Effects of photoperiod on growth of and denitrification by Pseudomonas chlororaphis in the root zone of Glyceria maxima, studied in a gnotobiotic microcosm

TY - JOUR

T1 - Effects of photoperiod on growth of and denitrification by Pseudomonas chlororaphis in the root zone of Glyceria maxima, studied in a gnotobiotic microcosm

AU - Bodelier, P.L.E.

AU - Wijlhuizen, A.G.

AU - Blom, C.W.P.M.

AU - Laanbroek, H.J.

N1 - Reporting year: 1997 Metis note: 2226; CTE ; CL; PVP ; MWE ; ME; file:///L:/Endnotedatabases/NIOOPUB/pdfs/Pdfs1997/Bodelier_ea_2226.pdf

PY - 1997

Y1 - 1997

N2 - The emergent macrophyte Glyceria maxima was subjected to different photoperiods and grown with ammonium or nitrate as nitrogen source in presterilized microcosms with spatially separated root and non-root compartments. The microcosms were inoculated with the denitrifying bacterium Pseudomonas chlororaphis. The effect of the plant and the photoperiod on growth and denitrification by P. chlororaphis was assessed. The plant had a strong positive effect on the growth of the bacteria. The bacterial numbers in the root compartment of the planted microcosms were 19-32 times higher than found in the non-root sediment of the unplanted systems. Lengthening the photoperiod resulted in elevated bacterial numbers due to the higher carbon exudation of the plant. This effect was greater still with the nitrate-fed plants, where additional P. chlororaphis growth could proceed via denitrification, indicating oxygen-limiting conditions in the microcosms. Higher porewater N2O concentrations in the root compartments as compared to the non-root compartments, which were highest for the long photoperiod, were also indicative of a plant-induced stimulation of denitrification. An effect of a diurnal oxygen release pattern of G. maxima on denitrification could not be detected. The gnotobiotic microcosm used in this study represents st potential system for the study of the behaviour and interactions of important bacterial groups, such as nitrifying and denitrifying bacteria where plant roots drive bacterial activity. [KEYWORDS: denitrification; exudates; Glyceria maxima; microcosm; Pseudomonas chlororaphis; rhizosphere Nitrogen transformations; cereal plants; model system; soil; rhizosphere; nitrate; barley; seedlings; ammonium; wheat]

AB - The emergent macrophyte Glyceria maxima was subjected to different photoperiods and grown with ammonium or nitrate as nitrogen source in presterilized microcosms with spatially separated root and non-root compartments. The microcosms were inoculated with the denitrifying bacterium Pseudomonas chlororaphis. The effect of the plant and the photoperiod on growth and denitrification by P. chlororaphis was assessed. The plant had a strong positive effect on the growth of the bacteria. The bacterial numbers in the root compartment of the planted microcosms were 19-32 times higher than found in the non-root sediment of the unplanted systems. Lengthening the photoperiod resulted in elevated bacterial numbers due to the higher carbon exudation of the plant. This effect was greater still with the nitrate-fed plants, where additional P. chlororaphis growth could proceed via denitrification, indicating oxygen-limiting conditions in the microcosms. Higher porewater N2O concentrations in the root compartments as compared to the non-root compartments, which were highest for the long photoperiod, were also indicative of a plant-induced stimulation of denitrification. An effect of a diurnal oxygen release pattern of G. maxima on denitrification could not be detected. The gnotobiotic microcosm used in this study represents st potential system for the study of the behaviour and interactions of important bacterial groups, such as nitrifying and denitrifying bacteria where plant roots drive bacterial activity. [KEYWORDS: denitrification; exudates; Glyceria maxima; microcosm; Pseudomonas chlororaphis; rhizosphere Nitrogen transformations; cereal plants; model system; soil; rhizosphere; nitrate; barley; seedlings; ammonium; wheat]

U2 - 10.1023/A:1004212814097

DO - 10.1023/A:1004212814097

M3 - Article

SN - 0032-079X

VL - 190

SP - 91

EP - 103

JO - Plant and Soil

JF - Plant and Soil

IS - 1

ER -