Agronomy

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7 pages, 215 KiB

Open AccessEditorial

Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses

by Monica Boscaiu and Ana Fita

Agronomy 2020, 10(9), 1308; https://doi.org/10.3390/agronomy10091308 - 2 Sep 2020

Cited by 23 | Viewed by 4097

Abstract

Abiotic stress represents a main constraint for agriculture, affecting plant growth and productivity. Drought and soil salinity, especially, are major causes of reduction of crop yields and food production worldwide. It is not unexpected, therefore, that the study of plant responses to abiotic [...] Read more.

Abiotic stress represents a main constraint for agriculture, affecting plant growth and productivity. Drought and soil salinity, especially, are major causes of reduction of crop yields and food production worldwide. It is not unexpected, therefore, that the study of plant responses to abiotic stress and stress tolerance mechanisms is one of the most active research fields in plant biology. This Special Issue compiles 22 research papers and 4 reviews covering different aspects of these responses and mechanisms, addressing environmental stress factors such as drought, salinity, flooding, heat and cold stress, deficiency or toxicity of compounds in the soil (e.g., macro and micronutrients), and combination of different stresses. The approaches used are also diverse, including, among others, the analysis of agronomic traits based on morphological characteristics, physiological and biochemical studies, and transcriptomics or transgenics. Despite its complexity, we believe that this Special Issue provides a useful overview of the topic, including basic information on the mechanisms of abiotic stress tolerance as well as practical aspects such as the alleviation of the deleterious effects of stress by different means, or the use of local landraces as a source of genetic material adapted to combined stresses. This knowledge should help to develop the agriculture of the (near) future, sustainable and better adapted to the conditions ahead, in a scenario of global warming and environmental pollution. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

Research

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12 pages, 1468 KiB

Open AccessArticle

Response to the Cold Stress Signaling of the Tea Plant (Camellia sinensis) Elicited by Chitosan Oligosaccharide

by Yingying Li, Qiuqiu Zhang, Lina Ou, Dezhong Ji, Tao Liu, Rongmeng Lan, Xiangyang Li and Linhong Jin

Agronomy 2020, 10(6), 915; https://doi.org/10.3390/agronomy10060915 - 26 Jun 2020

Cited by 41 | Viewed by 5158

Abstract

Cold stress caused by a low temperature is a significant threat to tea production. The application of chitosan oligosaccharide (COS) can alleviate the effect of low temperature stress on tea plants. However, how COS affects the cold stress signaling in tea plants is [...] Read more.

Cold stress caused by a low temperature is a significant threat to tea production. The application of chitosan oligosaccharide (COS) can alleviate the effect of low temperature stress on tea plants. However, how COS affects the cold stress signaling in tea plants is still unclear. In this study, we investigated the level of physiological indicators in tea leaves treated with COS, and then the molecular response to the cold stress of tea leaves treated with COS was analyzed by transcriptomics with RNA-Sequencing (RNA-Seq). The results show that the activity of superoxide dismutase (SOD) activity, peroxidase (POD) activity, content of chlorophyll and soluble sugar in tea leaves in COS-treated tea plant were significantly increased and that photosynthesis and carbon metabolism were enriched. Besides, our results suggest that COS may impact to the cold stress signaling via enhancing the photosynthesis and carbon process. Our research provides valuable information for the mechanisms of COS application in tea plants under cold stress. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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16 pages, 1013 KiB

Open AccessEditor’s ChoiceArticle

The Use of Proline in Screening for Tolerance to Drought and Salinity in Common Bean (Phaseolus vulgaris L.) Genotypes

by Sugenith Arteaga, Lourdes Yabor, María José Díez, Jaime Prohens, Monica Boscaiu and Oscar Vicente

Agronomy 2020, 10(6), 817; https://doi.org/10.3390/agronomy10060817 - 9 Jun 2020

Cited by 81 | Viewed by 5859

Abstract

The selection of stress-resistant cultivars, to be used in breeding programmes aimed at enhancing the drought and salt tolerance of our major crops, is an urgent need for agriculture in a climate change scenario. In the present study, the responses to water deficit [...] Read more.

