Agronomy

520 KiB

Open AccessShort Note

In Winter Wheat, No-Till Increases Mycorrhizal Colonization thus Reducing the Need for Nitrogen Fertilization

by Julien Verzeaux, David Roger, Jérôme Lacoux, Elodie Nivelle, Clément Adam, Hazzar Habbib, Bertrand Hirel, Frédéric Dubois and Thierry Tetu

Agronomy 2016, 6(2), 38; https://doi.org/10.3390/agronomy6020038 - 21 Jun 2016

Cited by 14 | Viewed by 6013

Abstract

Arbuscular mycorrhizal fungi (AMF) play a major role in the uptake of nutrients by agricultural plants. Nevertheless, some agricultural practices can interrupt fungal-plant signaling and thus impede the establishment of the mycorrhizal symbiosis. A field experiment performed over a 5-year period demonstrated that [...] Read more.

Arbuscular mycorrhizal fungi (AMF) play a major role in the uptake of nutrients by agricultural plants. Nevertheless, some agricultural practices can interrupt fungal-plant signaling and thus impede the establishment of the mycorrhizal symbiosis. A field experiment performed over a 5-year period demonstrated that both the absence of tillage and of nitrogen (N) fertilization improved AMF colonization of wheat roots. Moreover, under no-till conditions, N uptake and aboveground biomass production did not vary significantly between N-fertilized and N-unfertilized plots. In contrast, both N uptake and above ground biomass were much lower when N fertilizer was not added during conventional tillage. This finding strongly suggests that for wheat, no-till farming is a sustainable agricultural system that allows a gradual reduction in N fertilizer use by promoting AMF functionality and at the same time increasing N uptake. Full article

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1599 KiB

Open AccessArticle

The Effect of Anaerobic and Aerobic Fish Sludge Supernatant on Hydroponic Lettuce

by Simon Goddek, Zala Schmautz, Ben Scott, Boris Delaide, Karel J. Keesman, Sven Wuertz and Ranka Junge

Agronomy 2016, 6(2), 37; https://doi.org/10.3390/agronomy6020037 - 21 Jun 2016

Cited by 62 | Viewed by 16255

Abstract

The mobilization of nutrients from fish sludge (i.e., feces and uneaten feed) plays a key role in optimizing the resource utilization and thus in improving the sustainability of aquaponic systems. While several studies have documented the aerobic and anaerobic digestion performance [...] Read more.

The mobilization of nutrients from fish sludge (i.e., feces and uneaten feed) plays a key role in optimizing the resource utilization and thus in improving the sustainability of aquaponic systems. While several studies have documented the aerobic and anaerobic digestion performance of aquaculture sludge, the impact of the digestate on plant growth has yet to be understood. The present study examines the impact of either an aerobic or an anaerobic digestion effluent on lettuce plant growth, by enriching a mixture of aquaculture and tap water with supernatants from both aerobic and anaerobic batch reactors. The lettuce plants grown in the hydroponic system supplied with supernatant from an anaerobic reactor had significantly better performance with respect to weight gain than both, those in the system where supernatant from the aerobic reactor was added, as well as the control system. It can be hypothesized that this effect was caused by the presence of NH₄⁺ as well as dissolved organic matter, plant growth promoting rhizobacteria and fungi, and humic acid, which are predominantly present in anaerobic effluents. This study should therefore be of value to researchers and practitioners wishing to further develop sludge remineralization in aquaponic systems. Full article

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Graphical abstract

455 KiB

Open AccessReview

The Elusive Boreal Forest Thaumarchaeota

by Malin Bomberg

Agronomy 2016, 6(2), 36; https://doi.org/10.3390/agronomy6020036 - 15 Jun 2016

Cited by 9 | Viewed by 5325

Abstract

In recent years, Archaea have, with increasing frequency, been found to colonize both agricultural and forest soils in temperate and boreal regions. The as yet uncultured group I.1c of the Thaumarchaeota has been of special interest. These Archaea are widely distributed in mature [...] Read more.

