Guntur Venkata Subbarao

Japan International Research Center for Agricultural Sciences | JIRCAS · Crop, Livestock and Environment Division

Biological nitrification inhibition (BNI) is a plant function where root systems release antibiotic compounds (BNIs) specifically aimed at suppressing nitrifiers to limit soil-nitrate formation in the root zone. Little is known about BNI-activity in maize (Zea mays L.), the most important food, feed, and energy crop. Two categories of BNIs are rele...

Background and aims Biological nitrification inhibition (BNI) is a chemical ecological phenomenon whereby plants specifically suppress nitrification by releasing inhibiting compounds from roots, an effective strategy for improving nitrogen uptake by limiting nitrogen losses from agricultural fields. During this study, we have aimed at characterizin...

Sorghum (Sorghum bicolor) roots are well-known for the release of Biological Nitrification Inhibitors (BNIs), such as sorgoleone (SGLN) and methyl 3-4-hydroxyphenyl propionate (MHPP). However, the deployment of sor-ghums with BNIs in agriculture practices has not been widely investigated and evaluated. In this study, sorghum and maize were intercro...

Synthetic nitrification inhibitors (SNI) and biological nitrification inhibitors (BNI) are promising tools to limit nitrogen (N) pollution derived from agriculture. Modern wheat cultivars lack sufficient capacity to exude BNIs, but, fortunately, the chromosome region (Lr#n-SA) controlling BNI production in Leymus racemosus , a wild relative of whea...

Nitrification and denitrification are soil biological processes responsible for large nitrogen losses from agricultural soils and generation of the greenhouse gas (GHG) N2O. Increased use of nitrogen fertilizer and the resulting decline in nitrogen use efficiency (NUE) are a major concern in agroecosystems. This nitrogen cycle in the rhizosphere is...

In the low fertility acid soils of the Orinoquian savannas of Colombia, Urochloa humi-dicola cv. Tully or Humidicola is one of the most widely planted tropical forage grasses for improving livestock productivity. Low nutritional quality of this grass limits sustainable livestock production in this region. In this study, we conducted a phenotypic ev...

Purpose Rapid nitrification leads to loss of nitrogen (N) fertilizer in agricultural systems. Plant produced/derived biological nitrification inhibitors (BNIs) are an effective eco-strategy to rein-in soil nitrification to improve crop-N uptake and nitrogen use efficiency (NUE) in production systems. Sorgoleone is the major component of hydrophobic...

Foreword for special issue on Biological Nitrification Inhibition

To control agronomic N losses and reduce environmental pollution, biological nitrification inhibition (BNI) is a promising strategy. BNI is an ecological phenomenon by which certain plants release bioactive compounds that can suppress nitrifying soil microbes. Herein, we report on two hydrophobic BNI compounds released from maize root exudation ( 1...

Biological nitrification inhibitors (BNIs) are released from plant roots as exudates to repress nitrifier activity in agricultural soils, and this can improve nitrogen (N) recovery from fertilizer and enhance the N-use-efficiency (NUE). This review summarizes the current understanding of the regulatory mechanisms of BNIs release from roots of plant...

Roots secrete a vast array of low molecular weight compounds into the soil broadly referred to as root exudates. It is a key mechanism by which plants and soil microbes interact in the rhizosphere. The effect of drought stress on the exudation process and composition is rarely studied, especially in cereal crops. This study focuses on comparative m...

The capacity of several plant species or landraces to inhibit nitrification in soil (biological nitrification inhibition, BNI) has been assessed in certain tropical pastures. These assessments are commonly based on potential net nitrification rates, which do not differentiate between gross nitrification and other processes that may reduce the amoun...

This position paper summarizes the current understanding of biological nitrification inhibition (BNI) to identify research needs for accelerating the development of BNI as a N2O mitigation strategy for grazed livestock systems. We propose that the initial research focus should be on the systematic screening of agronomically desirable plants for the...

