Agronomy

Open AccessArticle

Identification of Wheat Germplasm Resistance to Late Sowing

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Samia Mahgoub Omer Basheir

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Agronomy 2023, 13(4), 1010; https://doi.org/10.3390/agronomy13041010 (registering DOI) - 29 Mar 2023

Abstract

To evaluate the performance of wheat plant height and spike-related traits under delayed sowing conditions, a screening trial was conducted for wheat germplasm that exhibits resistance to late sowing and early maturity. The differences and stability of plant height and spike-related traits under [...] Read more.

To evaluate the performance of wheat plant height and spike-related traits under delayed sowing conditions, a screening trial was conducted for wheat germplasm that exhibits resistance to late sowing and early maturity. The differences and stability of plant height and spike-related traits under different sowing dates were analyzed using 327 wheat germplasm sources from a wide range of areas. The results showed that mean values of wheat plant height and spike-related traits generally decreased along with the delay in sowing dates. Broad-sense heritability of plant height (PH), internode length below spike (ILBS), spike length (SL), spikelet per spike (SPS), and spike number (SN) under multiple environments were all above 85%. Ten varieties, including Xiangmai 35, Pingyang 27, Huaimai 23, Huaimai 22, Emai 6, Zhenmai 12, Xiaoyan 81, Shannong 7859, Annong 1589, and Shuiyuan 86 indicated stable performance under different sowing dates, which harboring good resistance to late sowing. The results of this study laid a foundation for breeding high-yield wheat varieties that are resistant to late sowing. Full article

(This article belongs to the Special Issue Strategies for Enhancing Abiotic Stress Tolerance in Crops)

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Open AccessArticle

Remediation of Cd and Cu Contaminated Agricultural Soils near Oilfields by Biochar Combined with Sodium Humate-Wood Vinegar

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Agronomy 2023, 13(4), 1009; https://doi.org/10.3390/agronomy13041009 (registering DOI) - 29 Mar 2023

Abstract

Soil contaminations by heavy metals near oilfields have been widely reported and are causing great concern. Thus, it is highly desirable to develop cost-effective materials and methods to avoid heavy metal residues contaminating soil and food. An effective, environmentally friendly, and inexpensive remediation [...] Read more.

Soil contaminations by heavy metals near oilfields have been widely reported and are causing great concern. Thus, it is highly desirable to develop cost-effective materials and methods to avoid heavy metal residues contaminating soil and food. An effective, environmentally friendly, and inexpensive remediation material for heavy metal-polluted soil was designed and prepared using biochar (BC) combined with humic acid (HA) resulting from sodium humate (NaHA) simply reacting with wood vinegar (BHW). After adding BHW, the chemical fractions of copper and cadmium in the soil undergo larger changes. Meanwhile, the availability of heavy metals decreases. The maximum adsorption capacity of copper and cadmium in the soil using the BHW is larger than that only using biochar. The adsorption kinetics ensures that the adsorption process of Cd²⁺ and Cu²⁺ ions on BHW is chemical adsorption, which is best fitted using the pseudo-second-order rate equation. The thermodynamics guarantees that the metal ions adsorb on the heterogeneous surface of BHW in multilayer, which is credited to the enhancement of oxygen-containing groups in the biochar combined with the humic acid. The remediation material BHW holds promise for the immobilization of heavy metal in the soils and could be recommended based on its economic feasibility, high efficacy, and environmental safety. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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Open AccessArticle

High-Voltage Electrostatic Fields Adversely Affect the Performance of Diamondback Moths over Five Consecutive Generations

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Agronomy 2023, 13(4), 1008; https://doi.org/10.3390/agronomy13041008 (registering DOI) - 29 Mar 2023

Abstract

Changing electrical environments can influence the performance of herbivorous insects and adversely affect their control strategies. The diamondback moth, Plutella xylostella (L.), is a pest that devastates cruciferous vegetables. An age–stage, two-sex life table of P. xylostella over multiple generations was established to [...] Read more.

Changing electrical environments can influence the performance of herbivorous insects and adversely affect their control strategies. The diamondback moth, Plutella xylostella (L.), is a pest that devastates cruciferous vegetables. An age–stage, two-sex life table of P. xylostella over multiple generations was established to describe the effect of varying high-voltage electrostatic field (HVEF) exposure on their performance after the age-cohort eggs were exposed to HVEF at an intensity of 5.0 kV/cm for different durations. The results show that direct HVEF exposure adversely affected the population dynamics parameters of P. xylostella over multiple generations. In particular, the net reproduction rate, intrinsic natural increase rate, and finite increase rate of the P. xylostella population significantly decreased in the third and fifth generations under HVEF exposure for 10 min, while the mean generation time and doubling time significantly increased. Similarly, HVEF exposure for 10 min rapidly reduced the survival rate of adult P. xylostella in the first generation, and subsequently, it declined evenly and slowly. Meanwhile, the fecundity parameters of P. xylostella revealed that HVEF exposure for 10 min had the strongest inhibition effect on reproduction over five consecutive generations. In addition, HVEF exposure significantly increased the superoxide dismutase activity to produce extra hydrogen peroxide; however, increased catalase and peroxidase activity or reduced peroxidase activity triggered the accumulation of malondialdehyde in instar P. xylostella, especially after 10 min of treatment. The present findings provide experimental evidence and a theoretical basis for developing control strategies for P. xylostella under new HVEF environments. Full article

