Denitrification in rice
1989
El Massry, A.A. | Gaafer, S.A. (Soil and Water Research Inst., Giza (Egypt). Agricultural Research Center)
A greenhouse sand culture experiment studied the effect of different pH levels on degree of denitrification as well as on growth and yield of rice plants. The pH levels were 4, 5, 6, 7, 8 and 9. Hoagland and Arnon nutrient solution was used. Results obtained from the two treatments, i.e., with and without NO3-N in the nutrient solution, are as follows: 1) Nitrate ion was in low concentration (from 5 to 8 mg/liter) on the first day, up to pH 6, in the treatment that received nutrient solution with NO3-N source. However the concentration increased on the second and third day. 2) The nitrite ion was in moderate concentration (11-14 mg/liter) on the first day, up to pH 6, in the treatment that received nutrient solution with NO3-N it increased, then on the second and the third days (19-23 and 28-32 mg/liter, respectively). The nitrite ion accumulation was very high beyond pH 6. 3) In general, a highly significant positive correlation was found between pH values and nitrite ion accumulation on the three successive days following irrigation. 4) The pH of the media showed a highly significant negative correlation with plant height and number of tillers in both treatments. 5) A highly significant negative correlation was found between pH and grain dry weight in the two treatments. 6) Increase of nitrite accumulation was associated with decreased growth and yield of rice plants.
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