The selection of stress-resistant cultivars, to be used in breeding programmes aimed at enhancing the drought and salt tolerance of our major crops, is an urgent need for agriculture in a climate change scenario. In the present study, the responses to water deficit and salt stress treatments, regarding growth inhibition and leaf proline (Pro) contents, were analysed in 47 Phaseolus vulgaris genotypes of different origins. A two-way analysis of variance (ANOVA), Pearson moment correlations and principal component analyses (PCAs) were performed on all measured traits, to assess the general responses to stress of the investigated genotypes. For most analysed growth variables and Pro, the effects of cultivar, treatment and their interactions were highly significant (p < 0.001); the root morphological traits, stem diameter and the number of leaves were mostly due to uncontrolled variation, whereas the variation of fresh weight and water content of stems and leaves was clearly induced by stress. Under our experimental conditions, the average effects of salt stress on plant growth were relatively weaker than those of water deficit. In both cases, however, growth inhibition was mostly reflected in the stress-induced reduction of fresh weight and water contents of stems and leaves. Pro, on the other hand, was the only variable showing a negative correlation with all growth parameters, but particularly with those of stems and leaves mentioned above, as indicated by the Pearson correlation coefficients and the loading plots of the PCAs. Therefore, in common beans, higher stress-induced accumulation of Pro is unequivocally associated with a stronger inhibition of growth; that is, with a higher sensitivity to stress of the corresponding cultivar. We propose the use of Pro as a suitable biochemical marker for simple, rapid, large-scale screenings of bean genotypes, to exclude the most sensitive, those accumulating higher Pro concentrations in response to water or salt stress treatments. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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21 pages, 8779 KiB

Open AccessEditor’s ChoiceArticle

Phytotoxic Effects of Three Natural Compounds: Pelargonic Acid, Carvacrol, and Cinnamic Aldehyde, against Problematic Weeds in Mediterranean Crops

by Marta Muñoz, Natalia Torres-Pagán, Rosa Peiró, Rubén Guijarro, Adela M. Sánchez-Moreiras and Mercedes Verdeguer

Agronomy 2020, 10(6), 791; https://doi.org/10.3390/agronomy10060791 - 2 Jun 2020

Cited by 40 | Viewed by 7271

Abstract

Weeds and herbicides are important stress factors for crops. Weeds are responsible for great losses in crop yields, more than 50% in some crops if left uncontrolled. Herbicides have been used as the main method for weed control since their development after the [...] Read more.

Weeds and herbicides are important stress factors for crops. Weeds are responsible for great losses in crop yields, more than 50% in some crops if left uncontrolled. Herbicides have been used as the main method for weed control since their development after the Second World War. It is necessary to find alternatives to synthetic herbicides that can be incorporated in an Integrated Weed Management Program, to produce crops subjected to less stress in a more sustainable way. In this work, three natural products: pelargonic acid (PA), carvacrol (CV), and cinnamic aldehyde (CA) were evaluated, under greenhouse conditions in postemergence assays, against problematic weeds in Mediterranean crops Amaranthus retroflexus, Avena fatua, Portulaca oleracea, and Erigeron bonariensis, to determine their phytotoxic potential. The three products showed a potent herbicidal activity, reaching high efficacy (plant death) and damage level in all species, being PA the most effective at all doses applied, followed by CA and CV. These products could be good candidates for bioherbicides formulations. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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16 pages, 3025 KiB

Open AccessArticle

Resilience Capacity Assessment of the Traditional Lima Bean (Phaseolus lunatus L.) Landraces Facing Climate Change

by María Isabel Martínez-Nieto, Elena Estrelles, Josefa Prieto-Mossi, Josep Roselló and Pilar Soriano

Agronomy 2020, 10(6), 758; https://doi.org/10.3390/agronomy10060758 - 26 May 2020

Cited by 18 | Viewed by 5227

Abstract

Agriculture is highly exposed to climate warming, and promoting traditional cultivars constitutes an adaptive farming mechanism from climate change impacts. This study compared seed traits and adaptability in the germinative process, through temperature and drought response, between a commercial cultivar and Mediterranean Phaseolus [...] Read more.

