Want Better Tomatoes? Add Carbon Dioxide and a Pinch of Salt!

Who isn’t nuts about fresh tomatoes plucked from a garden at the peak of ripeness? And who doesn’t bask in the adulation of those to whom we give them?

According to work recently published by Maria Sanchez-González et al. (2015), the more years you garden, the more tasty your tomatoes are likely to get, as atmospheric carbon dioxide increases. And, if you add a pinch of salt to the soil, they’ll taste even better.

Here’s the story:

The authors note “the South-Eastern region of Spain is an important area for both production and exportation of very high quality tomatoes for fresh consumption.” This is primarily due to favorable growing conditions such as a mild climate, good soils and saline waters that promote “exceptional fruit quality of some varieties,” including the Raf tomato hybrid. However, Sánchez-González et al. additionally note that, “despite the high value of Raf tomatoes in the Spanish national market, their productivity is relatively low and the consumer does not always get an acceptable quality, often because the fruit growth conditions, mainly thermal and osmotic, were not adequate.” Against this backdrop, the team of six researchers set out to determine if they could improve the production value of this high value commercial crop by manipulating the environmental conditions in which the tomatoes are grown. To accomplish this objective, they grew hybrid Raf tomato plants (Lycopersicon esculentum Mill. cv. Delizia) in controlled environment greenhouses at two salinity levels (low and high) under ambient (350 ppm) and elevated (800 ppm) CO₂ concentrations. Then over the course of the growing season, and at harvest, they measured several parameters related to the growth and quality of the hybrid tomatoes. And what did their analysis of those measurements reveal?

According to the researchers, the high salinity treatment “increased firmness, total soluble solids content, titratable acidity and the percentage of dry matter of the fruit,” leading them to conclude that the high salinity growth medium “is necessary to obtain high quality tomato fruits.” However, this benefit did not come without a price, as higher salinity decreased marketable yield (47% less), fruit numbers (9.5% less), and average weight of the fruits (19% less) when compared to tomatoes grown under low salinity conditions. With respect to CO₂, elevated levels increased tomato yield, fruit numbers and average weight of the fruits in the low salinity treatment, and they reduced the deleterious effects of salinity on these measures in the high salinity treatment. Additionally, elevated CO₂ shortened the time required for fruit development by two days and it had little to no effect on fruit quality. Consequently, the authors conclude by stating “the results of this work suggest that the utilization of a [high salinity] nutrient solution … is necessary to obtain high quality tomato fruits and CO₂ application increases its production,” while adding “CO₂ enrichment allows increase in the production of a high value commercial crop grown under saline conditions by reducing the time needed for complete fruit development without compromising organoleptic quality.”

In the future, therefore, the Spanish national market of hybrid Raf tomatoes will benefit thanks to the ever-increasing CO₂ concentration of the atmosphere. And so will home gardeners.

In addition to what Sanchez-Gonzalez et al. recently published, research done by Joseph Heckman at Rutgers (the State University of New Jersey and the name of a popular and very tasty heirloom tomato) shows that tomatoes grown in sea water (or the commercially-available equivalent for aquarium use) taste better. Further research has shown that this effect isn’t just limited to commercial varieties. It’s been tested on Burpee’s widely grown Early Girl, which contains much of the genetic material from their “boy” series (Big Boy, Better Boy, Lemon Boy, Brandy Boy, etc…), so that it looks like the flavor enhancement will occur across a wide spread of varieties.

And, as has been shown repeatedly in crop and plant science, the additional CO₂ is a cost-free enhancer of crop yields, including tomatoes. In combination with saline water, you’ll get more and even better tomatoes, and even more adulation for your tasty fruits.

Reference

Sánchez-González, M.J., Sánchez-Guerrero, M.C., Medrano, E., Porras, M.E., Baeza, E.J. and Lorenzo, P. 2015. Influence of pre-harvest factors on quality of a winter cycle, high commercial value, tomato cultivar. Scientia Horticulturae 189: 104-111.

Also, see: http://www.growingformarket.com/articles/Improve-tomato-flavor