EFFECT OF JASMONIC ACID ON THE STOMATAL AND NONSTOMATAL LIMITATION OFLEAF PHOTOSYNTHESIS IN BARLEY LEAVES

The effect of long-term (7 days) and short-term (up to 2 h) treatment of barley plants with jasmonic acid (JA) on the components contributin g to stomatal and nonstomatal limitation of photosynthesis was studied . Net CO2 assimilation rate (A) responses to intercellular CO2 concent ration (C-i), i.e., A/C-i curves, were used to assess the photosynthet ic ability. Long-term treatment of barley plants with JA led to a noti ceable decrease in both the initial slope of the A/C-i curves and the maximum A at saturating C-i. The proportion of stomatal and nonstomata l factors in limitation of photosynthesis depended on the applied JA c oncentration. Short-term treatment with JA affected neither the stomat al conductivity for CO2 nor the rate of photosynthetic CO2 assimilatio n. We suggest that JA may affect photosynthesis indirectly, either as a stress-modulating substance, or through the alterations in gene expr ession.