Air Fine bubbles promote lettuce growth in deepflow technique

https://youtube.com/shorts/SVEiViUhuss

We investigated the effects of microbubbles, generated by a swivelling microbubble generator in hydroponics nutrient solution, on the growth of leaf
lettuce (Lactuca sativa). Twenty-four lettuce seedlings at the four- to five-leaf stage each were transplanted into two culture containers at 21 ± 1 degC (day) and 18 ± 1 degC (night) under fluorescent lamps that provided a photosynthetic photon flux of 173 ± 18 and 171 ± 16 mmolm–2s–1 averaged at eight points at the canopy level for microand macrobubbles conditions, respectively, during a photoperiod of 16 h per day.
Seedlings were cultivated for 2 weeks in two deep flow technique (DFT) hydroponics culture systems in which micro- or macrobubbles were produced, respectively, by a microbubble aerator and aquarium aeration stones. The nutrientsolution was maintained at a temperature of 22 ± 1 C during the experiment. Fresh and dry weights of the microbubble-treated lettuce were 2.1 and 1.7 times larger, respectively, than those of the macrobubble-treated lettuce. Although the reasons for growth promotion by microbubbles are still under investigation, we speculate that the larger specific surface area of the microbubbles and negative electronic charges on the microbubbles surfaces may promote growth because microbubbles can attract positively charged ions that are dissolved in the nutrient solution. These results indicate that microbubbles generated in a DFT hydroponics culture system can remarkably promote plant growth.

Although the reasons for growth promotion by the microbubbles are still under investigation, one of the possibilities is the larger specific surface area of microbubbles when compared with macrobubbles. Numerous microbubbles adhered to the root. This seems to positively stimulate root growth by supplying oxygen directly to the surface of roots.

Negative electronic charges on microbubbles surface may help roots absorb nutrient salts because microbubbles can attract positively charged ions
that are dissolved in the nutrient solution, such as calcium, magnesium, potassium, and ammonium (Takahashi, 2005). In conclusion, the advantage of
using microbubbles was demonstrated in a DFT hydroponics culture system, remarkably promoting lettuce growth. Further study will be
required to elucidate the relationship between the specific properties of microbubbles and plant root growth.