Fan et al. (2020) -- CO2 fertilization increases bell pepper growth up to 39%, and water use efficiency by up to 100%

 Source:

http://www.co2science.org/articles/V23/nov/a9.php

Fan, X., Cao, X., Zhou, H., 

Hao, L., Dong, W., He, C., 

Xu, M., Wu, H., Wang, L., 

Chang, Z. and Zheng, Y. 

2020

Carbon dioxide fertilization effect on plant growth under soil water stress associates with changes in stomatal traits, leaf photosynthesis, and foliar nitrogen of bell pepper (Capsicum annuum L.)

Environmental and Experimental Botany 179: 104203, doi.org/10.1016/j.envexpbot.2020.104203.

"Every year water stress causes significant crop reductions across the globe. To combat its effects, farmers and land managers often apply irrigation, though its application is not always possible for various reasons (e.g., a lack of infrastructure or cost).  

 

...Fan et al. state elevated CO2 "did substantially boost leaf photosynthesis under both the full irrigation and water stress conditions," raising it by 39%, 15%, 25% and 16% in the full irrigation, mild stress, moderate stress and severe stress treatments, respectively

... Higher CO2 also led to a reduction in stomatal conductance and leaf transpiration. ... plant water use efficiency (plant growth per unit of water used) was also stimulated under elevated CO2. ... this parameter improved by approximately 100% in the full irrigation and moderate water stress treatments and by more than 50% in the severe water stress treatment, albeit there was no change in the mild stress water treatment.

... rising atmospheric CO2 increases the productivity and growth of bell pepper, fully ameliorating the retarding effects of water stress under all but the severest level of water stress. What is more, it accomplishes this incredible feat using less water per unit of plant biomass produced."