In recent years, Archaea have, with increasing frequency, been found to colonize both agricultural and forest soils in temperate and boreal regions. The as yet uncultured group I.1c of the Thaumarchaeota has been of special interest. These Archaea are widely distributed in mature vegetated acidic soils, but little has been revealed of their physiological and biological characteristics. The I.1c Thaumarchaeota have been recognized as a microbial group influenced by plant roots and mycorrhizal fungi, but appear to have distinct features from their more common soil dwelling counterparts, such as the Nitrosotalea or Nitrososphaera. They appear to be highly dependent on soil pH, thriving in undisturbed vegetated soils with a pH of 5 or below. Research indicate that these Archaea require organic carbon and nitrogen sources for growth and that they may live both aerobically and anaerobically. Nevertheless, pure cultures of these microorganisms have not yet been obtained. This review will focus on what is known to date about the uncultured group I.1c Thaumarchaeota formerly known as the “Finnish Forest Soil” (FFS) Archaea. Full article

(This article belongs to the Special Issue Interactions between Plant Rhizosphere and Soil Organisms)

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1401 KiB

Open AccessArticle

Municipal Compost as a Nutrient Source for Organic Crop Production in New Zealand

by Abie Horrocks, Denis Curtin, Craig Tregurtha and Esther Meenken

Agronomy 2016, 6(2), 35; https://doi.org/10.3390/agronomy6020035 - 20 May 2016

Cited by 32 | Viewed by 6875

Abstract

About 1% of New Zealand farmland is managed organically. Nitrogen is the nutrient most likely to limit organic crop production. A potential solution is incorporation of compost to supply N. About 726,000 t of municipal garden and kitchen wastes are sent to landfills [...] Read more.

About 1% of New Zealand farmland is managed organically. Nitrogen is the nutrient most likely to limit organic crop production. A potential solution is incorporation of compost to supply N. About 726,000 t of municipal garden and kitchen wastes are sent to landfills annually. Composting offers a means of reducing the impact of landfill wastes on the wider environment. Organically certified compost (N content typically 2% to 2.5%) is available from some municipal composting plants. To be effectively used on organic farms, the rate of N release (mineralization) must be known. Laboratory incubations were conducted to quantify mineralization of compost N under controlled (temperature and moisture) conditions. Nitrogen availability and crop yields from a one-off application of compost (25–100 t·ha⁻¹) were also assessed in two field trials (using cereal and forage crops). The results suggested that a relatively small part (13%–23%) of compost N was used by the crops in 3–4 years. Much of this was mineral N present at the time of application. Mineralization rates in the laboratory and field studies were much lower than expected from published work or compost C:N ratio (considered an important indicator of N mineralization potential of composts). Full article

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Graphical abstract

783 KiB

Open AccessCommunication

Effect of Irrigation Timing on Root Zone Soil Temperature, Root Growth and Grain Yield and Chemical Composition in Corn

by Xuejun Dong, Wenwei Xu, Yongjiang Zhang and Daniel I. Leskovar

Agronomy 2016, 6(2), 34; https://doi.org/10.3390/agronomy6020034 - 19 May 2016

Cited by 16 | Viewed by 7126

Abstract

High air temperatures during the crop growing season can reduce harvestable yields in major agronomic crops worldwide. Repeated and prolonged high night air temperature stress may compromise plant growth and yield. Crop varieties with improved heat tolerance traits as well as crop management [...] Read more.

High air temperatures during the crop growing season can reduce harvestable yields in major agronomic crops worldwide. Repeated and prolonged high night air temperature stress may compromise plant growth and yield. Crop varieties with improved heat tolerance traits as well as crop management strategies at the farm scale are thus needed for climate change mitigation. Crop yield is especially sensitive to night-time warming trends. Current studies are mostly directed to the elevated night-time air temperature and its impact on crop growth and yield, but less attention is given to the understanding of night-time soil temperature management. Delivering irrigation water through drip early evening may reduce soil temperature and thus improve plant growth. In addition, corn growers typically use high-stature varieties that inevitably incur excessive respiratory carbon loss from roots and transpiration water loss under high night temperature conditions. The main objective of this study was to see if root-zone soil temperature can be reduced through drip irrigation applied at night-time, vs. daytime, using three corn hybrids of different above-ground architecture in Uvalde, TX where day and night temperatures during corn growing season are above U.S. averages. The experiment was conducted in 2014. Our results suggested that delivering well-water at night-time through drip irrigation reduced root-zone soil temperature by 0.6 °C, increase root length five folds, plant height 2%, and marginally increased grain yield by 10%. However, irrigation timing did not significantly affect leaf chlorophyll level and kernel crude protein, phosphorous, fat and starch concentrations. Different from our hypothesis, the shorter, more compact corn hybrid did not exhibit a higher yield and growth as compared with taller hybrids. As adjusting irrigation timing would not incur an extra cost for farmers, the finding reported here had immediate practical implications for farm scale adaptation to hot environments. Full article

