Intraspecific variation in the salt tolerance in Conyza canadensis

Abstract

Plant populations inhabiting along environmental gradients often exhibit differential responses to environmental stresses. Conyza canadensis is an introduced plant species and it occurs in a wide geographic range from coastal to inland area. In spite of its huge impact on plant growth and productivity, the intraspecific variation of C. canadensis in response to the soil salinity has not been tested yet. In this study, we compared phenotypic responses of C. canadensis natural populations which live in the high or low concentration of soil salinity. Testing populations were selected in three different regions to access the general pattern of population differentiation. In order to examine the effect of the NaCl on plant traits, three different concentrations of NaCl was applied. Depending on the electrical conductivity of soil samples, control was 0 dS/m, the medium was 4 dS/m and high was 8 dS/m. During three months, I measured a germination rate and phenotypic traits. As results, even though high salt populations had more damaged leaf area and sodium concentration in leaves, they showed higher growth rate with heavier total biomass, longer and more leaves in high salt conditions compared to low salt populations. Moreover, the low SLA of high salt populations indicated that they had more water in leaves under drought stress induced by salts. Notably, high salt populations had heavier total biomass in both control and high salt conditions, implying that salt resistance does not have physiological cost on the plant growth. Jo Aram (조아람). Intraspecific variation in the salt tolerance in Conyza canadensis (망초의 염분 스트레스에 대한 종내 반응 비교 연구). School of Earth Sciences and Environmental Engineering. 2019. 55p. Prof. Kim Eunsuk ii Differences of traits between high- and low salt populations varied among regions, implying that differential evolutionary ecological mechanisms affect salt resistance of current C. canadensis populations in the coastal area. The results of this study showed intraspecific variation in the salt tolerance in C. canadensis. However, molecular studies about enzymatic antioxidant and ion processing mechanism should be conducted to confirm the biological mechanisms of salt tolerance. In addition, population genetic study is required to evaluate genetic differentiation between high- and low salt populations.