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Open AccessEditor’s ChoiceArticle
Differential Response of Sugar Beet to Long-Term Mild to Severe Salinity in a Soil–Pot Culture
Agriculture 2019, 9(10), 223; https://doi.org/10.3390/agriculture9100223 - 13 Oct 2019
Cited by 16
Abstract
Attempts to cultivate sugar beet (Beta vulgaris spp. vulgaris) in the sub-tropical saline soils are ongoing because of its excellent tolerance to salinity. However, the intrinsic adaptive physiology has not been discovered yet in the sub-tropical climatic conditions. In this study, [...] Read more.
Attempts to cultivate sugar beet (Beta vulgaris spp. vulgaris) in the sub-tropical saline soils are ongoing because of its excellent tolerance to salinity. However, the intrinsic adaptive physiology has not been discovered yet in the sub-tropical climatic conditions. In this study, we investigated morpho-physiological attributes, biochemical responses, and yield of sugar beet under a gradient of salinity in the soil–pot culture system to evaluate its adaptive mechanisms. Results exhibited that low and high salinity displayed a differential impact on growth, photosynthesis, and yield. Low to moderate salt stress (75 and 100 mM NaCl) showed no inhibition on growth and photosynthetic attributes. Accordingly, low salinity displayed simulative effect on chlorophyll and antioxidant enzymes activity which contributed to maintaining a balanced H2O2 accumulation and lipid peroxidation. Furthermore, relative water and proline content showed no alteration in low salinity. These factors contributed to improving the yield (tuber weight). On the contrary, 250 mM salinity showed a mostly inhibitory role on growth, photosynthesis, and yield. Collectively, our findings provide insights into the mild–moderate salt adaptation strategy in the soil culture test attributed to increased water content, elevation of photosynthetic pigment, better photosynthesis, and better management of oxidative stress. Therefore, cultivation of sugar beet in moderately saline-affected soils will ensure efficient utilization of lands. Full article
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Open AccessEditor’s ChoiceArticle
Effect of Wilting Intensity, Dry Matter Content and Sugar Addition on Nitrogen Fractions in Lucerne Silages
Agriculture 2019, 9(1), 11; https://doi.org/10.3390/agriculture9010011 - 05 Jan 2019
Cited by 9
Abstract
Pre-ensiling treatments can significantly influence the composition of lucerne (Medicago sativa L.) silages (LS). Besides dry matter (DM) content and availability of water-soluble carbohydrates (WSC), wilting intensity may exert a strong impact on the crude protein (CP; nitrogen [N] × 6.25) fractions. [...] Read more.
Pre-ensiling treatments can significantly influence the composition of lucerne (Medicago sativa L.) silages (LS). Besides dry matter (DM) content and availability of water-soluble carbohydrates (WSC), wilting intensity may exert a strong impact on the crude protein (CP; nitrogen [N] × 6.25) fractions. The present study aimed to evaluate the effects of DM level, wilting intensity, and sucrose addition on N compounds and fermentation products in LS. Pure lucerne stand (cultivar Plato) was wilted with either high or low intensity to DM contents of 250 and 350 g kg−1, respectively, and ensiled with or without the addition of sucrose. Non-protein-N (NPN) concentration in LS was affected by all pre-ensiling treatments and with 699 g kg−1 CP, NPN was lowest in high-intensity wilted high-DM LS with sucrose addition. No effects were observed on in vitro-estimated concentrations of utilizable CP at the duodenum, a precursor to metabolizable protein. Sucrose addition and higher DM level decreased acetic acid and ammonia-N concentration in the silages. Therefore, the present study demonstrated the beneficial manipulation of CP fractions in LS by high-intensity wilting to higher DM contents and that the provision of WSC may be necessary for sufficient silage fermentation and protein preservation. Full article
(This article belongs to the Special Issue Quality and Production of Forage) Printed Edition available
Open AccessEditor’s ChoiceArticle
Sorption to Biochar Impacts β-Glucosidase and Phosphatase Enzyme Activities
Agriculture 2018, 8(10), 158; https://doi.org/10.3390/agriculture8100158 - 10 Oct 2018
Cited by 13
Abstract
Extracellular enzymes catalyze biogeochemical reactions in soil, cycling carbon and nutrients in agricultural systems. Enzymes respond quickly to soil management, including organic amendment inputs, such as biochar, a charcoal-like solid byproduct of bioenergy production. In a previous agricultural field trial, a pine biochar [...] Read more.