Agriculture is highly exposed to climate warming, and promoting traditional cultivars constitutes an adaptive farming mechanism from climate change impacts. This study compared seed traits and adaptability in the germinative process, through temperature and drought response, between a commercial cultivar and Mediterranean Phaseolus lunatus L. landraces. Genetic and phylogenetic analyses were conducted to characterize local cultivars. Optimal germination temperature, and water stress tolerance, with increasing polyethylene glycol (PEG) concentrations, were initially evaluated. Base temperature, thermal time, base potential and hydrotime were calculated to compare the thermal and hydric responses and competitiveness among cultivars. Eight molecular markers were analyzed to calculate polymorphism and divergence parameters, of which three, together with South American species accessions, were used to construct a Bayesian phylogeny. No major differences were found in seed traits, rather different bicolored patterns. A preference for high temperatures and fast germination were observed. The ‘Pintat’ landrace showed marked competitiveness compared to the commercial cultivar when faced with temperature and drought tolerance. No genetic differences were found among the Valencian landraces and the phylogeny confirmed their Andean origin. Promoting landraces for their greater resilience is a tool to help overcome the worldwide challenge deriving from climate change and loss of agrobiodiversity. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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19 pages, 2244 KiB

Open AccessArticle

Physiological and Biochemical Responses to Salt Stress in Cultivated Eggplant (Solanum melongena L.) and in S. insanum L., a Close Wild Relative

by Marco Brenes, Andrea Solana, Monica Boscaiu, Ana Fita, Oscar Vicente, Ángeles Calatayud, Jaime Prohens and Mariola Plazas

Agronomy 2020, 10(5), 651; https://doi.org/10.3390/agronomy10050651 - 4 May 2020

Cited by 37 | Viewed by 5886

Abstract

Eggplant (Solanum melongena) has been described as moderately sensitive to salinity. We characterised the responses to salt stress of eggplant and S. insanum, its putative wild ancestor. Young plants of two accessions of both species were watered for 25 days [...] Read more.

Eggplant (Solanum melongena) has been described as moderately sensitive to salinity. We characterised the responses to salt stress of eggplant and S. insanum, its putative wild ancestor. Young plants of two accessions of both species were watered for 25 days with an irrigation solution containing NaCl at concentrations of 0 (control), 50, 100, 200, and 300 mM. Plant growth, photosynthetic activity, concentrations of photosynthetic pigments, K⁺, Na⁺, and Cl⁻ ions, proline, total soluble sugars, malondialdehyde, total phenolics, and total flavonoids, as well as superoxide dismutase, catalase, and glutathione reductase specific activities, were quantified. Salt stress-induced reduction of growth was greater in S. melongena than in S. insanum. The photosynthetic activity decreased in both species, except for substomatal CO₂ concentration (Ci) in S. insanum, although the photosynthetic pigments were not degraded in the presence of NaCl. The levels of Na⁺ and Cl⁻ increased in roots and leaves with increasing NaCl doses, but leaf K⁺ concentrations were maintained, indicating a relative stress tolerance in the two accessions, which also did not seem to suffer a remarkable degree of salt-induced oxidative stress. Our results suggest that the higher salt tolerance of S. insanum mostly lies in its ability to accumulate higher concentrations of proline and, to a lesser extent, Na⁺ and Cl⁻. The results obtained indicate that S. insanum is a good candidate for improving salt tolerance in eggplant through breeding and introgression programmes. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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20 pages, 1825 KiB

Open AccessArticle

Main Root Adaptations in Pepper Germplasm (Capsicum spp.) to Phosphorus Low-Input Conditions

by Leandro Pereira-Dias, Daniel Gil-Villar, Vincente Castell-Zeising, Ana Quiñones, Ángeles Calatayud, Adrián Rodríguez-Burruezo and Ana Fita

Agronomy 2020, 10(5), 637; https://doi.org/10.3390/agronomy10050637 - 1 May 2020

Cited by 9 | Viewed by 4969

Abstract

Agriculture will face many challenges regarding food security and sustainability. Improving phosphorus use efficiency is of paramount importance to face the needs of a growing population while decreasing the toll on the environment. Pepper (Capsicum spp.) is widely cultivated around the world; [...] Read more.