(This article belongs to the Special Issue New Insights into Pathogen, Insect Pest, and Weed Control in Field and Greenhouse Cropping Systems)

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Open AccessArticle

The Effect of Farming Management and Crop Rotation Systems on Chlorophyll Content, Dry Matter Translocation, and Grain Quantity and Quality of Wheat (Triticum aestivum L.) Grown in a Semi-Arid Region of Iran

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Agronomy 2023, 13(4), 1007; https://doi.org/10.3390/agronomy13041007 (registering DOI) - 29 Mar 2023

Abstract

To find suitable farming management approaches in the semi-arid climate of Iran, we set up an experiment combining three farm management practices with four crop rotation systems over four growing seasons (two winter and two summer seasons), from 2018 to 2020. The three [...] Read more.

To find suitable farming management approaches in the semi-arid climate of Iran, we set up an experiment combining three farm management practices with four crop rotation systems over four growing seasons (two winter and two summer seasons), from 2018 to 2020. The three farm management practices comprised: intensive (IF, with inorganic inputs, removal of crop residues from the soil, and weeds chemically controlled), organic (OF, with organic inputs, a return 30% of crop residues in the soil, and weeds mechanically controlled), and integrated (INT, with mineral/organic inputs, return 15% of crop residues to the soil, integrated weed control). The four crop rotation systems were: fallow-wheat (F-W), maize-wheat (M-W), sesame-wheat (S-W), and mung bean-wheat (B-W). Treatment effects were assessed by chlorophyll (Chl) content, photosynthetic parameters, and wheat grain quality and quantity measurements. All management practices from the first to the second year resulted in increases in the total Chl content and post-anthesis photosynthesis (PAP). The total Chl content under INT was improved through a greater increase in Chl-b compared to Chl-a. Dry matter remobilisation (DMR) was higher under INT than under IF. The highest (39) and lowest (23) grain number per spike were obtained in IF under B-W and OF under F-W, respectively. B-W produced the highest grain yield (541.4 g m⁻²). The protein contents in farming with organic matter inputs were higher than that under IF. INT produced an optimum level of wheat yield despite a 50% reduction in chemical inputs, and this was achieved through the fast absorption of chemical elements at the beginning of growth, and having access—at the grain filling stage—to elements derived from organic matter decomposition, and through the utilisation of DMR. Our results indicate that implementing B-W and S-W under INT is a promising strategy for this region. However, the results need to be further evaluated by long-term experiments. Full article

(This article belongs to the Special Issue Sustainable Circular Agricultural Food Production Systems)

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Open AccessEditorial

Developing Temperature-Resilient Plants: A Matter of Present and Future Concern for Sustainable Agriculture

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Ali Raza

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Daojie Wang

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Xiling Zou

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Channapatna S. Prakash

Agronomy 2023, 13(4), 1006; https://doi.org/10.3390/agronomy13041006 (registering DOI) - 29 Mar 2023

Abstract

Plants are decisive for nurturing life on Earth, but climate change threatens global food security, poverty decrease, and sustainable agriculture [...] Full article

(This article belongs to the Special Issue Developing Temperature-Resilient Plants: Responses and Mitigation Strategies)

Open AccessArticle

Will Climate Change Affect the Disease Progression of Septoria Tritici Blotch in Northern Europe?

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Ketel Christian Prahl

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Holger Klink

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Mario Hasler

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Joseph-Alexander Verreet

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Tim Birr

Agronomy 2023, 13(4), 1005; https://doi.org/10.3390/agronomy13041005 (registering DOI) - 29 Mar 2023

Abstract

Septoria tritici blotch (STB), caused by the fungus Zymoseptoria tritici Desm., is the most important disease affecting wheat in Northern Europe. There is a strong correlation between STB and weather variables; therefore, research on climate change and epidemiology is essential. In a long-term [...] Read more.

