Contents lists available at ScienceDirect Industrial Crops & Products journal homepage: www.elsevier.com/locate/indcrop Research Paper Phytotoxicity and cytotoxicity of Citrus aurantiifolia essential oil and its major constituents: Limonene and citral Saroj Kumari Fagodia a , Harminder Pal Singh b, ⁎ , Daizy Rani Batish a, ⁎ , Ravinder Kumar Kohli a,c a Department of Botany, Panjab University, Chandigarh, 160014, India b Department of Environment Studies, Panjab University, Chandigarh, 160014, India c Central University of Punjab, Bathinda, India ARTICLE INFO Keywords: Allium cepa Cytotoxicity Mitotic index Monoterpenes Natural herbicide Phytotoxicity ABSTRACT The essential oils are fast emerging as the source of natural herbicides owing to their environmentally benign properties. The focus of the present study, thus, was to investigate the phytotoxicity and cytotoxicity of Citrus aurantiifolia oil, and its major constituents-citral and limonene. C. aurantiifolia oil was selected due to its extreme commercialisation and safe nature. GC–MS analysis revealed that C. aurantiifolia oil is rich in monoterpenes (83.93%), with limonene (40.92%) and citral (27.46%) as the major compounds. Phytotoxicity was assessed against three agricultural weeds, Avena fatua, Echinochloa crus-galli and Phalaris minor, at concentration ranging from 0.10–1.50 mg/ml. Percent germination, IC 50 value and seedling growth (root and coleoptile length) were significantly reduced in a dose-response manner. C. aurantiifolia oil, citral and limonene caused alteration in the cell cycle of Allium cepa root meristematic cells as evidenced by decrease in mitotic index (MI) and increase in chromosomal aberrations at progressive concentrations (0.01–0.10 mg/ml) and time periods (3 h and 24 h). Cytotoxic evaluation confirmed mitodepressive effect of the tested volatiles though the intensity was variable. Overall, citral was the most toxic followed by C. aurantiifolia oil and limonene. The significant phytotoxic ac- tivity of C. aurantiifolia oil and citral suggests the possibility of being developed into eco-friendly and acceptable products for weed management in agriculture system. 1. Introduction The extensive use of synthetic herbicides has increased environ- mental pollution, toxicological implications to human health and the risk of development of resistance/cross-resistance among weed species (Dayan and Duke, 2014). From the agricultural perspective, increasing resistance among weeds is a matter of serious concern. Of late, due to increased consumer concerns and need for safe food production, more emphasis is laid on the search for environment-friendly and safer her- bicides (Dayan et al., 2009). Alternative green measures such as natural plant products have, therefore, been evaluated as next-generation herbicides and crop protectants (Duke, 2014). These products exhibit great structural diversity, generally lack halogens, possess short en- vironmental half-lives and novel molecular target sites (Dayan et al., 2009). Their use not only offers a solution for sustainable agriculture but also safeguard human health and the ecosystem (Dayan and Duke, 2014). Among these, essential oils and their main components can be exploited as valuable tools for integrated pest management in organic agriculture (Batish et al., 2008; Dayan et al., 2009; Kordali et al., 2015; Isman, 2016). These possess environmentally benign properties, and are generally regarded as safe (GRAS) chemicals (Isman, 2000; Tworkoski, 2002). Some of the essential oils like citronellal-rich eucalypt oil of Eucalyptus citriodora (Singh et al., 2005), eugenol-rich clove oil of Eu- genia caryophyllus (Stoklosa et al., 2012) and manuka oil of Leptos- permum scoparium rich in leptospermone (Dayan et al., 2011) possess good weed suppressing potential. Since their use for weed management seems to be promising, it is worthwhile to screen essential oils from commonly gown plants. Citrus aurantiifolia (Christm.) Swingle, commonly known as key lime, is a shrubby tree cultivated extensively in hot subtropical and tropical regions of the world including India (Morton, 1987). Its es- sential oil is one of the major commercial products and has a long history of human consumption. It is widely used as a source of anti- oxidant, flavouring agent in food products and pharmaceutical industry (Chamblee et al., 1997). In fact, the citric industry is one of the world’s largest agro-industry and the essential oils obtained from different varieties of citrus are gaining interest, largely due to their relatively safe nature and worldwide acceptance by consumers (Sawamura, 2000). C. aurantiifolia oil possesses antimicrobial, fungicidal and insecticidal property that suggests its potential in the development of broad http://dx.doi.org/10.1016/j.indcrop.2017.07.005 Received 16 March 2017; Received in revised form 24 May 2017; Accepted 2 July 2017 ⁎ Corresponding authors. E-mail addresses: hpsingh_01@yahoo.com (H.P. Singh), daizybatish@yahoo.com, daizybatish@gmail.com (D.R. Batish). Industrial Crops & Products 108 (2017) 708–715 0926-6690/ © 2017 Elsevier B.V. All rights reserved. MARK