Study of Tunisian plant extracts as bioherbicide

Weeds constantly compete with crops for water and nutrient resources reducing yield, quality and consequently causing huge economic losses (Araniti et al., 2015) that can rise up to 34% in major crops (Jabran et al., 2015). Actually, the current trend is to find a biological product to minimize the perceived impacts from synthetic herbicides in agriculture production (Sbai et al., 2016). In this context, the herbicidal activity of ten crude different extracts obtained from aerial parts of Tunisian spontaneous plants was determined on post-emergence at 7.5, 20 and 34 g/L against Trifolium incanatum, sylibum marianum and Phalaris minor. Aerial plant materials were grounded and macerated with methanol for 24H. Methanol was then eliminated using a rotavapor. The yield of plant extracts varied between 5.29% and 29.71 % following the species. Extracts 6, 8, and 3 exhibit the best activity in terms of visual effect by spraying on weeds. Moreover, a formulation was carried out to improve their efficiency. The results showed that formulated E6 has completely punctured Trifolium incanatum and has inhibited growth of Phalaris minor and Sylibum marianum. A fractionation of E6 was then carried out. Five fractions were obtained and tested on Trifolium incanatum. Among these fractions, F2 formulated at 20 g/L showed a very similar effect to a commercial bioherbicide. It caused the total death of Trifolium incanatum 9 days after spraying. Based on bioassay-guided fractionation, five compounds were identified which can be employed in developing new types of bioherbicides for controlling weeds on crops. In addition, the strong weed suppressive ability of formulated F2 therefore offers interesting possibilities as an effective natural environment-friendly approach for weed management.