Weed Seed Bank and Dynamics of Weed Flora as Influenced by Tillage and Weed Control Methods in Maize (Zea Mays L.)

To study the effect of tillage and weed control methods on weed seed bank and composition of weed flora in maize (Zea mays L.), a field experiment was conducted at CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur during Kharif seasons of 2002 and 2003. The weed seed bank study revealed that while raised seedbed resulted in lowest number of seeds of D. sanguinalis, E. colona and P. dichotomiflorum at 0–10 cm depth, their population was reduced to a lowest level by zero tillage at 10–20 cm and 20–30 cm soil depths. However, lowest number of C. benghalensis seeds was recorded in zero tillage at all the soil depths. Dynamics of weed flora followed the trend of weed seed distribution in the soil and resulted in significantly lowest population and dry matter of D. sanguinalis, E. colona and B. ramosa in raised seedbed and of C. benghalensis in zero tillage plots. Conventional tillage was the next best in significantly reducing the population and dry matter of D. sanguinalis and C. benghalensis, thereby being statistically at par with raised seedbed significantly increased the grain yield of the maize. Atrazine 1.5 kg ha⁻¹ being at par with acetachlor 1.25 kg ha¹ resulted in significantly lower count and dry matter of D. sanguinalis, E. colona, Commelina benghalensis and other weeds. Aceatchlore 1.25 kg ha⁻¹ gave complete control of B. ramosa. Consequently, atrazine and acetachlor increased the grain yield of maize by 75.2 and 71.7 per cent, respectively over unweeded check.