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Agronomy, Volume 7, Issue 3 (September 2017)

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Cover Story The ‘Push–Pull’ cropping system exploits plant volatile semiochemicals to repel insect pests from [...] Read more.
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Research

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Open AccessArticle Yield Stability in Winter Wheat Production: A Survey on German Farmers’ and Advisors’ Views
Agronomy 2017, 7(3), 45; doi:10.3390/agronomy7030045
Received: 8 May 2017 / Revised: 9 June 2017 / Accepted: 22 June 2017 / Published: 26 June 2017
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Abstract
Most of the available research studies have focused on the production of high grain yields of wheat and have neglected yield stability. However, yield stability is a relevant factor in agronomic practice and, therefore, is the focus of this comprehensive survey. The aim
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Most of the available research studies have focused on the production of high grain yields of wheat and have neglected yield stability. However, yield stability is a relevant factor in agronomic practice and, therefore, is the focus of this comprehensive survey. The aim was to first describe the importance of yield stability as well as currently used practical management strategies that ensure yield stability in wheat production and secondly, to obtain potential research areas supporting yield stability in the complex system of agronomy. The target groups were German farmers with experience in wheat production and advisors with expertise in the field of wheat cultivation or research. A sample size of 615 completed questionnaires formed the data basis of this study. The study itself provides evidence that the yield stability of winter wheat is even more important than the amount of yield for a large proportion of farmers (48%) and advisors (47%). Furthermore, in the view of the majority of the surveyed farmers and advisors, yield stability is gaining importance in climate change. Data analysis showed that site adapted cultivar choice, favorable crop rotations and integrated plant protection are ranked as three of the most important agronomic management practices to achieve high yield stability of wheat. Soil tillage and fertilization occupied a middle position, whereas sowing date and sowing density were estimated with lower importance. However, yield stability is affected by many environmental, genetic and agronomic factors, which subsequently makes it a complex matter. Hence, yield stability in farming practice must be analyzed and improved in a systems approach. Full article
(This article belongs to the Special Issue Biological Technology Platforms Accelerating Crop Improvement)
Open AccessArticle Assessment of Conservation Agriculture Practices by Smallholder Farmers in the Eastern Cape Province of South Africa
Agronomy 2017, 7(3), 46; doi:10.3390/agronomy7030046
Received: 20 April 2017 / Revised: 16 May 2017 / Accepted: 28 May 2017 / Published: 2 July 2017
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Abstract
Conservation agriculture (CA) can sustainably address soil degradation and improve crop yields. However, the success of CA amongst South African smallholder farmers is not known. The aims of the study were to find out: (1) the extent of CA practice by the Eastern
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Conservation agriculture (CA) can sustainably address soil degradation and improve crop yields. However, the success of CA amongst South African smallholder farmers is not known. The aims of the study were to find out: (1) the extent of CA practice by the Eastern Cape smallholder farmers; (2) perceptions towards CA amongst smallholder farmers with some history of practising the technology; and (3) the impact of practised CA components on soil quality indicators. Diagnostic survey techniques and soil sampling in farmers’ fields were employed to gather data from five districts of the Eastern Cape, South Africa. The most common CA principle adopted by surveyed farmers was no-till (34.81%), whilst crop rotation and residue retention were practised by only 25.93% and 22.22% of the farmers, respectively. Education level and CA training influenced the likelihood of a farmer to practise no-till farming, whilst the likelihood of farmers to retain residues was influenced by education level and access to grazing lands. Lack of appropriate equipment and costly herbicides were the major constraining factors to practising CA. Crop residue retention conflicted with the common practice of free-range livestock grazing. Cabbage, maize and beans were the most common crops of choice for the few farmers that practised crop rotations. No significant (p > 0.05) improvement on soil quality indicators was observed with CA compared to the conventional farming method. The noted high dependency on government grants by the smallholder farmers could be a disincentive towards the adoption of agricultural innovations such as CA. Identification of practical key CA entry points is recommended, bearing in mind the noted impediments to CA adoption. Full article
