Effect of plastic mulch and burial depth on purple nutsedge (Cyerperus rotundus) emergence and growth

Cyperus rotundus L. causes high yield losses in fruiting vegetables and cucurbits in eastern and southeastern parts of Iran. Greenhouse and field experiments were conducted to investigate the effect of mulch type (1- and 2-layer black and clear low-density polyethylene (LDPE) sheets as well as a non-mulched control) and tuber burial depth (0, 2.5, 5, 10, 20, 30, 40, and 50 cm) on C. rotundus above- and belowground growth. All experiments were conducted using three different populations from Birjand, Kahnooj, and Jiroft. It was found that the greatest suppression of C. rotundus growth in all populations was observed in plots covered with 2-layer black LDPE, so that no above- or belowground growth was found with this type of LDPEs. It was also concluded that C. rotundus can emerge from tuber burial depths in the range of 30-50 cm depending on the population studied, indicating mechanical operations that bury the tubers in soil depths even as deep as 50 cm (e.g. moldboard ploughing), cannot guarantee to suppress the emergence and tuber production of this noxious weed species. Our study clearly showed that using a 2-layer black LDPE can be recommended as a promising technique for the control of C. rotundus rather than implementing a deep tillage.