Septoria tritici blotch (STB), caused by the fungus Zymoseptoria tritici Desm., is the most important disease affecting wheat in Northern Europe. There is a strong correlation between STB and weather variables; therefore, research on climate change and epidemiology is essential. In a long-term survey across 25 years, we evaluated the epidemiological development of STB at a representative location under maritime climatic conditions. The surveys conducted between 1996 and 2021 showed an increase in disease severity of STB with respect to time. At the survey location, the plants were also evaluated for other diseases, but other foliar diseases were only observed with negligible severities. However, a continuous increase in the severity of STB was observed throughout the survey. During the survey period, there was no significant relationship between disease severity and single weather parameters (e.g., temperature and precipitation). However, seasonal changes in the progression of conducive STB conditions within the season were observed during the survey. Therefore, STB infections occurred at increased temperatures due to infections later during the growth season. In general, the distribution of conducive weather conditions, which supports an infection, determines the epidemiological behaviour of STB during the growing season. Due to these enhanced STB epidemics, a decline in wheat production has been observed, especially in agronomic practices of maritime climates. This is particularly the case if temperature and precipitation during the growing season are affected by climate change. Full article

(This article belongs to the Special Issue Pests, Pesticides and Food Safety in a Changing Climate)

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Open AccessArticle

Inflorescence Trait Diversity and Genotypic Differentiation as Influenced by the Environment in Elymus nutans Griseb. from Qinghai–Tibet Plateau

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Agronomy 2023, 13(4), 1004; https://doi.org/10.3390/agronomy13041004 (registering DOI) - 29 Mar 2023

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The alpine forage grass species Elymus nutans Griseb. is widely distributed in the Qinghai–Tibet Plateau and the Himalayas due to its high adaptability. However, it has become threatened by climate warming and excessive grazing. Thus, understanding its genetic and phenotypic information is crucial [...] Read more.

The alpine forage grass species Elymus nutans Griseb. is widely distributed in the Qinghai–Tibet Plateau and the Himalayas due to its high adaptability. However, it has become threatened by climate warming and excessive grazing. Thus, understanding its genetic and phenotypic information is crucial to aid resource management and conservation efforts. In this study, microsatellite markers were developed based on RNA-seq transcriptome data from E. nutans Griseb. varieties ‘Aba’ and ‘Kangbei’, resulting in the identification of 48,457 SSRs from 304,554 de novo assembled unigenes. Seventeen polymorphic markers, 13 inflorescence phenotypic traits, and seed shattering values were determined for 31 E. nutans accessions collected from eastern Tibet. The molecular markers generated 134 well-amplified bands with a mean Nei’s genetic diversity of 0.31 and a Shannon information index of 0.46. Pairwise genetic similarity ranged from 0.554 to 0.895, with an average of 0.729. Based on the molecular marker data, all accessions were divided into two classes via the unweighted pair-group method with arithmetic mean (UPGMA), the Markov chain Monte Carlo method, and the principal coordinate analysis (PCA) method. We used Tassel analysis to determine 11 loci with a significant relationship to phenotypic traits, and Pearson’s correlation analysis showed that some inflorescence traits were significantly influenced by the environment. Furthermore, we detected strong patterns of isolation by both environment (IBE) and distance (IBD) via Mantel analysis. This study provides valuable insights into the genetic and phenotypic differentiation of E. nutans, informing germplasm resource evaluation and future breeding. Full article

(This article belongs to the Special Issue Integrated Ways to Improve Forage Production and Nutritional Value)

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Open AccessArticle

Estimation of Fv/Fm in Spring Wheat Using UAV-Based Multispectral and RGB Imagery with Multiple Machine Learning Methods

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Agronomy 2023, 13(4), 1003; https://doi.org/10.3390/agronomy13041003 - 29 Mar 2023

Abstract

The maximum quantum efficiency of photosystem II (Fv/Fm) is a widely used indicator of photosynthetic health in plants. Remote sensing of Fv/Fm using MS (multispectral) and RGB imagery has the potential to enable high-throughput screening of plant health in agricultural and ecological applications. [...] Read more.

