Cps 240 cell holder

To obtain chlorophylls, 0.5 g of frozen leaf was homogenized with an acetone-hexane solution (2:3) (25 mL). They were then centrifuged at 3500× g for 6 min at 4 °C, and the absorbance of the supernatant was measured with a spectrophotometer (Shimadzu UV-1800 model with the CPS-240 cell holder, Shimadzu Europa GmbH, Duisburg, Germany) at 663, 645, 505 and 453 nm. The concentration of chlorophyll a (Chl a), b (Chl b) and a + b (Chl a + b) were obtained using the formulas of Nagata and Yamashita [31 ].

Chlorophylls a and b (Chl a and Chl b) were extracted from 1 g of frozen cauliflower leaves (−80 °C) with 25 mL of extraction buffer (acetone–hexane (2:3)). Leaf samples were homogenized using a Polytron and centrifuged at 3500 rpm for 6 min, at 4 °C. Afterwards, the absorbance of the supernatant was measured at 663, 645, 505, and 453 nm with a spectrophotometer (Shimadzu UV-1800 model with the CPS-240 cell holder, Shimadzu Europa GmbH, Duisburg, Germany). The contents of chlorophylls a and b, lycopene, and β-carotene were determined by using the Nagata and Yamashita [67 (link)] equations:



On the same leaf used for gas exchange, the maximum potential quantum efficiency of PSII (Fv/Fm) was determined following the procedure previously described by Piñero et al. [68 (link)]. These measurements were performed by using a portable modulated fluorometer OS-30P (Opti-Science, Hudson, NH, USA). Fv is the variable fluorescence from a dark-adapted leaf and Fm is the maximal fluorescence from a dark-adapted, mature fully expanded leaf. A special leaf clip holder was allocated to each leaf to maintain dark conditions for at least 30 min before reading. The analyses of chlorophyll, lycopene, β-Carotene, and Fv/Fm were run in five repetitions per treatment.