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Open AccessArticle Effect of Constitutive miR164 Expression on Plant Morphology and Fruit Development in Arabidopsis and Tomato
Agronomy 2017, 7(3), 48; doi:10.3390/agronomy7030048
Received: 13 April 2017 / Revised: 7 July 2017 / Accepted: 11 July 2017 / Published: 15 July 2017
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Abstract
Several miRNAs are conserved in different plant families, but their abundance and target genes vary between species, organs, and stages of development. Target genes of miRNAs are mostly transcription factors, involved in the control of many plant developmental processes, including fruit development. MiR164
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Several miRNAs are conserved in different plant families, but their abundance and target genes vary between species, organs, and stages of development. Target genes of miRNAs are mostly transcription factors, involved in the control of many plant developmental processes, including fruit development. MiR164 is a conserved miRNA, highly expressed in fruits, and is validated to target a subset of genes of the NAC-domain transcription factor gene family. The objective of this work was to analyze the phenotypic effects of the constitutive expression of miR164 during the life cycle of Arabidopsis and tomato. MiR164 overexpression (164-OE) lines for Arabidopsis and tomato were generated and analyzed during plant development. The constitutive miR164 expression showed that miR164 affected the morphology of Arabidopsis and tomato, and it affected the transition from the vegetative to the reproductive phase in Arabidopsis. Moreover, the miR164 overexpression affected the time required for each developmental stage of tomato fruit. These results suggest that miR164 plays general and specific roles during development in Arabidopsis and tomato, including fruit development, which could be exploited for the improvement of traits of agronomic interest in important species. Full article
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Open AccessArticle Impact of Different Agricultural Waste Biochars on Maize Biomass and Soil Water Content in a Brazilian Cerrado Arenosol
Agronomy 2017, 7(3), 49; doi:10.3390/agronomy7030049
Received: 31 May 2017 / Revised: 3 July 2017 / Accepted: 14 July 2017 / Published: 20 July 2017
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Abstract
Arenosols in the Brazilian Cerrado are increasingly being used for agricultural production, particularly maize. These sandy soils are characterized by low soil organic matter, low available nutrients, and poor water-holding capacity. For this reason, adding biochar as a soil amendment could lead to
[...] Read more.
Arenosols in the Brazilian Cerrado are increasingly being used for agricultural production, particularly maize. These sandy soils are characterized by low soil organic matter, low available nutrients, and poor water-holding capacity. For this reason, adding biochar as a soil amendment could lead to improved water and nutrient retention. A greenhouse experiment was carried out using twelve biochars derived from four feedstocks (cotton husks, swine manure, eucalyptus sawmill residue, sugarcane filtercake) pyrolized at 400, 500 and 600 °C and applied at 5% w/w. The biochars’ effect on maize biomass was examined, along with their contribution to soil physical properties including water retention, electrical conductivity (EC), and grain size distribution. After six weeks, maize plants in soils with eucalyptus and particularly filtercake biochar had higher biomass compared to those in soils with cotton and swine manure biochars. The latter’s low biomass was likely related to excessive salinity. In general, our biochars showed potential for increasing θ in sandy soils compared to the soil alone. Filtercake and eucalyptus biochars may improve soil aeration and water infiltration, while applying cotton and swine manure biochars at levels <5% to avoid high salinity could contribute to improved soil water retention in Cerrado Arenosols. Full article
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Open AccessArticle Detection and Response of Sugarcane against the Infection of Sugarcane Mosaic Virus (SCMV) in Indonesia
Agronomy 2017, 7(3), 50; doi:10.3390/agronomy7030050
Received: 16 June 2017 / Revised: 5 July 2017 / Accepted: 10 July 2017 / Published: 24 July 2017
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Abstract
Sugarcane mosaic virus (SCMV) is one among many viruses that infect sugarcane, cause yield loss, and become serious disease agents on sugarcane plantations. Since the morphological symptoms of SCMV are similar to other symptoms caused by Sugarcane streak mosaic virus (SCSMV) or nitrogen
