Paper Reviewed
Sanchez-Gonzalez, M.J., Sanchez-Guerrero, M.C., Medrano, E., Porras, M.E., Baeza, E.J. and Lorenzo, P. 2016. Carbon dioxide enrichment: a technique to mitigate the negative effects of salinity on the productivity of high value tomatoes. Spanish Journal of Agricultural Research 14: e0903.

In a study conducted in two adjacent greenhouses covered with polyethylene plastic film at La Mojonera, Almeria, Spain -- which were equipped with a pipe water heating system, roof and sidewall vents, external mobile shading screen and a system for the injection of pure CO2 -- the six Spanish scientists grew hybrid Raf tomato plants (Solanum lycopersicum L. cv. Delizia) that they grafted onto cv. Rambo plants of the same species. In both greenhouses these plants were supplied with a nutrient solution adjusted to two salinity levels -- 5 dS/m (EC5) and 7 dS/m (EC7) -- by adding 25 mM and 45 mM of NaCl, respectively, to the irrigation water that was supplied to the plants throughout the subsequent 203 days of the study.

This increase in salinity, in the words of Sanchez-Gonzalez et al., "negatively affected the leaf area index, the specific leaf area, the water use efficiency, the radiation use efficiency and dry weight accumulation" of the tomato plants, resulting in "lower marketable yield." However, and this is a very important "however," they also report that "radiation use efficiency and dry weight accumulation were increased [by CO2 enrichment of the greenhouse air], resulting in higher marketable yield, through positive effects on fruit number and their average weight."

In light of these several very positive findings, the six Spanish scientists write -- in the concluding sentence of their paper -- that "adequate climate management, through greenhouse CO2 enrichment based on a strategy linked to ventilation, could have an important and positive influence in mitigating the negative effect of salinity on productivity of this high value cultivar without compromising fruit quality."