Extracellular enzymes catalyze biogeochemical reactions in soil, cycling carbon and nutrients in agricultural systems. Enzymes respond quickly to soil management, including organic amendment inputs, such as biochar, a charcoal-like solid byproduct of bioenergy production. In a previous agricultural field trial, a pine biochar amendment caused an approximately 40% decrease in the enzyme activities of β-glucosidase (BG) and phosphatase (PHOS). The large surface area of the pine biochar has the potential to sorb nutrients and other organic molecules. To test if sorption caused decreased enzyme activity, we used a laboratory assay to quantify the activity of two sorbed enzymes: BG and acid PHOS, involved in the cycling of carbon and phosphorous. The enzymes were incubated with three solid phases: (1) the high surface area pine biochar, (2) the agricultural soil, and (3) a low surface area grass biochar, for an additional comparison. We quantified the sorbed enzymes at pH 6, 7, and 8, using a Bradford protein assay, and measured the immobilized enzyme activities via high-throughput fluorometric analysis. After sorption onto pine biochar, detectable BG and PHOS activity levels dropped by over 95% relative to the soil, supporting direct sorption as one mechanism that reduces enzyme activity in biochar amended soil. This laboratory assay demonstrated that sorption could account for the lack of priming of native soil organic matter and changes in soil phosphorous cycling after pine biochar addition. Full article
(This article belongs to the Special Issue Biochar and Soil: What Is behind Its Impacts?)
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Open AccessEditor’s ChoiceArticle
A Novel Machine Learning Method for Estimating Biomass of Grass Swards Using a Photogrammetric Canopy Height Model, Images and Vegetation Indices Captured by a Drone
Agriculture 2018, 8(5), 70; https://doi.org/10.3390/agriculture8050070 - 17 May 2018
Cited by 40
Abstract
Silage is the main feed in milk and ruminant meat production in Northern Europe. Novel drone-based remote sensing technology could be utilized in many phases of silage production, but advanced methods of utilizing these data are still developing. Grass swards are harvested three [...] Read more.
Silage is the main feed in milk and ruminant meat production in Northern Europe. Novel drone-based remote sensing technology could be utilized in many phases of silage production, but advanced methods of utilizing these data are still developing. Grass swards are harvested three times in season, and fertilizer is applied similarly three times—once for each harvest when aiming at maximum yields. Timely information of the yield is thus necessary several times in a season for making decisions on harvesting time and rate of fertilizer application. Our objective was to develop and assess a novel machine learning technique for the estimation of canopy height and biomass of grass swards utilizing multispectral photogrammetric camera data. Variation in the studied crop stand was generated using six different nitrogen fertilizer levels and four harvesting dates. The sward was a timothy-meadow fescue mixture dominated by timothy. We extracted various features from the remote sensing data by combining an ultra-high resolution photogrammetric canopy height model (CHM) with a pixel size of 1.0 cm and red, green, blue (RGB) and near-infrared range intensity values and different vegetation indices (VI) extracted from orthophoto mosaics. We compared the performance of multiple linear regression (MLR) and a Random Forest estimator (RF) with different combinations of the CHM, RGB and VI features. The best estimation results with both methods were obtained by combining CHM and VI features and all three feature classes (CHM, RGB and VI features). Both estimators provided equally accurate results. The Pearson correlation coefficients (PCC) and Root Mean Square Errors (RMSEs) of the estimations were at best 0.98 and 0.34 t/ha (12.70%), respectively, for the dry matter yield (DMY) and 0.98 and 1.22 t/ha (11.05%), respectively, for the fresh yield (FY) estimations. Our assessment of the sensitivity of the method with respect to different development stages and different amounts of biomass showed that the use of the machine learning technique that integrated multiple features improved the results in comparison to the simple linear regressions. These results were extremely promising, showing that the proposed multispectral photogrammetric approach can provide accurate biomass estimates of grass swards, and could be developed as a low-cost tool for practical farming applications. Full article
(This article belongs to the Special Issue Remote Sensing in Agricultural System)
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Review

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Open AccessEditor’s ChoiceReview
Perennial Energy Grasses: Resilient Crops in a Changing European Agriculture
Agriculture 2019, 9(8), 169; https://doi.org/10.3390/agriculture9080169 - 01 Aug 2019
Cited by 8
Abstract
This review describes the multiple utilization of perennial grasses as resilient crops for a multifunctional agriculture. Beyond its role of producing food, feed and fiber, the concept of multifunctional agriculture includes many other functions, such as ecosystem services, renewable energy production and a [...] Read more.