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437 KiB

Open AccessArticle

Impact of Pre-Anthesis Water Deficit on Yield and Yield Components in Barley (Hordeum vulgare L.) Plants Grown under Controlled Conditions

by Zakaria I. Al-Ajlouni, Ayed M. Al-Abdallat, Abdul Latief A. Al-Ghzawi, Jamal Y. Ayad, Jamal M. Abu Elenein, Nisreen A. Al-Quraan and P. Stephen Baenziger

Agronomy 2016, 6(2), 33; https://doi.org/10.3390/agronomy6020033 - 18 May 2016

Cited by 35 | Viewed by 6978

Abstract

Drought at pre-anthesis stages can influence barley growth and results in yield losses. Therefore, it is important to understand how drought at pre-anthesis can affect different traits associated with yield reduction in barley. The objective of this study was to understand the relevance [...] Read more.

Drought at pre-anthesis stages can influence barley growth and results in yield losses. Therefore, it is important to understand how drought at pre-anthesis can affect different traits associated with yield reduction in barley. The objective of this study was to understand the relevance of the genetic background of major flowering time genes in barley plants subjected to pre-anthesis drought and its impact on yield and yield components. A glasshouse experiment using a Randomized Complete Block Design was conducted to investigate the effect of drought and its timing on yield and yield components on eleven barley genotypes, which were selected to represent genetic diversity of major flowering time genes (PPDH1, PPDH2, HvVrn1, HvVrn2 and HvVrn3). Barley plants were exposed to three water regimes, non-stressed and stressed, which was applied at two pre-anthesis growth stages, tillering (SS) and stem elongation (SE). Results identified differences among genotypes in all measured traits. Grain yield, grain number and "thousand kernel weight" were reduced in all genotypes due to drought, irrespective of the growth stage. Early flowering genotypes had better performance as reflected in higher yield compared with late flowering genotypes. Results verified the fundamental importance of early flowering to improve productivity in response to pre-anthesis drought. The results of this study can help in selecting barley lines for future breeding purposes with improved resilience to drought conditions in Mediterranean environments. Full article

(This article belongs to the Special Issue QTL Mapping of Drought Tolerance)

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955 KiB

Open AccessArticle

Prairies Thrive Where Row Crops Drown: A Comparison of Yields in Upland and Lowland Topographies in the Upper Midwest US

by Adam C. Von Haden and Mathew E. Dornbush

Agronomy 2016, 6(2), 32; https://doi.org/10.3390/agronomy6020032 - 13 May 2016

Cited by 7 | Viewed by 5840

Abstract

Cellulosic biofuel production is expected to increase in the US, and the targeted establishment of biofuel agriculture in marginal lands would reduce competition between biofuels and food crops. While poorly drained, seasonally saturated lowland landscape positions are marginal for production of row crops [...] Read more.

Cellulosic biofuel production is expected to increase in the US, and the targeted establishment of biofuel agriculture in marginal lands would reduce competition between biofuels and food crops. While poorly drained, seasonally saturated lowland landscape positions are marginal for production of row crops and switchgrass (Panicum virgatum L.), it is unclear whether species-diverse tallgrass prairie yield would suffer similarly in saturated lowlands. Prairie yields typically increase as graminoids become more dominant, but it is uncertain whether this trend is due to greater aboveground net primary productivity (ANPP) or higher harvest efficiency in graminoids compared to forbs. Belowground biomass, a factor that is important to ecosystem service provisioning, is reduced when switchgrass is grown in saturated lowlands, but it is not known whether the same is true in species-diverse prairie. Our objectives were to assess the effect of topography on yields and live belowground biomass in row crops and prairie, and to determine the mechanisms by which relative graminoid abundance influences tallgrass prairie yield. We measured yield, harvest efficiency, and live belowground biomass in upland and lowland landscape positions within maize silage (Zea mays L.), winter wheat (Triticum aestivum L.), and restored tallgrass prairie. Maize and winter wheat yields were reduced by more than 60% in poorly drained lowlands relative to well-drained uplands, but diverse prairie yields were equivalent in both topographic settings. Prairie yields increased by approximately 45% as the relative abundance of graminoids increased from 5% to 95%. However, this trend was due to higher harvest efficiency of graminoids rather than greater ANPP compared to forbs. In both row crops and prairie, live belowground biomass was similar between upland and lowland locations, indicating consistent biomass nutrient sequestration potential and soil organic matter inputs between topographic positions. While poorly drained, lowland landscape positions are marginal lands for row crops, they appear prime for the cultivation of species-diverse tallgrass prairie for cellulosic biofuel. Full article

