An overnight chill induces a delayed inhibition of photosynthesis at midday in mango (Mangifera indica L.).
Allen D. J., Ratner K., Giller Y. E., Gussakovsky E. E., Shahak Y., Ort D. R.
Author Affiliation: Photosynthesis Research Unit of USDA/ARS, Department of Plant Biology, University of Illinois, Urbana, IL 61801-3838, USA.
Journal of Experimental Botany 51 : 1893-1902
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. For controlled environment experiments, mango cv. Tommy Atkin scions on cv. Turpentine rootstock were used; while for outdoor experiments in Bet-Dagan, Israel, Tommy Atkin scions on 13/1 rootstock were used. Unlike tomato, chilling at temperatures between 5°C and 7°C overnight (11 h) produced no significant inhibition of light-saturated CO2 assimilation (A) during the first hours following rewarming to 30 and 23°C in the dark for one hour, in controlled environment conditions and in the field, respectively. 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 ribulose-bisphosphate carboxylase 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 days 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 CO2 following the dark chill.