Potencial fitotóxico de extratos foliares de Aloe arborescens Miller (Asphodelaceae) produzidos em diferentes épocas do ano

Abstract

RESUMO -(Análise do potencial fitotóxico de extratos foliares de Aloe arborescens Miller (Asphodelaceae) produzidos em diferentes épocas do ano). Este trabalho visou analisar o potencial fitotóxico de extratos foliares de Aloe arborescens Miller sobre a germinação e crescimento de plântulas de alface (Lactuca sativa L.). Amostras de folhas foram coletadas nas quatro estações climáticas e maceradas em etanol P.A. por 28 dias. Os extratos produzidos foram fracionados em extratos etanólico e clorofórmico e tiveram as concentrações reduzidas a 1%. Os bioensaios de ação fitotóxica foram desenvolvidos em triplicata, sob luz constante e temperatura ambiente. Apenas o extrato clorofórmico de primavera mostrou forte atividade fitotóxica sobre a germinação das sementes de alface (16,67%). Todos os extratos reduziram significativamente a primeira contagem, índice de velocidade germinação (IVG) e o crescimento do eixo hipocótilo-radicular (EHR) das plântulas de alface, porém os extratos clorofórmicos mostraram maior atividade fitotóxica, gerando alterações morfológicas mais intensas sobre as plântulas de alface e apresentaram maiores teores de compostos fenólicos. Apesar de todos os extratos clorofórmicos inibirem fortemente o crescimento das folhas cotiledonares das plântulas de alface, não se observaram neste último efeito, variações em função dos períodos de coleta. Palavras-chave: alelopatia, Aloe, fitotoxicidade, sazonalidade ABSTRACT -(Analysis of the phytotoxic potential of Aloe arborescens Miller leaf extracts (Asphodelaceae) produced at different times of the year). This study aimed to analyze seasonal variation in the phytotoxic potential of Aloe arborescens Miller leaf extract on lettuce (Lactuca sativa L.) germination and growth. Leaf samples were collected in the four seasons and were macerated in ethanol P.A. for 28 days. The extracts were fractionated into solutions made with ethanol and chloroform, and concentrations were reduced to 1%. Phytotoxic activity bioassays were carried out in triplicate, under constant light and ambient temperature. Only the spring chloroform extract showed strong phytotoxic activity on lettuce seed germination (16.67%). All extracts significantly reduced the first count, germination velocity index (GVI) and growth of the hipocotyl-root axis (HRA) of the lettuce plants. However, the chloroform extracts showed greater phytotoxic activity, producing more intense morphology alterations on lettuce plants and showed greater content of phenolic compounds.

Effect of dietary supplementation with propolis and Aloe barbadensis extracts on hematological parameters and parasitism in Nile tilapia

“…These compounds may cause damage to the intestinal epithelium if used as supplements for long periods or at high concentrations. Nevertheless, the antifungal, antiinflammatory, hypoglycemic, hemagglutination and mitogenic activity towards lymphocytes remains the main feature of interest in studying this product (CHOI & CHUNG, 2003;TAI-NIN CHOW et al, 2005;MURAKAMI et al, 2009). Several polysaccharides have been detected and isolated from the pulp of aloe, including mannose, galactose, arabinose, glucuronic acid and pectic acid (NI et al, 2004).…”

Phytotoxic and antioxidant activity of seven native fruits of Brazil

“…Representatives of the coumarin, quinone, flavonoid and tannin classes are also known to be inhibitors of seed germination and plant growth (Harbone 1997;Malheiros & Peres 2001). There have also been studies showing that the concentration of phenolic compounds is correlated with the germination and growth of seedlings (Reigosa et al 1999;Murakami et al 2009). Polyphenols such as tannins, flavonoids and phenolic acids are the most common compounds with allelopathic effects found in botanical species.…”

Monoterpenes from the essential oil from Brazilian propolis affect seedling cellular elongation

“…'Mimosa') were distributed on the paper disks inside each Petri dish. All steps were run in triplicate, using a laminar flow chamber (Murakami et al 2009). The dishes were maintained at 25°C in germination chamber with 12-h photoperiod during 7 days, a time period long enough to detect negative effects of the oil on seedling root growth (Murakami et al 2009).…”

“…All steps were run in triplicate, using a laminar flow chamber (Murakami et al 2009). The dishes were maintained at 25°C in germination chamber with 12-h photoperiod during 7 days, a time period long enough to detect negative effects of the oil on seedling root growth (Murakami et al 2009). The germination percentage and the germination speed index (GSI) were determined on days 1, 4 and 7 after the beginning of the tests.…”

“…The germination percentage and the germination speed index (GSI) were determined on days 1, 4 and 7 after the beginning of the tests. On the last day, the length of the hypocotyl-radicular axis and the seedling cotyledons was measured with a manual caliper (Murakami et al 2009). The significance of the differences between means corresponding to germination percentage, GSI, hypocotyl-radicular axis and cotyledons sizes was evaluated by pairwise comparisons with the Student's t test.…”