G. Deckmyn et I. Impens, COMBINED EFFECTS OF ENHANCED UV-B RADIATION AND NITROGEN DEFICIENCY ON THE GROWTH, COMPOSITION AND PHOTOSYNTHESIS OF RYE (SECALE-CEREALE), Plant ecology, 128(1-2), 1997, pp. 235-240
The interactive effects of N-deficiency and enhanced UV-B radiation on
growth, photosynthesis and pigmentation of rye were studied. The plan
ts were grown for 5 weeks in growth chambers with high (700 mu mol m(-
2) s(-2)) irradiance levels. A 30% difference in UV-B at plant level w
as achieved by using different thicknesses of UV-B transparent Plexigl
ass. One half of the plants received optimal N nutrition, while the ot
her received half of this dose. Both enhanced UV-B and N deficiency st
rongly decreased production (from 24-33%). The combined effect was add
itive (no interaction) on most parameters, including total dry weight
production which was 52% lower than in the control series. Significant
interaction was found on the root/shoot ratio. While reduced N supply
induced an increase in the ratio at normal UV-B irradiation, under th
e increased UV-B, N deficiency had no effect on the root/shoot ratio.
The reduced biomass due to UV-B was clearly correlated to a reduction
in photosynthesis. At optimal N supply the plants increased the produc
tion of protective pigments in response to UV-B, but at reduced N supp
ly this response was lacking. The increased N content of the high UV-B
/high N plants could be a result of increased flavonoid production as
well as changes in light penetration in the canopy.