The impact of tropospheric O3 on leaf number duration and tuber yield of the potato (Solanum tuberosum L.) cultivars Bintje and Kardal

Ozone (O3) is a major phytotoxic air pollutant with the potential to cause severe yield losses in potato (Solanum tubersosum L.) and in other crops. The present study was aimed (i) to investigate the O3 sensitivity of two potato cultivars (Bintje and Kardal) in relation to their earliness in maturation, and (ii) to analyse possible O3 effects on potato tuber dry mass (DM) production in relation to leaf duration. The experiment was performed in the southwest of Sweden using open-top chamber (OTC) technique. The crops were exposed to three levels of O3: charcoal-filtered air (CF), non-filtered air (NF) and non-filtered air + 26 nmol mol−1 O3 (NF+). In addition, ambient air plots were used to monitor the impact of the OTC enclosure. Leaf number duration (LND) was calculated as the number of leaves integrated over the temperature sum accumulation during the season. In the present study, the O3 effects on potato were characterised by visible injury of the leaves and earlier leaf senescence. The haulm/plant DM ratio was significantly lower in NF+ compared to CF and NF. The conclusions were (i) that the early to intermediate maturing cultivar Bintje tended to suffer more from O3 injury than the late maturing cultivar Kardal, (ii) that this was due to a difference in the ability to compensate for haulm damage by the development of new leaves rather than to a difference in leaf O3 sensitivity, and (iii) that a rather low O3 exposure can induce a significant reduction in LND in potato. The O3 effects on tuber DM (−2% in NF+ and +31% increase in CF, both compared to NF) could not be statistically demonstrated, although there was a strong correlation between LND and tuber DM.