Total Pageviews

Tuesday, June 11, 2019

Dong et al (2018) -- Elevated CO2 improves vegetable nutritional quality -- meta-analysis of 57 studies

Dong, J., Gruda, N., Lam, 
S.K., Li, X. and Duan, Z. 


"Effects of elevated CO2 on
nutritional quality of vegetables: 
A review."

Frontiers in Plant Science 9: 
Article 924, 
doi: 10.3389/fpls.2018.00924.

Dong et al. (2018) say 
"a comprehensive review 
of recent studies explaining 
and targeting the key role of the 
effect of elevated CO2 on 
vegetable quality is lacking." 

CO2-induced plant nutritional enhancements 
far outweigh any CO2-induced plant nutritional 

Future rising atmospheric CO2 concentrations 
will bring future health benefits to human and 
animal plant consumers.

The team of five researchers 
performed a meta-analysis 
of 57 existing studies.

The 57 published works included 
CO2 enrichment studies on 
   root vegetables 
(carrot, radish, sugar beet and turnip), 
   stem vegetables 
(broccoli, celery celtuce, Chinese kale, 
ginger, onion, potato and scallion), 
   leafy vegetables 
(cabbage, Chinese cabbage, 
chives, fenugreek, Hongfengcat, 
lettuce, oily sowthistle, palak 
and spinach) and 
   fruit vegetables 
(cucumber, hot pepper, 
strawberry, sweet pepper 
and tomato). 

They examined 
of nutritional quality,
including soluble sugars, 
organic acids, protein, 
nitrates, antioxidants 
and minerals.

A CO2-induced stimulation 
of soluble sugar accumulation 
in the edible parts of vegetables
-- elevated CO2 "increased the 
concentrations of fructose, 
glucose, total soluble sugar, 
total antioxidant capacity, 
total phenols, total flavonoids, 
ascorbic acid, and calcium 
in the edible part of vegetables
by 14.2%, 13.2%, 17.5%, 
59.0%, 8.9% 45.5%, 9.5%, 
and 8.2%, respectively, 
but decreased 
the concentrations 
of protein, nitrate, 
magnesium, iron, 
and zinc by 9.5%, 
18.0%, 9.2%, 
16.0%, and 9.4%. 

Concentrations of titratable acidity, 
total chlorophyll, carotenoids, lycopene, 
anthocyanins, phosphorus, potassium, 
sulfur, copper, and manganese 
were not affected.

Dong et al. say that 
"overall, elevated CO2 
promotes the accumulation of 
antioxidants in vegetables, 
thus improving 
vegetable quality," 
while adding that 
"the CO2-induced stimulation of 
total antioxidant capacity, total phenols, 
total flavonoids, ascorbic acid, and 
chlorophyll b indicate an improvement 
of beneficial compounds in vegetables." 

Decreases in protein, nitrate, 
magnesium, iron, and zinc 
were also observed in the 

Those slight declines can be reduced, 
if not reversed, by several approaches 
that were investigated and discussed 
by the authors, including: 

selecting vegetable species or cultivars 
that possess greater ability in carbon fixation 
and synthesis of required quality-related 

optimizing other environmental factors 
(e.g., moderate CO2 concentrations, 
moderate light intensity, 
increased N availability, 
or increased fertilization of Fe or Zn) 
to promote carbon fixation and 
nutrient uptake interactively 
when growing plants under elevated CO2

 harvesting vegetable products earlier 
in cases of over maturity and reduced 
benefit of elevated CO2 
to vegetative growth; and 

combining elevated CO2 
with mild environmental stress 
(e.g., ultraviolet-B radiation 
or salinity) in instances 
when this enhances 
vegetable quality 
and might counteract 
the dilution effect 
or direct metabolic pathways 
toward the synthesis of 
health-beneficial compounds."