ISSN:
1399-3054
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
The adaptability of the thylakoid membrane to extended photoperiod (from natural to 24 h) was studied using a photoperiod-sensitive species (Lycopersicon esculentum Mill. cv. Trend) and a non-photoperiod-sensitive species (Capsicum annuum L. cv. Delphin). Our results have shown that thylakoid membranes of both species adapt to an extended photoperiod by increasing their photosystem II to photosystem I ratio (PSII/PSI) in order to provide a more balanced energy distribution between both photosystems to improve quantum yield. In tomato plants, these results correspond with a lower chlorophyll (Chl) a/b ratio, a decrease in Chl associated with PSI light-harvesting chlorophyll a/b protein complexes and with an increase in Chl associated with PSII light-harvesting chlorophyll a/b protein complexes. In spite of these changes, the electron transport capacity through PSII and PSI per unit of Chl and the light saturation point of PSII remained unchanged. The inability of tomato plants to use supplemental light for an extended photoperiod is not the result of photoinhibitory conditions. In pepper plants a significant increase in electron transport capacity and in the light saturation point of PSII was found. There was a significant increase in CO2 assimilation when the light period was increased from 12 to 24 h. In contrast to tomato, pepper plants adapt to a 24-h photoperiod by increasing their carboxylation capacity which is accompanied by an increase in electron transport capacity and the light saturation point.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1399-3054.1995.tb00986.x
