vulgaris L. The higher density of Bemisia tabaci (Genn.) adults on C. sativus can be due to the higher amount of pentacosane and octacosane in this plant. The occurrence of Brevicoryne brassicae (L.) only in Brassica spp. can be accounted for by the nonacosane of these plants. The low trichome density and greater palmitic acid level can explain the greatest damage by Aphis gossypii Glover in A. esculentum. Empoasca sp. was more frequent in P. vulgaris followed by A. esculentum, which are plants with lower K content. Solanum melongena was attacked more by Hydrangea similis (Walker) and Epitrix sp. perhaps because of higher palmitic acid and 11,14,17-eicosatrienoic methyl ester concentrations in their leaves. Frankliniella sp. exhibited more damage in C. sativus probably owing to higher pentacosane and octacosane in its leaves. Sistena sp. was more frequent in C. maxima and had higher octadecane levels and trichome density. The presence of ∞-humulene and hexacosane can explain the damage by Tuta absoluta (Meyrick) on L. esculentum

Produção do maxixe-do-reino em função do sistema de tutoramento e do espaçamento Yield of achocha as a result of the staking system and spacing

Foram avaliadas as características produtivas do maxixe-do-reino [Cyclanthera pedata L. Schrad.)], em função de sistemas de tutoramento e do espaçamento. O experimento foi conduzido na UFMG em Montes Claros. Empregou-se o delineamento experimental de blocos ao acaso, com quatro repetições e arranjo em faixas 3 x 2, sendo três sistemas de tutoramento (cerca vertical, cerca cruzada com varas e cerca cruzada com fitilho de polietileno) e dois espaçamentos entre plantas (1,0 x 0,5 m e 1,0 x 1,0 m), totalizando 24 parcelas. Cada faixa correspondeu a um sistema de condução. As características produtivas dos frutos em número e em peso foram significativamente maiores nas plantas cultivadas no sistema de cerca vertical, onde cada planta produziu, em média, 56 frutos, equivalendo ao peso de 2,68 kg. Nesse sistema houve melhor fixação dos ramos no tutor e menor incidência de frutos danificados por contato com o solo. No espaçamento 1,0 x 1,0 m houve maior rendimento de frutos por planta em número e em peso, resultante do menor efeito competição entre plantas por água, nutrientes e luz. Já, a produtividade por área foi menor devido ao menor número de plantas por ha.<br>A field experiment was carried out to evaluate the yield of achocha [Cyclanthera pedata L. Schrad.) ] in Montes Claros, Minas Gerais State, Brazil, as a result of the staking system and within-row spacing. The experimental design was of randomized blocks with four replications, arranged in a scheme 3 x 2, being three staking systems (vertical fence, pole-trellised fence and polyethylene ribbon-trellised fence) and two within-row spacings (1,0 x 1,0 m and 1,0 x 0,5 m), totalizing 24 plots. The fruit number and weight were significantly higher from plants cultivated in the system of vertical fence, where each plant produced 56 fruits on average, corresponding to 2,68 kg. In this system plants presented better fixation to the tutor, besides having minor incidence of damaged fruits caused by the contact with the soil. Highest number, weight of fruits and yield were observed when within-row spacing of 1,0 x 1,0 m was adopted, due to lesser effect of competition between plants for water, nutrients and light. However the yield per area was less due to lower number of plants per ha

Forma física, suplementação enzimática e nível nutricional de rações para frangos de corte na fase inicial: desempenho e digestibilidade dos nutrientes Physical form, enzymatic supplementation and nutritional levels of diet for broilers chickens in the initial phase: performance and nutrients digestibility

Foram conduzidos dois experimentos, utilizando um total de 1.440 frangos de corte machos de 8 a 21 dias de idade, para avaliar a forma física da ração, o uso de enzimas e os níveis nutricionais em dietas à base de milho e farelo de soja. Foi adotado delineamento inteiramente casualizado, em esquema fatorial 2 × 2 × 2, com duas formas físicas de ração (farelada ou triturada); sem ou com complexo enzimático (amilase, celulase e protease) e dois níveis nutricionais (95 ou 100% das recomendações). No experimento 1, 1.200 aves foram distribuídas nos oito tratamentos, com cinco repetições de 30 aves cada, para avaliação de consumo de ração, do ganho de peso e da conversão alimentar. Simultaneamente, realizou-se o experimento 2 (ensaio de metabolismo), no qual 240 aves receberam os tratamentos experimentais, com seis repetições de cinco aves cada. Aos 18 dias de idade, iniciou-se a coleta total de excretas, realizada uma vez ao dia, por três dias consecutivos, para determinação da energia metabolizável (EMAn) e dos coeficientes de metabolizabilidade de matéria seca (CMMS), proteína bruta (CMPB) e extrato etéreo das rações experimentais. A forma física da ração e o nível nutricional influenciaram o consumo de ração das aves, mas não o ganho de peso. Houve interação nível nutricional × forma física da ração para EMAn e metabolizabilidade da matéria seca e proteína bruta. A forma física melhora a energia e o CMMS enquanto as enzimas influenciam a metabolizabilidade da matéria seca e proteína bruta. Com exceção do CMPB, as demais características são influenciadas pelo nível nutricional da dieta.<br>A total of 1440 male broiler chickens from 8 to 21 days old was assigned to two experiments to evaluate the physical form of diet, use of enzymes and nutritional levels of corn-soybean meal based diets. A completely randomized design as a 2 × 2 × 2 factorial scheme, two physical forms of diet (meal or crushed), with or without enzimatic complex (amylase, cellulase and protease) and two nutritional levels (95 or 100% of the recommendations), was used. In the experiment 1, 1200 birds were assigned to the eight treatments with five replicates of 30 chickens each, to evaluate the feed intake (FI), weight gain (WG) and feed conversion (FC). The experiment 2 was carried out simultaneously with the metabolism assay, when 240 birds were allotted to eight experimental treatments with six replicates of five birds each. The total excreta collection started at 18 days of age, once a day for three consecutive days, to determine the metabolizable energy (AMEn) and the metabolizability coefficients of dry matter (MCDM), crude protein (MCCP) and ether extract of the experimental diets. The dietary physical form and nutritional level affected feed intake, but not weight gain. Dietary nutritional level × physical form interaction on AMEn and metabolizability of the dry matter and crude protein was also observed. The physical form improves energy and MCDM while the enzymes influence the metabolizability of dry matter and crude protein. Except for MCCP, the other characteristics are influenced by the dietary nutritional level