Do low land rice varieties prefer Ammonium or Nitrate
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Date
2013-07-04
Authors
Lalanthi, M. W. C
Dandeniya, W. S.
Chandrasiri, U.
Journal Title
Journal ISSN
Volume Title
Publisher
The university of Perdeniya
Abstract
Almost 70% of applied nitrogen (N) in rice fields is lost under the present agronomic practices in Sri Lanka. Supply of N to match the plant requirement is one strategy to enhance N use efficiency. Rice assimilates N in the form of ammonium <formula> and nitrate <formula>. Conflicting findings on the preferred form of N by lowland rice is reported in recent literature. A study was conducted at the Regional Rice Research and Development Center, Bombuwala with the aim of determining preferred N forms (<formula> and/or <formula>) of three rice varieties bred for lowland rice cultivation in Sri Lanka.
Three varieties of rice, Bw 272-6b, Bw 363 and Bw 267-3, were grown with three different <formula> ratio (100:0, 50:50, 0:100) to supplement N in hydroponic growth medium and maintained until 40 days after germination (DAG). At 40 DAG shoot N content and dry biomass were measured. In another experiment, soil collected from a rice field was amended with urea or <formula> with or without a nitrification inhibitor (Dyciandiamide – DCD) and the same varieties were grown. At 40 DAG plants were harvested to measure dry biomass. Data were statistically analyzed using SAS software.
Differences in <formula> in growth medium affected plant performance differently for the three varieties when grown hydroponically. Only Bw 267-3 showed higher biomass accumulation under only <formula> treatment (100:0) compared to the other two N treatments. Bw 272-6b and Bw 363 varieties were indifferent to the form of N available in the medium when plants were grown hydroponically. Shoot N content was highest in plants that received dual N forms for all three varieties. The highest N uptake for Bw 272-6b and Bw 363 were observed at dual N forms treatment (14.46 and 15.05 mg/plant, respectively). Bw 267-3 showed the highest N uptake under only <formula> treatment (15.92 mg/plant). The least uptake of N was observed under only <formula> treatment (0:100) for all three varieties. When plants were grown in soil, application of Urea without DCD, which facilitates a <formula> and <formula> containing medium, resulted in higher biomass accumulation irrespective of the variety in comparison to the other N-fertilizer treatments that facilitate either a <formula> dominating (Urea+DCD) or<formula> dominating (<formula>+DCD and <formula>) environment. The least biomass accumulation was observed in plants fertilized with <formula>+DCD. Bw 363 and Bw 272-6b can be grown in <formula> dual N forms but Bw 267-3 prefers <formula> only.
It is concluded that the magnitude of response to <formula> in the growth medium is dependent on the variety of rice.
Description
Keywords
LOW LAND RICE , AMMONIUM , NITRATE
Citation
Peradeniya University Research Sessions Purse 2012, Book of Abstracts, University of Peradeniya, Sri Lanka, Vol-17, July.4.2013 P 231