Effect of different fertilizing time on the chloroplast ultrastructure in later growing stage

By pot experiment,the effects of different nitrogen application time on chloroplast ultrastructure was studied in later growing stage of spring maize.The results showed that the chlorophyll content was the highest,the structure of chloroplast and mitochondrion was integrated and the granum lamellae was rich,when the fertilizer nitrogen was applied with a ratio of 1:3:1 in base fertilizer,jointing fertilizer and big trumpet fertilizer.With decreasing topdressing numbers until no nitrogen application,the chlorophyll content decreased,its structure changed from oblong to sphere and its lamellae ruptured;the lamellae structure gradually arranged disorderly,the membrane of mitochondrion was destroyed and the number of cristae decreased.So the proper increasing of the number of nitrogen topdressing could enhance the chlorophyll content and improve chloroplast ultrastructure.