title: An overnight chill induces a delayed inhibition of photosynthesis at midday in mango (Mangifera indica L.).
abstract: The effect of a cold night on photosynthesis in herbaceous chilling-sensitive crops, like tomato, has been extensively studied and is well characterized. This investigation examined the behaviour of the sub-tropical fruit tree, mango, to enable comparison with these well-studied systems. Unlike tomato, chilling between 5 degrees C and 7 degrees C overnight produced no significant inhibition of light-saturated CO(2) assimilation (A:) during the first hours following rewarming, measured either under controlled environment conditions or in the field. By midday, however, there was a substantial decline in A:, which could not be attributed to photoinhibition of PSII, but rather was associated with an increase in stomatal limitation of A: and lower Rubisco activity. Overnight chilling of tomato can cause severe disruption in the circadian regulation of key photosynthetic enzymes and is considered to be a major factor underlying the dysfunction of photosynthesis in chilling-sensitive herbaceous plants. Examination of the gas exchange of mango leaves maintained under constant conditions for 2 d, demonstrated that large depressions in A: during the subjective night were primarily the result of stomatal closure. Chilling did not disrupt the ability of mango leaves to produce a circadian rhythm in stomatal conductance. Rather, the midday increase in stomatal limitation of A: appeared to be the result of altered guard cell sensitivity to CO(2) following the dark chill.
authors: Photosynthesis Research Unit of USDA/ARS and Department of Plant Biology, University of Illinois, Urbana, IL 61801-3838, USA.
authors: D J
authors: DJ
authors: Allen
authors: K
authors: K
authors: Ratner
authors: Y E
authors: YE
authors: Giller
authors: E E
authors: EE
authors: Gussakovsky
authors: Y
authors: Y
authors: Shahak
authors: D R
authors: DR
authors: Ort
mesh_terms: D002940:Circadian Rhythm; D003080:Cold Temperature; D010788:Photosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000037:antagonists & inhibitors; D014197:Trees / Q000502:physiology*
chemical_list: D045322:Photosynthetic Reaction Center Complex Proteins