This review describes the multiple utilization of perennial grasses as resilient crops for a multifunctional agriculture. Beyond its role of producing food, feed and fiber, the concept of multifunctional agriculture includes many other functions, such as ecosystem services, renewable energy production and a contribution to the socio-economic viability of rural areas. Traditionally used for feed, some perennial grasses—known as perennial energy grasses (e.g., miscanthus—Miscanthus × giganteus Greef et Deuter, giant reed—Arundo donax L., switchgrass—Panicun virgatum L., reed canary grass—Phalaris arundinacea L.)—have been recommended as a biomass source for both energy and non-energy applications, and ecosystem services. Perennial grasses are lignocellulosic, low-cost feedstock, able to grow in variable environments including marginal lands. Due to their high yield, resilient traits, biomass composition, energy and environmental sustainability, perennial grasses are a candidate feedstock to foster the bio-based economy and adapt to a changing agriculture. However, perennial grasses for biomass production are largely undomesticated crops, or are at early stages of development. Hence, a great potential for improvements is expected, provided that research on breeding, agronomy, post-harvest logistic and bioconversion is undertaken in order to deliver resilient genotypes growing and performing well across a broad range of environmental conditions, climatic uncertainty, marginal land type and end-use destinations. Full article
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Open AccessEditor’s ChoiceReview
The Interactions of Rhizodeposits with Plant Growth-Promoting Rhizobacteria in the Rhizosphere: A Review
Agriculture 2019, 9(7), 142; https://doi.org/10.3390/agriculture9070142 - 04 Jul 2019
Cited by 19
Abstract
Rhizodeposits, root exudates, and root border cells are vital components of the rhizosphere that significantly affect root colonization capacity and multiplication of rhizosphere microbes, as well as secretion of organic bioactive compounds. The rhizosphere is an ecological niche, in which beneficial bacteria compete [...] Read more.
Rhizodeposits, root exudates, and root border cells are vital components of the rhizosphere that significantly affect root colonization capacity and multiplication of rhizosphere microbes, as well as secretion of organic bioactive compounds. The rhizosphere is an ecological niche, in which beneficial bacteria compete with other microbiota for organic carbon compounds and interact with plants through root colonization activity to the soil. Some of these root-colonizing beneficial rhizobacteria also colonize endophytically and multiply inside plant roots. In the rhizosphere, these components contribute to complex physiological processes, including cell growth, cell differentiation, and suppression of plant pathogenic microbes. Understanding how rhizodeposits, root exudates, and root border cells interact in the rhizosphere in the presence of rhizobacterial populations is necessary to decipher their synergistic role for the improvement of plant health. This review highlights the diversity of plant growth-promoting rhizobacteria (PGPR) genera, their functions, and the interactions with rhizodeposits in the rhizosphere. Full article
(This article belongs to the Special Issue Plant-Microbe Interactions)
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Open AccessEditor’s ChoiceReview
A Critical Review on Soil Chemical Processes that Control How Soil pH Affects Phosphorus Availability to Plants
Agriculture 2019, 9(6), 120; https://doi.org/10.3390/agriculture9060120 - 08 Jun 2019
Cited by 44
Abstract
Occasionally, the classic understanding of the effect of pH on P uptake from soils is questioned through the claim that maximum P uptake occurs at a pH much lower than 6.5–7. The purpose of this paper was to thoroughly examine that claim and [...] Read more.
Occasionally, the classic understanding of the effect of pH on P uptake from soils is questioned through the claim that maximum P uptake occurs at a pH much lower than 6.5–7. The purpose of this paper was to thoroughly examine that claim and provide a critical review on soil processes that control how soil pH affects P solubility and availability. We discuss how individual P retention mechanisms are affected by pH in isolation and when combined in soils, and how both real and apparent exceptions to the classic view can occasionally occur due to dynamics between mechanisms, experimental techniques (equilibration time, method of soluble P extraction, and pH adjustment), and plant species that thrive under acidic conditions. While real exceptions to the rule of thumb of maximum P availability at near neutral pH can occur, we conclude that the classic textbook recommendation is generally sound. Full article
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Open AccessEditor’s ChoiceReview
The Multi-Level Perspective in Research on Sustainability Transitions in Agriculture and Food Systems: A Systematic Review
Agriculture 2019, 9(4), 74; https://doi.org/10.3390/agriculture9040074 - 10 Apr 2019
Cited by 15
Abstract
The multi-level perspective (MLP) is a prominent transition framework. The MLP posits that transitions come about through interaction processes within and among three analytical levels: niches, socio-technical regimes and a socio-technical landscape. This systematic review provides an overview on the use of the [...] Read more.
