Cold tolerance of diverse stevia cultigens under controlled environment conditions

Low temperature is a major limiting factor for the growth and development of many crops, including stevia ( Stevia rebaudiana Bertoni), a natural low‐calorie sweetener. In this study, 14 stevia half‐sib families selected from several populations were evaluated for chilling stress using controlled growth chambers. The experiment was set up as a split‐plot arrangement in a randomized complete block design. Whole plots were chilling temperatures (2, 0, –2, or ‐4 °C) and subplots were the combination of 14 cultigens and 5 chilling durations (2–10 d of chilling). Genetic differences were large at chilling temperatures of +2 °C for a duration of 10 d, 0 °C for 8 d, or –2 °C for a duration of 6 d. Ten days of chilling induced severe damage in all cultigens except for the three with the highest tolerance (7947‐3, 7918‐1, and 7686‐6). In this study, 5 of 14 cultigens were highly susceptible, 8 were moderately susceptible, and 1 was tolerant after 6 d of chilling at –2 °C (7947‐3).