Low 15N Natural Abundance in Shoot Tissue of Brachiaria humidicola Is an Indicator of Reduced N Losses Due to Biological Nitrification Inhibition (BNI)

Karwat, Hannes; Egenolf, Konrad; Núñez, Jonathan; Rao, Idupulapati M.; Rasche, Frank; Arango, Jacobo; Moreta, Danilo; Arévalo, Ashly; Cadisch, Georg

doi:10.3389/fmicb.2018.02383

Cited by 20 publications

(21 citation statements)

References 34 publications

(56 reference statements)

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“…Lower δ 15 N values indicate reduced soil microbial nitrification, a process known for strong isotopic N fractionation, which results in 15 N enrichment of source N (soil NH 4 + ) ( 39 , 40 ). Brachiaria grass genotypes that have a high BNI capacity in root systems show lower δ 15 N in leaf tissues compared to low BNI capacity genotypes ( 41 ). Lower grain δ 15 N observed in BNI-MUNAL, 16% lower ( P < 0.002) than in MUNAL control ( SI Appendix , Fig.…”

Section: Resultsmentioning

confidence: 99%

Enlisting wild grass genes to combat nitrification in wheat farming: A nature-based solution

Subbarao

Kishii

Bozal-Leorri

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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Active nitrifiers and rapid nitrification are major contributing factors to nitrogen losses in global wheat production. Suppressing nitrifier activity is an effective strategy to limit N losses from agriculture. Production and release of nitrification inhibitors from plant roots is termed “biological nitrification inhibition” (BNI). Here, we report the discovery of a chromosome region that controls BNI production in “wheat grass” Leymus racemosus (Lam.) Tzvelev, located on the short arm of the “Lr#3Nsb” (Lr#n), which can be transferred to wheat as T3BL.3NsbS (denoted Lr#n-SA), where 3BS arm of chromosome 3B of wheat was replaced by 3NsbS of L. racemosus. We successfully introduced T3BL.3NsbS into the wheat cultivar “Chinese Spring” (CS-Lr#n-SA, referred to as “BNI-CS”), which resulted in the doubling of its BNI capacity. T3BL.3NsbS from BNI-CS was then transferred to several elite high-yielding hexaploid wheat cultivars, leading to near doubling of BNI production in “BNI-MUNAL” and “BNI-ROELFS.” Laboratory incubation studies with root-zone soil from field-grown BNI-MUNAL confirmed BNI trait expression, evident from suppression of soil nitrifier activity, reduced nitrification potential, and N2O emissions. Changes in N metabolism included reductions in both leaf nitrate, nitrate reductase activity, and enhanced glutamine synthetase activity, indicating a shift toward ammonium nutrition. Nitrogen uptake from soil organic matter mineralization improved under low N conditions. Biomass production, grain yields, and N uptake were significantly higher in BNI-MUNAL across N treatments. Grain protein levels and breadmaking attributes were not negatively impacted. Wide use of BNI functions in wheat breeding may combat nitrification in high N input–intensive farming but also can improve adaptation to low N input marginal areas.

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Section: Resultsmentioning

confidence: 99%

Enlisting wild grass genes to combat nitrification in wheat farming: A nature-based solution

Subbarao

Kishii

Bozal-Leorri

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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“…In the corn-Urochloa intercrop, the recovery of N in fertilizer was higher than in corn monoculture (Almeida et al, 2018d) and the greater recovery in soil profiles between 0.6 and 1.0 m was probably related to Urochloa roots reaching deep layers, thus reducing N-losses by leaching. Reduced leaching might as well be attributed to the BNI promoted by Urochloa root exudation (Karwat et al, 2018). Also, Galdos et al (2020) reported that the finer roots of U. brizantha promoted a more complex pore system in the soil, reducing solute flow and reducing N leaching when compared to corn or even U. ruziziensis.…”

Section: N Cyclingmentioning

confidence: 99%

Urochloa in Tropical Agroecosystems

Baptistella¹,

Andrade

Favarin³

et al. 2020

Front. Sustain. Food Syst.

