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Daily temperature drop prevents inhibition of photosynthesis in tomato plants under continuous light
- Ikkonen, E. N., Shibaeva, T. G., Rosenqvist, E., Ottosen, C. -O.
- Photosynthetica 2015 v.53 no.3 pp. 389-394
- Solanum lycopersicum var. lycopersicum, adverse effects, chlorosis, circadian rhythm, leaf development, leaves, photochemistry, photosystem II, plantlets, temperature, tomatoes
- The negative effects of continuous light (CL) seen in tomato plants are often claimed to be linked to effects of offsetting the diurnal rhythm. In this study we tested whether a short-term daily temperature drop prevents the decreased photosynthetic performance seen in tomato plants grown under CL. Tomato (Lycopersicon esculentum Mill.) plantlets were grown at constant temperature of 26°C under 16-h day (16D) or 24-h day (24D) at 150 μmol m⁻² s⁻¹ PPFD. Some 24D plants were treated daily by 2 h temperature drop from 26 to 10°C (24D+DROP). Physiological disorder, such as severe leaf chlorosis, a large decrease in net photosynthetic rate, maximal quantum yield of PSII photochemistry, and the effective quantum yield of PSII photochemistry were observed in 24D, but not in 16D and 24D+DROP plants. The daily 2-h drop in temperature eliminated a negative effect of CL on photosynthesis and prevented the development of leaf chlorosis in tomato plants. This could be due to a change in carbohydrate metabolism as the short drop in temperature might allow maintenance of the diurnal rhythms.