Interference and economic threshold level of little seed canary grass in wheat under different sowing times

Abstract

Little seed canary grass (LCG) is a pernicious weed of wheat crop causing enormous yield losses. Information on the interference and economic threshold (ET) level of LCG is of prime significance to rationalize the use of herbicide for its effective management in wheat fields. The present study was conducted to quantify interference and ET density of LCG in mid-sown (20 November) and late-sown (10 December) wheat. Experiment was triplicated in randomized split-plot design with sowing dates as the main plots and LCG densities (10, 20, 30, and 40 plants m(-2)) as the subplots. Plots with two natural infestations of weeds including and excluding LCG were maintained for comparing its interference in pure stands with designated densities. A season-long weed-free treatment was also run. Results indicated that composite stand of weeds, including LCG, and density of 40 LCG plants m(-2) were more competitive with wheat, especially when crop was sown late in season. Maximum weed dry biomass was attained by composite stand of weeds including LCG followed by 40 LCG plants m(-2) under both sowing dates. Significant variations in wheat growth and yield were observed under the influence of different LCG densities as well as sowing dates. Presence of 40 LCG plants m(-2) reduced wheat yield by 28 and 34% in mid- and late-sown wheat crop, respectively. These losses were much greater than those for infestation of all weeds, excluding LCG. Linear regression model was effective in simulating wheat yield losses over a wide range of LCG densities, and the regression equations showed good fit to observed data. The ET levels of LCG were 6-7 and 2.2-3.3 plants m(-2) in mid- and late-sown wheat crop, respectively. Herbicide should be applied in cases when LCG density exceeds these levels under respective sowing dates.

Crop Growth and Yield Losses in Wheat Due to Little Seed Canary Grass Infestation Differ with Weed Densities and Changes in Environment

“…However, an interesting aspect of this study was the higher growth reduction under higher LCG density even when compared with UWC in late sowing. This trend might be due to the fact that LCG offers worse competition to less vigorous late-sown wheat (SD 2 ) as compared with the mixed weed flora under same conditions (Hussain et al, 2015).…”

“…Better leaf growth in SD 1 and WFC as compared with SD 2 and plots having different densities of LCG, UWC, or UWC-LCG lead to higher CGR, LAD, and TDM. Later these improved growth attributes also reflected in the form of better yield attributes and yield (Hussain et al, 2015). The NAR of a crop represents the net photosynthetic rate per unit LAD.…”

“…Weeds can incur a grain yield loss of 48% in wheat (Khan and Haq, 2002). However, the magnitude of weed-related losses depends on the type and density of a particular weed species, its time of emergence, and the duration of the interference (Estorninos et al, 2005;Hussain et al, 2015;Fahad et al, 2015). Crop yield usually declines with increased weed density and interference duration and yield losses are more severe when resources are limited and weeds and crops emerge simultaneously (Zimdahl, 2007).…”

“…Wheat and LCG have similar growth habits and adaptations to winter cropping regimes and any mismanagement in input usage can shift the advantage in favor of weeds (Hussain et al, 2015). In the context of global climate changes, LCG is supposed to inflict more interference on wheat due to its higher resource use efficiency and vigorous growth in response to elevated CO 2 level.…”

Wheat Residue Incorporation Modulate Emergence and Seedling Growth of Canary Grass by Affecting Biochemical Attributes and Soil Properties

“…In agriculture, the suppressive allelopathic effects can be exploited for sustainable pest and weed control (Khanh et al, 2005). It is novel approach offering multiple solutions to overcome problems decreasing food availability under rising global population (Hussain et al, 2014).…”