ISHS Acta Horticulturae 174: Symposium Greenhouse Climate and its Control
CARBON PARTITIONING IN TOMATO LEAVES EXPOSED TO CONTINUOUS LIGHT |
| Authors: | Fern M. Bradley, Harry W. Janes |
| Abstract:
Tomato plants exposed to continuous illumination develop leaf injury symptoms (chlorosis and reduced leaf growth) after 5 to 7 days. This leaf injury phenomenon exhibited both photosynthetic and photoperiodic components. Plants exhibited lessening degrees of injury as the light period was reduced from 24 to 18 hours. However, when plants received equal total irradiation during a 24- versus an 18-hour light period, the continuously lit plants developed injury, but the 18-hour plants did not. Changes in carbon assimilation and partitioning in tomato leaves were monitored over time to determine whether accumulation of excess photosynthesis was related to development of injury. Starch and sugar levels increased over time in the third leaf of plants continuously lighted in comparison to the third leaf of plants in a 12-hour photoperiod. However, partitioning of starch as a percentage of dry weight of the third leaf remained constant before and after the appearance of injury. Carbon fixation did not decline relative to the control until after the appearance of injury symptoms. | |
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