2020 Volume 58 Issue 2 Pages 37-42
Sesame (Sesamum indicum) seedlings were cultured under regimes of differing air temperature and photoperiod in a plant factory under artificial light to evaluate these factors for inducing leaf browning. In experiment 1, plants were cultured under continuous lighting either at a constant air temperature of 28℃, or fluctuating air temperature of 28℃ with a 10℃ difference (06:00―18:00; 33℃, 18:00―06:00; 23℃), or with a 15℃ difference (06:00―18:00; 35.5℃, 18:00―06:00; 20.5℃). Leaf browning was induced intensively by constant 28℃ and avoided by air temperature fluctuation, especially with the 15℃ difference. Shoot fresh weight and number of nodes were not significantly different among all the treatments. In experiment 2, plants were cultured under continuous lighting or a 12-h photoperiod either at a constant (28℃) or a fluctuating temperature (28℃ with a 15℃ difference). Leaf browning was induced by constant 28℃ and avoided by air temperature fluctuation, regardless of photoperiod. Shoot fresh weight under a treatment with combination of temperature fluctuation with 15℃ difference and continuous lighting was significantly greater than that under the other treatments. These results suggest that leaf browning of sesame seedlings is induced by constant air temperature and can be prevented by air temperature fluctuation.
