Effects of ultraviolet-B radiation on common bean (Phaseolus vulgaris L.) plants grown under nitrogen deficiency
This work reports on the significance of UV-B absorbing compounds and DNA photorepair in protecting bean plants from UV-B radiation under nitrogen restriction. Bean plants grown in sterile vermiculite and irrigated periodically with a nutrient solution containing 12 or 1 mM of nitrate were irradiated with 22 Î¼W cm -2 of UV-B, 4 h daily during 10 days after the first trifoliate leaf was developed. This intensity was equivalent to 3.2 kJ m -2 per day, approximately. PAR fluence rate was 350 Â± 50 Î¼mol quanta m -2 s -1. Control plants did not receive UV-B irradiation. Leaf expansion was negatively affected by both nitrate restriction and UV-B irradiation. This decrease was paralleled by a significant increase in starch, which was exacerbated by the combined action of both factors. Combined action of low nitrogen and UV-B also negatively affected the CO 2 assimilation rate and the stomatal conductance. Formation of UV-B absorbing compounds was significantly increased by both UV-B irradiation and nitrogen restriction and this increase was exacerbated by the combination of both factors. No significant increase in dimer formation was detected in irradiated plants at the UV-B dose used. Significant dimer formation was only obtained by using very high UV-B intensities. This suggests that under an irradiation level of 22 Î¼W cm -2 of UV-B, which is close to natural conditions, protective mechanisms such as pigment screening and DNA photorepair were probably sufficient to prevent any dimer formation in leaves. Â© 2007 Elsevier B.V. All rights reserved.
|Título según WOS:||Effects of ultraviolet-B radiation on common bean (Phaseolus vulgaris L.) plants grown under nitrogen deficiency|
|Título según SCOPUS:||Effects of ultraviolet-B radiation on common bean (Phaseolus vulgaris L.) plants grown under nitrogen deficiency|
|Título de la Revista:||ENVIRONMENTAL AND EXPERIMENTAL BOTANY|
|Editorial:||PERGAMON-ELSEVIER SCIENCE LTD|
|Fecha de publicación:||2007|
|Página de inicio:||360|