Investigation of morpho-physiological and biochemical characteristics of forage corn (Zea mays L.) cultivars in response to weeds competition and different herbicide concentrations of tribenurone methyl

Weeds compete with crop for growth resources and more competitive species will receive more resources.

In order to investigate the effect of tribenuron methyl on growth, physiological and biochemical characteristics of two forage corn cultivars and characteristics of field weeds, a factorial experiment was conducted in a randomized complete block design with three replications at the Research Farm, Faculty of Agriculture, Tarbiat Modares University in 2017. The factors consisted of four doses of tribenuron methyl in soil (0, 20, 40 and 60 g ha-1) and two corn cultivars (N.S 640 and SC 704). Each block included 10 plots and each plot consisted of eight rows and one row without plant between plots. To evaluate the characteristics of weeds, a weed free (hand weeding) plot (alone corn), and a plot without corn were also considered in each replication.

The results showed that over time, weed leaf area index increased and total weed density increased until the middle of the growth period and then decreased. Common purslane (Portulaca oleracea) and red-root pigweed (Amaranthus retroflexus) were the dominant weeds in the fields. The main effect of cultivar and interaction between herbicide concentration and cultivar was not significant in all traits and only the main effect of herbicide concentration was significant.

In general, the results showed that in all forage corn cultivars, the use of 60 g tribenuron methyl ha-1 caused better weed control and reduced competition, increased chlorophyll content, pigment activity and plant photosynthetic rate,