Development of lines of radish differing in resistance to O3 and SO2

The potential for developing intraspecific lines of radish (Raphanus sativus L. cv, Cherry Belle) based on their relative resistance to either O3 or SO2 was examined using growth‐analysis techniques. Plants were exposed to either 0–10μ 1−1 O3 or 0.50 μ 1 −1 SO2 for 4 h day−1, 3 days week−1, for 3 weeks. Resistant and sensitive individuals were then selected and divided into four groups: O3 resistant (O3R), O3 sensitive (O3S), SO2 resistant (SO2R), and SO2 sensitive (SO2S) Cross‐pollinations were made among plants within the selected groups and seed collected. F1 populations were raised from the resulting seed and exposed to the same exposure regime. Net photosynthesis and stomatal conductance were measured during the final two fumigations, and plants were harvested immediately following the final exposure, divided into component parts, dried and weighed. O3 and SO2 generally caused biomass reductions in all the F1 groups. O3 reduced below ground growth more than SO2 leading to greater reductions in root/shoot ratios. O3R plants were resistant to both pollutants, showing little biomass reduction particularly from O3. Root/shoot ratios of these plants were altered less by pollutant exposure than non‐selected radishes. Shoot growth of SO2R plants was greater in O3 or SO2 than non‐selected plants, but below ground growth was similar. Selection for plants sensitive to either pollutant was not apparent from growth analysis, as growth of the sensitive plants was generally the same as that of non‐selected plants. Gas exchange results indicated greater stomatal conductance in O3S plants in filtered air than either non‐selected or O3R plants, while O3S plants had lower conductance rates in the O3 treatment. Copyright © 1989, Wiley Blackwell. All rights reserved

Duke Scholars

Author William E. Winner DKU Faculty