Susceptibility of Lycopersicon spp. to Ozone Injury1

Accessions, breeding lines, and varieties of Lycopersicon spp. and one accession of Solarium pennellii Correll were evaluated for sensitivity to controlled concentrations of O 3 and to ambient air at Waltham, Massachusetts. The plant material was exposed in different stages of development to controlled O 3 concentrations of 0.25 ppm for 3 hours, 0.05 ppm for 2 weeks and to 0.10 ppm for 4 weeks. Based upon the degree of foliar injury, the tested material was separated into tolerant, intermediate and sensitive populations. The highest degree of tolerance was observed in L. esculentum Mill, and the highest degree of sensitivity in L. pimpinellifolium . Germination of pollen from inflorescences exposed to 0.10 ppm was reduced 40% in sensitive accessions of L. pimpinellifolium when placed on artificial medium. No significant reduction was observed in the most tolerant accession of L. esculentum. Differences in percent germination were not observed when pollen of sensitive and tolerant accessions was placed on artificial medium and exposed to 0.10 ppm O 3 for a six-hour period. Reciprocal cross pollinations between exposed and unexposed populations led to normal fruit development with viable seeds.