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Increasing biodiversity is an important issue in more secure and sustainable agriculture. Diversified systems are more resilient to climate change, environmental stresses and enhance soil health, nutrient cycling and nutrient use efficiency. In tropical agroecosystems, cover crops and intercrops are an alternative toward a more diverse and sustainable production. Urochloa spp. (syn. Brachiaria spp.) are perennial grasses, known for their high biomass production. They are commonly used as cover and companion crops in conservation agriculture in the tropics and the residues left in the field after cutting protect the soil and provide nutrient to the next crop cycle or intercropped culture. Urochloa species roots are vigorous, abundant and deep, as opposed to the more shallow and scarce roots of common crops. These traits contribute to carbon sequestration, soil organic matter stabilization and nutrient cycling. Urochloa roots also improve soil physical characteristics and influence soil nutrient dynamics, reducing nutrient losses and enhancing cycling, what is key to achieve greater nutrient use efficiency in agriculture. For instance, Urochloa root exudates can reduce nitrogen losses by denitrification and leaching through a process called biological nitrification inhibition; root exudates can mobilize recalcitrant phosphorus from soils and make it available for plant uptake; the deep roots of these grasses have the potential to recover nutrients that are virtually lost away from the root zone of other crops. This review compiles scientific progress regarding the introduction of Urochloa in agroecosystems, mainly on the aspects related to the contribution to more secure and sustainable agriculture.

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“…Indeed, Urochloa spp. have a variety of strategies, which could affect the δ 15 N signature of their biomass [31]. First, grasses of the genus Urochloa can obtain 20% to 40% of their total N in the plant from the atmosphere through the association with N fixing bacteria (i.e., non-symbiotic N 2 fixation) [32,33].…”

Section: Introductionmentioning

confidence: 99%

Urochloa Grasses Swap Nitrogen Source When Grown in Association with Legumes in Tropical Pastures

et al. 2020

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The degradation of tropical pastures sown with introduced grasses (e.g., Urochloa spp.) has dramatic environmental and economic consequences in Latin America. Nitrogen (N) limitation to plant growth contributes to pasture degradation. The introduction of legumes in association with grasses has been proposed as a strategy to improve N supply via symbiotic N2 fixation, but the fixed N input and N benefits for associated grasses have hardly been determined in farmers’ pastures. We have carried out on-farm research in ten paired plots of grass-alone (GA) vs. grass-legume (GL) pastures. Measurements included soil properties, pasture productivity, and sources of plant N uptake using 15N isotope natural abundance methods. The integration of legumes increased pasture biomass production by about 74%, while N uptake was improved by two-fold. The legumes derived about 80% of their N via symbiotic N2 fixation. The isotopic signature of N of grasses in GA vs. GL pastures suggested that sources of grass N are affected by sward composition. Low values of δ15N found in some grasses in GA pastures indicate that they depend, to some extent, on N from non-symbiotic N2 fixation, while δ15N signatures of grasses in GL pastures pointed to N transfer to grass from the associated legume. The role of different soil–plant processes such as biological nitrification inhibition (BNI), non-symbiotic N2 fixation by GA pastures and legume–N transfer to grasses in GL pastures need to be further studied to provide a more comprehensive understanding of N sources supporting the growth of grasses in tropical pastures.

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Low 15N Natural Abundance in Shoot Tissue of Brachiaria humidicola Is an Indicator of Reduced N Losses Due to Biological Nitrification Inhibition (BNI)

Cited by 20 publications

References 34 publications

Enlisting wild grass genes to combat nitrification in wheat farming: A nature-based solution

Enlisting wild grass genes to combat nitrification in wheat farming: A nature-based solution

Urochloa in Tropical Agroecosystems

Urochloa Grasses Swap Nitrogen Source When Grown in Association with Legumes in Tropical Pastures

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