The multi-level perspective (MLP) is a prominent transition framework. The MLP posits that transitions come about through interaction processes within and among three analytical levels: niches, socio-technical regimes and a socio-technical landscape. This systematic review provides an overview on the use of the MLP in research on agro-food sustainability transitions. In particular, it analyses the understanding, conceptualisation and operationalisation of niches, regimes and landscapes. Niches considered in the selected papers include agro-ecology, organic agriculture, permaculture, conservation agriculture, integrated farming, and alternative food networks. Regime refers to industrial, conventional agriculture. The researched regime is often not clearly described and its operationalisation is a matter of deliberation. Landscape level is generally overlooked; when it is considered it refers to international trends and developments. Many scholars highlight the inadequacy of transition pathways in the MLP for the agro-food sector. Moreover, transition impacts are rarely addressed and the research field generally overlooks the analysis of the sustainability of niches and, consequently, of transitions. Research on transitions in the agro-food sector borrows from the MLP its generalizability and poor empirical operationalisation of niche, regime and landscape concepts. Therefore, integrative conceptualisation and operationalisation of the MLP elements is required to accommodate the complexity of sustainability transition processes and the peculiarities of the agro-food system. Full article
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Open AccessEditor’s ChoiceReview
Advancing Intercropping Research and Practices in Industrialized Agricultural Landscapes
Agriculture 2018, 8(6), 80; https://doi.org/10.3390/agriculture8060080 - 08 Jun 2018
Cited by 23
Abstract
Sustainable intensification calls for agroecological and adaptive management of the agrifood system. Here, we focus on intercropping and how this agroecological practice can be used to increase the sustainability of crop production. Strip, mixed, and relay intercropping can be used to increase crop [...] Read more.
Sustainable intensification calls for agroecological and adaptive management of the agrifood system. Here, we focus on intercropping and how this agroecological practice can be used to increase the sustainability of crop production. Strip, mixed, and relay intercropping can be used to increase crop yields through resource partitioning and facilitation. In addition to achieving greater productivity, diversifying cropping systems through the use of strategic intercrops can increase yield stability, reduce pests, and improve soil health. Several intercropping systems are already implemented in industrialized agricultural landscapes, including mixed intercropping with perennial grasses and legumes as forage and relay intercropping with winter wheat and red clover. Because intercropping can provide numerous benefits, researchers should be clear about their objectives and use appropriate methods so as to not draw spurious conclusions when studying intercrops. In order to advance the practice, experiments that test the effects of intercropping should use standardized methodology, and researchers should report a set of common criteria to facilitate cross-study comparisons. Intercropping with two or more crops appears to be less common with annuals than perennials, which is likely due to differences in the mechanisms responsible for complementarity. One area where intercropping with annuals in industrialized agricultural landscapes has advanced is with cover crops, where private, public, and governmental organizations have harmonized efforts to increase the adoption of cover crop mixtures. Full article
(This article belongs to the Special Issue Sustainable Crop Production Intensification)
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Open AccessEditor’s ChoiceReview
Macro and Micronutrient Storage in Plants and Their Remobilization When Facing Scarcity: The Case of Drought
Agriculture 2018, 8(1), 14; https://doi.org/10.3390/agriculture8010014 - 16 Jan 2018
Cited by 23
Abstract
Human mineral malnutrition or hidden hunger is considered a global challenge, affecting a large proportion of the world’s population. The reduction in the mineral content of edible plant products is frequently found in cultivars bred for higher yields, and is probably increased by [...] Read more.
Human mineral malnutrition or hidden hunger is considered a global challenge, affecting a large proportion of the world’s population. The reduction in the mineral content of edible plant products is frequently found in cultivars bred for higher yields, and is probably increased by intensive agricultural practices. The filling of grain with macro and micronutrients is partly the result of a direct allocation from root uptake and remobilization from vegetative tissues. The aim of this bibliographic review is to focus on recent knowledge obtained from ionomic analysis of plant tissues in order to build a global appraisal of the potential remobilization of all macro and micronutrients, and especially those from leaves. Nitrogen is always remobilized from leaves of all plant species, although with different efficiencies, while nutrients such as K, S, P, Mg, Cu, Mo, Fe and Zn can be mobilized to a certain extent when plants are facing deficiencies. On the opposite, there is few evidence for leaf mobilization of Ca, Mn, Ni and B. Mechanisms related to the remobilization process (remobilization of mineral forms from vacuolar and organic compounds associated with senescence, respectively) are also discussed in the context of drought, an abiotic stress that is thought to increase and known to modulate the ionic composition of grain in crops. Full article
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