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Comparative Effect of Nitrogen Forms on Nitrogen Uptake and Cotton Growth Under Salinity Stress
- Dai, Jianlong, Duan, Liusheng, Dong, Hezhong
- Journal of plant nutrition 2015 v.38 no.10 pp. 1530-1543
- Gossypium hirsutum, ammonium nitrogen, cotton, hydroponics, leaves, nitrate nitrogen, nitrates, nitrogen, nutrient uptake, photosynthesis, root growth, roots, salinity, salt stress, seedlings, sodium, sodium chloride, surface area, viability
- The effects of nitrogen (N) forms (ammonium- or nitrate-N) on plant growth under salinity stress [150 mmol sodium chloride (NaCl)] were studied in hydroponically cultured cotton. Net fluxes of sodium (Na ⁺), ammonium (NH ₄⁺), and nitrate (NO ₃⁻) were also determined using the Non-Invasive Micro-Test Technology. Plant growth was impaired under salinity stress, but nitrate-fed plants were less sensitive to salinity than ammonium-fed plants due mainly to superior root growth by the nitrate-fed plants. The root length, root surface area, root volume, and root viability of seedlings treated with NO ₃-N were greater than those treated with NH ₄-N with or without salinity stress. Under salinity stress, the Na ⁺ content of seedlings treated with NO ₃-N was lower than that in seedlings treated with NH ₄-N owing to higher root Na ⁺ efflux. A lower net NO ₃⁻ efflux was observed in roots of nitrate-fed plants relative to the net NH ₄⁺ efflux from roots of ammonium-fed plants. This resulted in much more nitrogen accumulation in different tissues, especially in leaves, thereby enhancing photosynthesis in nitrate-fed plants under salinity stress. Nitrate-N is superior to ammonium-N based on nitrogen uptake and cotton growth under salinity stress.