PHOTOSYNTHETIC APPARATUS OF CHILLING SENSITIVE PLANTS .24. EFFECT OF CHILLING OF ZEA-MAYS L AND CAPSICUM-ANNUUM-L LEAVES ON INACTIVATION OF OXYGEN EVOLUTION AND CONTENT OF FREE FATTY-ACIDS IN CHLOROPLASTS

The effect of chilling of several Capsicum annuum L. cultivars and Zea mays L. inbred lines on the inactivation of oxygen evolution and the level of free fatty acids (FFA) in chloroplasts was studied. The content of FFA upon chilling of both maize and red pepper leaves at 0-degrees-C and 4.5-degrees-C, respectively, was related to the inactivation of oxygen evolution taken as primary index of chilling tolerance (Kaniuga et al. 1978). FFA content in fresh (control) chloroplasts of maize and red pepper ranged from 0.19 to 0.94 and from 0.31 to 1.98-mu-mol/mg Chl, respectively. Two sets of plants can be differentiated in each plant species on the basis of FFA content: below and above 0.4 and 1.0-mu-mol FFA/mg Chl in maize and red pepper, respectively. In some maize lines FFA accumulation outmarch a decrease in oxygen evolution, whereas in few red pepper cultivars significant or moderate inactivation of oxygen evolution upon chilling did not coincide with the level of FFA. In general, the tendency of an increased inactivation of oxygen evolution upon chilling was accompanied by a higher level of FFA in chloroplasts. The present data seem to suggest that FFA level in chloroplasts of chilled leaves of closely related plant species is a characteristic but less precise index of chilling tolerance than both measurement of galactolipase activity in fresh chloroplasts and inactivation of oxygen evolution following cold stress as it was reported for domestic and wild tomatoes (Gemel et al. 1988).