Potencial alelopático de extratos de plantas sobre espécies cultivadas e daninhas

Abstract

Weeds are a major cause of economic losses in crops, they are spending a lot of resources and efforts to manage infestations of these species. Improper management of these species may result in loss of quality of economic crops and reduced productivity. For its control the most widely used method is the chemical control with herbicides because they are readily available and require little manpower. The large scale use of active herbicide resistance of plants is generated, and environmental problems. In this sense alternative methods for weed control is becoming more popular. This study aimed to identify plant species that have allelopathic compounds with potential for producing mycoherbicides. The experiment consisted of two trials, arranged in a completely randomized design. The first experiment involved the canola extracts (Brassica napus), radish (Raphanus sativus), ryegrass (Lolium multiflorium), vetch (Vicia sativa), jack-bean (Canavalia ensiformis), timbó (Ateleia glazioviana), castor bean (Ricinus communis L.), maria-mole (Senecio brasiliensis), velvet bean (Mucuna Puriens), sunn hemp (Crotalaria juncea) and pigeon pea (Cajanus cajan) 20% of the seed germination black-jack (Bidens pilosa), lettuce (Lactuca sativa) and cucumber (Cucumis sativus). The second were tested doses of 0 kg / m2; 1.65 kg / m2; 3.31 kg / m2; 8.26 kg / m2; 16.53 kg / m2; 41.32 kg / m2; 82.64 kg / m2 in lettuce seedlings, cucumber, beggarticks and sorghum (Sorghum sudanense). The seeds and seedlings were kept in germination camera. Evaluations of seeds were carried out 7 days and seedling two days after the application of the extracts. In the first experiment, the extracts of three canola cultivars, rye, vetch and castor reduced in 100% germination of lettuce. Germination beggar-ticks was reduced by more than 80% by extracts of canola cultivars, ryegrass, maria-mole, castor beans, crotalaria and vetch. For germination of cucumber extract which had more effect was to sunn hemp, reducing by 39% seed germination. In the second trial were obtained phytotoxic effects on black-jack and sorghum, lettuce and cucumber seedlings suffered no significant effects. Data were submitted to analysis of variance and means compared by Tukey test and Duncan at 5% significance level. It is necessary to conduct more research on techniques that allow the concentration of the extract.