Agriculture will face many challenges regarding food security and sustainability. Improving phosphorus use efficiency is of paramount importance to face the needs of a growing population while decreasing the toll on the environment. Pepper (Capsicum spp.) is widely cultivated around the world; hence, any breakthrough in this field would have a major impact in agricultural systems. Herein, the response to phosphorus low-input conditions is reported for 25 pepper accessions regarding phosphorus use efficiency, biomass and root traits. Results suggest a differential response from different plant organs to phosphorus starvation. Roots presented the lowest phosphorus levels, possibly due to mobilizations towards above-ground organs. Accessions showed a wide range of variability regarding efficiency parameters, offering the possibility of selecting materials for different inputs. Accessions bol_144 and fra_DLL showed an interesting phosphorus efficiency ratio under low-input conditions, whereas mex_scm and sp_piq showed high phosphorus uptake efficiency and mex_pas and sp_bola the highest values for phosphorus use efficiency. Phosphorus low-input conditions favored root instead of aerial growth, enabling increases of root total length, proportion of root length dedicated to fine roots and root specific length while decreasing roots’ average diameter. Positive correlation was found between fine roots and phosphorus efficiency parameters, reinforcing the importance of this adaptation to biomass yield under low-input conditions. This work provides relevant first insights into pepper’s response to phosphorus low-input conditions. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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16 pages, 833 KiB

Open AccessArticle

The Antioxidant Profile Evaluation of Some Tomato Landraces with Soil Salinity Tolerance Correlated with High Nutraceuticaland Functional Value

by Renata M. Sumalan, Sorin I. Ciulca, Mariana A. Poiana, Diana Moigradean, Isidora Radulov, Monica Negrea, Manuela E. Crisan, Lucian Copolovici and Radu L. Sumalan

Agronomy 2020, 10(4), 500; https://doi.org/10.3390/agronomy10040500 - 2 Apr 2020

Cited by 36 | Viewed by 4204

Abstract

Romania has a wide variety of local landraces and heirloom genotypes. Our study aims to assess the performance of twenty halotolerant tomato landraces, collected from areas with medium and high levels of soil salinity, in terms ofthe accumulation of antioxidant compounds in fruits [...] Read more.

Romania has a wide variety of local landraces and heirloom genotypes. Our study aims to assess the performance of twenty halotolerant tomato landraces, collected from areas with medium and high levels of soil salinity, in terms ofthe accumulation of antioxidant compounds in fruits and to cluster them according to their nutraceutical components. The tomatoes used in the study were harvested once they had attained full ripeness and then analyzed for lycopene (Lyc), ascorbic acid content (AsA), total phenolic content (TPC), and total antioxidant capacity (TAC). The results revealed major differences between genotypes in terms of nutraceutical values. According to principal component analysis, the tomato landraces were grouped into five clusters, characterized by different proportions of compounds with antioxidant activity. The high/moderate nutritional values of Lyc, TAC, TPC, and AsA were obtained from varieties taken from local lands with high soil salinity, over 6.5 dS m⁻¹. These findings support the idea that metabolites and secondary antioxidants are involved in the process of stress adaptation, thereby increasing salinity tolerance in tomatoes. Our results show that there are tomato landraces with a tolerance of adaptation to conditions of high soil salinity and provide information on their ability to synthesize molecules with antioxidant functions that protect plants against oxidative damage. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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12 pages, 1788 KiB

Open AccessArticle

Substrate Application of 5-Aminolevulinic Acid Enhanced Low-temperature and Weak-light Stress Tolerance in Cucumber (Cucumis sativus L.)

by Ali Anwar, Jun Wang, Xianchang Yu, Chaoxing He and Yansu Li

Agronomy 2020, 10(4), 472; https://doi.org/10.3390/agronomy10040472 - 29 Mar 2020

Cited by 26 | Viewed by 3656

Abstract

5-Aminolevulinic acid (ALA) is a type of nonprotein amino acid that promotes plant stress tolerance. However, the underlying physiological and biochemical mechanisms are not fully understood. We investigated the role of ALA in low-temperature and weak-light stress tolerance in cucumber seedlings. Seedlings grown [...] Read more.

