Ammonia-oxidizing bacteria and archaea grow under contrasting soil nitrogen conditions

Abstract. Future climate scenarios suggest an increased frequency of summer drought periods in the European Alpine Region. Drought can affect soil nitrogen (N) cycling, by altering N transformation rates, as well as the abundances of ammonia-oxidizing bacteria and archaea. However, the extent to which drought affects N cycling under in situ conditions is still controversial. The goal of this study was to analyse effects of drought on soil N turnover and ammonia-oxidizer abundances. To this end we conducted a rain-exclusion experiment at two differently managed mountain grassland sites, an annually mown and occasionally fertilized meadow and an abandoned grassland. Soils were sampled before, during and after drought and were analysed for gross rates of N mineralization, microbial uptake of inorganic N, nitrification, and the abundances of bacterial and archaeal ammonia oxidizers based on gene copy numbers of the amoA gene (AOB and AOA, respectively). Our results showed that the response to drought differed between the two sites. Effects were stronger at the managed meadow, where NH4+ immobilization rates increased and AOA abundances decreased. At the abandoned site gross nitrification and NO3− immobilization rates decreased during drought, while neither AOB, nor AOA abundances were affected. The different responses of the two sites to drought were likely related to site specific differences, such as soil organic matter content, nitrogen pools and absolute soil water content, resulting from differences in land-management. At both sites rewetting after drought had only minor short-term effects on the parameters that had been affected by drought, and seven weeks after the drought no effects of drought were detectable anymore. Thus, our findings indicate that drought can have distinct transient effects on soil nitrogen cycling and ammonia-oxidizer abundances in mountain grasslands and that the effect strength could be modulated by grassland management.

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Combining Ability and Gene Action of Tropical Maize (Zea mays L.) Inbred Lines under Low and High Nitrogen Conditions

Journal of Agricultural Science ◽

10.5539/jas.v9n4p222 ◽

2017 ◽

Vol 9 (4) ◽

pp. 222 ◽

Cited By ~ 5

Author(s):

Mafouasson Apala Hortense Noëlle ◽

Kenga Richard ◽

Gracen Vernon ◽

Yeboah Agyei Martin ◽

Mahamane Nasser Laouali ◽

...

Keyword(s):

Grain Yield ◽

Soil Nitrogen ◽

Combining Ability ◽

Gene Action ◽

Inbred Lines ◽

Hybrid Breeding ◽

Gene Effect ◽

Single Cross ◽

Additive Gene ◽

Nitrogen Conditions

This study was conducted to determine combining ability and gene action in elite maize inbred lines under low and high soil nitrogen conditions for hybrid breeding. Forty two tropical inbred lines (three testers and 39 lines) were crossed using line × tester mating design. The resulting 117 F1 hybrids, along with 4 hybrids used as checks, were evaluated using an 11 × 11 lattice design with two replications for grain yield and yield related traits during the 2012 and 2013 cropping seasons at two sites (Mbalmayo and Nkolbisson). Results revealed predominant additive gene effect under high soil nitrogen (N) conditions. Non-additive gene effect influenced grain yield under low soil and thus could be exploited for hybrid development. Under high N conditions inbred lines CLYN246, J16-1, CLWN201, TL-11-A-1642-5, CLQRCWQ26 and 1368 were good general combiners. Lines CML 343, ATP S6 20-Y-1, CLWN201, 1368, ATP S9 30 Y-1 and CLQRCWQ26 were good general combiners for grain yield under low N. They could be used to develop low N tolerant varieties. Different single cross hybrid combinations were identified for high grain yields under both low and high N conditions. The selected lines and single cross hybrids are a useful source of valuable genetic material for future maize hybrid breeding or direct production under low N.

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Effects of drought on nitrogen turnover and abundances of ammonia-oxidizers in mountain grassland

Biogeosciences ◽

10.5194/bg-11-6003-2014 ◽

2014 ◽

Vol 11 (21) ◽

pp. 6003-6015 ◽

Cited By ~ 28

Author(s):

L. Fuchslueger ◽

E.-M. Kastl ◽

F. Bauer ◽

S. Kienzl ◽

R. Hasibeder ◽

...

