En. Zavorueva et al., PHOTOSYNTHETIC APPARATUS OF CUCUMBER AND PEA-PLANTS GROWN UNDER RED-LIGHT WITH DISCRETE OR CONTINUOUS SPECTRA, Russian journal of plant physiology, 43(2), 1996, pp. 191-199
The effect of light sources with discrete or continuous spectra of red
light (50 W/m(2), 600-700 nm) on the structural and functional charac
teristics of chloroplasts were studied in leaves of cucumber (Cucumis
sativum L.) plants, which die under strong red light, and pea (Pisum s
ativum L.) plants, which tolerate red light under the same conditions.
Leaf condition was assessed by measuring thermo- and photoinduced cha
nges in the chlorophyll fluorescence yield and the photochemical and p
hotophosphorylating activities of the chloroplasts. Different response
s of the pigment apparatus of pea and cucumber plants to red light wit
h continuous or line spectra were revealed. Pea plants responded to di
screte-spectrum light by changing P-700 content, the ratio of antenna
chlorophyll to P-700 and the position of the low-temperature peak of t
he temperature-induced chlorophyll fluorescence yield. In cucumber pla
nts, disturbances in the energy transfer from the short-wavelength pig
ments to chlorophyll a were observed, In both plants, the effects of l
ine spectrum light on the pigment apparatus were reversible; the ratio
of cyclic to noncyclic photophosphorylation, photosynthetic control,
and the extent of the coupling of photosynthetic electron transport to
photophosphorylation did not change compared the control light. The n
eed for examining the line spectra of light sources for growing plants
under moderate intensities of artificial light (about 50 W/m(2) of ph
otosynthetically active radiation) is discussed.