Physiological response and heat tolerance evaluation of Lotus corniculatus under high temperature stress

In order to study physiological response and evaluate heat tolerance of Lotus corniculatus under high temperature stress, leaf relative electrolyte leakage, contents of malondialdehyde(MDA), proline(Pro) and activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were analyzed using 8 germplasms of L.corniculatus under different temperature treatments (35 ℃,45 ℃, and with 22 ℃ as control). The heat tolerance of 8 germplasms was comprehensively evaluated by principal components analysis and fuzzy subordinate function based on the tested 6 indices. The leaf relative electrolyte leakage, MDA content, proline content, activities of catalase (CAT) and peroxidase (POD) increased with the temperature increasing except germplasm B01 which did not have higher POD activity at higher temperature. The activity of superoxide dismutase (SOD) was higher at moderate temperature (35 ℃) compared with the other two temperature treatments. Principal component analysis was applied to analyze the total effects of these six tested indices which showed that the first and second compont of PCA contributed to 85.41%. Based on the comprehensive evaluation value (D), the heat tolerance of these eight L.corniculatus germplasms was estimated as B08＞B04＞B05＞B18＞B03＞B12＞B02＞B01.