Crop Protection 133 (2020) 105162 Available online 26 March 2020 0261-2194/© 2020 Elsevier Ltd. All rights reserved. Using sorghum to suppress weeds in autumn planted maize Muhammad Farooq a, b, c, * , Ismail Khan b , Ahmad Nawaz d , Mumtaz A. Cheema e , Kadambot H. M. Siddique c a Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Quboos University, Al-Khoud 123, Oman b Department of Agronomy, Faculty of Agriculture, University of Agriculture, Faisalabad, 38040, Pakistan c The UWA Institute of Agriculture, The University of Western Australia, LB 5005, Perth, WA, 6001, Australia d College of Agriculture, Bahauddin Zakariya University, Bahadur Sub-Campus, Layyah, 31200, Pakistan e Memorial University Grenfell Campus, 20 University Drive, Corner Brook, NL, Canada A R T I C L E INFO Keywords: Cereals Allelopathy Sorghum mulch Crop rotation Crop water extracts ABSTRACT Weeds reduce the yield of maize (Zea mays L.) by utilizing the available resources such as water, nutrient and space. The phenomenon of allelopathy offers pragmatic option to suppress weeds in cereals including maize. This study was conducted to evaluate the weed suppression potential of sorghum in maize sown on beds or fat felds in post-sorghum and fallow plots. Sorghum-based weed management treatments included: i) control, ii) sorghum mulch (SM) at 8 t ha 1 , iii) sorghum water extract (SWE) at 18 L ha 1 , and iv) SM þ SWE. The post-sorghum planted maize had signifcantly lower density (23.1%) and biomass (23.6%) of weeds than post-fallow planted maize. Weed density and dry biomass was 17.2% and 18.1% less in bed-sown maize than the fat-sown maize, respectively. Application of sorghum based treatments signifcantly reduced weed infestation in both maize cropping systems, however, combined application of SM and SWE in post sorghum bed-sown maize was the most effective treatment. Bed-sown maize planted in post-sorghum plots produced higher grain yield than post-fallow bed-sown maize or post-sorghum/post-fallow fat-sown maize. The treatment SM þ SWE produced the taller plants and had more number of grains per cob, higher seed weight, grain and biological yields, and harvest index in post sorghum bed-sown wheat than other sorghum based treatments. In conclusion, the combined application of SM þ SWE in bed-sown maize in post-sorghum felds provided fair control of weeds and increased maize grain yield. 1. Introduction Weeds interfere with crop growth cascades by utilizing water, nu- trients and space (Zimdahl, 2013), and can cause yield losses up to 34% in major feld crops, which is greater than that caused by other crop pests (Jabran et al., 2015). Like other crops, weeds are a major threat to proftable maize (Zea mays L.) production (Oerke, 2006). The magnitude of the yield losses caused by weeds depends on weed density, duration of weed competition and weed species (Dalley et al., 2006). In Pakistan, crowfoot grass [Dactyloctenium aegyptium (L.) Willd.], puncture vine (Tribulus terrestris L.), bermuda grass [Cynodon dactylon (L.) Pers.), Pall.] and purple nutsedge (Cyperus rotundas L.) have emerged as major weed species that infest maize crop (Tahir et al., 2009). Synthetic herbicides are powerful agents used to control weeds in various crops. However, un-wise use of synthetic herbicides can perturb the ecosystem and cause health-related issues. Repetitive use of herbicides having same mode of action can result in herbicide-resistant weed biotypes (Bhowmik and Inderjit, 2003). Manual weed control is an effective technique for weed management, but is labor intensive, tire- some and slow. The looming labor crisis is driving weed scientists to fnd new methods of weed management (Carballido et al., 2013; Gianessi, 2013). Weed control through mechanical means is less common in Pakistan due to the lack of suitable weed control machinery. Allelopathy is regarded as a naturally occurring ecological phe- nomenon in which the allelochemicals released by the plants and mi- croorganisms affects the growth cascades of other plants and microorganisms (Farooq et al., 2011; Cheng and Cheng, 2015). The activity of allelochemicals is concentration dependent; they promote growth at low concentration and retard growth at high concentration (Nawaz et al., 2018). Indeed, the released allelochemicals from plants and microorganism affect nutrient chelation, plant defenses, microbial activities and soil fertility (Inderjit et al., 2011; Cheng and Cheng, 2015) * Corresponding author. Department of Plant Sciences, College of Agricultural and Marine Sciences, Sultan Quboos University, Al-Khoud 123, Oman. E-mail addresses: farooqcp@gmail.com, farooqcp@squ.edu.om (M. Farooq). Contents lists available at ScienceDirect Crop Protection journal homepage: www.elsevier.com/locate/cropro https://doi.org/10.1016/j.cropro.2020.105162 Received 27 May 2019; Received in revised form 4 March 2020; Accepted 20 March 2020