(This article belongs to the Special Issue Advanced Agronomy with Impact for Food Security)

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Graphical abstract

168 KiB

Open AccessEditorial

Towards a Better Understanding of Agronomic Efficiency of Nitrogen: Assessment and Improvement Strategies

by Francesco Montemurro and Mariangela Diacono

Agronomy 2016, 6(2), 31; https://doi.org/10.3390/agronomy6020031 - 10 May 2016

Cited by 35 | Viewed by 5302

Abstract

Agronomic N-use efficiency is the basis for economic and environmental efficiency, and an effective agro-ecosystem management practice, improving nutrient use efficiency, is a crucial challenge for a more sustainable production of horticultural, industrial and cereal crops. However, discrepancy between theory and practice still [...] Read more.

Agronomic N-use efficiency is the basis for economic and environmental efficiency, and an effective agro-ecosystem management practice, improving nutrient use efficiency, is a crucial challenge for a more sustainable production of horticultural, industrial and cereal crops. However, discrepancy between theory and practice still exists, coming from large gaps in knowledge on net-N immobilization/mineralization rates in agro-ecosystems, as well as on the effects of indigenous and applied N to crop response. A more thorough understanding of these topics is essential to improve N management in agricultural systems. To this end, the present Special Issue collects research findings dealing with different aspects of agronomic efficiency of N in different agro-ecosystems, and environmental impact derived from fertilization management practices. In particular, the Special Issue contains selected papers, which concern a wide range of topics, including analyzing tools, options of management, calculation equation and modeling approaches. Full article

(This article belongs to the Special Issue Towards a Better Understanding of Agronomic Efficiency of Nitrogen in Different Agro-Ecosystems)

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Open AccessArticle

Little Potential of Spring Wheat Genotypes as a Strategy to Reduce Nitrogen Leaching in Central Europe

by Juan Manuel Herrera, Christos Noulas, Peter Stamp and Didier Pellet

Agronomy 2016, 6(2), 29; https://doi.org/10.3390/agronomy6020029 - 9 May 2016

Cited by 10 | Viewed by 4442

Abstract

Nitrogen (N) losses negatively impact groundwater quality. Spring wheat genotypes varying in N-fertilizer recovery were studied (by using lysimeters) for their potential to minimize NO₃-N leaching during spring and summer, over a three-year period. Additionally, we examined to what extent root [...] Read more.

Nitrogen (N) losses negatively impact groundwater quality. Spring wheat genotypes varying in N-fertilizer recovery were studied (by using lysimeters) for their potential to minimize NO₃-N leaching during spring and summer, over a three-year period. Additionally, we examined to what extent root growth and NO₃-N leaching explain the well-known difference found between apparent and isotopic N recovery. The genotypes were grown under low (2 g m⁻²) and high (27 g m⁻²) N fertilizer supply. On average, the apparent and isotopic recoveries of N fertilizer by wheat were 43% and 51%, respectively. The three genotypes varied in fertilizer N recovery but not in NO₃-N leaching, which only accounted for 15% of the applied N fertilizer. The differences in N uptake, fertilizer N recovery and root growth among the genotypes were not associated with the leached NO₃-N because root growth and N uptake were not well synchronized with NO₃-N leaching. Already at stem elongation 70% to 98% of the season-long NO₃-N leaching had already taken place. Thus, the ability to minimize in-season NO₃-N leaching by using spring wheat genotypes with higher fertilizer N recovery was limited because maximum N leaching occurred in the early crop season. Full article

