“The use of CO 2 enrichment to boost
yields, quality, and growth rates under
hydroponic production is, however,
widely used in commercial greenhouse
horticulture and has an even greater
potential in enclosed growing spaces.”
CO 2 Efficiency
To make the most of CO 2 enrichment, other growth factors
need to be considered and manipulated. Carbon dioxide
enrichment will produce the best results in terms of
plant growth, yield increases, and shortening the time to
maturity where there is high light to power rapid levels
of photosynthesis. If light is insufficient or below the light
saturation point for the crop, then boosted CO 2 levels cannot
be fully utilized by the plants. Temperature also plays a role in
the efficient use of CO 2 . Under conditions of high light and CO 2
enrichment, temperatures can be run higher than they would
normally, and this maximizes the effect of additional CO 2 .
Studies have shown that for tomato plants, a threefold level of
CO 2 enrichment will increase net photosynthesis by about
50 per cent in both dull and bright light, but if leaf temperature
is also raised (to 86°F), the increase in net CO 2 fixation can
be as high as 100 per cent in bright light. This means that
while boosting CO 2 in an indoor hydroponic system will boost
growth rates, consideration should be given at the same time
to manipulation of the other environmental
factors of light and temperature if the
valuable CO 2 is to be used with the
highest degree of efficiency.
Top: CO 2 assists with root development on cuttings and clones in many
species. Bottom: CO 2 introduced to a growing area needs to be thoroughly
mixed and distributed through dense canopies for maximum uptake.
While CO 2 enrichment is largely used on fruiting crops such
as tomatoes, capsicum, and cucumber, it can benefit a wide
range of plant species. Indoor gardens with ornamental,
potted, and flowering plants also respond to CO 2 enrichment
with increased rates of growth and leaf area, increased rates
of flowering, more lateral breaks, earlier flowering, greater
flower number, reduced flower drop, and increased flower
diameter as well as improved leaf color and reduced time to
maturity. Carbon dioxide also assists with root development
on cuttings and clones in many species and may be applied
via enrichment of the air or through the use of carbonated mist.
44
Maximum Yield