CHLOROPLAST ULTRASTRUCTURAL DEVELOPMENT DURING THE ONTOGENY OF THE 2ND LEAF OF WHEAT UNDER NITROGEN DEFICIENCY

Development of mesophyll cell chloroplasts during ontogeny of second w heat (Triticum aestivum L.) leaf was compared in plants grown in full nutrient solution (+N) and in nutrient solution without nitrogen (-N). Chloroplast size and ultrastructure were evaluated quantitatively by means of transmission electron microscopy and stereology. In -N plants compared to +N ones, the life span of the second leaf was shortened a nd chloroplast development modified; the most striking feature was the accumulation of starch. Moreover, mature chloroplasts of -N plants we re smaller and had smaller relative partial volume of thylakoids and l arger relative partial volume of plastoglobules than those of +N plant s.