Effects of Nitrogen Levels on Anatomy, Growth, and Chlorophyll Content in Sunflower (Helianthus annuus L.) Leaves

Nitrogen nutrition strongly affected the individual leaf expansion, formation and development of palisade and spongy cells, chloroplast membrane organization and number of grana thylakoids, chlorophyll a, and b proportion, chloroplast length and width, epidermal cell division and expansion in sunflower (Helianthus annuus L.) leaves. Nitrogen levels remarkably affected the development of phloem transfer cells, thereby loading and unloading capacity of phloem. Nitrogen nutrition environment exert developmental control on phloem size via cytokinin production by increased root growth in sunflower.