Abstract
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.
Highlights
Effects of nitrogen on leaf number, individual leaf area, leaf area per plant, leaf area index, and photosynthetic rate per unit leaf area, biomass production and yield have been documented (Steer & Hocking, 1983; Milford et al, 1985; Vos & Biemond, 1992; Trápani & Hall, 1996; Gasal & Lemaire, 2002)
Sunflower is a model plant with opposite and alternate phyllotaxy to study the leaf development. In this investigation, effect of different nitrogen levels was studied on anatomy, growth and chlorophyll contents in sunflower leaves grown in net house under natural environmental conditions
Leaves were fully expanded at this stage and no change was observed on 11th day of measurements
Summary
Effects of nitrogen on leaf number, individual leaf area, leaf area per plant, leaf area index, and photosynthetic rate per unit leaf area, biomass production and yield have been documented (Steer & Hocking, 1983; Milford et al, 1985; Vos & Biemond, 1992; Trápani & Hall, 1996; Gasal & Lemaire, 2002). The carbon (C) and nitrogen (N) assimilates produced are exported to the growing regions of the plant where they are incorporated into new vegetative cells and tissues, giving rise to reproductive organs and seed, completing the growth cycle (Ourry et al, 2001). The photosynthetic rate per unit of leaf area is affected by nitrogen partitioning in thylakoid membranes, enzymes of photosynthetic carbon reduction cycle, nitrogen assimilation (Millard & Catt, 1988; Farquhar et al, 1980; Kumari, 2011) and prolongation of leaf area duration (Pearman et al, 1979). Sunflower is a model plant with opposite and alternate phyllotaxy to study the leaf development. In this investigation, effect of different nitrogen levels was studied on anatomy, growth and chlorophyll contents in sunflower leaves grown in net house under natural environmental conditions
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