The maximum quantum efficiency of photosystem II (Fv/Fm) is a widely used indicator of photosynthetic health in plants. Remote sensing of Fv/Fm using MS (multispectral) and RGB imagery has the potential to enable high-throughput screening of plant health in agricultural and ecological applications. This study aimed to estimate Fv/Fm in spring wheat at an experimental base in Hanghou County, Inner Mongolia, from 2020 to 2021. RGB and MS images were obtained at the wheat flowering stage using a Da-Jiang Phantom 4 multispectral drone. A total of 51 vegetation indices were constructed, and the measured Fv/Fm of wheat on the ground was obtained simultaneously using a Handy PEA plant efficiency analyzer. The performance of 26 machine learning algorithms for estimating Fv/Fm using RGB and multispectral imagery was compared. The findings revealed that a majority of the multispectral vegetation indices and approximately half of the RGB vegetation indices demonstrated a strong correlation with Fv/Fm, as evidenced by an absolute correlation coefficient greater than 0.75. The Gradient Boosting Regressor (GBR) was the optimal estimation model for RGB, with the important features being RGBVI and ExR. The Huber model was the optimal estimation model for MS, with the important feature being MSAVI2. The Automatic Relevance Determination (ARD) was the optimal estimation model for the combination (RGB + MS), with the important features being SIPI, ExR, and VEG. The highest accuracy was achieved using the ARD model for estimating Fv/Fm with RGB + MS vegetation indices on the test sets (Test set MAE = 0.019, MSE = 0.001, RMSE = 0.024, R² = 0.925, RMSLE = 0.014, MAPE = 0.026). The combined analysis suggests that extracting vegetation indices (SIPI, ExR, and VEG) from RGB and MS remote images by UAV as input variables of the model and using the ARD model can significantly improve the accuracy of Fv/Fm estimation at flowering stage. This approach provides new technical support for rapid and accurate monitoring of Fv/Fm in spring wheat in the Hetao Irrigation District. Full article

(This article belongs to the Special Issue Current Research on Hyperspectral and Multispectral Imaging and Their Applications in Precision Agriculture Ⅱ)

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Open AccessArticle

Soil-Water Effects of Good Agricultural and Environmental Conditions Should Be Weighed in Conjunction with Carbon Farming

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Agronomy 2023, 13(4), 1002; https://doi.org/10.3390/agronomy13041002 - 29 Mar 2023

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Soil-water practice is essential for farm sustainability, thereby establishing the reference level for agricultural policy of the European Union (EU). This paper focuses on the critical gap in the knowledge surrounding comparison of soil-water effects of Good Agricultural and Environmental Conditions (GAEC) and [...] Read more.

Soil-water practice is essential for farm sustainability, thereby establishing the reference level for agricultural policy of the European Union (EU). This paper focuses on the critical gap in the knowledge surrounding comparison of soil-water effects of Good Agricultural and Environmental Conditions (GAEC) and carbon farming. We aim to interrogate the tasks assigned to soil-water standards during the 2005–2020 timeframe and identify soil-water effects under selected soil-water GAEC topics. The farm-level and landscape-scale effects were weighed for each standard. The investigation included an extensive meta-review of documents that featured scientific work on sustainable practice. In each GAEC document, soil-water sustainability was weighed vis-a-vis carbon farming. Our main finding was that the identification of soil-water effects within GAEC was addressed both at farm-enterprise level (E) and landscape scale (L). This identification was very similar among the sampled Member States (Czech Republic, Hungary, Poland, and Slovakia). A small differentiation was detected in how exact the guidance under each standard was in each of these Member States, and hence how the prioritization was scored, ranging from 1, most influential, to 5, least influential. The scores that prevailed were 2.5–5 on the part of the scoring instrument. Carbon farming is a welcome addition to the corpus of good farming practice and is complementary to GAEC. Full article

(This article belongs to the Special Issue Low Carbon Agriculture and Low Reactive Nitrogen Losses under Intensification)

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Open AccessFeature PaperArticle

Effects of Planting Pre-Germinated Buds on Stand Establishment in Sugarcane

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Hima Varsha Madala

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Ricardo A. Lesmes-Vesga

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Calvin D. Odero

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Lakesh K. Sharma

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Hardev S. Sandhu

Agronomy 2023, 13(4), 1001; https://doi.org/10.3390/agronomy13041001 - 29 Mar 2023

Abstract

Sugarcane (a complex hybrid of Saccharum spp.) is propagated vegetatively by using stem pieces of mature cane with healthy buds. Abiotic and biotic stress may cause pre-germination of these buds, which may have an impact on both emergence and plant cane stand establishment. [...] Read more.

Sugarcane (a complex hybrid of Saccharum spp.) is propagated vegetatively by using stem pieces of mature cane with healthy buds. Abiotic and biotic stress may cause pre-germination of these buds, which may have an impact on both emergence and plant cane stand establishment. There is very limited information available in the literature. A greenhouse study was conducted with single-budded seed pieces of three levels of bud germination (ungerminated buds, Pop-eyes, and Lalas) from three different cultivars (CP 96-1252, CPCL 05-1201, and CPCL 02-0926) planted in pots and repeated over time. Data on growth parameters (tiller count, primary shoot height, SPAD, and dry biomass of shoots and roots) at early growth showed that Lalas produced more tillers and higher shoot dry biomass than Pop-eyes and ungerminated buds. Both Lalas and Pop-eyes produced higher root dry biomass than ungerminated buds in one of the two experiments. The cultivar had a significant effect on primary shoot height and SPAD. A small plot field experiment was conducted with cultivar CP 96-1252 to validate the results of greenhouse experiments, and similar results were reported for tiller count. The results indicate that pre-germinated buds may have a neutral or positive effect on early sugarcane growth and establishment. Further on-farm research needs to be conducted to confirm these results before using pre-germinated buds as a potential seed source for the late season planting of sugarcane. Full article

