INFLUENCE DE LA TEMPERATURE NOCTURNE SUR LES ECHANGES GAZEUX DE LA TOMATE
We tested the influence of four night temperatures (N.T.) : 20°C, 14°C, 10°C and 7°C, applied during one night, on the gas exchanges of young Tomato plants (40 to 60 days after sowing) grown in climatized chambers at 22/14°C day/night temperatures, 12h photoperiod.
The main results are :
- the water vapour exchanges are quite unaffected by night temperature. There is only a slight positive effect of warm nights.
- Nighttime respiration is very dependent on temperature : about zero at 7°C, it more than doubles between 10 and 20°C
- Daytime assimilation is best after 14°C N.T. (which is the growth N.T.): it is slightly reduced after 20°C (by the end of the day) and 10°C (both at beginning and end of the light period).
A single night at 7°C is sufficient to distrub strongly subsequent CO2 assimilation, which is not only reduced, but also totally disconnected from transpiration and stomatal aperture.
- As a consequence, the 24 hours CO2 balance of the plant is best at 14°C and 10°C N.T., and 20% less at 20°C and 7°C N.T.
- For older plants (110 to 130 days after sowing), night-time respiration is bigger, and more dependent upon temperature; daytime assimilation is less after 14°C than after 10°C N.T.
Longuenesse, J.J. (1981). INFLUENCE DE LA TEMPERATURE NOCTURNE SUR LES ECHANGES GAZEUX DE LA TOMATE. Acta Hortic. 115, 39-48