Chlorophyll content and MSI
Chlorophyll content was estimated according to the method
of Hiscox and Israelstam (1979). 50 mg leaves were dissolved
in 5 ml of DMSO (dimethyl sulphoxide), and then
placed in an oven at 60 C for 24 h. The optical density of
chlorophyll ‘a’ and ‘b’ was measured at 663 and 645 nm,
respectively, and chlorophyll content was calculated.
Membrane stability index was determined as per the protocol
of Gupta et al. (2003). Leaves (200 mg) of control and heattreated
plants were thoroughly washed in double distilled
water, and thereafter placed in 25 ml of double distilled
water at 45 C for 30 min. After the end of this period, their
electrical conductivity was recorded by conductivity bridge
(C1). Subsequently, the same samples were placed on boiling
water bath (100 C) for 10 min and their electrical conductivity
was recorded (C2). The membrane stability index was
calculated as MSI = [1 - (C1/C2)] 9 100.