ABSTRACT: Paper and plastic bags have been mainly used in fruit bagging of pineapple production. However, they are often discarded as agricultural wastes after harvest of pineapple fruit and threaten environment. In this study, effects of white non-woven fabric bag, expandable polyethylene bag, black plastic bag and kraft paper bag on fruit quality of pineapple cv. ‘MD-2’ were investigated. Results showed that fruits with fruit bagging showed no sunburn. When expandable polyethylene bag was used, fruits of pineapple cv. ‘MD-2’ showed better external qualities, nutrition qualities and texture properties. Expandable polyethylene bag made of degradable and recyclable materials could be recommended as a promising practice to reduce agricultural waste in pineapple production.

RESUMO: Sacos de papel e plástico têm sido usados principalmente no ensacamento de frutas na produção de abacaxi. No entanto, eles são frequentemente descartados como resíduos agrícolas, após a colheita da fruta do abacaxi, e ameaçam o meio ambiente. Neste estudo, os efeitos da sacola de tecido, não tecido branco, sacola de polietileno expansível, sacola plástica preta e sacola de papel artesanal na qualidade do fruto do abacaxi cv. ‘MD-2’ foram investigados. Os resultados mostraram que as frutas ensacadas não apresentaram queimaduras solares. Quando foi utilizada a bolsa de polietileno expansível, as frutas de abacaxi cv. ‘MD-2’ mostraram melhores qualidades externas, qualidades nutricionais e propriedades de textura. O saco de polietileno expansível feito de materiais degradáveis e recicláveis pode ser recomendado como uma prática promissora para reduzir o desperdício agrícola na produção de abacaxi.

ABSTRACT Anaerobic digestion is important for the management of livestock manure with high ammonia level. Although ammonia effects on anaerobic digestion have been comprehensively studied, the molecular mechanism underlying ammonia inhibition still remains elusive. In this study, based on metatranscriptomic analysis, the transcriptional profile of microbial community in anaerobic digestion under low (1500 mg L-1) and high NH4 + (5000 mg L-1) concentrations, respectively, were revealed. The results showed that high NH4 + concentrations significantly inhibited methane production but facilitated the accumulations of volatile fatty acids. The expression of methanogenic pathway was significantly inhibited by high NH4 + concentration but most of the other pathways were not significantly affected. Furthermore, the expressions of methanogenic genes which encode acetyl-CoA decarbonylase and methyl-coenzyme M reductase were significantly inhibited by high NH4 + concentration. The inhibition of the co-expressions of the genes which encode acetyl-CoA decarbonylase was observed. Some genes involved in the pathways of aminoacyl-tRNA biosynthesis and ribosome were highly expressed under high NH4 + concentration. Consequently, the ammonia inhibition on anaerobic digestion mainly focused on methanogenic process by suppressing the expressions of genes which encode acetyl-CoA decarbonylase and methyl-coenzyme M reductase. This study improved the accuracy and depth of understanding ammonia inhibition on anaerobic digestion.