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Sugarcane mosaic virus (SCMV) is one among many viruses that infect sugarcane, cause yield loss, and become serious disease agents on sugarcane plantations. Since the morphological symptoms of SCMV are similar to other symptoms caused by Sugarcane streak mosaic virus (SCSMV) or nitrogen deficiency, the detection of SCMV is important through accurate diagnostic-like ELISA or RT-PCR. This research aimed to study the causative mosaic pathogen of SCMV in East Java, Indonesia, including mosaic development. The results showed that the mosaic symptom is present in all sugarcane plantations with 78% and 65% disease incidence and severity, respectively. Moreover, the detection procedure based on an amplification of cDNA of the coat protein gene sequence confirmed that SCMV was the causative agent of mosaic disease on sugarcane. Re-inoculation of healthy sugarcane plants with plant sap from a symptomatic leaf from the field showed similar mosaic or yellowish chlorotic areas on the leaf blade, and appeared on the fourth leaves upward from the inoculation leaf, in addition to showing different levels of peroxidase but not total phenol. Mosaic also correlated with the amount of total chlorophyll. Although Sucrose phosphate synthase (SPS) protein accumulation and activity were at a lower level in infected leaves, sucrose accumulation was at a higher level in the same leaves. Full article
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Open AccessArticle Evaluation of Agronomic Traits and Drought Tolerance of Winter Wheat Accessions from the USDA-ARS National Small Grains Collection
Agronomy 2017, 7(3), 51; doi:10.3390/agronomy7030051
Received: 12 May 2017 / Revised: 14 July 2017 / Accepted: 17 July 2017 / Published: 31 July 2017
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Abstract
Wheat accessions from the USDA-ARS National Small Grains Collection (NSGC) are a potential genetic resource for variety improvement. This study assessed the agronomic performance and drought tolerance in 198 winter wheat accessions under irrigated and terminal drought environments in the 2012–2013 season, and
[...] Read more.
Wheat accessions from the USDA-ARS National Small Grains Collection (NSGC) are a potential genetic resource for variety improvement. This study assessed the agronomic performance and drought tolerance in 198 winter wheat accessions under irrigated and terminal drought environments in the 2012–2013 season, and repeated the test under terminal drought only during the 2013–2014 season. The 198 accessions were classified into three maturity groups, early, intermediate, and late based on heading data. In all three environments, the early accessions had the best agronomic performance, produced higher grain yield, thousand-kernel weight and grain volume weight, and had earlier heading date and shorter plant height. The intermediate accessions had similar grain yield and thousand-kernel weight as the early accessions in the irrigated environment, but had lower thousand-kernel weight in the terminal drought environments. Terminal drought had significant effects on grain yield, plant height, thousand-kernel weight, and grain volume weight. The positive correlation between GY and HD suggests that the ‘late early’ types in the early maturity were the most successful. Out of 198 accessions evaluated, twenty-three had high yield stability and drought tolerance according to the drought susceptibility index and membership function value of drought tolerance. The eight of twenty-three accessions identified (four early and four intermediate) had high grain yield in three environments. Some of these accessions have been further used in bi-parental mapping studies and by breeders for grain yield and drought tolerance improvement. Full article
Open AccessArticle Variability and Correlations among Groundnut Populations for Early Leaf Spot, Pod Yield, and Agronomic Traits
Agronomy 2017, 7(3), 52; doi:10.3390/agronomy7030052
Received: 9 May 2017 / Revised: 27 July 2017 / Accepted: 28 July 2017 / Published: 5 August 2017
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Abstract
The present experiment was conducted in Mali to study the genetic variability and correlation of early leaf spot (ELS) resistance parameters and agro-morphological traits in groundnut using two F3 populations from crosses QH243C X NAMA and TS32-1 X NAMA. Estimates of genotypic coefficient
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The present experiment was conducted in Mali to study the genetic variability and correlation of early leaf spot (ELS) resistance parameters and agro-morphological traits in groundnut using two F3 populations from crosses QH243C X NAMA and TS32-1 X NAMA. Estimates of genotypic coefficient of variation and phenotypic coefficient of variation revealed high value for pod yield, kernel yield, and ELS score at 60 and 80 days after sowing for the cross QH243C X NAMA. Low-to-moderate GCV and PCV were obtained for the remaining traits for both crosses. High heritability values coupled with high genetic advance as percentage of mean recorded for ELS_II, defoliation percent, pod yield in cross QH243C X NAMA; shelling percent for the cross TS32-1 X NAMA and ELS_III; and