Custódio Donizete dos Santos

Resistance induction in wheat plants by silicon and aphids

Dentre os fatores limitantes da producao triticola brasileira esta o ataque de insetos-praga, podendo-se destacar o pulgao-das-gramineas Schizaphis graminum (Rondani) (Hemiptera: Aphididae). O controle quimico e predominante no manejo desse pulgao, tornando a producao dependente do uso de inseticidas. Este trabalho avalia o efeito do silicio e da infestacao previa com pulgoes na inducao de resistencia ao pulgao-das-gramineas em plantas de trigo. Os tratamentos foram: testemunha; adubacao com silicato de calcio; infestacao das plantas com pulgoes; adubacao com silicato de calcio + infestacao das plantas com pulgoes. Trinta e cinco dias apos emergencia das plântulas foi realizado teste de preferencia com chance de escolha; determinacao da taxa de crescimento da populacao do pulgao (rm) e quantificacao da atividade de tres enzimas envolvidas na defesa das plantas: peroxidase, polifenoloxidase e fenilalanina amonia-liase. A adubacao silicatada e a infestacao previa com pulgoes induzem resistencia em plantas de trigo ao pulgao-das-gramineas.

Antinutrients in the cassava (Manihot esculenta Crantz) leaf powder at three ages of the plant

In Brazil, the cassava leaf meal (CLM) has been used to strive against undernourishment because it is a high source of vitamins and minerals. However, the wide variation in the chemical composition of the different cultivars, as well as their antinutritional substances may be a restriction to their uses. The levels of some antinutrients in CLM from five cultivars at three ages of the plant (TAP) were investigated, in order to select the cultivars and plant ages that would be more appropriate for human consumption. The lowest contents of antinutrients were observed in the 12-month old plants, except for nitrate and hemagglutinin from which the lowest contents were found for the 17 month old ones. The cultivar IAC 289-70 had the lowest antinutrient levels, except for saponin and oxalate. Thus, the cultivar IAC 289-70 at 12 months is the most appropriate for human consumption.

Inhibition of pancreatic lipase by extracts of Baccharis trimera (Less.) DC., Asteraceae: evaluation of antinutrients and effect on glycosidases

In order to confirm the traditional use of Baccharis trimera (Less.) DC., Asteraceae, for the reduction of weight, plant extracts were evaluated on the activity of pancreatic lipase (PL), an enzyme responsible for hydrolysis of triacylglycerols in the diet for its subsequent absorption. The aqueous and infused extracts did not show inhibitory activity on the PL, the ethanol inhibited 16% (66 ALI/g) and methanol extract inhibited 78% (241 ALI/g). The methanol extract of B. trimera (MEB) was subjected to a wash with decreasing solvent polarity (n-hexane, ethyl acetate and methanol) and only the methanol fraction inhibited the lipase by 72% (230 ALI/g). We evaluated the MEB and infused inhibitory activity on the enzymes α-amylase and α and β-glycosidases. The α-amylase was not inhibited by any of the extracts, the enzyme α-glucosidase was inhibited by both extracts in the same proportion (46.9±0.1) and β-glucosidase was inhibited by 73% by the methanol extract and 65% by the infused. We also evaluated the presence of anti-nutrients. We detected the presence of saponins, polyphenols and trypsin inhibitors in the two samples. Tests performed in vivo can assess at which therapeutic concentration the presence of these anti-nutrients can be harmful to health.

Nutrients in the cassava (Manihot esculenta Crantz) leaf meal at three ages of the plant

The high number of cassava cultivars adapted to many different regions provides a wide variation in the chemical composition of cassava leaves meal (CLM). Therefore, the contents of some nutrients in CLM from five cultivars at three ages of the plant were investigated in order to select the cultivars and ages with superior levels of these nutrients. When the plants were 12 months old, the highest levels of crude protein (CP), b-carotene, iron, magnesium, phosphorus and sulfur were observed. The IAC 289-70 cv. showed the highest levels of magnesium, as well as considerable contents of CP, b-carotene, iron, zinc and sulfur, which did not differ statistically from the cultivars showing the highest levels of these nutrients.

Uso de silício como indutor de resistência em batata a Myzus persicae (Sulzer) (Hemiptera: Aphididae)

The aphid Myzus persicae (Sulzer) is an important pest of potato and causes direct harm, due to the quantity of sap extracted and for being vector of important phytovirus. This work was carried out to evaluate the action of silicon as a resistance inducer of potato to M. persicae. Four treatments were tried: foliar fertilization with silicon acid at 1%; soil fertilization with 250 ml silicic acid solution at 1%; foliar fertilization with silicon acid at 1% + soil fertilization with 250 ml silicic acid solution at 1%; and a control. The treatments were applied thirty days after the explants emergence. Fifteen days after the application of the treatments, feeding preference and some biological aspects of the aphids were evaluated. After, the content of tannins and lignin present in the leaves and the activity of the enzymes peroxidase and phenylalanine ammonia-lyase were also determined. The silicon fertilization did not affect the preference of the aphids; however it reduced fecundity and the rate of population growth of the insects. The lignin percentage increased in the leaves of plants fertilized with silicon via soil and/or foliar and the percentage of tannins increased only in the leaves fertilized via soil plus foliar. The silicon acted as a resistance inducer to M. persicae in potato.

