Climate-smart crop-livestock systems for smallholders in the tropics: Integration of new forage hybrids to intensify agriculture and to mitigate climate change through regulation of nitrification in soil

Rao, Idupulapati M.; Ishitani, Manabu; Miles, John W.; Peters, Michael; Tohmé, Joe; Arango, Jacobo; Moreta, Danilo; López, H. Bastidas; Castro, Aracely; Hoek, Rein van der; Martens, Siriwan D.; Hyman, Glenn; Tapasco, Jeimar; Duitama, Jorge; Suárez, Harold; Borrero, Gonzalo; Núñez, Jonathan; Hartmann, Katharina; Domínguez, Moralba Garcia; Sotelo, Mauricio; Vergara, Daniel; Lavelle, Patrick; Subbarao, G. V.; Rincón, Álvaro; Plazas, C.; Mendoza, R.; Rathjen, Lena; Karwat, Hannes; Cadisch, Georg

doi:10.17138/tgft(2)130-132

Cited by 23 publications

(11 citation statements)

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“…Biological nitrification inhibition differences among Bh accessions or hybrids have been revealed ( Subbarao et al, 2007 ; Rao et al, 2014 ; Nuñez et al, 2018 ) and the effect of high BNI is expected to reduce

formation and leaching ( Subbarao et al, 2009 , 2013 ). But experimental evidence for the latter is lacking.…”

Section: Discussionmentioning

confidence: 99%

“…Five apomictic Bh hybrids (Bh08 selection: Bh08-1149, Bh08-700, Bh08-675, Bh08-696, Bh08-1253) and two germplasm accessions of Bh (CIAT 16888, CIAT 679 cv. Tully) were used as test genotypes ( Rao et al, 2014 ). Bh stolons were first propagated from a Bh stock collection at UHOH and transferred to a turf-based culture substrate for 3 weeks for root establishment.…”

Section: Methodsmentioning

confidence: 99%

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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)

et al. 2018

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The tropical forage grass Brachiaria humidicola (Bh) suppresses the activity of soil nitrifiers through biological nitrification inhibition (BNI). As a result, nitrate (NO3−) formation and leaching are reduced which is also expected to tighten the soil nitrogen (N) cycle. However, the beneficial relationship between reduced NO3− losses and enhanced N uptake due to BNI has not been experimentally demonstrated yet. Nitrification discriminates against the 15N isotope and leads to 15N depleted NO3−, but 15N enriched NH4+ in soils. Leaching of 15N depleted NO3− enriches the residual N pool in the soil with 15N. We hypothesized that altered nitrification and NO3− leaching due to diverging BNI magnitudes in contrasting Bh genotypes influence soil 15N natural abundance (δ15N), which in turn is reflected in distinct δ15N in Bh shoot biomass. Consequently, high BNI was expected to be reflected in low plant δ15N of Bh. It was our objective to investigate under controlled conditions the link between shoot value of δ15N in several Bh genotypes and leached NO3− amounts and shoot N uptake. Additionally, plant 15N and N% was monitored among a wide range of Bh genotypes with contrasting BNI potentials in field plots for 3 years. We measured leaf δ15N of young leaves (regrown after cutback) of Bh and combined it with nitrification rates (NRs) of incubated soil to test whether there is a direct relationship between plant δ15N and BNI. Increased leached NO3− was positively correlated with higher δ15N in Bh, whereas the correlation between shoot N uptake and shoot δ15N was inverse. Field cultivation of a wide range of Bh genotypes over 3 years decreased NRs in incubated soil, while shoot δ15N declined and shoot N% increased over time. Leaf δ15N of Bh genotypes correlated positively with NRs of incubated soil. It was concluded that decreasing plant δ15N of Bh genotypes over time reflects the long-term effect of BNI as linked to lower NO3− formation and reduced NO3− leaching. Accordingly, a low δ15N in Bh shoot tissue verified its potential as indicator of high BNI activity of Bh genotypes.

