Chllling stress and Chllling tolerance of sweet potato as sensed by chlorophyll fluorescence

摘要

We studied changes in the chlorophyll (Chl) fluorescence components in Chllling-stressed sweet potato (Ipomoea batatas L. Lam) cv. Tainung 57 (TN57, Chllling-tolerant) and cv. Tainung 66 (TN66, Chllling-susceptible). Plants under 12-h photoperiod and400 MU mol m~(-2) s~(-1) irradiance at 24/20 deg C (day/night) were treated by a 5-d Chllling period at 7/7 degC. Compared to TN66, TN57 exhibited a significantly greater basic Chl fluorescence (F_0), maximum fluorescence (F_m), maximum fluorescence yield during actinic irradiation (F_m'), and the quantum efficiency of electron transport through photosystem 2, PS2 (PHI_(PS2)). Chllling stress resulted in decrease in the potential efficiency of PS2 (F_v/F_m), PHI_(PS2), non-photochemical fluorescence quenChlng (NPQ), non-photochemical quenChlng (q_N), and the occurrence of Chllling injury in TN66. Chllling increased the likelihood of photoinhibition, characterized by a decline in the Chl fluorescence of both cultivars, and photoinhibition during low temperature stress generally occurred more rapidly in TN66.