(This article belongs to the Special Issue Towards a Better Understanding of Agronomic Efficiency of Nitrogen in Different Agro-Ecosystems)

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Open AccessArticle

Design, Development, and Performance Evaluation of a Trash-Board Moldboard Plow for the Interaction between Soil and Straw with Two Different Water Content Levels

by Farid E. Abdallah, Weimin Ding, Qishuo Ding and Genxing Pan

Agronomy 2016, 6(2), 30; https://doi.org/10.3390/agronomy6020030 - 6 May 2016

Cited by 3 | Viewed by 5807

Abstract

A two-year field study was conducted to investigate the performance of a lightweight trash-board moldboard plow (with and without a trash-board), as influenced by stubble height and water content. Both fields were measured for the performance of a trash-board moldboard plow when used [...] Read more.

A two-year field study was conducted to investigate the performance of a lightweight trash-board moldboard plow (with and without a trash-board), as influenced by stubble height and water content. Both fields were measured for the performance of a trash-board moldboard plow when used during the optimization of the plowing depth, the water content, and the reaction forces. The results showed that in the first year, when a trash-board was required, the results were significantly different. The fields had lower draft and reaction force in the soil with only stubble height, which was greater than that in the soil with dense straw for all water content levels. This was also observed in the second year for the whole depth. This study shows that the moldboard plow with a trash-board provided minimum draft and reaction forces with only straw and heavy straw. The results indicate that straw nearby shear significantly increased displacement for all treatments, with variance of straw nearby moldboard. Hence, the results verify that a trash-board continuously created large soil fragmentation with different water content. Straw labels create a position of straw which also allows for better results. It is important to install trash-boards with the moldboard plow for heavy straw incorporation. Full article

(This article belongs to the Special Issue Interactions between Plant Rhizosphere and Soil Organisms)

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Graphical abstract

759 KiB

Open AccessEditorial

Development and Integration of an SSR-Based Molecular Identity Database into Sugarcane Breeding Program

by Yong-Bao Pan

Agronomy 2016, 6(2), 28; https://doi.org/10.3390/agronomy6020028 - 25 Apr 2016

Cited by 11 | Viewed by 5312

Abstract

Sugarcane breeding is very difficult and it takes 12 to 14 years to develop a new cultivar for commercial production. This is because sugarcane varieties are highly polyploid, inter-specific hybrids with 100 to 130 chromosomes that may vary across geographical areas. Other obstacles/constraints [...] Read more.

Sugarcane breeding is very difficult and it takes 12 to 14 years to develop a new cultivar for commercial production. This is because sugarcane varieties are highly polyploid, inter-specific hybrids with 100 to 130 chromosomes that may vary across geographical areas. Other obstacles/constraints include the small size of flowers that may not synchronize but may self-pollinate, difficulty in distinguishing hybrids from self progenies, extreme (G × E) interactive effect, and potential variety mis-identification during vegetative propagation and varietal exchange. To help cane breeders circumvent these constraints, a simple sequence repeats (SSR)-based molecular identity database has been developed at the United States Department of Agriculture-Agricultural Research Service, Sugarcane Research Unit in Houma, LA. Since 2005, approximately 2000 molecular identities have been constructed for clones of sugarcane and related Saccharum species that cover geographical areas including Argentina, Australia, Bangladesh, China, Colombia, India, Mexico, Pakistan, South Africa, Thailand, USA (Louisiana, Florida, Texas, and Hawaii), and Venezuela. The molecular identity database is updated annually and has been utilized to: (1) provide molecular descriptors to newly registered cultivars; (2) identify in a timely fashion any mislabeled or unidentifiable clones from cross parents and field evaluation plots; (3) develop de novo clones of energy cane with S. spontaneum cytoplasm; (4) provide clone-specific fingerprint information for assessing cross quality and paternity of polycross; (5) determine genetic relatedness of parental clones; (6) select F₁ hybrids from (elite × wild) or (wild × elite) crosses; and (7) investigate the inheritance of SSR markers in sugarcane. The integration of the molecular identity database into the sugarcane breeding program may improve the overall efficacy of cultivar development and commercialization. Full article

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781 KiB

Open AccessCommunication

Apricot Breeding at the Faculty of Horticulture in Lednice

by Boris Krška and Zdeněk Vachůn

Agronomy 2016, 6(2), 27; https://doi.org/10.3390/agronomy6020027 - 21 Apr 2016

Cited by 10 | Viewed by 5887

Abstract

The aim of the apricot-breeding program in the Horticultural Faculty in Lednice, that has been developed since 1981, is to obtain new adaptable cultivars, which combine most of the valuable biological traits. Standard breeding techniques, such as crossing by emasculation and hand pollination, [...] Read more.