5-Aminolevulinic acid (ALA) is a type of nonprotein amino acid that promotes plant stress tolerance. However, the underlying physiological and biochemical mechanisms are not fully understood. We investigated the role of ALA in low-temperature and weak-light stress tolerance in cucumber seedlings. Seedlings grown in different ALA treatments (0, 10, 20, or 30 mg ALA·kg⁻¹ added to substrate) were exposed to low temperature (16/8 ˚C light/dark) and weak light (180 μmol·m⁻²·s⁻¹ photosynthetically active radiation) for two weeks. Treatment with ALA significantly alleviated the inhibition of plant growth, and enhanced leaf area, and fresh and dry weight of the seedlings under low-temperature and weak-light stress. Moreover, ALA increased chlorophyll (Chl) a, Chl b, and Chl a+b contents. Net photosynthesis rate, stomatal conductance, transpiration rate, photochemical quenching, non-photochemical quenching, actual photochemical efficiency of photosystem II, and electron transport rate were significantly increased in ALA-treated seedlings. In addition, ALA increased root activity and antioxidant enzyme (superoxide dismutase, peroxidase, and catalase) activities, and reduced reactive oxygen species (hydrogen peroxide and superoxide radical) and malondialdehyde accumulation in the root and leaf of cucumber seedlings. These findings suggested that ALA incorporation in the substrate alleviated the adverse effects of low-temperature and weak-light stress, and improved Chl contents, photosynthetic capacity, and antioxidant enzyme activities, and thus enhanced cucumber seedling growth. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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18 pages, 14806 KiB

Open AccessArticle

Differential Aquaporin Response to Distinct Effects of Two Zn Concentrations after Foliar Application in Pak Choi (Brassica rapa L.) Plants

by Hamideh Fatemi, Chokri Zaghdoud, Pedro A. Nortes, Micaela Carvajal and Maria del Carmen Martínez-Ballesta

Agronomy 2020, 10(3), 450; https://doi.org/10.3390/agronomy10030450 - 24 Mar 2020

Cited by 37 | Viewed by 4600

Abstract

Zinc (Zn) is considered an essential element with beneficial effects on plant cells; however, as a heavy metal, it may induce adverse effects on plants if its concentration exceeds a threshold. In this work, the effects of short-term and prolonged application of low [...] Read more.

Zinc (Zn) is considered an essential element with beneficial effects on plant cells; however, as a heavy metal, it may induce adverse effects on plants if its concentration exceeds a threshold. In this work, the effects of short-term and prolonged application of low (25 µM) and high (500 µM) Zn concentrations on pak choi (Brassica rapa L.) plants were evaluated. For this, two experiments were conducted. In the first, the effects of short-term (15 h) and partial foliar application were evaluated, and in the second a long-term (15 day) foliar application was applied. The results indicate that at short-term, Zn may induce a rapid hydraulic signal from the sprayed leaves to the roots, leading to changes in root hydraulic conductance but without effects on the whole-leaf gas exchange parameters. Root accumulation of Zn may prevent leaf damage. The role of different root and leaf aquaporin isoforms in the mediation of this signal is discussed, since significant variations in PIP1 and PIP2 gene expression were observed. In the second experiment, low Zn concentration had a beneficial effect on plant growth and specific aquaporin isoforms were differentially regulated at the transcriptional level in the roots. By contrast, the high Zn concentration had a detrimental effect on growth, with reductions in the root hydraulic conductance, leaf photosynthesis rate and Ca²⁺ uptake in the roots. The abundance of the PIP1 isoforms was significantly increased during this response. Therefore, a 25 µM Zn dose resulted in a positive effect in pak choi growth through an increased root hydraulic conductance. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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15 pages, 1696 KiB

Open AccessEditor’s ChoiceArticle

New Eco-Friendly Polymeric-Coated Urea Fertilizers Enhanced Crop Yield in Wheat

by Ricardo Gil-Ortiz, Miguel Ángel Naranjo, Antonio Ruiz-Navarro, Marcos Caballero-Molada, Sergio Atares, Carlos García and Oscar Vicente

Agronomy 2020, 10(3), 438; https://doi.org/10.3390/agronomy10030438 - 23 Mar 2020

Cited by 54 | Viewed by 7852

Abstract

Presently, there is a growing interest in developing new controlled-release fertilizers based on ecological raw materials. The present study aims to compare the efficacy of two new ureic-based controlled-release fertilizers formulated with water-soluble polymeric coatings enriched with humic acids or seaweed extracts. To [...] Read more.