Textura de goiabas "Pedro Sato" submetidas à aplicação de cloreto de cálcio

Among the techniques used to maintain the post-harvest quality of fruits, stands out the application of calcium, usually associated to the refrigeration. However, not all the producers have access to cold cameras, therefore it was aimed at in this work, to evaluate the isolated treatment with calcium chloride in the maintenance of the appearance of guavas (Psidium guajava L.) destined to the consumption “in nature”, stored in environmental conditions. The hydrothermical treatment at the temperature of 30oC, with calcium chloride 1g/100 mL, was tested comparing with fruits without treatment. Soon after the fruits were stored under environmental conditions (22,6oC (±1), UR 75% (±5) for four days. After the storage, the contents of total and soluble pectin and the pectinametilesterase and poligalacturonase activities were evaluated. The employment of calcium affected the analyzed characteristics providing smaller content of soluble pectin and lower activities of pectinametilesterase and poligalacturonase, promoting a less intense softening, maintaining the firmness of the fruits during the storage period.

Alterações pós-colheita da "fruta-de-lobo" (Solanum lycocarpum St. Hil.) durante o amadurecimento: análises físico-químicas, químicas e enzimáticas

Estudaram-se, neste trabalho, algumas modificacoes fisico-quimicas, quimicas e enzimaticas, em pos-colheita, durante o amadurecimento da fruta-de-lobo, comparando-as com as de outros frutos. Os frutos colhidos de plantas nativas no inicio do estadio de amadurecimento foram selecionados e armazenados durante 18 dias a temperatura ambiente (17,1 a 26,9oC). Os frutos foram lavados com agua destilada, descascados, picados, congelados em nitrogenio liquido e liofilizados ate massa constante. O delineamento experimental utilizado foi o inteiramente casualizado, com quatro repeticoes de 3 frutos. Os valores de pH e acidez titulavel nao variaram estatisticamente durante o amadurecimento. A atividade de amilase e os teores de amido diminuiram gradativamente com o aumento dos acucares soluveis totais e nao redutores, enquanto os teores dos redutores se mantiveram constantes. Os teores de pectinas totais e soluveis diminuiram, enquanto a atividade de pectinametilesterase manteve-se constante. As atividades das enzimas poligalacturonase e polimetilgalacturonase nao foram detectadas no fruto. Observou-se diminuicao dos teores de polifenois e das atividades das enzimas peroxidase e polifenoloxidase e consequente diminuicao do escurecimento da polpa do fruto.

Quantificação de Polifenóis e Digestibilidade Protéica de Famílias de Feijoeiro Comum

O feijao e um dos alimentos encontrados em maior quantidade em todo o territorio nacional e e cultivado em quase todos os Estados. E uma importante fonte proteica na dieta do povo brasileiro, estando presente na alimentacao da populacao rural e urbana. No presente trabalho, quantificaram-se os polifenois e determinaram-se os niveis de digestibilidade proteica de cem familias de feijoeiro comum (Phaseolus vulgaris L.) obtidas do cruzamento entre os genotipos Amarelinho e CI 107. Os polifenois afetam a qualidade do feijao, causando escurecimento, endurecimento e, ainda, podem reduzir a digestibilidade proteica. Pelos resultados obtidos, pode-se encontrar 13 familias com teores reduzidos de polifenois e boa digestibilidade proteica in vitro, as quais poderao ser utilizadas em programas de melhoramento dessa importante cultura.

Embalagens e recobrimento em lichias (Litchi chinensis Sonn.) armazenadas sob condições não controladas

A lichia (Litchi chinensis Sonn.) e um fruto subtropical de alto potencial comercial devido ao seu sabor levemente acidificado, excelente aroma, alto valor nutritivo e atrativa cor vermelha da casca. Ainda no campo, a cor da casca altera-se facilmente, tornando-se escurecida em resposta a estresses (alteracoes da umidade relativa e ataque de patogenos). Apos colhida, a casca da lichia perde rapidamente sua cor vermelha. O escurecimento da casca tem sido atribuido a rapida degradacao da antocianina, assim como: a rapida perda de umidade pelo fruto e a atividade de enzimas oxidativas como polifenoloxidases e peroxidases. Dada essa alta perecibilidade, o controle do escurecimento e fundamental para o aumento na vida util pos-colheita, visando ao mercado interno e a exportacao de frutas. Avaliou-se, neste trabalho, o comportamento pos-colheita de lichias da cv. Bengal quanto ao escurecimento da casca e as modificacoes relacionadas com a qualidade da polpa de lichias submetidas a diferentes embalagens: bandeja recoberta com filme de polietileno de baixa densidade com e sem perfuracoes e frutos recobertos com pelicula de fecula de mandioca (3%). Os frutos foram mantidos em temperatura ambiente (25,1oC±1,5oC; 69,3%±8,62%UR) e armazenados por seis dias. Foram realizadas analises fisicas, quimicas e bioquimicas no dia 0 e a cada 2 dias, ate osexto dia de armazenamento. A embalagem recoberta com filme de polietileno perfurado apresentou-se eficiente na reducao da perda de massa, escurecimento da casca e na manutencao do teor de antocianina da casca de lichias durante seis dias de armazenamento, em temperatura ambiente.

Caracterização química do óleo essencial de folhas de goiabeira (Psidium guajava L.) e seus efeitos no comportamento da lagarta-do-cartucho do milho Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae)

The aim of this research was to obtain and characterize essential oil from leaves of Psidium guajava cv. Pedro Sato, and its possible effects on fall armyworm Spodoptera frugiperda behavior. The essential oil was obtained through steam distillation, by using a modified Clevenger apparatus, and the chemical composition was later analyzed by gas chromatography coupled to mass spectroscopy GC-MS. In order to evaluate the essential oil effect on the armyworm of 1st instars behavior, four treatments were tested; two with oil at 0.01 and 0.001 % in ethanol/water 1:1 concentration; two controls with water and the other with ethanol/water 1:1. The results showed that the above analyzed essential oil constituted of a-terpineole (0.9%), 1,8-cineole (7.0%), â-caryophyllene (7.2%) and the caryophyllene oxide (13.8%). It was also found that the essential oil showed a repellent effect toward the fall armyworm at 0.01% concentration.