It is essential to increase food production to meet the projected population increase while reducing environmental loads. Biological nitrification inhibition (BNI)-enabled wheat genetic stocks are under development through chromosome engineering by transferring chromosomal regions carrying the BNI trait from a wild relative (Leymus racemosus (Lam.)...

The Japan International Research Center for Agricultural Sciences (JIRCAS) working with partners such as CGIAR and its research centers, has made notable progress in creating farming solutions directed at the needs of poor farmers worldwide. This review discusses two critical achievements—development and deployment of differential systems for blast...

Significance Globally, wheat farming is a major source of nitrogen pollution. Rapid generation of soil nitrates cause nitrogen leakage and damage ecosystems and human health. Here, we show the 3Ns b S chromosome arm in wild grass (Leymus racemosus) that controls root nitrification inhibitor production can be transferred into elite wheat cultivars,...

The control of nitrogen (N) flows via nitrates leaching and nitrous oxide emission is crucial for a safe environment. Some plants have shown abilities to suppress soil nitrification by releasing biological inhibitors, such as sorgoleone in sorghum. We hypothesized that the N uptake capacity of plants partly influences soil nitrification, and so do...

Aims: Biological nitrification inhibition (BNI) has been reported as an emerging technology to control soil nitrifier activity for effective N-utilization in cropping systems. Brachiaria have been reported to suppress nitrifier populations by releasing nitrification inhibitors from roots through exudation. Substantial BNI activity has been reported...

Modern intensively managed pastures that receive large external nitrogen (N) inputs account for high N losses in form of nitrate (NO3–) leaching and emissions of the potent greenhouse gas nitrous oxide (N2O). The natural plant capacity to shape the soil N cycle through exudation of organic compounds can be exploited to favor N retention without aff...

Background It is an integral property of sorghum (Sorghum bicolor L.) to extensively release biological nitrification inhibitors (BNIs) under NH4+ nutrition, in comparison to NO3− nutrition. Our previous research indicated that plasma membrane (PM) H+-ATPase activity was stimulated by NH4+ and low rhizosphere pH, which in turn provided the driving...

Sorgoleone is a secondary sorghum metabolite released from roots. It has allelopathic properties and is considered to inhibit ammonia-oxidizing archaea (AOA) and bacteria (AOB) responsible for the rate-limiting step (ammonia oxidation) in nitrification. Low activity of these microorganisms in soil may contribute to slow down nitrification and reduc...

The name of the author was incorrectly spelled as “Filippo Carannant”. The correct spelling is “Filippo Carannante” and is now presented correctly in this article.

In order to meet the growing demands from the population explosion, the future agriculture system needs to be more productive and resource efficient than the current production systems. The green revolution has revolutionized the food production in the last five decades but largely driven by intensive resource use, in particular nitrogen and water....

Aim Utilization of biological nitrification inhibition (BNI) strategy can reduce nitrogen losses in agricultural systems. This study is aimed at characterizing BNI activity in a plant-soil system using a biparental hybrid population of Brachiaria humidicola (Bh), a forage grass with high BNI potential but of low nutritional quality. Methods Soil n...

Soil microbial activity is recognized as an important factor affecting nitrogen release from slow-release fertilizers. However, studies on the effect of size and activity of soil microflora on fertilizers degradation provided contrasting results. To date, no clear relationships exist between soil microbial activity and the release of nitrogen from...

Background Sorghum roots release two categories of biological nitrification inhibitors (BNIs) – hydrophilic-BNIs and hydrophobic-BNIs. Earlier research indicated that rhizosphere pH and plasma membrane (PM) H+ATPase are functionally linked with the release of hydrophilic BNIs, but the underlying mechanisms are not fully elucidated. This study is de...

Accelerated soil-nitrifier activity and rapid nitrification are the cause of declining nitrogen-use efficiency (NUE) and enhanced nitrous oxide (N2O) emissions from farming. Biological nitrification inhibition (BNI) is the ability of certain plant roots to suppress soil-nitrifier activity, through production and release of nitrification inhibitors....

