EFFECTS OF NITROGEN SUPPLY ON PHOTOSYNTHETIC TRAITS OF MAIZE

Nitrogen significantly affects chlorophyll content, photosynthetic rate and chlorophyll fluorescence of the leaves of maize seedlings. With a decline in the rate of N supply, chlorophyll content, net photosynthetic rate (Pn), light saturation point, light compensation point maximal photochemical quantum yield of PS II (Fv/Fm), actual quantum yield of PS II (ФPS II) and photochemical quenching co-efficient (qP) decreased and non-photochemical quenching (NPQ) increased. As compared with adequate N supply, lower N rate induced a decrease in chlorophyll content, Pn, ФPS II, Fv/Fm and qP and an increase in NPQ to different extents in different maize varieties. The fluctuation was the smallest in Yayu 2, followed by Xidan 2, Nongda 108 and Denghai 1 and was the greatest in Changdan 14.