plant height, kernel yield in both crosses, indicate the significant role of additive gene action for inheritance of these traits. Correlation analysis indicated that pod and kernel yield were significant and positively correlated with 100 kernel weight and shelling percent. For cross QH243C X NAMA, kernel yield showed significant positive correlation with all ELS resistance components but the correlation was not significant for the cross TS32-1 X NAMA. Positive and significant correlation was observed between ELS resistance components themselves, suggesting that these components could be controlled by a similar polygenic system. The findings suggest that early generation selection should be effective for days to first flowering, days to 50% flowering, plant height, pod yield, kernel yield, 100 kernel weight and early leaf spot resistance which recorded the highest value of heritability in the two crosses. Full article
Open AccessArticle Characterisation of Faba Bean (Vicia faba L.) Transcriptome Using RNA-Seq: Sequencing, De Novo Assembly, Annotation, and Expression Analysis
Agronomy 2017, 7(3), 53; doi:10.3390/agronomy7030053
Received: 31 May 2017 / Revised: 25 July 2017 / Accepted: 2 August 2017 / Published: 8 August 2017
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Abstract
RNA sequencing (RNA-Seq) is a deep sequencing method used for transcriptome profiling. RNA-Seq assemblies have successfully been used for a broad variety of applications, such as gene characterisation, functional genomic studies, and gene expression analysis, particularly useful in the absence of a well-studied
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RNA sequencing (RNA-Seq) is a deep sequencing method used for transcriptome profiling. RNA-Seq assemblies have successfully been used for a broad variety of applications, such as gene characterisation, functional genomic studies, and gene expression analysis, particularly useful in the absence of a well-studied genome reference sequence. This study reports on the development of reference unigene sets from faba bean using RNA-Seq. Two Australian faba bean cultivars (Doza and Farah) that differ in terms of disease resistance, breeding habit, and adaptation characteristics, and have been extensively used in breeding programs, were utilised in this study. The de novo assembly resulted in a total of 58,962 and 53,275 transcripts with approximately 67 Mbp (1588 bp N50) and 61 Mbp (1629 bp N50) for Doza and Farah, respectively. The generated transcripts have been compared to the protein and nucleotide databases of NCBI, as well as to the gene complements of several related legume species such as Medicago truncatula, soybean, and chickpea. Both assemblies were compared to previously-published faba bean transcriptome reference sets for the degree of completeness and utility. Annotation of unigenes has been performed, and patterns of tissue-specific expression identified. The gene complement derived from this comprehensive transcriptome analysis shows that faba bean, despite its complex 13 Gbp genome, compares well to other legumes in expressed gene content. This study in faba bean represents the most comprehensive reference transcriptomes from two different Australian cultivars available to date and it provides a valuable resource for future genomics-assisted breeding activities in this species. Full article
(This article belongs to the Special Issue Application of Sequencing Technologies to Crop Breeding)
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Open AccessArticle Combination of Lactic Acid-Based Deep Eutectic Solvents (DES) with β-Cyclodextrin: Performance Screening Using Ultrasound-Assisted Extraction of Polyphenols from Selected Native Greek Medicinal Plants
Agronomy 2017, 7(3), 54; doi:10.3390/agronomy7030054
Received: 23 June 2017 / Revised: 6 August 2017 / Accepted: 9 August 2017 / Published: 14 August 2017
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Abstract
A series of novel l-lactic acid-based deep eutectic solvents (DES) were tested for polyphenol extraction performance, using organically grown, native Greek medicinal plants. The extractions were ultrasonically-assisted and the effect of the addition of β-cyclodextrin (β-CD) as extraction booster was also tested,
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A series of novel l-lactic acid-based deep eutectic solvents (DES) were tested for polyphenol extraction performance, using organically grown, native Greek medicinal plants. The extractions were ultrasonically-assisted and the effect of the addition of β-cyclodextrin (β-CD) as extraction booster was also tested, at a concentration of 1.5% (w/v). The estimation of total polyphenol yield (YTP) suggested that DES composed of l-lactic acid and nicotinamide and l-lactic acid and l-alanine, both at a molar ratio of 7:1, are promising solvents giving significantly higher yields compared with 60% (v/v) aqueous ethanol and water. However, when β-CD was combined with DES comprised of l-lactic acid and ammonium acetate (molar ratio 7:1), the extraction yields obtained in some instances were equal of even higher. The pattern was not consistent when the yield in total flavonoids (YTFn) was considered, indicating water, 60% (v/v) aqueous ethanol and l-lactic acid:sodium acetate (molar ratio 7:1) to be the most efficient solvents. In this case, the effect of β-CD was of rather lower magnitude. The examination of the antioxidant activity of the extracts generated showed that there is a close correlation mainly with their concentration in total polyphenols. Full article