Aims Sorghum (Sorghum bicolor) roots release biological nitrification inhibitors (BNIs) to suppress soil nitrification. Presence of NH4+ in the rhizosphere stimulates BNIs release and it is hypothesized to be functionally associated with plasma membrane (PM) H+-ATPase activity. However, whether the H+-ATPase is regulated at the transcriptional leve...

As global demand for livestock products (such as meat, milk, and eggs) is expected to double by 2050, necessary increases to future production must be reconciled with negative environmental impacts that livestock cause. This paper describes the LivestockPlus concept and demonstrates how the sowing of improved forages can lead to the sustainable int...

Soil nitrogen (N) loss due to rapid nitrification (oxidation of ammonium to nitrate) is a serious problem with economic and environmental implications. As a result, a large proportion of N ferti-lisers applied to crops are lost to the environment via nitrate leaching and nitrous oxide emissions. The tropical pasture grass Brachiaria humidicola (Bh)...

As global demand for livestock products (such as meat, milk and eggs) is expected to double by 2050, necessary increases to future production must be reconciled with negative environmental impacts that livestock cause. This paper describes the LivestockPlus concept and demonstrates how the sowing of improved forages can lead to the sustainable inte...

Nitrification is an oxidation process, part of the larger nitrogen (N) cycle in the soil, and is mediated by microorganisms that transform ammonium (NH + 4) to the water soluble nitrate (NO 3-), producing nitrous oxide (N 2 O, a potent greenhouse gas) as a by-product. Researchers at CIAT-Colombia, in collaboration with JIRCAS-Japan, reported that t...

Background and aims Nitrification and denitrification are the two most important processes that contribute to greenhouse gas emission and inefficient use of nitrogen. Suppressing soil nitrification through the release of ni-trification inhibitors from roots is a plant function, and termed "Biological Nitrification Inhibition (BNI)". We report here...

Tropical forage grasses and legumes as key components of sustainable crop-livestock systems in Latin America and the Caribbean have major implications for improving food security, alleviating poverty, restoring degraded lands and mitigating climate change. Climate-smart tropical forage crops can improve the livestock productivity of smallholder far...

Summary Nitrification and denitrification are the primary drivers for generating reactive-N (NO3-, N2O and NO) the two processes of N-cycle, largely responsible for soil-N losses, resulting poor N-recovery and low-NUE in agricultural systems. Suppressing soil-nitrifier activity facilitates retention of soil mineral-N as ammonium, leads to better ut...

Forage-based livestock production plays a key role in national and regional economies, for food security and poverty alleviation, but is considered a major contributor to agricultural GHG emissions. While demand for livestock products is predicted to increase, there is political and societal pressure both to reduce environmental impacts and to conv...

Nitrogen (N), the most critical and essential nutrient for plant growth, largely determines the productivity in both extensive and intensive grassland systems. Nitrification and denitrification processes in the soil are the primary drivers of generating reactive N (NO3-, N2O and NO), largely responsible for N loss and degradation of grasslands. Sup...

Agriculture and livestock production systems are two major emitters of greenhouse gases. Methane with a GWP (global warming potential) of 21, and nitrous oxide (N2O) with a GWP of 300, are largely emitted from animal production agriculture, where livestock production is based on pasture and feed grains. The principal biological processes involved i...

Agriculture and livestock production are major contributors to greenhouse gas emissions. Forage-based systems dominate much of agriculture in the tropics, providing livelihoods to farmers but also affecting local and global environments. In this chapter, we attempt to answer the question: How can farmers and livestock keepers improve their liveliho...

Background Agriculture is the single largest geo-engineering initiative that humans have initiated on planet Earth, largely through the introduction of unprecedented amounts of reactive nitrogen (N) into ecosystems. A major portion of this reactive N applied as fertilizer leaks into the environment in massive amounts, with cascading negative effect...

Aims and background The ability to suppress soil nitrification through the release of nitrification inhib-itors from plant roots is termed 'biological nitrification inhibition' (BNI). Earlier, we reported that sorghum roots release higher BNI-activity when grown with NH 4 + , but not with NO 3 -as N source. Also for BNI release, rhizosphere pH of <...

