Effects of Salinity and Mixed Ammonium and Nitrate Nutrition on the Growth and Nitrogen Utilization of Barley |
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| Authors: | A Ali T C Tucker T L Thompson & M Salim |
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| Institution: | Soil Salinity Laboratory, Land Resources Research Institute, National Agricultural Research Centre, Park Road, Islamabad 45500, Pakistan;Department of Soil and Water Science, University of Arizona, Tucson, AZ, USA |
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| Abstract: | The absorption and utilization of nitrogen (N) by plants are affected by salinity and the form of N in the root medium. A hydroponic study was conducted under controlled conditions to investigate growth and N uptake by barley ( Hordeum vulgare L.) supplied with five different NH4+-N/NO3?-N ratios at electrical conductivity of 0 and 8 dS m?1. The five NH4+-N/NO3-N ratios were 0/100, 25/75, 50/50, 75/25 and 100/0, each giving a total N supply of 100 mg N l?1 in the root medium. A mixed N supply of NH4+ and NO3? resulted in greater accumulation of N in plants than either NO3? or NH4+ as the sole N source. Plants produced a significantly higher dry matter yield when grown with mixed N nutrition than with NH4+ or NO3? alone. Total dry matter production and root and shoot N contents decreased with increasing salinity in the root medium. The interaction between salinity and N nutrition was found to be significant for all the variables. A significant positive correlation (r=0.97) was found between nitrogen level in the plant shoot and its dry matter yield. |
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| Keywords: | dry matter yield mixed NH4+ and NO3?-N nitrogen uptake salt stress |
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