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.