Improving lettuce plant growth and preventing tip-burn occurrence by using a multi-fan system in a plant factory

In a plant factory, reducing running costs and improving plant quality are always two important goals.
In this experiment, a multi-fan system (MFS), which can provide uniform airflow on plant canopy was developed for improving lettuce plant growth and preventing tipburn occurrence.
Leaf boundary layer resistance, sensible heat flux and latent heat flux of lettuce plants were estimated.
The cultivation unit without MFS was used as a control (CS). The results showed that the MFS was able to provide an average air velocity of 0.75 m s^‑1with a coefficient of variation of 65%. While the average air velocity of 0.23 m s^‑1 with a coefficient of variation of 4.3% was estimated under the CS. The leaf boundary layer resistance decreased significantly with the increase in air velocity.
On average, the leaf boundary layer resistance of 53.9 and 101.4 s m^‑1 was shown for lettuce plants grown with and without MFS, respectively.
Therefore, the sensible heat flux and latent heat flux of lettuce plants were 40 and 46% higher than those under the CS, respectively.
The fresh and dry weights of lettuce plants were 12 and 6% higher by using the MFS than those under the CS, respectively.
No tipburn injury was observed on the inner and newly developed leaves of lettuce plants grown under the MFS. Conversely, 5 leaves plant^‑1 on average were injured with tipburn under the CS. The above results indicated that lettuce plant growth can be improved and tipburn occurrence can be alleviated due to the decrease in the leaf boundary layer resistance and the increase in the transpiration rate.

International Symposium on Advanced Technologies and Management for Innovative Greenhouses: GreenSys2019

H.A. Ahmed, Y.X. Tong, Q.C. Yang

leaf boundary layer resistance, heat exchange, lettuce growth, tipburn occurrence

https://doi.org/10.17660/ActaHortic.2020.1296.123