The aim of the apricot-breeding program in the Horticultural Faculty in Lednice, that has been developed since 1981, is to obtain new adaptable cultivars, which combine most of the valuable biological traits. Standard breeding techniques, such as crossing by emasculation and hand pollination, self-pollination and open pollination, were employed. A total of 1.154 crossings were produced from more than 110 different parents. So far more than 20,000 seedlings have been obtained, of which about 13,000 have already been evaluated. The most interesting selections were grafted and planted in trial orchards (we now have more than 650 elite genotypes). Ten of these have already been registered, and further promising new hybrids have been submitted for registration and law right protection (Betinka, Candela, Sophia and Adriana). The basic prerequisite for the initiation of the breeding program was a large collection of genetic resources, established and gradually supplemented since the 1970s. At the present time, we preserve and manage more than 300 accessions of apricot trees. In the frame of the descriptive work of the genetic resources and in order to use in breeding, a collection of apricots has been evaluated. We selected the genotypes and characters relating to an increased level of adaptation to the environment. Full article

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Open AccessReview

Nitrogen Economy and Nitrogen Environmental Interactions in Conifers

by Rafael A. Cañas, Fernando De la Torre, Maria Belén Pascual, Concepción Avila and Francisco M. Cánovas

Agronomy 2016, 6(2), 26; https://doi.org/10.3390/agronomy6020026 - 20 Apr 2016

Cited by 13 | Viewed by 8851

Abstract

Efficient acquisition, assimilation and economy of nitrogen are of special importance in trees that must cope with seasonal periods of growth and dormancy over many years. The ability to accumulate nitrogen reserves and to recycle N determine to a great extent the growth [...] Read more.

Efficient acquisition, assimilation and economy of nitrogen are of special importance in trees that must cope with seasonal periods of growth and dormancy over many years. The ability to accumulate nitrogen reserves and to recycle N determine to a great extent the growth and production of forest biomass. The metabolic relevance of two key amino acids, arginine and phenylalanine, as well as other processes potentially involved in the nitrogen economy of conifers are discussed in the current review. During their long life cycles, conifers not only cope with cyclical annual and long-term changes in the environment but also interact with other organisms such as herbivores and symbionts. The interactions of biotic and abiotic factors with conifer nitrogen metabolism will also be outlined in this review. Full article

(This article belongs to the Special Issue Nitrogen Transport and Assimilation in Plants)

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537 KiB

Open AccessReview

Emerging and Established Technologies to Increase Nitrogen Use Efficiency of Cereals

by Juan M. Herrera, Gerardo Rubio, Lilia Levy Häner, Jorge A. Delgado, Carlos A. Lucho-Constantino, Samira Islas-Valdez and Didier Pellet

Agronomy 2016, 6(2), 25; https://doi.org/10.3390/agronomy6020025 - 19 Apr 2016

Cited by 86 | Viewed by 14098

Abstract

Nitrogen (N) fertilizers are one of the most expensive inputs in agricultural settings. Additionally, the loss of N increases costs, contributes to soil acidification, and causes off-site pollution of the air, groundwater and waterways. This study reviews current knowledge about technologies for N [...] Read more.

Nitrogen (N) fertilizers are one of the most expensive inputs in agricultural settings. Additionally, the loss of N increases costs, contributes to soil acidification, and causes off-site pollution of the air, groundwater and waterways. This study reviews current knowledge about technologies for N fertilization with potential to increase N use efficiency and reduce its negative effects on the environment. Classic inorganic sources such as urea and ammonium sulfate are the major sources utilized, while controlled N release fertilizers have not been significantly adopted for cereals and oil crops. Microorganisms, with the exception of Rhizobium sp. in soybeans, are also not widely used nowadays (e.g., plant growth-promoting bacteria and cynobacteria). The interest in implementing new N fertilization knowledge is stimulating the development of sensors to diagnose the N status and decision support systems for integrating several variables to optimize sources, rates and methods of application. Among potential new technologies we identified the incipient development of nanofertilizers, nutrient formulations to coat seeds, and recycled nutrients. Furthermore, increasing concern about the environmental consequences of N may facilitate the implementation of innovations outside the farm such as more effective regulations to guide N fertilization and methods to manufacture N fertilizers that are more energy-efficient and less CO₂ equivalent emitting. Full article