(This article belongs to the Special Issue Cropping Systems and Agronomic Management Practices of Field Crops)

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Open AccessReview

Transgene-Free Genome Editing for Biotic and Abiotic Stress Resistance in Sugarcane: Prospects and Challenges

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Sakthivel Surya Krishna

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S R Harish Chandar

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Maruthachalam Ravi

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Ramanathan Valarmathi

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Kasirajan Lakshmi

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Perumal Thirugnanasambandam Prathima

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Ramaswamy Manimekalai

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Rasappa Viswanathan

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Govindkurup Hemaprabha

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Chinnaswamy Appunu

Agronomy 2023, 13(4), 1000; https://doi.org/10.3390/agronomy13041000 - 29 Mar 2023

Abstract

Sugarcane (Saccharum spp.) is one of the most valuable food and industrial crops. Its production is constrained due to major biotic (fungi, bacteria, viruses and insect pests) and abiotic (drought, salt, cold/heat, water logging and heavy metals) stresses. The ever-increasing demand for [...] Read more.

Sugarcane (Saccharum spp.) is one of the most valuable food and industrial crops. Its production is constrained due to major biotic (fungi, bacteria, viruses and insect pests) and abiotic (drought, salt, cold/heat, water logging and heavy metals) stresses. The ever-increasing demand for sugar and biofuel and the rise of new pest and disease variants call for the use of innovative technologies to speed up the sugarcane genetic improvement process. Developing new cultivars through conventional breeding techniques requires much time and resources. The advent of CRISPR/Cas genome editing technology enables the creation of new cultivars with improved resistance/tolerance to various biotic and abiotic stresses. The presence of genome editing cassette inside the genome of genome-edited plants hinders commercial exploitation due to regulatory issues. However, this limitation can be overcome by using transgene-free genome editing techniques. Transgene-free genome editing approaches, such as delivery of the RNPs through biolistics or protoplast fusion, virus-induced genome editing (VIGE), transient expression of CRISPR/Cas reagents through Agrobacterium-mediated transformation and other approaches, are discussed. A well-established PCR-based assay and advanced screening systems such as visual marker system and Transgene killer CRISPR system (TKC) rapidly identify transgene-free genome edits. These advancements in CRISPR/Cas technology speed up the creation of genome-edited climate-smart cultivars that combat various biotic and abiotic stresses and produce good yields under ever-changing conditions. Full article

(This article belongs to the Special Issue Application of Molecular Marker Technology in Crop Breeding)

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Open AccessArticle

Banana Pseudostem Visual Detection Method Based on Improved YOLOV7 Detection Algorithm

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Agronomy 2023, 13(4), 999; https://doi.org/10.3390/agronomy13040999 - 28 Mar 2023

Abstract

Detecting banana pseudostems is an indispensable part of the intelligent management of banana cultivation, which can be used in settings such as counting banana pseudostems and smart fertilization. In complex environments, dense and occlusion banana pseudostems pose a significant challenge for detection. This [...] Read more.

Detecting banana pseudostems is an indispensable part of the intelligent management of banana cultivation, which can be used in settings such as counting banana pseudostems and smart fertilization. In complex environments, dense and occlusion banana pseudostems pose a significant challenge for detection. This paper proposes an improved YOLOV7 deep learning object detection algorithm, YOLOV7-FM, for detecting banana pseudostems with different growth conditions. In the loss optimization part of the YOLOV7 model, Focal loss is introduced, to optimize the problematic training for banana pseudostems that are dense and sheltered, so as to improve the recognition rate of challenging samples. In the data augmentation part of the YOLOV7 model, the Mixup data augmentation is used, to improve the model’s generalization ability for banana pseudostems with similar features to complex environments. This paper compares the AP (average precision) and inference speed of the YOLOV7-FM algorithm with YOLOX, YOLOV5, YOLOV3, and Faster R-CNN algorithms. The results show that the AP and inference speed of the YOLOV7-FM algorithm is higher than those models that are compared, with an average inference time of 8.0 ms per image containing banana pseudostems and AP of 81.45%. This improved YOLOV7-FM model can achieve fast and accurate detection of banana pseudostems. Full article

(This article belongs to the Special Issue Applications of Deep Learning in Smart Agriculture - Volume II)

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Open AccessArticle

Comparative Transcriptome of Isonuclear Alloplasmic Strain Revealed the Important Role of Mitochondrial Genome in Regulating Flammulina filiformis

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Agronomy 2023, 13(4), 998; https://doi.org/10.3390/agronomy13040998 - 28 Mar 2023

Abstract

The golden–needle mushroom Flammulina filiformis is one of the most precious cultivated edible fungi in the world. Despite recent progress in the study of F. filiformis, there is still a gap in the regulation of the mitochondrial genome during browning, which poses [...] Read more.

