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Tropospheric Ozone and Interspecific Competition between Yellow Nutsedge and Pima Cotton
Author(s) -
Grantz D. A.,
Shrestha Anil
Publication year - 2006
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci2005.06.0167
Subject(s) - biology , interspecific competition , shoot , competition (biology) , weed , agronomy , crop , horticulture , botany , ecology
Plant competition may be altered by ongoing climate change, including rising tropospheric O 3 This may depend less on the O 3 tolerance of isolated species than on O 3 effects on the mechanisms of competition. To explore this possibility, we investigate the growth and gas exchange responses of a crop–weed system in partial additive competition in open‐top chambers (OTCs). Yellow nutsedge ( Cyperus esculentus L.) and Pima cotton ( Gossypium barbadense L.) were grown in pots in ratios of 0:1, 1:1, 2:1, and 3:1, plus 1:0 to contrast with 0:1. O 3 concentrations (12‐h means) were 12.8 nL L −1 (low O 3 , LO3), 79.9 nL L −1 (medium O 3 , MO3), and 122.7 nL L −1 (high O 3 , HO3). Cotton was more sensitive than nutsedge to O 3 (reduction at HO3: 75 vs. 20% in shoot growth, 33 vs. 20% in assimilation). Cotton was inhibited by O 3 and by competition and the interaction was significant for leaf properties of cotton and tuber production in nutsedge. A coefficient of competition (slope of inverse cotton shoot biomass vs. nutsedge density) was significantly increased at HO3. The species were mutually inhibitory to similar extents. Root respiration declined with O 3 in nutsedge but increased in cotton, though both species reduced allocation below‐ground. Nutsedge tuber production increased inconsistently with O 3 Rising tropospheric O 3 may decrease the current C 4 advantage of nutsedge in water use efficiency (WUE) and stomatal avoidance of O 3 , but appears likely to increase the competitiveness of nutsedge with respect to cotton.