Abstract: This study investigated the effect of a uniconazole (S₃₃₀₇) spray on cold resistance of adzuki bean in a pot experiment in an artificial climate chamber. Cold tolerant and cold sensitive cultivars Baoqinghong and Tianjinhong, respectively, were selected for study. Regulation of chilling injury and protection of the root system were key points of interest. A low temperature treatment (15 ℃) and spraying of S₃₃₀₇ (20 mg·L^-1) were imposed during plant establishment. The 15 ℃ low temperature treatment was applied for durations of 1, 2, 3, 4, or 5 days. Data collected for the two cultivars included root physical data and physiological indicators. Qualitatively, low temperature treatment increased soluble sugar and proline contents, enhanced superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) antioxidant enzyme activities and reduced malondialdehyde (MDA) content. However, the low temperature decreased adzuki bean yield. Quantitatively, soluble sugar and proline levels, and SOD, POD, and CAT activities after 3 days of low temperature exposure were increased for Baoqinghong and Tianjinhong cultivars by: 59.21% and 52.57%, 10.12% and 25.39%, 14.92% and 11.01%, 5.93% and 0.75%, and 53.33% and 13.33%, respectively, compared with regular temperature treatment. Meanwhile, values for the adzuki bean soluble protein contents after 5 days of low temperature exposure for the two cultivars were significantly increased, by 6.27% and 3.15%, respectively, and corresponding increases for MDA content were 45.41% and 51.08%. Yield decreases compared with controls were, respectively, 19.39% and 41.69% for Baoqinghong and Tianjinhon cultivars. By comparison, after 3 days low temperature exposure following spraying with S₃₃₀₇ soluble sugar, proline, SOD, POD and CAT parameters of Baoqinghong and Tianjinhong were increased by 22.01% and 0.46%, 8.55% and 1.40%, 13.45% and 24.06%, 23.60% and 15.95%, and 4.35% and 5.88%, respectively, compared with controls; while MDA yield after 5 days low temperature exposure was decreased by 9.05% and 4.37%, and yield was decreased by 23.06% and 43.88%. In conclusion, the chilling injury of adzuki bean was ameliorated by spraying of S₃₃₀₇ treatment and yield loss was decreased, which was linked to increased levels of soluble sugar and proline, increased activities SOD, PAD and CAT, and decreased the content of MDA.

Key words: low temperature, uniconazole, adzuki bean, root, chilling resistance, yield