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Stimulation of nodulation in field peas (Pisum sativum) by low concentrations of ammonium in hydroponic cultureAlthough the inhibitory effects of high concentrations of mineral N (> 1.0 mM) on nodule development and function have often been studied, the effects of low, static concentrations of NH4+ (< 1.0 mM) on nodulation are unknown. In the present experiments we examine the effects of static concentrations of NH4+ at 0, 0.1 and 0.5 mM in flowing, hydroponic culture on nodule establishment and nitrogenase activity in field peas [Pisum sativum L. cv. Express (Svalof AB)] for the initial 28 days after planting (DAP). Peas grown in the presence of low concentrations of NH4+ had significantly greater nodule numbers (up to 4-fold) than plants grown without NH4+. Nodule dry weight per plant was significantly higher at 14, 21 and 28 DAP in plants grown in the presence of NH4+, but individual nodule mass was lower than in plants grown without NH4+. The nodulation pattern of the plants supplied with NH4+ was similar to that often reported for supernodulating mutants, however the plants did not express other growth habits associated with supernodulation. Estimates of N2 fixation indicate that the plus-NH4+ peas fixed as much or more N2 than the plants supplied with minus-NH4+ nutrient solution. There were no significant differences in nodule numbers, nodule mass or NH4+ uptake between the plants grown at the two concentrations of NH4+. Nodulation appeared to autoregulate by 14 DAP in the minus-NH4+ treatment. Plant growth and N accumulation in the minus-NH4+ plants lagged behind those of the plus-NH4+ treatments prior to N2 fixation becoming well established in the final week of the experiment. The plus-NH4+ treatments appeared not to elicit autoregulation and plants continued to initiate nodules throughout the experiment.
Document ID
20040121839
Acquisition Source
Ames Research Center
Document Type
Reprint (Version printed in journal)
Authors
Waterer, J. G.
(Univ. of Manitoba Winnipeg, Canada)
Vessey, J. K.
Raper, C. D. Jr
Raper CD, J. r.
Date Acquired
August 22, 2013
Publication Date
January 1, 1992
Publication Information
Publication: Physiologia plantarum
Volume: 86
Issue: 2
ISSN: 0031-9317
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: NCC2-101
Distribution Limits
Public
Copyright
Other
Keywords
NASA Program CELSS
NASA Discipline Life Support Systems
Non-NASA Center
NASA Discipline Number 61-10

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