RESUMO
Sweet potato-bioethanol yield was evaluated in response to potassium fertilizer application. Experiments were performed using a 5 × 2 factorial design in which factors included the amount of K2O applied to the soil, with five levels (0, 30, 60, 120, and 240 kg ha-1) and genotype, with two levels (industrial genotype BDGPI #25 and table genotype BDGPM #04). Root yield, root starch and soluble solid contents, bioethanol yield, and economic viability of potassium application for bioethanol production were evaluated. Potassium affected root yield of both genotypes, with the highest yield observed at 140 kg K2O ha-1. Root starch concentration at harvest depended on genotype potential rather than potassium dose. Soluble solid content in fresh roots was lower than that in cooked roots, in which case, maximum conversion efficiency was observed at 109,69 and at 123.75 kg K2O ha-1 for BDGPM#04 and BDGPI#25, respectively. Bioethanol yield reached 10,484 and 9,839 L ha-1 at 151.87 and 136 kg K2O ha-1 for BDGPI#25 and BDGPM#04, respectively. Genotype BDGPI#25 was more efficient than sugarcane in converting potassium to bioethanol at 151.87 kg K2O ha-1, producing 10,484.29 L of bioethanol. In turn, BGDPM#04 showed maximum conversion efficiency relative to sugarcane at 122 kg K2O ha-1.
RESUMO
Intact roots and transversal root segments of sweet-potato (Ipomea batatas L. Lam) were partially or completely submerged in water. In partially submerged roots less than 10% of the dermal surface remained exposed to air through a vent. Internal atmosphere pressure in partially submerged roots remained a few millimeters bellow the atmospheric pressure, while a much larger and nearly linear pressure reduction occurred in completely submerged roots. This linear phase caused a pressure reduction larger than 1m of water column. After that, the pressure started to rise slowly. The observed pressure reduction was smaller than the one observed in the constant pressure manometry procedure where the roots were sealed with epoxy resin, which precluded any water infiltration and changes of root volume. Partially submerged intact roots and segments were less subject to intercellular water infiltration than the completely submerged ones. The mass increase of submerged intact roots was caused mainly by water absorption, a process which is known to exclude molecules with a size larger than a few nanometers. In transversely segmented roots most water entered by intercellular volume infiltration, which may introduce fungi spores and bacteria and other particles inside the damaged organ.
Raízes intactas e segmentos transversais de batata-doce (Ipomea batatas L. Lam) foram totalmente ou parcialmente imersos em água. Raízes ou segmentos parcialmente imersos ficaram com menos de 10% da superfície externa fora da água, em um suspiro. Nestes ensaios a pressão da atmosfera interna das raízes parcialmente imersas manteve-se apenas alguns milímetros inferior a pressão atmosférica. Nas raízes totalmente imersas a pressão reduziu-se quase linearmente até mais de 1m de coluna de água e depois voltou a aumentar lentamente. Nas raízes intactas ou nos seus segmentos transversais totalmente imersos, houve maior infiltração de água nos volumes intercelulares do que nas raízes ou segmentos parcialmente imersos. Nas raízes intactas praticamente houve apenas absorção de água através das paredes e membranas celulares. Nos segmentos a infiltração de água através dos volumes intercelulares foi dominante. Considerando-se as dimensões transversais dos volumes intercelulares, sugere-se que partículas como bactérias e esporos possam ser arrastados para o interior órgão pela infiltração de água durante a lavação dos tecidos mecânicamente danificados.
RESUMO
Intact roots and transversal root segments of sweet-potato (Ipomea batatas L. Lam) were partially or completely submerged in water. In partially submerged roots less than 10% of the dermal surface remained exposed to air through a vent. Internal atmosphere pressure in partially submerged roots remained a few millimeters bellow the atmospheric pressure, while a much larger and nearly linear pressure reduction occurred in completely submerged roots. This linear phase caused a pressure reduction larger than 1m of water column. After that, the pressure started to rise slowly. The observed pressure reduction was smaller than the one observed in the constant pressure manometry procedure where the roots were sealed with epoxy resin, which precluded any water infiltration and changes of root volume. Partially submerged intact roots and segments were less subject to intercellular water infiltration than the completely submerged ones. The mass increase of submerged intact roots was caused mainly by water absorption, a process which is known to exclude molecules with a size larger than a few nanometers. In transversely segmented roots most water entered by intercellular volume infiltration, which may introduce fungi spores and bacteria and other particles inside the damaged organ.
Raízes intactas e segmentos transversais de batata-doce (Ipomea batatas L. Lam) foram totalmente ou parcialmente imersos em água. Raízes ou segmentos parcialmente imersos ficaram com menos de 10% da superfície externa fora da água, em um suspiro. Nestes ensaios a pressão da atmosfera interna das raízes parcialmente imersas manteve-se apenas alguns milímetros inferior a pressão atmosférica. Nas raízes totalmente imersas a pressão reduziu-se quase linearmente até mais de 1m de coluna de água e depois voltou a aumentar lentamente. Nas raízes intactas ou nos seus segmentos transversais totalmente imersos, houve maior infiltração de água nos volumes intercelulares do que nas raízes ou segmentos parcialmente imersos. Nas raízes intactas praticamente houve apenas absorção de água através das paredes e membranas celulares. Nos segmentos a infiltração de água através dos volumes intercelulares foi dominante. Considerando-se as dimensões transversais dos volumes intercelulares, sugere-se que partículas como bactérias e esporos possam ser arrastados para o interior órgão pela infiltração de água durante a lavação dos tecidos mecânicamente danificados.