PJB-1996-30
FOLIAR ABSORPTION OF 15NH3 BY WHEAT AND RICE VARIETIES
MUHAMMAD ASHRAF, SYYED RAZI ABBAS SHAMS*AND FAROOQ-E-AZAM
Abstract
Plant tops are considered as both sink and source of various N gases and other air pollutants which therefore, may influence the gaseous N content of the environment. Five varieties each of wheat (Triticum aestivum L. and T. durum L.) viz., Pak-81, LU-26, Sarsabz, Durum and M-143 and rice (Oryza sativa L.) viz., 8as-370, Bas-385, DM-25 , Kashmir Basmati and IR-6, were compared for NH3 absorption and its correlation with leaf area and N content of the plants. Eight week old plants grown in plastic pots were exposed to 15NH3 for 24 h in an air-tight canopy able to provide a limited supply of CO2 . Labelled NH3 was generated by reacting 15N-labelled ammonium sulphate with NaOH in the canopy. Total N and 15N content of the dried and powdered plant material was then determined. Upto 44% in rice and 50% in wheat of the 15NH3 generated in the canopy was assimilated by the plants. Varietal differences in foliar absorption of NH3 were observed. No correlation was obtained between leaf area and the amount of 15NH3 absorbed by different varieties indicating that NH3 absorption was not solely dependent on leaf area and/or photosynthetic activity, of the plants.
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