The golden–needle mushroom Flammulina filiformis is one of the most precious cultivated edible fungi in the world. Despite recent progress in the study of F. filiformis, there is still a gap in the regulation of the mitochondrial genome during browning, which poses a serious threat to the golden–needle mushroom industry. Comparative transcriptome analysis of two isonuclear alloplasmic strains showed that changes in the mitochondrial genome lead to different gene expression and key biological pathways at different stages in the two isonuclear alloplasmic strains. Furthermore, transcriptome analysis revealed that the mitochondrial genome has a significant role in the regulation of a multitude of critical metabolic pathways relating to the browning of F. filiformis fruiting bodies. Functional enrichment analysis showed that the differentially expressed genes were mainly involved in many vital processes of mitochondria, mitochondrial membrane, and multiple amino acid metabolisms of F. filiformis. Taken together, the current study highlights the crucial role of the mitochondrial genome in the growth of F. filiformis and could be beneficial to genetic breeding of elite varieties of edible fungi. Full article

(This article belongs to the Special Issue Edible and Medicinal Fungi in Sustainable Agricultural Production: Technology and Applications)

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Open AccessArticle

Changes in Soil Rhizobia Diversity and Their Effects on the Symbiotic Efficiency of Soybean Intercropped with Maize

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Agronomy 2023, 13(4), 997; https://doi.org/10.3390/agronomy13040997 - 28 Mar 2023

Abstract

It has been established that maize/soybean intercropping can improve nitrogen use efficiency. However, few studies have addressed how maize/soybean intercropping affects nitrogen-fixing bacterial diversity and N fixation efficiency of intercropped soybean. In this study, nitrogen-fixing bacterial communities, N fixation efficiency, and their relationships [...] Read more.

It has been established that maize/soybean intercropping can improve nitrogen use efficiency. However, few studies have addressed how maize/soybean intercropping affects nitrogen-fixing bacterial diversity and N fixation efficiency of intercropped soybean. In this study, nitrogen-fixing bacterial communities, N fixation efficiency, and their relationships with soil properties under three nitrogen fertilization application rates (N0 0 kg/ha, N1 40 kg/ha, N2 80 kg/ha) were explored through field experiments. Nitrogen fixation and nitrogen-fixing bacteria diversity were assessed using ¹⁵N natural abundance, Illumina high-throughput sequencing, and nifH (nitrogen fixation) gene copies quantification in the rhizosphere soil of intercropped soybean. The results showed that nitrogen application rates significantly decreased the nitrogen-fixing bacteria diversity, nitrogen fixation efficiency, and nifH gene copies in the rhizosphere soil. Nitrogen fixation efficiency, nodule number, and dry weight of intercropped soybean were highest in the N0 treatment, and nitrogen fixation was the highest in the N1 treatment. The nitrogen-fixing efficiency in N0, N1, and N2 treatments increased by 69%, 59%, and 42% and the nodule number of soybean was 10%, 22%, and 21%, respectively, compared with monocultures. The soybean nitrogen-fixing bacteria diversity in intercropping under N0 and N1 treatments significantly increased compared with monocultures. There was a significant positive correlation between soil nifH gene copies and N fixation efficiency and a negative correlation with soil available nitrogen. Bradyrhizobium abundance in soybean rhizosphere soil decreased significantly with the increase in nitrogen application rates and was significantly correlated with soil AN (available nitrogen) and pH content in the soybean rhizosphere. These results help us to understand the mechanisms by which nitrogen use efficiency was improved, and nitrogen fertilizer could be reduced in legume/Gramineae intercropping, which is important to improve the sustainability of agricultural production. Full article

(This article belongs to the Special Issue Metagenomic Analysis for Unveiling Agricultural Microbiome)

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Open AccessArticle

Transpiration Efficiency of Some Potato Genotypes under Drought

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Zohreh Salehi-Soghadi

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Md. Saiful Islam

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Ahmad M. Manschadi

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Hans-Peter Kaul

Agronomy 2023, 13(4), 996; https://doi.org/10.3390/agronomy13040996 - 28 Mar 2023

Abstract

Potato (Solanum tuberosum L.) is the third most consumed food crop after rice and wheat in the world. It is a short-duration crop, suitable for growing in a wide range of environments, but abiotic factors can limit potato production, and drought is [...] Read more.