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Open AccessArticle Impacts of Fertilization Type on Soil Microbial Biomass and Nutrient Availability in Two Agroecological Zones of Ghana
Agronomy 2017, 7(3), 55; doi:10.3390/agronomy7030055
Received: 11 July 2017 / Revised: 12 August 2017 / Accepted: 16 August 2017 / Published: 21 August 2017
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Abstract
The decline in soil productivity amidst efforts to increase crop yield in Sub Saharan Africa (SSA) has made it imperative to assess the current fertilization management approaches. This study was conducted in two agroecological zones (i.e., Guinea Savannah (GS) and Deciduous forest (DF))
[...] Read more.
The decline in soil productivity amidst efforts to increase crop yield in Sub Saharan Africa (SSA) has made it imperative to assess the current fertilization management approaches. This study was conducted in two agroecological zones (i.e., Guinea Savannah (GS) and Deciduous forest (DF)) of Ghana to evaluate how different fertilization schemes in the long term (>5 years) impacted the soil biochemical properties. Soil samples under four fertilization schemes (inorganic fertilizer only, low-to-medium organic residues only, inorganic fertilizers plus low-to-medium organic residues, and no fertilization) from 20 farmers’ field were sampled from March to April 2015. Soil biochemical quality indicators were determined using standard procedures. Overall, the average chemical and microbial biomass contents for most indicators were significantly higher in DF compared to GS. Relative to the reference sites, soil quality improvement were observed under inorganic fertilization in both agroecologies in contrast to significant soil deterioration (26.5%) under sole organic residue application in GS. Furthermore, the results showed that increased inorganic fertilization rate alone or combination with organic residues improved soil quality relative to the reference. The present results suggest the need to raise the current fertilizer application rates, especially in GS in order to enhance optimum soil productivity. Full article
(This article belongs to the Special Issue Sustaining soil functions in agro-ecosystems)
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Open AccessArticle Responses of Fourteen Vietnamese Rice (Oryza sativa L.) Cultivars to High Temperatures during Grain Filling Period under Field Conditions
Agronomy 2017, 7(3), 57; doi:10.3390/agronomy7030057
Received: 22 July 2017 / Revised: 18 August 2017 / Accepted: 23 August 2017 / Published: 28 August 2017
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Abstract
High temperatures significantly affect rice grain yield and quality. However, little information is known about the response of indica cultivars, especially Vietnamese cultivars, to high temperature. In this study, field experiments were conducted in 2015 and 2016 to evaluate the response of Vietnamese
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High temperatures significantly affect rice grain yield and quality. However, little information is known about the response of indica cultivars, especially Vietnamese cultivars, to high temperature. In this study, field experiments were conducted in 2015 and 2016 to evaluate the response of Vietnamese cultivars under high temperatures during the grain filling period. The high temperature was applied after the first cultivar started anthesis, by opening two sides of a plastic chamber that housed the cultivar when the temperature reached above 36 °C under field conditions. The difference in the maximum temperature between the control and the high temperature treatment was about 1.3 °C to 10.1 °C in 2015, and 0.73 °C to 10.2 °C in 2016. Decreases in crop growth rate (CGR) and yield were correlated with increased temperature conditions during the grain filling period. The grain yield of 14 Vietnamese cultivars fell to 81.5 and 79.4% of the control in 2015 and 2016, respectively. The variable with the greatest impact on grain yield was spikelet sterility induced by high temperature. Under high temperature conditions during the grain filling period, the percentage of grain chalkiness in the high temperature-treatment group increased compared to the control. Our study showed that Vietnamese rice yield and quality were significantly affected by high temperature. Full article
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Open AccessArticle Response of Chlorophyll, Carotenoid and SPAD-502 Measurement to Salinity and Nutrient Stress in Wheat (Triticum aestivum L.)
