Effects of Atmospheric CO2 and Light Intensity on Spinach
Proietti, S., Moscatello, S., Giacomelli, G.A. and Battistelli, A. 2013. Influence of the interaction between light intensity and CO2 concentration on productivity and quality of spinach (Spinacia oleracea L.) grown in fully controlled environment. Advances in Space Research 52: 1193-1200.
Focusing on both the quantity and quality aspects of such food production, Proietti et al. grew spinach (Spinacia oleracea L.) plants from seed at a density of eight seeds per each of several 1-L pots filled with perlite and placed in controlled-environment chambers where the young plants were grown at two different levels of light intensity (photosynthetic photon flux density of 200 and 800 Ámol/m2/sec) and two different levels of atmospheric CO2 concentration (360 and 800 ppm), and where they were also irrigated with a full-strength nutrient solution twice a week for five full weeks after the expansion of the young plants' cotyledons.
In response to the experimental increase in light intensity, plant fresh weights rose by 104%, while plant dry weights rose by 141%; and in response to the increase in atmospheric CO2 concentration, plant fresh weights rose by 64%, while plant dry weights rose by 66%. In terms of the food quality of the spinach plants, the four researchers found that "growth under high CO2 and high light conditions strongly enhanced the organoleptic quality of spinach [i.e., its taste, color, odor or feel], particularly if eaten as raw salad." And, based on other of their findings, they concluded that "environmental factors (light and CO2) can be efficiently controlled to increase beneficial (ascorbic acid) but not detrimental (oxalic acid) metabolites."
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