RESUMO -Objetivou-se estabelecer correlações entre características quantitativas e qualitativas e avaliar a influência dessas características sobre a produção e a qualidade do milho para silagem. Utilizaram-se dados do Programa de Avaliação de Cultivares de Milho para Silagem IAC/APTA/ESALQ para cálculo das correlações de Pearson entre as variáveis. A produção de matéria seca (MS) digestível foi afetada tanto pelas produções de massa e de grãos quanto pelas digestibilidades da planta e do colmo. A produção de matéria seca digestível apresentou os maiores coeficientes de correlação com a produção de MS (0,85); com as produções de grãos na ensilagem (0,60) e na maturidade (0,68); com produção de matéria verde (0,47); e com o índice de espigas (0,48). Os coeficientes de correlação entre a produção de matéria seca digestível e a digestibilidade da planta inteira (0,44) e da fração colmo (0,38) foram inferiores aos obtidos para a produção de matéria seca. A digestibilidade da planta dependeu principalmente da digestibilidade do colmo (0,60) e dos parâmetros relacionados aos grãos.Na ausência de informações específicas sobre os cultivares de milho para silagem, pode-se optar por aqueles de maior produção de grãos à maturidade, em razão da elevada correlação dessa característica com produção de matéria seca e com produção de matéria seca digestível.Palavras-chave: correlação, digestibilidade, grãos, matéria seca, proteína, Zea mays Agronomic and nutritional characteristics of the corn hybrids for silage production ABSTRACT -The objective of this work was to establish correlations between quantitative and qualitative variables and to evaluate their influence on the corn quality for ensilage production. Data from the Corn Hybrids for Silage EvaluationProgram were used (IAC/APTA/ESALQ). Pearson correlations between the variables were calculated. The digestible dry matter (DM) production was affected not only by forage and grain productions, but also by the whole plant and stem digestibility. The digestible dry matter production presented the highest correlation coefficients with the total dry matter production (0.85) and with the grain production at ensiling (0.60) and maturity (0.68), production of fresh forage (0.47) and with the plant ears index (0.48). The correlation coefficients between the digestible DM production and the whole plant digestibility (0.44) and the stem fraction (0.38) were lower than those observed for the DM production. The whole plant digestibility depended mainly on the stem digestibility (0.60) and on parameters related to the grains. It may be concluded that when specific information on corn hybrids is not available, those with higher production of grains at maturity are selected due to their elevated correlation with DM production and digestible DM.Key Words: correlation, digestibility, dry matter, grains, protein, Zea mays IntroduçãoAs características mais desejáveis em uma cultura para ensilagem são a elevada produção de matéria seca, as altas concentrações de proteína bruta e energia (alta d...
The productivity criterion was adopted to evaluate stink bug damage. Based on both growing seasons and mainly considering productivity, a few lines could be selected within each maturation group for new fi eld studies or for hybridizations in breeding programs. Among the early germplasm varieties, lines IAC 98-4540, IAC 98-4576, and IAC 98-3123 can be highlighted as promising; the latter also showed little defoliation by A. gemmatalis; in the semi-early group, IAC 98-4017, IAC 98-2663, and IAC 98-4250 were prominent, with steady productivity in both years; in the medium group, IAC 98-4136, the most productive, as well as IAC 98-4140 and IAC 98-4133, all with little defoliation, can be pointed out as promising.
Evaluation of Damage in Soybean Genotypes of Three Maturity Groups Caused by Stink Bugs and Defoliators ABSTRACT-The damage of stinkbugs and defoliators in soybean genotypes was evaluated, under field conditions, at Tarumã and Ribeirão Preto, State of São Paulo, Brazil. Three experiments, one for each of three maturity group, were carried out, in the 1997/98 and 1998/99 seasons. In Tarumã, infestations of Diabrotica speciosa (Germar) and Cerotoma sp. occurred in both seasons and Anticarsia gemmatalis Hubn. in the second; in Ribeirão Preto, this caterpillar occurred only in the second year. Only in the first year in Tarumã, stinkbug infestations [predominantly Piezodorus guildinii (West.)], fluctuated above the economic injury level (EIL); in Ribeirão Preto, the stinkbug infestations did not exceed the EIL. Defoliaton damage was estimated by the percentage of eaten leaf area (PAFC). Percentage of foliar retention (PRF) and yield were used to evaluate the stinkbug damage. Considering both years and both locations, among the early maturing genotypes (110 days), 'IAC-22' showed susceptibility to defoliators while 'IAC-17' confirmed its resistance to this group of pests as well as to stinkbugs. Among the genotypes of 120-day maturity group, IAC 93-3379 could be distinguished for the high yield, showing stability by this criteria. IAC 93-3275 and IAC 93-3237 presented low yield and high PAFC and PRF, mainly in Tarumã. Regarding the genotypes of 135-day maturity group, susceptibility to stinkbugs was observed in 'IAC Holambra-Stwart', 'IAC PL-1' and IAC 87-2048; however, this line showed high yield under low infestation. Also, IAC 78-2318, IAC 93-1789 and IAC 93-1796 presented the lowest PRF, indicating to be less susceptible to this disorder.
