Weed Research (2009) 49, 217-224

J.G. Liu, K.J. Mahoney, P.H. Sikkema and C.J. Swanton (2009)
The importance of light quality in crop-weed competition
Weed Research 49 (2), 217-224
Abstract: Plant competition is thought to be driven by limiting resources. We propose that plant competition is triggered initially by the red to far-red light ratio (R:FR) originating from neighbouring plants, followed by a series of complex physiological processes, which exclude direct resource competition. Field experiments were conducted in 2005 and 2006 in which maize (Zea mays) was grown hydroponically. The effect of R:FR signal being reflected from the leaf surface of Amaranthus retroflexus was isolated by avoiding direct competition for light, water and nutrients. Results showed that the low R:FR reflected from the leaf surface of A. retroflexus did alter the carbon allocation pattern of maize when compared with maize growing free of weeds. Prior to silking, maize grown under low R:FR experienced temporal changes in plant height, persistent changes throughout the sampling period in root and shoot dry weights and rate of leaf appearance, but no changes in leaf area. At silking, low R:FR reduced ear and total plant dry weight. These results support the hypothesis that changes in R:FR acts as an early signal of pending competition by initiating a shade avoidance response. Data from this experiment suggest that once a plant is physiologically triggered into a shade avoidance response, these plants do so at a physiological cost, which may constrain plant development and possibly reduce reproductive fitness.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Clarence J. Swanton, Kris J. Mahoney

Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Amaranthus retroflexus (weed)	Maize/corn (Zea mays)