RT Journal T1 Effect of Nitrogen on Nitrogenase Activity of Diazotrophs and Total Bacterial Population in Rice Soil A1 N. Ayuni A1 O. Radziah A1 U. A. A. Naher A1 Q.A. Panhwar A1 M. S. Halimi JF Journal of Animal and Plant Sciences JO JAPS SN 1018-7081 VO 25 IS 5 SP 1358 OP 1364 YR 2015 FD 2015/10/01 DO DOI NA AB

Nitrogen (N) is the most limiting nutrient for rice and thisinput is required in the largest quantity for rice production. Laboratory and glasshouse studies were conducted at Universiti Putra Malaysiato determine the effect of urea-N on diazotrophs (Stenotrophomonas maltophila) growth and colonization on the rice roots and the effect of inoculation on bacterial population. Stenotrophomonas maltophila was grown under laboratory condition and applied with five levels of nitrogen in the form of urea (urea-N) (0, 50, 100, 200 and 300 mg L-1). The same treatments were given to rice plants under glasshouse condition for growth performance effect. Results showed that application of urea-N significantly influenced the population and nitrogenase activity of Stenotrophomonas maltophila. Nitrogenase activity was reduced with increased of urea-N application. The bacteria showed highest acetylene reduction assay (ARA) value of 0.042 µmol C2H4 h-1 mL-1 at 0 mg L-1 urea-N and the ARA was totally inhibited at 300 mg L-1 urea-N. In glasshouse study, the rhizosphere population was reduced by 7.6% with addition of 50 kgha-1, and endosphere population was reduced by 8% with addition of 200 kgha-1 of urea-N. However, photosynthesis and plant biomass were significantly increased by inoculation without affecting the non-rhizosphere population. In general high application of N negatively affected the nitrogenase activity, diazotrophs colonization on rice roots, photosynthesis and plant growth. 

K1 Acetylene reduction assay, diazotrophs, growth, photosynthesis, plant biomass, Stenotrophomonas maltophila PB Pakistan Agricultural Scientists Forum LK https://thejaps.org.pk/AbstractView.aspx?mid=2015-JAPS-185