Agronomy 2017, 7(3), 61; doi:10.3390/agronomy7030061
Received: 31 July 2017 / Revised: 29 August 2017 / Accepted: 8 September 2017 / Published: 12 September 2017
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Abstract
Abiotic stress can alter key physiological constituents and functions in green plants. Improving the capacity to monitor this response in a non-destructive manner is of considerable interest, as it would offer a direct means of initiating timely corrective action. Given the vital role
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Abiotic stress can alter key physiological constituents and functions in green plants. Improving the capacity to monitor this response in a non-destructive manner is of considerable interest, as it would offer a direct means of initiating timely corrective action. Given the vital role that plant pigments play in the photosynthetic process and general plant physiological condition, their accurate estimation would provide a means to monitor plant health and indirectly determine stress response. The aim of this work is to evaluate the response of leaf chlorophyll and carotenoid (Ct) content in wheat (Triticum aestivum L.) to changes in varying application levels of soil salinity and fertilizer applied over a complete growth cycle. The study also seeks to establish and analyze relationships between measurements from a SPAD-502 instrument and the leaf pigments, as extracted at the anthesis stage. A greenhouse pot experiment was conducted in triplicate by employing distinct treatments of both soil salinity and fertilizer dose at three levels. Results showed that higher doses of fertilizer increased the content of leaf pigments across all levels of soil salinity. Likewise, increasing the level of soil salinity significantly increased the chlorophyll and Ct content per leaf area at all levels of applied fertilizer. However, as an adaptation process and defense mechanism under salinity stress, leaves were found to be thicker and narrower. Thus, on a per-plant basis, increasing salinity significantly reduced the chlorophyll (Chlt) and Ct produced under each fertilizer treatment. In addition, interaction effects of soil salinity and fertilizer application on the photosynthetic pigment content were found to be significant, as the higher amounts of fertilizer augmented the detrimental effects of salinity. A strong positive (R2 = 0.93) and statistically significant (p < 0.001) relationship between SPAD-502 values and Chlt and between SPAD-502 values and Ct content (R2 = 0.85) was determined based on a large (n = 277) dataset. We demonstrate that the SPAD-502 readings and plant photosynthetic pigment content per-leaf area are profoundly affected by salinity and nutrient stress, but that the general form of their relationship remains largely unaffected by the stress. As such, a generalized regression model can be used for Chlt and Ct estimation, even across a range of salinity and fertilizer gradients. Full article
(This article belongs to the Special Issue Crop Salinity Tolerance)
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Review

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Open AccessReview Ultrasound Assisted Extraction for the Recovery of Phenolic Compounds from Vegetable Sources
Agronomy 2017, 7(3), 47; doi:10.3390/agronomy7030047
Received: 31 May 2017 / Revised: 20 June 2017 / Accepted: 30 June 2017 / Published: 7 July 2017
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Abstract
Vegetable sources and agro-industrial residues represent an important source of phenolic compounds that are useful in a wide range of applications, especially those with biological activities. Conventional techniques of phytochemical extraction have been associated with a high consumption of organic solvents that limits