Presently, there is a growing interest in developing new controlled-release fertilizers based on ecological raw materials. The present study aims to compare the efficacy of two new ureic-based controlled-release fertilizers formulated with water-soluble polymeric coatings enriched with humic acids or seaweed extracts. To this end, an experimental approach was designed under controlled greenhouse conditions by carrying out its subsequent field scaling. Different physiological parameters and crop yield were measured by comparing the new fertilizers with another non polymeric-coated fertilizer, ammonium nitrate, and an untreated ‘Control’. As a result, on the microscale the fertilizer enriched with humic acids favored a better global response in the photosynthetic parameters and nutritional status of wheat plants. A significant 1.2-fold increase in grain weight yield and grain number was obtained with the humic acid polymeric fertilizer versus that enriched with seaweed extracts; and also, in average, higher in respect to the uncoated one. At the field level, similar results were confirmed by lowering N doses by 20% when applying the humic acid polymeric-coated produce compared to ammonium nitrate. Our results showed that the new humic acid polymeric fertilizer facilitated crop management and reduced the environmental impact generated by N losses, which are usually produced by traditional fertilizers. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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23 pages, 4221 KiB

Open AccessArticle

Assessing the Potential of Extra-Early Maturing Landraces for Improving Tolerance to Drought, Heat, and Both Combined Stresses in Maize

by Charles Nelimor, Baffour Badu-Apraku, Antonia Yarney Tetteh, Ana Luísa Garcia-Oliveira and Assanvo Simon-Pierre N’guetta

Agronomy 2020, 10(3), 318; https://doi.org/10.3390/agronomy10030318 - 25 Feb 2020

Cited by 32 | Viewed by 4148

Abstract

Maize landrace accessions constitute an invaluable gene pool of unexplored alleles that can be harnessed to mitigate the challenges of the narrowing genetic base, declined genetic gains, and reduced resilience to abiotic stress in modern varieties developed from repeated recycling of few superior [...] Read more.

Maize landrace accessions constitute an invaluable gene pool of unexplored alleles that can be harnessed to mitigate the challenges of the narrowing genetic base, declined genetic gains, and reduced resilience to abiotic stress in modern varieties developed from repeated recycling of few superior breeding lines. The objective of this study was to identify extra-early maize landraces that express tolerance to drought and/or heat stress and maintain high grain yield (GY) with other desirable agronomic/morpho-physiological traits. Field experiments were carried out over two years on 66 extra-early maturing maize landraces and six drought and/or heat-tolerant populations under drought stress (DS), heat stress (HS), combined both stresses (DSHS), and non-stress (NS) conditions as a control. Wide variations were observed across the accessions for measured traits under each stress, demonstrating the existence of substantial natural variation for tolerance to the abiotic stresses in the maize accessions. Performance under DS was predictive of yield potential under DSHS, but tolerance to HS was independent of tolerance to DS and DSHS. The accessions displayed greater tolerance to HS (23% yield loss) relative to DS (49% yield loss) and DSHS (yield loss = 58%). Accessions TZm-1162, TZm-1167, TZm-1472, and TZm-1508 showed particularly good adaptation to the three stresses. These landrace accessions should be further explored to identify the genes underlying their high tolerance and they could be exploited in maize breeding as a resource for broadening the genetic base and increasing the abiotic stress resilience of elite maize varieties. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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15 pages, 3906 KiB

Open AccessArticle

Transcriptomic Analysis of Female Panicles Reveals Gene Expression Responses to Drought Stress in Maize (Zea mays L.)

