Journal of Food, Agriculture and Environment

Interference of redroot pigweed (Amaranthus retroflexus L.) in sunflower hybrids

Author(s):

Bahram Mirshekari *, Sahar Baser Kouchebagh, Negar Valizadeh, Arezoo Mirmozaffari Roudsari

Recieved Date: 2010-06-09, Accepted Date: 2010-10-20

Abstract:

In evaluation of redroot pigweed (Amaranthus retroflexus L.) interference effect on sunflower (Helianthus annuus L.) an experiment was performed in a randomized complete block design with three replications and three factors with a factorial combinations including redroot pigweed density (D₁=8.3, D₂=25 and D₃=41.7 weeds/m²), time of redroot pigweed emergence (I₁=emerged simultaneously with sunflower; I₂=15 and I₃=30 days after sunflower emergence) and sunflower cultivar (Azarghol, Hysun 33 and Allstar RM). Redroot pigweed plants were provided from two-leaves weed seedlings sown in tissue pots in greenhouse condition. Results showed that when redroot pigweeds were emerged along with sunflower, stem height of sunflower decreased. In full season competition of 41.7 weeds/m², leaf area index decreased from 4.57, 4.20 and 3.90 in control plots to 3.69, 3.12 and 2.56 in Azarghol, Hysun and Allstar, respectively. In Allstar variety, redroot pigweed density was more effective than it’s interference time with a view to effect on sunflower leaf area index. Azarghol could tolerate 8.3 weeds/m² at 15 days and 41.7 weeds/m² at 30 days after sunflower emergence, without any significant reduction in grain yield. Allstar, on the other hand, experienced higher yield loss as compared to Azarghol and Hysun. The model of Cousens was suitable for yield estimation of Hysun and Allstar hybrids, but the model of Cousens et al. ⁶ was the best description for the yield of Azarghol at interference with redroot pigweed. In Hysun and Allstar, none of the studied treatments could produce similar yields with control plots.

Keywords:

Interference, leaf area index, redroot pigweed, sunflower, yield estimation

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Journal: Journal of Food, Agriculture and Environment
Year: 2010
Volume: 8
Issue: 3&4
Category: Agriculture
Pages: 810-814

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