The use of soybean cultivars resistant to insects and diseases reduces the application of pesticides, decreasing production costs and promoting a sustainable agriculture. The damage of stink bugs and defoliators and the severity of powdery mildew (Microsphaera diffusa) in soybean of three maturity groups were evaluated under field conditions, at Tarumã and Ribeirão Preto, State of São Paulo, Brazil. Three experiments, one for each group, were carried out in the 1999/2000 and 2000/2001 growing seasons. In 1999/2000, the disease occurred in Tarumã; in that year, infestation of chrysomelids (Cerotoma sp. and Colaspis sp.) was observed in Ribeirão Preto. Low infestations of stink bugs occurred in both years and locations, but in Tarumã, at the stage of plant maturation, the insect population exceeded the economic injury level. The severity of powdery mildew was evaluated using a scale varying from 1 (no symptom) to 5 (more than 50% of leaves with symptoms). Chrysomelid injuries were estimated by the percentage of leaf area removed, and stink bug damage was evaluated by the percentage of leaf retention (LRP) and yield. Within the early maturity group (110 days), IAC 94-2675 showed good yield levels, low LRP, and resistance to powdery mildew. In the genotypes of the 120-day maturity group, IAC 94-5, IAC 94-1172, IAC 94-1017, IAC 94-133, and IAC 94-745 presented good yield; the last two behaved as resistant to the disease. With regard to the genotypes of the 135-day maturity group, IAC 93-1564 and IAC 94-2939 showed good yield, low LRP, and resistance to powdery mildew. Keywords: Glycine max, Microsphaera diffusa, host plant resistance, stink bugs, defoliators DANOS DE INSETOS E SEVERIDADE DE OÍDIO EM CULTIVARES E LINHAGENS DE SOJA
O estudo estimou o custo operacional de produção da soja convencional e transgênica no Médio Paranapanema, Estado de São Paulo. Foram utilizados resultados de três experimentos de avaliação regional com 19 cultivares de soja, sendo 17 convencionais e 2 transgênicas. As estruturas de custo utilizadas foram custo operacional efetivo (COE) e o custo operacional total (COT). O COT, por hectare, da soja transgênica foi 10,7% menor que o da soja convencional. Porém, o custo unitário por saca foi menor para a soja convencional em razão da produtividade. A produtividade média foi de 35,2 e de 31,3 para as cultivares convencionais e transgênicas, respectivamente. A maior diferença porcentual no COT ocorreu nos itens "sementes" e "herbicidas". A variação do custo de produção por saca da soja convencional foi de R$ 27,7 a R$ 39,5 e da soja transgênica R$ 29,5 e R$ 40,1. O alto custo dos insumos comprometeu a viabilidade da atividade nos dois sistemas de produção. Há necessidade de continuar a avaliação das cultivares de soja transgênica para conhecer as mais adaptadas regionalmente e tornar mais seguras as indicações técnicas.
RESUMOAvaliou-se o desempenho de 24 linhagens de soja do programa de melhoramento do Instituto Agronômico (IAC) em experimentos de campo em relação ao ataque de insetos e à incidência de oídio. Três experimentos, um para cada ciclo (precoce, semiprecoce e médio) foram instalados nas unidades experimentais de Assis (anos agrícolas 2001 e 2002/2003) e de Ribeirão Preto (2001. Para os três experimentos, o delineamento utilizado foi o de blocos ao acaso, com dez tratamentos e seis repetições. As injúrias foliares causadas por lagartas de Anticarsia gemmatalis Hübner foram estimadas visualmente, atribuindo-se uma porcentagem de desfolha à parcela inteira. Os danos de percevejos [Piezodorus guildinii (West.) e Euschistus heros (F.)] foram avaliados através da porcentagem de retenção foliar atribuída à parcela inteira e por meio da massa de grãos comerciáveis. A severidade de oídio (Microsphaera diffusa Cke. Pk.) foi estimada mediante escala de notas de 1 a 5, de acordo com a intensidade dos sintomas. Considerando-se os resultados das duas localidades, entre o germoplasma de ciclo precoce destaca-se a linhagem IAC 98-4307, com baixa retenção foliar e maior produtividade em presença de percevejos. No grupo de ciclo semiprecoce, observa-se que na linhagem IAC 98-2814 não há retenção foliar, porém, maior produtividade, caracterizando-se como resistente a percevejos, embora seja o genótipo mais desfolhado por lagartas e com maiores sintomas de oídio. Entre os genótipos de ciclo médio, IAC 98-2856 tem produtividade superior em presença de altas ou baixas infestações de percevejos, indicando possuir resistência do tipo tolerância, embora apresente retenção foliar sob baixa pressão de percevejos. Palavras-chave:Glycine max, resistência de plantas a insetos, Pentatomidae, Anticarsia gemmatalis, Microsphaera diffusa.
The growing demand for food has intensified the search for compounds of plant origin to protect field crops from predators and pathogens, as these compounds have less environmental impact and are considered healthier than synthetic compounds. Among plant species with insecticidal activity, Spathodea campanulata has been identified as a potential source of insecticidal compounds. Therefore, in this study we verified the insecticidal effect of nectar from S. campanulata against three different insects. In addition, the oxidant activity of nectar and proteomic assay were conducted to identify the insecticide potential. Both gross and dialyzate nectar showed a promising toxic effect against Euschistus heros (Fabr.), Helicoverpa zea (Boddie) and Anticarsia gemmatalis (Hübner) insects. According to oxidant tests, non-denatured nectar showed a higher oxidant activity than denatured nectar, in both albumin degradation and TBARS tests. SDS-PAGE and 2D-PAGE were used to characterize the nectar proteins, revealing 13 spots that were compatible to either proteins or peptides. The most relevant spots were analyzed by mass spectrometry, confirming the presence of proteins associated with insecticidal activity. In conclusion, it is hypothesized that S. campanulata nectar has insecticidal effects and this activity is linked to the classes of pro-oxidant proteins or peptides present in its chemical composition.
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