by Shuangjie Jia, Hongwei Li, Yanping Jiang, Yulou Tang, Guoqiang Zhao, Yinglei Zhang, Shenjiao Yang, Husen Qiu, Yongchao Wang, Jiameng Guo, Qinghua Yang and Ruixin Shao

Agronomy 2020, 10(2), 313; https://doi.org/10.3390/agronomy10020313 - 24 Feb 2020

Cited by 11 | Viewed by 4672

Abstract

Female panicles (FPs) play an important role in the formation of yields in maize. From 40 days after sowing to the tasseling stage for summer maize, FPs are developing and sensitive to drought. However, it remains unclear how FPs respond to drought stress [...] Read more.

Female panicles (FPs) play an important role in the formation of yields in maize. From 40 days after sowing to the tasseling stage for summer maize, FPs are developing and sensitive to drought. However, it remains unclear how FPs respond to drought stress during FP development. In this study, FP differentiation was observed at 20 and 30 days after drought (DAD) and agronomic trait changes of maize ears were determined across three treatments, including well-watered (CK), light drought (LD), and moderate drought (MD) treatments at 20, 25, and 30 DAD. RNA-sequencing was then used to identify differentially expressed genes (DEGs) in FPs at 30 DAD. Spikelets and florets were suppressed in LD and MD treatments, suggesting that drought slows FP development and thus decreases yields. Transcriptome analysis indicated that 40, 876, and 887 DEGs were detected in LD/CK, MD/CK, and MD/LD comparisons. KEGG pathway analysis showed that ‘biosynthesis of other secondary metabolites’ and ‘carbohydrate metabolism’ were involved in the LD response, whereas ‘starch and sucrose metabolism’ and ‘plant hormone signal transduction’ played important roles in the MD response. In addition, a series of molecular cues related to development and growth were screened for their drought stress responses. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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15 pages, 2934 KiB

Open AccessEditor’s ChoiceArticle

Comparison of Biochemical, Anatomical, Morphological, and Physiological Responses to Salinity Stress in Wheat and Barley Genotypes Deferring in Salinity Tolerance

by Muhammad Zeeshan, Meiqin Lu, Shafaque Sehar, Paul Holford and Feibo Wu

Agronomy 2020, 10(1), 127; https://doi.org/10.3390/agronomy10010127 - 15 Jan 2020

Cited by 186 | Viewed by 13716

Abstract

A greenhouse hydroponic experiment was performed using salt-tolerant (cv. Suntop) and -sensitive (Sunmate) wheat cultivars and a salt-tolerant barley cv. CM72 to evaluate how cultivar and species differ in response to salinity stress. Results showed that wheat cv. Suntop performed high tolerance to [...] Read more.

A greenhouse hydroponic experiment was performed using salt-tolerant (cv. Suntop) and -sensitive (Sunmate) wheat cultivars and a salt-tolerant barley cv. CM72 to evaluate how cultivar and species differ in response to salinity stress. Results showed that wheat cv. Suntop performed high tolerance to salinity, being similar tolerance to salinity with CM72, compared with cv. Sunmate. Similar to CM72, Suntop recorded less salinity induced increase in malondialdehyde (MDA) accumulation and less reduction in plant height, net photosynthetic rate (Pn), chlorophyll content, and biomass than in sensitive wheat cv. Sunmate. Significant time-course and cultivar-dependent changes were observed in the activities of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) in roots and leaves after salinity treatment. Higher activities were found in CM72 and Suntop compared to Sunmate. Furthermore, a clear modification was observed in leaf and root ultrastructure after NaCl treatment with more obvious changes in the sensitive wheat cv. Sunmate, rather than in CM72 and Suntop. Although differences were observed between CM72 and Suntop in the growth and biochemical traits assessed and modified by salt stress, the differences were negligible in comparison with the general response to the salt stress of sensitive wheat cv. Sunmate. In addition, salinity stress induced an increase in the Na⁺ and Na⁺/K⁺ ratio but a reduction in K⁺ concentrations, most prominently in Sunmate and followed by Suntop and CM72. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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17 pages, 6115 KiB

