Nearly all crops respond to increases in the air's CO2 content by displaying enhanced rates of photosynthesis and biomass production; and in this brief review of some recent pertinent papers, we find that tomato (Lycopersicon esculentum Mill.) is no exception to the rule.
In the study of Ziska et al. (2001), tomato plants grown at a nocturnal atmospheric CO2 concentration of 500 ppm displayed total plant biomass values that were 10% greater than those exhibited by control plants growing in air containing 370 ppm CO2. This result was likely the consequence of the elevated CO2 reducing the rate of nocturnal respiration in the plants, which would have allowed them to utilize the retained carbon to produce more biomass.
This CO2-induced benefit, as well as a host of other positive effects of atmospheric CO2 enrichment, are also manifest under unfavorable growing conditions. Jwa and Walling (2001), for example, reported that fungal infection reduced plant biomass in tomatoes growing in normal air by about 30%. However, in fungal-infected plants grown at twice-ambient atmospheric CO2 concentrations, the elevated CO2 completely ameliorated the growth-reducing effects of the pathogen.
In another stressful situation, Maggio et al. (2002) reported that a 500-ppm increase in the air's CO2 concentration increased the average value of the root-zone salinity threshold in tomato plants by about 60%. In addition, they reported that the water-use efficiency of the CO2-enriched plants was about twice that of the ambiently-grown plants.
In summary, as the CO2 content of the air increases, tomato plants will likely display greater rates of photosynthesis and biomass production, which should consequently lead to greater fruit yields, even under stressful conditions of fungal infection and high soil salinity.
For more information on tomato growth responses to atmospheric CO2 enrichment see Plant Growth Data: Tomato (dry weight, photosynthesis).
References
Jwa, N.-S. and Walling, L.L. 2001. Influence of elevated CO2 concentration on disease development in tomato. New Phytologist 149: 509-518.
Maggio, A., Dalton, F.N. and Piccinni, G. 2002. The effects of elevated carbon dioxide on static and dynamic indices for tomato salt tolerance. European Journal of Agronomy 16: 197-206.
Ziska, L.H., Ghannoum, O., Baker, J.T., Conroy, J., Bunce, J.A., Kobayashi, K. and Okada, M. 2001. A global perspective of ground level, 'ambient' carbon dioxide for assessing the response of plants to atmospheric CO2. Global Change Biology 7: 789-796.