Potato (Solanum tuberosum L.) is the third most consumed food crop after rice and wheat in the world. It is a short-duration crop, suitable for growing in a wide range of environments, but abiotic factors can limit potato production, and drought is the main one. Therefore, managing drought stress is of utmost importance under climate change conditions. Potato as a drought-sensitive crop needs choice of suitable genotypes for dry environments. In this study, transpiration efficiency (TE), soil water conservation and drought tolerance were analysed for potato genotypes from different origins. Three glasshouse experiments under different Vapor Pressure Deficit (VPD) conditions with water-stressed (WS) and well-watered (WW) plants resulted in significantly different total amounts of transpiration among the genotypes and water supply levels. Transpiration in WS plants was the same as with WW plants up to a specific threshold “Fraction of Transpirable Soil Water” (FTSW) and then sharply decreased in response to soil drying. Genotypes showed a substantial variation in FTSW thresholds (0.19 to 0.36 FTSW) under low VPD condition, which narrowed down (0.19 to 0.29) when air humidity was lower. Furthermore, we observed hardly any relationships between TE and FTSW threshold (r = 0.125) or TE and water saving (r = 0.031). Our results provide insights into genotypic interactions with VPD on FTSW threshold and TE under dry-down conditions in potato. Full article

(This article belongs to the Special Issue Cultivation Physiology, Molecular Biology and Molecular Breeding of Solanaceae)

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Open AccessArticle

Phytoremediation of Cadmium-, Lead-, and Nickel-Polluted Soils by Industrial Hemp

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Giorgio Testa

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Sebastiano Andrea Corinzia

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Salvatore Luciano Cosentino

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Barbara Rachele Ciaramella

Agronomy 2023, 13(4), 995; https://doi.org/10.3390/agronomy13040995 - 28 Mar 2023

Abstract

The restoration of polluted soils is crucial for ecosystem recovery services. Evidently, phytoremediation is a biological and sustainable technique that includes the use of plants to remediate heavy-metal-contaminated land; the plants should be tolerant to the contamination and capable of uptake or immobilization [...] Read more.

The restoration of polluted soils is crucial for ecosystem recovery services. Evidently, phytoremediation is a biological and sustainable technique that includes the use of plants to remediate heavy-metal-contaminated land; the plants should be tolerant to the contamination and capable of uptake or immobilization of the heavy metals in the soil. Moreover, defining an economically efficient approach to the remediation of a contaminated area, with the possibility of further utilization of phytoremediation biomass, renders energy crops a great option for this technique. Energy crops, in fact, are known for their ability to grow with low agricultural input, and later, the biomass product can be used to produce biofuels, bioenergy, and bioproducts in a sustainable and renewable way, creating economic potential, especially when these crops are cultivated in marginal lands. The aim of this work is to test two monoecious industrial hemp varieties in different levels of Cd, Pb, and Ni in soil. Both varieties were tolerant to levels of Cd and Pb contamination that were higher than the limit for commercial and industrial use, while Ni showed a significant effect at all the tested concentrations. The variety Futura 75 performed better than Kc Dora in terms of productivity and tolerance. Full article

(This article belongs to the Special Issue Social-Ecologically More Sustainable Agricultural Production)

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Open AccessArticle

Grafting and Soil with Drought Stress Can Increase the Antioxidant Status in Cucumber

by

Marcelino Cabrera De la Fuente

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Jesus Tomas Felix Leyva

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Rafael Delgado Martinez

,

Julia Medrano Macías

and

Rocio Maricela Peralta Manjarrez

Agronomy 2023, 13(4), 994; https://doi.org/10.3390/agronomy13040994 - 28 Mar 2023

Abstract

The availability of water and nutrients are determining factors for the growth and productivity of the cucumber crop. The implementation of the grafting techniques increases the efficiency in the absorption of resources such as water and nutrients, improving the quality, mineral content, and [...] Read more.

The availability of water and nutrients are determining factors for the growth and productivity of the cucumber crop. The implementation of the grafting techniques increases the efficiency in the absorption of resources such as water and nutrients, improving the quality, mineral content, and enzymatic activity of the fruit. The objective of this research work was to evaluate the effect of the anchor point (soil and substrate), graft (with and without graft), and irrigation volume (100 and 75%) on fruit quality, macro and microelement content, and enzymatic antioxidant activity. A total of eight treatments was established in a completely randomized experiment with a factorial design with a 2 × 2 × 2 arrangement. The results showed an increase in the fruit weight by 10% in grafted plants under 100% irrigation in the substrate, no significant differences between treatments were found in firmness or total soluble solids (TSS). Additionally, while there was a higher accumulation of potassium because of the graft, there was no difference for calcium. It was observed that the enzymatic activity was inhibited using the graft. The graft represents a viable option for the efficient use of water, both in the soil and substrate, being the substrate with the best environment for development, mitigating stress by decreasing enzymatic activity. Full article

(This article belongs to the Special Issue Agronomic Practices in Water-Saving Agriculture to Improve Crop Water Use Efficiency)

Open AccessArticle

Effect of Ecologically Restored Vegetation Roots on the Stability of Shallow Aggregates in Ionic Rare Earth Tailings Piles

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Agronomy 2023, 13(4), 993; https://doi.org/10.3390/agronomy13040993 - 28 Mar 2023

Abstract

Aggregate stability is considered an essential indicator of changes in the physical properties of soils, and vegetation roots play a crucial role in the stability of shallow soil aggregates in ionic rare earth tailings piles during ecological remediation. In this paper, the influence [...] Read more.

