Crop Science (2005) 45, 1587-1595

Anil Shrestha and D.A. Grantz (2005)
Ozone impacts on competition between tomato and yellow nutsedge above- and below-ground effects
Crop Science 45 (4), 1587-1595
Abstract: Tomato (Lycopersicon esculentum L.) production in the San Joaquin Valley (SJV) of California is challenged by air pollution and weeds. Differential ozone (O₃) tolerance of tomato cultivars and weed species may alter crop-weed competition. A study was conducted in open top chambers (OTCs) at the Kearney Research and Extension Center, Parlier, CA, to assess O₃ impacts on competition between tomato and a C₄ weed, yellow nutsedge (Cyperus esculentus L.). Processing tomato (cv. HD 8892 and EMP 113) and nutsedge (locally collected biotypes) were grown in pots for 4 to 8 wk. Population ratios ranged from a tomato plant alone (0:1) to a nutsedge plant alone (1:0), and included 1:1, 2:1, and 3:1. Ozone exposures were to 12 h means of 19.8, 78.0, and 142.3 nL/L. Chlorophyll content of leaves of tomato and nutsedge was reduced with increasing O₃. Carbon assimilation was reduced in nutsedge but not in tomato. Root respiration was not affected in either species. Tomato main stem length, shoot, and root biomass declined at the highest O₃ concentration under all levels of nutsedge competition. Nutsedge was much less affected. In the absence of O₃ exposure, interspecific competition (all population ratios combined) reduced tomato and nutsedge shoot and root biomass. Tomato was more sensitive to O₃ than nutsedge, but nutsedge was more sensitive to competition than was tomato. Nutsedge allocated greater resources to reproductive structures (tubers) at the highest O₃ exposure. As nutsedge reduced tomato productivity under low and moderate O₃ concentrations, it may become even more difficult to control, exert greater competitiveness, and colonize fields more rapidly because of greater tuber production, in projected near-future environments. Under conditions of greatly increasing ambient O₃ concentrations, nutsedge may become less competitive because of its sensitivity to O₃.
(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): Anil Shrestha, David A. Grantz

Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation
damage/losses/economics

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Cyperus esculentus (weed)	Tomato (Solanum lycopersicum)