Radish plant behaviour under short-term elevated ozone fumigation

Abstract

Effects of short-term ozone (O 3 ) fumigation on radish (Raphanus sativus L.) plants were examined in growth chambers under controlled environment conditions. Plants were exposed to 0 μg/m 3 (reference), 80 μg/m 3 , 160 μg/m 3 and 240 μg/m 3 O 3 concentrations for 7 h per day for five days. Day/night temperature was 21ºC/14ºC and photoperiod 16 h. Chlorophyll content was evaluated spectrophotometrically. Chromatographic analysis of saccharides was also undertaken. The results showed that elevated O 3 inhibited the growth of radish rhizocarps, net assimilation rate and biomass accumulation. O 3 induced leaf desiccation, necrosis and premature senescence, but a typical reaction of plants to O 3 stress was the rapid regeneration of new leaves. O 3 inhibited accumulation of carotenoids more than chlorophylls. The higher photosynthetic pigment content in newly generated radish leaves may be regarded as an adaptation of the photosynthetic system to O 3 . Leaf saccharide metabolism and incorporation depended on O 3 concentration. Rapid regeneration of new leaves and increased content of photosynthetic pigments is the typical reaction of radish plants to O 3 stress.