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Vegetable sources and agro-industrial residues represent an important source of phenolic compounds that are useful in a wide range of applications, especially those with biological activities. Conventional techniques of phytochemical extraction have been associated with a high consumption of organic solvents that limits the application of bioactive extracts, leading to the implementation of novel extraction technologies using mechanisms such as Ultrasound Assisted Extraction (UAE). In the present review, an analysis of the involved variables in the extraction yield of phenolic compounds through UAE is presented, highlighting the advantages of this technology based on the results obtained in various optimized studies. A comparison with other technologies and a proposal of its possible application for agro industrial residues as raw material of phenolic compounds is also indicated. Finally, it is concluded that UAE is a technology that is placed within the area of Sustainable Chemistry since it promotes the use of renewable raw materials through the extraction of phenolic compounds, implementing the substitution of organic solvents with solvents that do not present toxic effects, lowering the energy consumption when compared to conventional methods and minimizing process times and temperatures, which is useful for the extraction of thermo-labile compounds. Full article
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Open AccessReview Understanding Starch Structure: Recent Progress
Agronomy 2017, 7(3), 56; doi:10.3390/agronomy7030056
Received: 25 July 2017 / Revised: 19 August 2017 / Accepted: 22 August 2017 / Published: 25 August 2017
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Abstract
Starch is a major food supply for humanity. It is produced in seeds, rhizomes, roots and tubers in the form of semi-crystalline granules with unique properties for each plant. Though the size and morphology of the granules is specific for each plant species,
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Starch is a major food supply for humanity. It is produced in seeds, rhizomes, roots and tubers in the form of semi-crystalline granules with unique properties for each plant. Though the size and morphology of the granules is specific for each plant species, their internal structures have remarkably similar architecture, consisting of growth rings, blocklets, and crystalline and amorphous lamellae. The basic components of starch granules are two polyglucans, namely amylose and amylopectin. The molecular structure of amylose is comparatively simple as it consists of glucose residues connected through α-(1,4)-linkages to long chains with a few α-(1,6)-branches. Amylopectin, which is the major component, has the same basic structure, but it has considerably shorter chains and a lot of α-(1,6)-branches. This results in a very complex, three-dimensional structure, the nature of which remains uncertain. Several models of the amylopectin structure have been suggested through the years, and in this review two models are described, namely the “cluster model” and the “building block backbone model”. The structure of the starch granules is discussed in light of both models. Full article
(This article belongs to the Special Issue Starch Biosynthesis in Crop Plants)
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Open AccessReview Volatile Semiochemical Mediated Plant Defense in Cereals: A Novel Strategy for Crop Protection
Agronomy 2017, 7(3), 58; doi:10.3390/agronomy7030058
Received: 31 July 2017 / Revised: 27 August 2017 / Accepted: 29 August 2017 / Published: 1 September 2017
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Abstract
Plants have evolved highly intriguing ways of defending themselves against insect attacks, including through emission of defense volatiles. These volatiles serve the plant’s defense by directly repelling phytophagous insects and/or indirectly through attracting natural enemies antagonistic to the herbivores. Several laboratory studies established
[...] Read more.
