Weed Population and Nutrient Uptake by Wheat as Influenced by Different Tillage Practices and Weed Management Options in Ahvaz

Weeds often pose severe constraints in the potential yield of wheat, if not controlled at a critical period of the first 30 days after sowing. Several methods are developed to control weeds, viz. cultural, mechanical, and chemical have their own merits and demerits. Tillage is an age-old practice to control weeds. Tillage influences weed infestation, and thus interactions between tillage and weed control practices are commonly observed in crop production. Good tillage delays the emergence of weeds and provides a more favorable environment for early crop establishment. So, the competition for nutrients will be less.

This study was conducted to investigate the weed population and evaluate the nutrients uptake by wheat and weed in a split-plot design with three replications in the research farm of the Shahid Chamran University of Ahvaz in the year 2018-19. Tillage at three levels, including conventional tillage, minimum tillage, and zero tillage, as the main plot and weed control at six levels (uncontrolled, hand weeding, bromoxynil + MCPA herbicide, crop residue + Atlantis, Atlantis, and metribusin) as Post-emergence were considered in sub-plots applied on wheat of Mehregan cultivar.

In terms of the weed population, the highest weed population was observed in the zero tillage compared to conventional tillage and minimum tillage. In this regard, under uncontrolled treatment, the highest weed populations with an average of 16.3, 14.2, and 12.5 plants per square meter were observed at 30, 60, and 90 days after sowing, respectively. In the case of an interaction effect, it was found that in all three tillage systems, the highest amount of nutrients, including nitrogen, phosphorus, and potassium, absorbed by weeds was in the uncontrolled treatment. The reason was due to higher dry matter production and higher competition with wheat as it was incremental.

In general, considering the higher weed population in the zero tillage as compared to the conventional tillage, it seems that weed control in the zero tillage and minimum tillage, at least in Khuzestan province, is preferable to prevent moisture content and soil structure. Nutrient depletion by weed is less in conservation tillage so that nutrient availability will be as much as plant requirements.