Aims The ability to suppress soil nitrification through the release of nitrification inhibitors from plant roots is termed ‘biological nitrification inhibition’ (BNI). Here, we aimed at the quantification and characterization of the BNI function in sorghum that includes inhibitor production, their chemical identity, functionality and factors regula...

non-commercial research and educational use only. Not for reproduction, distribution or commercial use. This chapter was originally published in the book Advances in Agronomy, Vol. 114 published by Elsevier, and the attached copy is provided by Elsevier for the author's benefit and for the benefit of the author's institution, for non-commercial res...

Critical micronutrient concentrations in soils and plants have not been clearly determined for marginal soils where deficiencies are likely to occur. The objective of this study was to develop a reliable method for assessing micronutrient deficiency in soils and plants. Soybean plants [Glycine max (L.) Merr.] were grown in the A and B horizons of t...

Human activity has had by far the single largest infl uence on the global N cycle by introducing massive amounts of reactive N into the ecosystems. A major portion of this reactive N applied as fertilizer, leaks into the environment and has a cascading effect on human health; ecosystem diversity, functions and services; and global warming with nega...

The natural ability of plants to release chemical substances from their roots that have a suppressing effect on nitrifier activity and soil nitrification, is termed 'biological nitrification inhibition' (BNI). Though nitrifica-tion is one of the critical processes in the nitrogen cycle, unrestricted and rapid nitrification in agricultural systems c...

Biological nitrification inhibition by Brachiaria humidicola roots varies with soil type and inhibits nitrifying bacteria, but not other major soil microorganisms Abstract The tropical pasture grass Brachiaria humidiola (Rendle) Schweick releases nitrification inhibitory compounds from its roots, a phenomenon termed 'biological nitrification inhibi...

Nitrification, a key process in the global nitrogen cycle that generates nitrate through microbial activity, may enhance losses of fertilizer nitrogen by leaching and denitrification. Certain plants can suppress soil-nitrification by releasing inhibitors from roots, a phenomenon termed biological nitrification inhibition (BNI). Here, we report the...

The biological oxidation of ammonia (i.e. nitrification), results in the transformation of relatively immobile NH4+ into a highly mobile NO3-, which is vulnerable to losses through leaching and denitrification, resulting in low nitrogen-use efficiency in agricultural systems. The ability of certain plants to suppress soil nitrifier function by rele...

The tropical pasture grass, Brachiaria humidicola (Rendle) Schweick, produces nitrification inhibitory compounds (termed biological nitrification inhibitors or BNIs) in its shoot and root tissues and releases BNIs from its roots. In the present study, two BNI compounds were isolated and identified from the shoot tissue of B. humidicola using activi...

Nitrification results in poor nitrogen (N) recovery and negative environmental impacts in most agricultural systems. Some plant species release secondary metabolites from their roots that inhibit nitrification, a phenomenon known as biological nitrification inhibition (BNI). Here, we attempt to characterize BNI in sorghum (Sorghum bicolor). In solu...

Climate change could strongly affect the wheat crop that accounts for 21% of food and 200 million hectares of farmland worldwide. This article reviews some of the approaches for addressing the expected effects that climate change may likely inflict on wheat in some of the most important wheat growing areas, namely germplasm adaptation, system manag...

Biological nitrification inhibition (BNI) is a character that may result in a reduction of emissions of nitrous oxide (N 2 O), a green house gas that has more than 300 times the warming power of CO 2, as well as other forms of N which are lost to the environment. The BNI character has not been found in the three major crops; wheat, rice and maize....

Using a recombinant luminescent Nitrosomonas europaea assay to quantify biological nitrification inhibition (BNI), we found that a wild relative of wheat (Leymus racemosus (Lam.) Tzvelev) had a high BNI capacity and releases about 20 times more BNI compounds (about 30ATU g−1 root dry weight 24h−1) than Triticum aestivum L. (cultivated wheat). The r...