Plants have evolved highly intriguing ways of defending themselves against insect attacks, including through emission of defense volatiles. These volatiles serve the plant’s defense by directly repelling phytophagous insects and/or indirectly through attracting natural enemies antagonistic to the herbivores. Several laboratory studies established the potential of improving plant resistance against insect attacks by manipulating the plant-derived volatile semiochemicals emissions. Yet, more efforts need to be conducted to translate the promising laboratory studies to fight economically-important crop pests under real field conditions. This is needed to address an increasing demand for alternative pest control options driven by ecological and environmental costs associated with the use of broad-spectrum insecticides. The practical examples discussed in this review paper demonstrate the real prospect of exploiting an inducible and constitutive plant volatile semiochemicals for developing novel and ecologically-sustainable pest management strategies to protect cereal crops from damaging insect pests. Full article
(This article belongs to the Special Issue Plant Resistance for the Protection of Cereal Crops from Insect Pests)
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Open AccessReview Farming in Northern Ontario: Untapped Potential for the Future
Agronomy 2017, 7(3), 59; doi:10.3390/agronomy7030059
Received: 15 July 2017 / Revised: 29 August 2017 / Accepted: 30 August 2017 / Published: 6 September 2017
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Abstract
Farming in Northern Ontario is limited to less than 1% of the total land area available. With over 2000 farms, this is home to about 6% of the province’s population, concentrated in the five major southern border cities of Thunder Bay, Sault Ste.
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Farming in Northern Ontario is limited to less than 1% of the total land area available. With over 2000 farms, this is home to about 6% of the province’s population, concentrated in the five major southern border cities of Thunder Bay, Sault Ste. Marie, Timmins, Sudbury and North Bay, with a significant presence of indigenous (i.e., First Nations) and disadvantaged peoples. This review highlights the challenges and opportunities of agriculture in Northern Ontario and offers a few strategies for establishing and sustaining agricultural operations locally. The challenges of farming in this region include the prevalence of adverse climatic conditions, lack of crop/economic diversification, insufficient infrastructure and support services, presence of small local markets, an aging population and youth out-migration, attitudes of dependency on government and limited investment potential. Nevertheless, this region offers much potential for farming as it contains significant amounts of fertile soils, good road networks and affordable land to start up farm businesses. Furthermore, the changing climate could be a boon to improve growing conditions, with expanded cropping options and increased yields in recent years. Production and consumption of local foods, conducting innovative on-farm research that addresses the needs of local producers including First Nations peoples, fostering regional research centres, building relationships through networking, exchange of ideas through effective use of different extension avenues, and collaboration and assisting local producers with market development may help establish a more competitive and sustainable agrifood sector in Northern Ontario. Favourable government policies to support growers who have experienced damage to their crops, forages and livestock due to adverse climatic conditions will further help sustain and expand their agricultural operations. Full article
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Open AccessReview Glyphosate Efficacy of Different Salt Formulations and Adjuvant Additives on Various Weeds
Agronomy 2017, 7(3), 60; doi:10.3390/agronomy7030060
Received: 29 August 2017 / Revised: 30 August 2017 / Accepted: 1 September 2017 / Published: 6 September 2017
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Abstract
In many crops, weeds are managed by herbicides, mainly due to the decrease in crop yields and farmers’ incomes caused by them. In general, chemical control of weeds is considered to be an easy, relatively cheap, and highly effective method. However, not all
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In many crops, weeds are managed by herbicides, mainly due to the decrease in crop yields and farmers’ incomes caused by them. In general, chemical control of weeds is considered to be an easy, relatively cheap, and highly effective method. However, not all weeds can be successfully controlled, either because of their natural tolerance or their herbicide resistance. Glyphosate is one of the most widely used herbicides in the world. It can manage effectively a broad spectrum of weeds, and promotes conservation agriculture by significantly reducing conventional plough tillage. Unfortunately, its extensive use has led to the evolution of glyphosate resistance, which has evolved into a major problem for global crop production. Alternative herbicides are, in some cases, available, but they do not usually control certain weeds as efficiently as glyphosate. The transmission of herbicides to the target site is a complex process, and consists of several stages. Each herbicide is affected and can be manipulated by the product formulation for the optimization of its use. Many experiments have confirmed that different glyphosate salts and adjuvant additives are instrumental in the optimization of herbicide absorption and delivery processes. The objective of this paper is to provide a brief overview of these experiments and summarize the literature related to the effect of various glyphosate formulations and adjuvants on weed control. Determining the differences among formulations and adjuvants may lead to the further optimized long-term use of glyphosate. Full article
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