Chlorophyll fluorescence detects low oxygen stress in 'Elstar' apples.
Prange, R. K.; Schouten, S. P.; Kooten, O. van;
Postharvest Horticulture Series - Department of Pomology, University of California Year: 1997 Issue: No. 16 Pages: 57-64 Ref: 21 ref.
1997
บทคัดย่อ
Changes in several elements of the chlorophyll fluorescence emission curve, Fo, Fm and Fv/Fm (where Fv=Fm-Fo), were determined in Elstar apple fruits, first while in a low O2 atmosphere created by a continuous flow of N2, and then on removal from this treatment and after a shelf period (7 days at 2 deg C + 10 days at 20 deg ). Additionally, changes in chlorophyll fluorescence were compared with ethanol production, another non-destructive method of detecting low O2 stress. Fruits stored at recommended controlled atmosphere (CA) concentrations (1.2% O2 + 2.5% CO2) at 2 deg were removed in September, November and February during the 1996-97 storage season and held in air or 0.07% O2 (balance N2). In all 3 trials, there were no visible symptoms of low O2 injury in the low O2 treatment but ethanol and off-flavours increased. Fv/Fm dropped rapidly while under continuous exposure to low O2, but after the shelf period it was almost the same as in control fruits. Conversely, Fo increased rapidly while un
der continuous exposure to low O2, and after the shelf period it remained higher than in control fruits. This shelf response was stronger in the first 2 trials than in the 3rd trial. This study confirms that both Fv/Fm and Fo can be sensitive indicators of low O2 conditions but that the differences may not persist after removal from low O2, depending on storage duration, shelf time and the chlorophyll element being measured.