(This article belongs to the Special Issue Towards a Better Understanding of Agronomic Efficiency of Nitrogen in Different Agro-Ecosystems)

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Open AccessArticle

Evaluation of African-Bred Maize Germplasm Lines for Resistance to Aflatoxin Accumulation

by Robert L. Brown, W. Paul Williams, Gary L. Windham, Abebe Menkir and Zhi-Yuan Chen

Agronomy 2016, 6(2), 24; https://doi.org/10.3390/agronomy6020024 - 15 Apr 2016

Cited by 22 | Viewed by 5243

Abstract

Aflatoxins, produced by the fungus Aspergillus flavus, contaminate maize grain and threaten human food and feed safety. Plant resistance is considered the best strategy for reducing aflatoxin accumulation. Six maize germplasm lines, TZAR101–TZAR106, were released by the International Institute of Tropical Agriculture-Southern [...] Read more.

Aflatoxins, produced by the fungus Aspergillus flavus, contaminate maize grain and threaten human food and feed safety. Plant resistance is considered the best strategy for reducing aflatoxin accumulation. Six maize germplasm lines, TZAR101–TZAR106, were released by the International Institute of Tropical Agriculture-Southern Regional Research Center (IITA-SRRC) maize breeding collaboration for use in African National Programs and U.S. maize breeding programs. The present investigation was conducted to evaluate aflatoxin reduction by these lines in a U.S. environment. As germplasm lines, resistance was demonstrated by the lines tested in 2010 and 2014 trials. In 2010, TZAR106 was among the lines with the lowest toxin accumulation, and in 2014, along with TZAR102, supported low aflatoxin. When evaluated as single cross hybrids in 2012, 2013 and 2014, several crosses involving IITA-SRRC lines accumulated low toxin. In 2012, TZAR103 × HBA1 was one of 4 lines with the lowest concentration of aflatoxin. In 2014, five IITA-SRRC hybrids were among the lowest with TZAR102 × Va35 and TZAR102 × LH132 being the two lowest. Results demonstrate significant aflatoxin reduction by IITA-SRRC lines in a U.S. aflatoxin-conducive environment (at Mississippi State University). Further testing in different locations and environments is needed to further evaluate the potential usefulness of these germplasm lines. Full article

(This article belongs to the Special Issue Breeding for Disease Resistance)

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Open AccessFeature PaperArticle

Assessing Nitrogen Use Efficiency and Nitrogen Loss in a Forage-Based System Using a Modeling Approach

by Chiara Piccini, Claudia Di Bene, Roberta Farina, Bruno Pennelli and Rosario Napoli

Agronomy 2016, 6(2), 23; https://doi.org/10.3390/agronomy6020023 - 12 Apr 2016

Cited by 13 | Viewed by 6142

Abstract

In intensive agriculture, N supply often exceeds crop requirements, even in nitrate vulnerable zones (NVZ). In farmland, the N surplus gives rise to NO₃⁻ leaching and consequent groundwater pollution. The present study aimed at proposing measures to reduce N leaching and [...] Read more.

In intensive agriculture, N supply often exceeds crop requirements, even in nitrate vulnerable zones (NVZ). In farmland, the N surplus gives rise to NO₃⁻ leaching and consequent groundwater pollution. The present study aimed at proposing measures to reduce N leaching and hence improve N efficiency in a buffalo livestock farm located in the NVZ of Latina plain (Central Italy). The farm was cultivated with forage crops in a double annual crop rotation: Italian ryegrass (Lolium multiflorum Lam.) in winter and silage corn (Zea mays L.) in summer. Mineral and organic fertilizers were supplied to both crops. The annual N budget and soil solution NO₃-N concentrations were evaluated using a modeling approach. The performance of the WinEPIC model in simulating the response of the NO₃-N concentration in percolation to the N application rate was assessed and validated by field measurements of the NO₃-N concentration in the soil solution. Three scenarios were proposed to identify the best practice to minimize the environmental impact of N application without significant yield loss. Also, recommendations of best practices in N fertilization and animal manure spreading were given. This study thus provides useful preliminary information for decision-making in agriculture/environmental policies. Full article

