BIOEXTRACT ACTIVITY IN THE DEVELOPMENT OF PHOMOPSIS PHASEOLI VAR. SOJAE, FUSARIUM SP. AND IN THE TREATMENT OF SOYBEAN SEEDS

Abstract

Plant diseases cause high economic liabilities. They affect plants on the field and seeds during storage. Different techniques for the control of pathogens are employed to minimize negative impacts. Bio-extracts are alternatives when compared to conventional chemical control. Current analysis evaluates in vitro and in vivo anti-fungus activity of extracts of jatropha (Jatropha curcas L.), cypress (Cupressus sp.), nutsedge (Cyperus rotundus L.), garlic (Allium sativum L.), onion (Allium cepa L.) and ginger (Zingiber officinalis L.), in different processes, against Phomopsis phaseoli var. sojae, Fusarium sp., and their influence on germination and vigor of soybean seeds. Bio-extracts were prepared with 40 g of the plants (in natura and dried at 55±2°C) and a water-methanol solution (1:3). After filtering and the evaporation of the alcohol, the extracts were divided into two fractions: one was autoclaved and both were applied to isolates of pure cultures directly on the soybean seeds. Drying improved the efficiency of garlic, onion and ginger bio-extracts in in vitro control of Phomopsis phaseoli var. sojae, whereas cypress and jatropha bio-extracts were less efficient. Autoclave caused the loss of the fungus-toxic capacity of garlic, whereas it affected negatively onion seed vigor at 10% v/v. Non-autoclaved dry garlic extract controlled efficaciously the in vitro development of Phomopsis phaseoli var. sojae. The other bio-extracts failed to have any significant efficiency on pathogen control. All bio-extracts provided soybean seeds a lower germination rate when compared to treatment with Carbendazin+Tiran. Non-autoclaved onion and ginger bio-extracts and dehydrated nutsedge significantly improved the percentage of normal seedlings when compared to control. However, bio-extracts failed to decrease contamination rate of seeds for Fusarium spp. and Phomopsis phaseoli var. sojae. Auto-clave is, therefore, an important stage and affects differently the efficiency of the bio-extracts analyzed and the drying process of the vegetal material prior to the preparation of the bio-extracts.