Keyword(s):

Soil Nitrogen ◽

N Cycling ◽

Gene Copy ◽

Ammonia Oxidizer ◽

Summer Drought ◽

Ammonia Oxidizing Bacteria ◽

Ammonia Oxidizers ◽

Mountain Grassland ◽

In Situ Conditions ◽

Effects Of Drought

Abstract. Future climate scenarios suggest an increased frequency of summer drought periods in the European Alpine Region. Drought can affect soil nitrogen (N) cycling, by altering N transformation rates, as well as the abundances of ammonia-oxidizing bacteria and archaea. However, the extent to which drought affects N cycling under in situ conditions is still controversial. The goal of this study was to analyse effects of drought on soil N turnover and ammonia-oxidizer abundances in soil without drought history. To this end we conducted rain-exclusion experiments at two differently managed mountain grassland sites, an annually mown and occasionally fertilized meadow and an abandoned grassland. Soils were sampled before, during and after drought and were analysed for potential gross rates of N mineralization, microbial uptake of inorganic N, nitrification, and the abundances of bacterial and archaeal ammonia-oxidizers based on gene copy numbers of the amoA gene (AOB and AOA, respectively). Drought induced different responses at the two studied sites. At the managed meadow drought increased NH4+ immobilization rates and NH4+ concentrations in the soil water solution, but led to a reduction of AOA abundance compared to controls. At the abandoned site gross nitrification and NO3− immobilization rates decreased during drought, while AOB and AOA abundances remained stable. Rewetting had only minor, short-term effects on the parameters that had been affected by drought. Seven weeks after the end of drought no differences to control plots could be detected. Thus, our findings demonstrated that in mountain grasslands drought had distinct transient effects on soil nitrogen cycling and ammonia-oxidizers, which could have been related to a niche differentiation of AOB and AOA with increasing NH4+ levels. However, the effect strength of drought was modulated by grassland management.

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Parent-Progeny Relationships between Maize Inbreds and Hybrids: Analysis of Grain Yield and Its Determinants for Contrasting Soil Nitrogen Conditions

Crop Science ◽

10.2135/cropsci2013.02.0111 ◽

2013 ◽

Vol 53 (5) ◽

pp. 2147-2161 ◽

Cited By ~ 14

Author(s):

K. E. D'Andrea ◽

M. E. Otegui ◽

A. G. Cirilo ◽

G. H. Eyhérabide

Keyword(s):

Grain Yield ◽

Soil Nitrogen ◽

Maize Inbreds ◽

Nitrogen Conditions

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Quantitative trait loci for yield and correlated traits under high and low soil nitrogen conditions in tropical maize

Molecular Breeding ◽

10.1007/s11032-006-9041-2 ◽

2007 ◽

Vol 20 (1) ◽

pp. 15-29 ◽

Cited By ~ 55

Author(s):

Jean-Marcel Ribaut ◽

Yvan Fracheboud ◽

Philippe Monneveux ◽

Marianne Banziger ◽

Mateo Vargas ◽

...

Keyword(s):

Quantitative Trait Loci ◽

Soil Nitrogen ◽

Quantitative Trait ◽

Tropical Maize ◽

Correlated Traits ◽

Trait Loci ◽

Nitrogen Conditions

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Development of Extra-Early Provitamin A Quality Protein Maize Inbreds with Resistance/Tolerance to Striga hermonthica and Soil Nitrogen Stress

Agronomy ◽

10.3390/agronomy11050891 ◽

2021 ◽

Vol 11 (5) ◽

pp. 891

Author(s):

Solomon A. Oyekale ◽

Baffour Badu-Apraku ◽

Victor O. Adetimirin ◽

Nnanna Unachukwu ◽

Melaku Gedil

Keyword(s):

Soil Nitrogen ◽

Beta Carotene ◽

Sub Saharan Africa ◽

Provitamin A ◽

Striga Hermonthica ◽

Nitrogen Stress ◽

Maize Varieties ◽

Maize Inbreds ◽

Sub Saharan ◽

Nitrogen Conditions

A hemiparasitic plant, Striga hermonthica (Del.) Benth and soil nitrogen stress are the key constraints to maize (Zea mays L.) productivity in sub-Saharan Africa, where commonly cultivated maize is the normal endosperm type that is deficient in provitamin A, tryptophan and lysine (PVATL). Seventy-six extra-early maize inbreds with provitamin A, tryptophan, and lysine qualities (TZEEIORQ) were developed to address these constraints, and four checks were assessed under Striga, low and high nitrogen conditions at three locations in Nigeria. The inbreds were further genotyped with two beta-carotene hydroxylase 1 (crtRB1) markers, and their seeds were quantified for provitamin A content. Significant (P < 0.01) genetic variations were observed for grain yield and other agronomic attributes of the inbreds under varying environmental conditions. Levels of PVATL for the inbreds ranged from 2.21–10.95 µg g−1, 0.04–0.08%, and 0.19–0.39%, respectively. Beta-carotene marker, crtRB1-3′TE, was polymorphic and grouped the inbreds into two. The marker was effective in identifying inbreds with moderate provitamin A content. Inbreds TZEEIORQ 5, TZEEIORQ 52, and TZEEIORQ 55 exhibited resistance to Striga, tolerance to nitrogen stress with moderate levels of PVATL and could be invaluable sources of favorable alleles for breeding nutritionally improved maize varieties with resistance/tolerance to Striga and soil nitrogen stress.

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