(This article belongs to the Special Issue Towards a Better Understanding of Agronomic Efficiency of Nitrogen in Different Agro-Ecosystems)

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Open AccessArticle

Wheat Sown with Narrow Spacing Results in Higher Yield and Water Use Efficiency under Deficit Supplemental Irrigation at the Vegetative and Reproductive Stage

by Mubshar Hussain, Shahid Farooq, Khawar Jabran, Muhammad Ijaz, Abdul Sattar and Waseem Hassan

Agronomy 2016, 6(2), 22; https://doi.org/10.3390/agronomy6020022 - 6 Apr 2016

Cited by 23 | Viewed by 5333

Abstract

A decrease in water resources around the globe in irrigated agriculture has resulted in a steep decline in irrigation water availability. Therefore, management options for efficient use of available irrigation water are inevitable. Deciding the critical time, frequency and amount of irrigation are [...] Read more.

A decrease in water resources around the globe in irrigated agriculture has resulted in a steep decline in irrigation water availability. Therefore, management options for efficient use of available irrigation water are inevitable. Deciding the critical time, frequency and amount of irrigation are compulsory to achieve higher crop outputs. Hence, this two-year field study was conducted to assess the role of different row spacings, i.e., 20, 25 and 30 cm, on growth, productivity, and water use efficiency (WUE) of wheat under deficit supplemental irrigation (DSI) at the vegetative and reproductive phase by using surplus supplemental irrigation (SSI) throughout the growing season as the control. DSI at both growth stages, and the reproductive stage in particular, changed the crop allometry, yield and net income of wheat. However, narrow spacing (20 cm) resulted in efficient use of available irrigation water (DSI and SSI) with higher yield, WUE and economic returns. Interestingly, wider spacing resulted in a higher number of grains per spike with higher 1000-grain weight under SSI and DSI, but final yield output remained poor due to a lower number of productive tillers. It was concluded that reducing irrigation during the vegetative stage is less damaging compared with the reproductive phase; therefore, sufficient supplemental irrigation must be added at the reproductive stage, particularly during grain-filling. Further, narrow spacing (20 cm) resulted in efficient utilization of available irrigation water; therefore, wheat must be grown at a narrow spacing to ensure the efficient utilization of available irrigation water. Full article

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Different Responses of the Quality Parameters of Coriandrum sativum to Organic Substrate Mixtures and Fertilization

by Neith A. Pacheco L., Julia Cano-Sosa, Fernando Poblano C., Ingrid M. Rodríguez-Buenfil and Ana Ramos-Díaz

Agronomy 2016, 6(2), 21; https://doi.org/10.3390/agronomy6020021 - 5 Apr 2016

Cited by 7 | Viewed by 4765

Abstract

In order to standardize the quality of agricultural products, it is necessary to control the factors affecting plant development, such as plant nutrition. The best results in terms of homogeneity of the quality of vegetable crops were achieved using inert substrates and application [...] Read more.

In order to standardize the quality of agricultural products, it is necessary to control the factors affecting plant development, such as plant nutrition. The best results in terms of homogeneity of the quality of vegetable crops were achieved using inert substrates and application of nutrients; however, production costs are high due to the cost of irrigation systems and substrate management and importation. This work aims to evaluate the effect of the local substrate mix and the amount of organic fertilizer on different quality parameters of coriander. To evaluate the quality of coriander, we considered different parameters such as size, biomass, antioxidant capacity and aroma (evaluated by volatile compounds detection with gas chromatography). The results show that the culture system differentially affects each parameter, and the compounds associated with the aroma of coriander and the diameter of plants are sensitive to the culture system, while the length of plants, number of leaves and antioxidant activity are not affected by the concentration of fertilizer. Moreover, organic farming conditions do not reduce quality parameters of the crops when using adequate fertilization. Additionally, local substrates would be practical substitutes for expensive importations. Full article

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Agronomy, Volume 6, Issue 2 (June 2016) – 18 articles

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