RESUMO

Understanding sugarcane (Saccharum spp.) response to multiple pest injury, sugarcane borer (Diatraea saccharalis) and spittlebug (Mahanarva fimbriolata), is essential to make better management decisions. Moreover, the consequences of both pests on the sugarcane raw material quality have not yet been studied. A field experiment was performed in São Paulo State, Brazil, where sugarcane plants were exposed to pests individually or in combination. Plots consisted of a 2-m long row of caged sugarcane plants. Photosynthesis was measured once every 3 months (seasonal measurement). Yield and sugar production were assessed. The measured photosynthesis rate was negatively affected by both borer and spittlebug infestations. Photosynthesis reduction was similar on plants infested by both pests as well as by spittlebug individual infestation. Plants under spittlebug infestation resulted in yield losses and represented 17.6% (individual infestation) and 15.5% (multiple infestations). The sucrose content and the sucrose yield per area were reduced when plants were infested by multiple pests or spittlebug.

RESUMO

One of the most important steps is to clarify the juice, which are added synthetic polymer acrylamide base, aiming the fast settling of impurities present in the juice. However, this input is expensive and may have carcinogenic and neurotoxic actions to humans. The search for new natural flocculants that have similarity with the commercial product is of great value. A bioextract that may be promising and has coagulant action is the Moringa oleifera Lam. In this context, the objective of the research was to evaluate the consequences of the use of moringa seed extracts and various concentrations of commercial polymer, such as sedimentation aids in clarifying sugarcane juice in the ethanol production, comparing the efficiency of the bioextract moringa. In the treatment of the juice, excessive addition of flocculants can result in reduction of sugars. The bioflocculant moringa was similar in technological features and the fermentative viability compared to usual dose of commercial polymer in Brazil. The fermentation efficiency was also higher for this flocculant, followed by moringa extract. The results obtained in this research indicate potential to the moringa bioextract, particularly in countries where the doses of flocculants are higher than 5 mg.L-1.

Assuntos

RESUMO

ABSTRACT One of the most important steps is to clarify the juice, which are added synthetic polymer acrylamide base, aiming the fast settling of impurities present in the juice. However, this input is expensive and may have carcinogenic and neurotoxic actions to humans. The search for new natural flocculants that have similarity with the commercial product is of great value. A bioextract that may be promising and has coagulant action is the Moringa oleifera Lam. In this context, the objective of the research was to evaluate the consequences of the use of moringa seed extracts and various concentrations of commercial polymer, such as sedimentation aids in clarifying sugarcane juice in the ethanol production, comparing the efficiency of the bioextract moringa. In the treatment of the juice, excessive addition of flocculants can result in reduction of sugars. The bioflocculant moringa was similar in technological features and the fermentative viability compared to usual dose of commercial polymer in Brazil. The fermentation efficiency was also higher for this flocculant, followed by moringa extract. The results obtained in this research indicate potential to the moringa bioextract, particularly in countries where the doses of flocculants are higher than 5 mg.L-1.

Assuntos

RESUMO

Mahanarva fimbriolata (Stål) is an important pest in Latin America and causes significant reduction in sugarcane productivity. There is no information regarding the effect of this pest on the quality of cane juice used for sugar and alcohol production. This work aimed at evaluating the quality of sugarcane juice from plants attacked by spittlebugs. The experiment was arranged in a completely randomized design with 15 replications, and comprised two treatments: control and chemical treatment with thiamethoxam. An average of 9.2 +/- 4.44 spittlebug nymphs m-1 were found in the plots prior to insecticide application. Nymphs were counted 18, 35, 55, and 82 days after the initial sampling (december/2003). During the mid growing season (July 2004), the juice was extracted from stalks and analyzed for Brix, Pol, RS, pH, fiber, purity, TRS, dextran, starch, and total phenolic compounds. Stalk yield was also measured. Chemical treatment was efficient in reducing spittlebug population, and elevated both stalk yield and juice pH. The accumulated infestation expressed as insect-days was significantly and negatively correlated to yield, Pol, pH, and purity. The concentration of phenolic compounds increased with pest infestation, while dextran and starch levels were not affected. The infestation of 2.4 and 7.3 nymphs m-1 day-1 caused reductions of 8.3% and 29.8% in yield; 1.9% and 5.8% in Pol; 0.4% and 1.1% in pH and 0.4% and 1.2% in purity, respectively, in comparison to areas where the pest population was extremely low (< 0.1 nymphs m-1).

