EFFECT OF NITROGEN FERTILIZATION ON PHOTOSYNTHETIC PIGMENT AND FLUORESCENCE CHARACTERISTICS IN LEAVES OF WINTER WHEAT CULTIVARS ON DRYLAND

The relationship between the content of photosynthetic pigment and chlorophyll fluorescence parameters,and their response to nitrogen fertilization were investigated during the whole growth period of two drought-resis tance wheats on field experiment.Results showed that the content of photosynthetic pigment components was increased with the increasing of nitrogen fertilizer,but it was differed in different growing stages for two cultivars.Nitrogen fertilization could increase the Ф_(PSⅡ),qP in jointing stage,the Fv/Fm in flowering and ripening stage,and decrease qN in the whole growing stages significantly.The Ф_(PSⅡ),Fv/Fm and qP were increased but qN was decreased with increasing of chlorophyll a,the rate of heat dissipation was increased with the increasing of chlorophyll b,and the carotinoid increasing enhanced the rate of heat dissipation of dryland and carbon assimilation of irrigated cultivar.The Ф_(PSⅡ) and qN of dryland cultivar treated by control were higher than that of irrigated cultivar in jointing stage significant,indicating that the characteristics of drought-resistantce of winter wheat could be displayed in the jointing stage,and the drought-resistant capability could be increased by enhancing the practical photochemistry efficiency and heat dissipation in jointing stage.