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Ozone Impacts on Competition between Tomato and Yellow Nutsedge

Above- and Below-Ground Effects

^a Statewide Integrated Pest Management Program, Univ. of California, Kearney Agric. Center, 9240 South Riverbend Ave., Parlier, CA 93648
^b Dep. of Botany and Plant Sciences, Univ. of California, Riverside, CA, and Kearney Agric. Center, 9240 South Riverbend Ave., Parlier, CA 93648

View larger version (23K): [in a new window]   Fig. 1. Effect of ozone exposure on leaf chlorophyll concentration of (A) tomato leaves of different insertion levels (combined across all population ratios of nutsedge:tomato) and (B) exposed nutsedge leaves. Points (means) within a line associated with the same letter do not differ at P 0.05.

View larger version (24K): [in a new window]   Fig. 2. Effect of ozone exposure on photosynthetic carbon assimilation of (A) mature leaves, and (B) respiration of fine roots of tomato (circles) and nutsedge (squares). Mean separation as in Fig. 1.

View larger version (20K): [in a new window]   Fig. 3. Effect of ozone exposure on growth of tomato as (A) main stem length averaged over all population ratios of nutsedge:tomato, and (B) leaf area in the absence (open circles) or presence (averaged over all population ratios; solid circles) of nutsedge competition. Mean separation as in Fig. 1. In (B) ozone effects within lines were not significant, but weed competition effects between lines were significant.

View larger version (24K): [in a new window]   Fig. 4. Effect of ozone exposure on development of above-ground biomass of (A) tomato (shoot) and (B) nutsedge (shoot minus rhizomes and tubers). Open circles represent each species grown alone. Closed symbols represent the levels of competition specified as population ratio of nutsedge:tomato. Mean separation as in Fig. 1.

View larger version (21K): [in a new window]   Fig. 5. Effect of ozone exposure on development of below-ground biomass of tomato (circles; roots) and nutsedge (squares; roots plus rhizomes and tubers) grown alone. Mean separation as in Fig. 1.

View larger version (26K): [in a new window]   Fig. 6. The relative sensitivity to ozone exposure of (A) above-ground biomass, (B) below-ground biomass, and (C) ratio of above: below-ground biomass (defined as in Fig. 5) at harvest in tomato (circles) and nutsedge (squares) grown alone. Mean separation as in Fig. 1.

View larger version (20K): [in a new window]   Fig. 7. Effect of weed pressure on tuber production in nutsedge at three levels of ozone exposure. Mean separation as in Fig. 1.