Submitted to: Plant Physiology Supplement
Publication Type: Abstract only
Publication Acceptance Date: 7/19/2000
Publication Date: N/A
Citation: Interpretive Summary:
Technical 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 study examined how the behaviors of the subtropical fruit tree, mango, compared to these well-studied systems. Unlike tomato, chilling between 5 and 10C overnight produced no significant inhibition of light-saturated CO2 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. Over night 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. In contrast, examination of the gas-exchange of mango leaves maintained under constant conditions for two days, demonstrated that large depressions in A during subjective night were primarily the result of stomatal closure. Chilling did not disrupt the ability of mango leaves to produce circadian rhythm in stomatal conductance. Rather, the midday increase in stomatal limitation of A appears to be the result of altered guard cell sensitivity to CO2.