Aggregate stability is considered an essential indicator of changes in the physical properties of soils, and vegetation roots play a crucial role in the stability of shallow soil aggregates in ionic rare earth tailings piles during ecological remediation. In this paper, the influence of the law of ecologically restored vegetation roots on the stability of shallow aggregates of ionic rare earth tailing piles was investigated by means of field investigation tests, indoor experiments and mathematical statistics. The influence of different types of root systems on the stability of the shallow depth range aggregates of tailings piles was investigated; the correlation between vegetation root systems and the main physical parameters of rare earth tailings was clarified; and a mathematical correlation model characterizing the characteristic parameters of vegetation root systems was constructed. The evaluation index of the stability of rare earth tailings piles was constructed, and the influence of the law of the ecological restoration of vegetation root systems on the strength of shallow aggregates of ionic rare earth tailings piles was revealed. The results of the study showed that compared with the RD (root density), the root characteristic parameter with the largest response weight to the rare earth tailings pile is the RL (root length density), and the root characteristic parameter with the largest response weight to the water content is the RV (root volume). Suitable vegetation roots can effectively enhance the content of shallow large aggregates of rare ionic earth tailing piles. With the increase of the depth of a tailing pile, the content of large aggregates continues to decrease, and the content of micro aggregates continues increasing. This indicates that the vegetation root system changed the shallow soil of the rare earth tailing pile from disorderly to orderly through its own growth pattern, which effectively improved the stability of the shallow aggregates of the tailing pile and improved the physical properties of the tailing. Full article

(This article belongs to the Special Issue Soil Properties, Microorganisms and Plants in Soils after Amelioration)

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Open AccessArticle

Identification of HIR, EDS1 and PAD4 Genes Reveals Differences between Coffea Species That May Impact Disease Resistance

by

Sílvia Tavares

,

Helena Azinheira

,

Javier Valverde

,

A. Jesus-Muñoz Pajares

,

Pedro Talhinhas

and

Maria do Céu Silva

Agronomy 2023, 13(4), 992; https://doi.org/10.3390/agronomy13040992 - 28 Mar 2023

Abstract

Coffee, a widely consumed important agricultural product, is mainly produced from two species, Coffea arabica (Arabica coffee) and C. canephora (Robusta coffee). Timor Hybrid (HDT) is a population resulting from a natural cross between C. arabica and C. canephora. HDT derivatives have [...] Read more.

Coffee, a widely consumed important agricultural product, is mainly produced from two species, Coffea arabica (Arabica coffee) and C. canephora (Robusta coffee). Timor Hybrid (HDT) is a population resulting from a natural cross between C. arabica and C. canephora. HDT derivatives have a high spectrum of resistance to different races of Hemileia vastatrix (Hv), the causal agent of coffee leaf rust. A RNAseq database, obtained from HDT832/2 leaves inoculated with Hv (Host Resistance) and Uromyces vignae (Uv, Nonhost Resistance), showed the presence of genes implicated in the hypersensitive response and salicylic acid pathway. Hypersensitive Induced Reaction (HIR) gene family, Enhanced Disease Susceptibility1 gene (EDS1), and Phytoalexin Deficient 4 (PAD4) gene are involved in host and nonhost resistance. Relative expression calculated by RT-qPCR was used to confirm and expand the transcriptome analysis. HDTHIR4, HDTEDS1, and HDTPAD4 showed the highest upregulation in response to Hv and Uv inoculation, confirming a similar trend in host and nonhost resistance in HDT. HIR and EDS1/PAD4 gene families were characterized for the first time in the three available Coffea genomes. HIR genes were quite conserved between Coffea species. Surprisingly, EDS1 and PAD4 genes revealed major differences in gene structure. The PAD4 predicted protein from C. arabica does not include both conserved domains of the EDS1/PAD4 family, and the EDS1 putative protein from C. canephora includes a formin domain unusual in the same protein family. The variability shown by EDS1/PAD4 gene family may impact the disease resistance response of Coffea species, which can be surveyed for the gene sequences that will produce a more resistant phenotype. Full article

(This article belongs to the Special Issue Sustainable Strategies for the Control of Crop Diseases and Pests to Reduce Pesticides)

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