Assuntos

RESUMO

Mahanarva fimbriolata (Stål) is an important pest in Latin America and causes significant reduction in sugarcane productivity. There is no information regarding the effect of this pest on the quality of cane juice used for sugar and alcohol production. This work aimed at evaluating the quality of sugarcane juice from plants attacked by spittlebugs. The experiment was arranged in a completely randomized design with 15 replications, and comprised two treatments: control and chemical treatment with thiamethoxam. An average of 9.2 ± 4.44 spittlebug nymphs m-1 were found in the plots prior to insecticide application. Nymphs were counted 18, 35, 55, and 82 days after the initial sampling (december/2003). During the mid growing season (July 2004), the juice was extracted from stalks and analyzed for Brix, Pol, RS, pH, fiber, purity, TRS, dextran, starch, and total phenolic compounds. Stalk yield was also measured. Chemical treatment was efficient in reducing spittlebug population, and elevated both stalk yield and juice pH. The accumulated infestation expressed as insect-days was significantly and negatively correlated to yield, Pol, pH, and purity. The concentration of phenolic compounds increased with pest infestation, while dextran and starch levels were not affected. The infestation of 2.4 and 7.3 nymphs m-1 day-1 caused reductions of 8.3 percent and 29.8 percent in yield; 1.9 percent and 5.8 percent in Pol; 0.4 percent and 1.1 percent in pH and 0.4 percent and 1.2 percent in purity, respectively, in comparison to areas where the pest population was extremely low (< 0.1 nymphs m-1).

Mahanarva fimbriolata (Stål) é considerada praga importante na América Latina por reduzir a produtividade de cana-de-açúcar. Há pouca informação sobre o efeito do inseto na qualidade da cana que será utilizada para produção de açúcar e álcool. Assim, objetivou-se avaliar a qualidade do caldo da cana de plantas atacadas pela cigarrinha-das-raízes. Adotou-se o delineamento experimental inteiramente casualizado com 15 repetições e dois tratamentos: testemunha e controle químico com tiametoxam. Nas parcelas experimentais foram encontradas em média 9,2 ± 4,44 ninfas m-1 em monitoramento inicial (dezembro/2003). As ninfas foram contadas aos 18, 35, 55, e 82 dias após a primeira contagem, sendo a infestação expressa em insetos-dia acumulados. Em julho de 2004, procedeu-se à colheita de colmos e extração do caldo, analisando-se o Brix, Pol, açúcares redutores, pH, fibra, pureza, açúcares redutores totais, dextrana, amido, compostos fenólicos totais e produtividade. O controle químico reduziu a população do inseto e elevou a produtividade de colmos e do pH do caldo. A infestação acumulada foi correlacionada significativa e negativamente com a produtividade, Pol, pH, e pureza. O teor de compostos fenólicos aumentou com a elevação da infestação, enquanto que os valores de dextrana e amido não foram alterados. Infestações de 2,4 e 7,3 ninfas m-1 dia-1 causaram reduções da ordem de 8,3 por cento e 29,8 por cento na produtividade; 1,9 e 5,8 por cento na Pol; 0,4 por cento e 1,1 por cento no pH e 0,4 por cento e 1,2 por cento na pureza, respectivamente, em comparação com áreas de população baixa (< 0,1 ninfa m-1).

Assuntos