In India, dry-seeded rice (DSR) production systems are rapidly replacing conventional rice production
systems due to various advantages. DSR systems can be managed under zero-till (ZT) conditions or after a
preparatory tillage, often referred to as conventional tillage systems (CONT). Although previous reports
indicate the contribution of tillage to weed suppression, the effect of one-time preparatory tillage in a
DSR system could vary depending on the dominant weeds in the system, vertical seed distribution and
the weed seed dynamics. A study was conducted to test the efficacy of ZT and CONT and their interaction
with herbicide treatments on the weed population dynamics and rice grain yield in 2010 and 2011.
Tillage systems did not affect weed emergence, weed biomass, tiller production and crop yield. However,
herbicide treatments varied in their efficacy on individual weeds. Hand-weeding treatments and pendimethalin
combined with hand weeding did not effectively control Cyperus rotundus L. and Panicum
maximum Jacq. (a perennial grass weed with underground parts). The herbicide combination of metsulfuron
and chlorimuron was effective in controlling C. rotundus but not grass weeds. This indicates the
need for sequential applications of herbicides for grass weed control or integration of hand weeding to
achieve broad-spectrum weed control. Apart from hand weeding (three times), treatment with penoxsulamecyhalofop
and pendimethalin followed by (fb) hand weeding resulted in low weed density, high
tiller production and grain yield. The study clearly indicates that tillage does not always lead to weed
suppression compared with ZT, and herbicides must be chosen based on the dominant weeds in a
system. The results of this study are pertinent as herbicide-resistant weeds are rapidly evolving under
continuous herbicide selection pressure, which warrants studies on enhancing productivity through lowinput,
environmentally friendly and sustainable production technology.