Leaf gas exchange and chlorophyll fluorescence parameters
Leaf net photosynthetic capacity was measured with the flow-through
Q-box CO650 (Qubit Systems). All measurements were performed on fully
expended 2nd and 3rd leaf of the
plant between 9:00 to 11:00 h under the following conditions: a
saturating photosynthetic active radiation (PAR) of 1600 µ mol
m-2. s-1 supplied by LED light
source (A113), attached to leaf chamber continuously flushed with 350
ppm CO2 containing air at a flow rate of 50 ml.
min-1, air temperature of 25-26°C and relative
humidity of 55-60%. The measurements were taken after
CO2 output stabilized, and CO2 exchange
rate was calculated with the Logger Pro software (Qubit Systems). The
details of the maximum quantum yield (Fv/Fm) and Chlafluorescence analysis was performed by using a portable mini-PAM
chlorophyll fluorometer (Walz, Germany) fitted with standard fiber optic
and leaf clip holder. To measure Chla fluorescence, leaves were
kept in dark incubation for 30 min. For analysis, we used the following
conditions: intensities of measuring light (<0.1 µ mol
photons m-2. S-1), saturating pulse
(3000 µ mol photons m-2. S-1),
actinic light (170 µ mol photons m-2.
S-1) and far-red light (7 µ mol photons
m-2. S-1) respectively. The duration
of actinic light and saturation pulse were 0.8 and 30 s. Chlorophylla and b were estimated using Arnon, (1949) method.