Jss. Prakash et al., ALTERATIONS IN ELECTRON-TRANSPORT CHARACTERISTICS DURING SENESCENCE OF CUCUMIS COTYLEDONARY LEAVES - ANALYSIS OF THE EFFECTS OF INHIBITORS, Photosynthetica, 35(3), 1998, pp. 345-352
Cotyledonary leaves of Cucumis sativus cv. Poinsette exhibited senesce
nce-induced losses in chlorophyll (Chl) and protein contents within th
ree weeks since germination. Chi and protein concentrations in cotyled
onary leaves approached maximum on 6(th) d after germination and they
declined to 50 and 41 %, respectively, by the 20(th) day of growth. Ac
tivities of both photosystem (PS) 2 and PS1 decreased by 33 and 31%, r
espectively, on the 20th day, compared to the control 6th day. Changes
in sensitivity of PS2 to inhibitors like atrazine and dibromothymoqui
none and sensitivity of PS1 to KCN accompanied the changes in PS2 and
PS1 activities. Hence both the acceptor side of PS2 and the donor side
of PS1 are affected by senescence-induced changes in cucumber cotyled
onary leaves.