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Citral is a monoterpene commonly found as volatile component in many different aromatic plants. Although many studies have identified the presence of citral in phytotoxic essential oils, this work determines for the first time the potential herbicidal effect of citral on weeds. The use of citral against weeds and crops resulted in the potential for the management of barnyardgrass, redroot pigweed, and ribwort. Clear morphological differences were observed between adult thale cress plants exposed to citral in two different application methods: spraying and watering. Citral-sprayed and citral-watered thale cress plants showed completely different effects after treatment, suggesting that foliar or root absorption can determine the effectiveness of this compound. This work demonstrates that citral is effective not only on seedling metabolism but also on adult plants by inhibiting growth and development altering the plant oxidative status.
Nomenclature: Citral, 3,7-dimethyI-2,6-octadienaI, CAS 5392-40-5; barnyardgrass, Echinochloa crus-galli L. (Beauv.) ECHICRU; redroot pigweed, Amaranthus retroflexus L. AMARE; buckhorn plantain, Plantage lanceolata L. PLANLAN; thale cress, Arabidopsis thaliana L. ARATH.
Key words: Monoterpene, spraying, watering, phytotoxicity, weed management.
Weed control has always been an important area of study due to the negative influence that weed species have on crop productivity. The overuse of synthetic herbicides has resulted in the increase of soil and water contamination, loss of biodiversity and the appearance of many herbicide-resistant species, which makes weed control even more difficult. Although this could have been the trigger for seeking alternatives to synthetic chemical control, the appearance of genetically engineered herbicide-resistant crops has resulted in a dramatic increase in the use of synthetic chemicals, rather than a decrease (Owen 1997). Moreover, previous studies, mainly done with commercial herbicides, have demonstrated the increasing sensitivity or resistance of different treated plants to the applied herbicides depending on the application procedure (deBoer et al. 2011; Concenço et al. 2009).
Plants produce a large number of phytotoxins, which could potentially be used as herbicides (Duke et al. 2002). In the last few years, many efforts have been devoted to determine their mechanisms of action, a difficult task due to the many possible molecular targets they have. This apparently overwhelming task does, however, also present an opportunity for discovering new sites of action (Dayan et al. 2000), which will also depend on how...