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formation and leaching ( Subbarao et al, 2009 , 2013 ). But experimental evidence for the latter is lacking.…”

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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

et al. 2018

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“…Previous studies have reported that the use of nitrification inhibitors, either synthetic or plantbased (Biological Nitrification Inhibitors-BNIs) reduces soil nitrification rates and, thus, NO3leaching and N2O emissions (Subbarao et al 2009;Di et al 2010;Liu et al 2013;Byrnes et al 2017;Coskun et al 2017b;Beeckman et al 2018), and thus contributes towards increasing crop N use efficiency (NUE) (Moreta et al 2014;Sun et al 2016;Yang et al 2016). Studies of regulation of N soil dynamics associated to plant and soil microorganism interaction such as BNI and more recently the biological denitrification inhibition (BDI), have increased since they represent an ecologically friendly, sustainable and cost-effective strategy compared to the use of synthetic inhibitors (Bardon et al 2014;Rao et al 2014;Coskun et al 2017a, b;Subbarao et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Biological nitrification inhibition activity in a soil-grown biparental population of the forage grass, Brachiaria humidicola

et al. 2018

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Biological nitrification inhibition activity in a soil-grown biparental population of the forage grass, Brachiaria humidicola The International Center for Tropical Agriculture (CIAT) believes that open access contributes to its mission of reducing hunger and poverty, and improving human nutrition in the tropics through research aimed at increasing the eco-efficiency of agriculture. CIAT is committed to creating and sharing knowledge and information openly and globally. We do this through collaborative research as well as through the open sharing of our data, tools, and publications.

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“…It has high biomass production potential and produces nutritious herbage resulting in increased livestock productivity [ 3 , 4 ]. Brachiaria is adapted to drought and low-fertility soils, sequesters carbon through its large root system, enhances nitrogen use efficiency, and subsequently minimizes eutrophication and greenhouse gas emissions [ 5 – 8 ]. Brachiaria plays important roles in soil erosion control and ecological restoration.…”

Section: Introductionmentioning

confidence: 99%

Molecular Characterizations of Kenyan Brachiaria Grass Ecotypes with Microsatellite (SSR) Markers

et al. 2017

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Brachiaria grass is an emerging forage option for livestock production in Kenya. Kenya lies within the center of diversity for Brachiaria species, thus a high genetic variation in natural populations of Brachiaria is expected. Overgrazing and clearing of natural vegetation for crop production and nonagricultural uses and climate change continue to threaten the natural biodiversity. In this study, we collected 79 Brachiaria ecotypes from different parts of Kenya and examined them for genetic variations and their relatedness with 8 commercial varieties. A total of 120 different alleles were detected by 22 markers in the 79 ecotypes. Markers were highly informative in differentiating ecotypes with average diversity and polymorphic information content of 0.623 and 0.583, respectively. Five subpopulations: International Livestock Research Institute (ILRI), Kitui, Kisii, Alupe, and Kiminini differed in sample size, number of alleles, number of private alleles, diversity index, and percentage polymorphic loci. The contribution of within-the-individual difference to total genetic variation of Kenyan ecotype population was 81%, and the fixation index (F ST = 0.021) and number of migrant per generation (Nm = 11.58) showed low genetic differentiation among the populations. The genetic distance was highest between Alupe and Kisii populations (0.510) and the lowest between ILRI and Kiminini populations (0.307). The unweighted neighbor-joining (NJ) tree showed test ecotypes grouped into three major clusters: ILRI ecotypes were present in all clusters; Kisii and Alupe ecotypes and improved varieties grouped in clusters I and II; and ecotypes from Kitui and Kiminini grouped in cluster I. This study confirms higher genetic diversity in Kenyan ecotypes than eight commercial varieties (Basilisk, Humidicola, Llanero, Marandú, MG4, Mulato II, Piatá and Xaraés) that represent three species and one three-way cross-hybrid Mulato II. There is a need for further collection of local ecotypes and their morphological, agronomical, and genetic characterizations to support Brachiaria grass breeding and conservation programs.

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Climate-smart crop-livestock systems for smallholders in the tropics: Integration of new forage hybrids to intensify agriculture and to mitigate climate change through regulation of nitrification in soil

Cited by 23 publications

References 3 publications

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

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

Biological nitrification inhibition activity in a soil-grown biparental population of the forage grass, Brachiaria humidicola

Molecular Characterizations of Kenyan Brachiaria Grass Ecotypes with Microsatellite (SSR) Markers

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