Open AccessArticle

Transcriptomic Profiling of Pomegranate Provides Insights into Salt Tolerance

by Cuiyu Liu, Yujie Zhao, Xueqing Zhao, Jinping Wang, Mengmeng Gu and Zhaohe Yuan

Agronomy 2020, 10(1), 44; https://doi.org/10.3390/agronomy10010044 - 27 Dec 2019

Cited by 15 | Viewed by 3581

Abstract

Pomegranate (Punica granatum L.) is widely grown in arid and semi-arid soils, with constant soil salinization. To elucidate its molecular responses to salt stress on mRNA levels, we constructed 18 cDNA libraries of pomegranate roots and leaves from 0 (controls), 3, and [...] Read more.

Pomegranate (Punica granatum L.) is widely grown in arid and semi-arid soils, with constant soil salinization. To elucidate its molecular responses to salt stress on mRNA levels, we constructed 18 cDNA libraries of pomegranate roots and leaves from 0 (controls), 3, and 6 days after 200 mM NaCl treatment. In total, we obtained 34,047 genes by mapping to genome, and then identified 2255 DEGs (differentially expressed genes), including 1080 up-regulated and 1175 down-regulated genes. We found that the expression pattern of most DEGs were tissue-specific and time-specific. Among root DEGs, genes associated with cell wall organization and transmembrane transport were suppressed, and most of metabolism-related genes were over-represented. In leaves, 41.29% of DEGs were first suppressed and then recovered, including ions/metal ions binding-related genes. Also, ion transport and oxidation-reduction process were restricted. We found many DEGs involved in ABA, Ca²⁺-related and MAPK signal transduction pathways, such as ABA-receptors, Ca²⁺-sensors, MAPK cascades, TFs, and downstream functional genes coding for HSPs, LEAs, AQPs and PODs. Fifteen genes were selected to confirm the RNA-seq data using qRT-PCR. Our study not only illuminated pomegranate molecular responses to salinity, but also provided references for selecting salt-tolerant genes in pomegranate breeding processes. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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15 pages, 2056 KiB

Open AccessArticle

Treatment of Sweet Pepper with Stress Tolerance-Inducing Compounds Alleviates Salinity Stress Oxidative Damage by Mediating the Physio-Biochemical Activities and Antioxidant Systems

by Khaled A. Abdelaal, Lamiaa M. EL-Maghraby, Hosam Elansary, Yaser M. Hafez, Eid I. Ibrahim, Mostafa El-Banna, Mohamed El-Esawi and Amr Elkelish

Agronomy 2020, 10(1), 26; https://doi.org/10.3390/agronomy10010026 - 23 Dec 2019

Cited by 169 | Viewed by 10620

Abstract

Salinity stress occurs due to the accumulation of high levels of salts in soil, which ultimately leads to the impairment of plant growth and crop loss. Stress tolerance-inducing compounds have a remarkable ability to improve growth and minimize the effects of salinity stress [...] Read more.

Salinity stress occurs due to the accumulation of high levels of salts in soil, which ultimately leads to the impairment of plant growth and crop loss. Stress tolerance-inducing compounds have a remarkable ability to improve growth and minimize the effects of salinity stress without negatively affecting the environment by controlling the physiological and molecular activities in plants. Two pot experiments were carried out in 2017 and 2018 to study the influence of salicylic acid (1 mM), yeast extract (6 g L⁻¹), and proline (10 mM) on the physiological and biochemical parameters of sweet pepper plants under saline conditions (2000 and 4000 ppm). The results showed that salt stress led to decreasing the chlorophyll content, relative water content, and fruit yields, whereas electrolyte leakage, malondialdehyde (MDA), proline concentration, reactive oxygen species (ROS), and the activities of antioxidant enzymes increased in salt-stressed plants. The application of salicylic acid (1 mM), yeast extract (6 g L⁻¹), and proline (10 mM) markedly improved the physiological characteristics and fruit yields of salt-stressed plants compared with untreated stressed plants. A significant reduction in electrolyte leakage, MDA, and ROS was also recorded for all treatments. In conclusion, our results reveal the important role of proline, SA, and yeast extracts in enhancing sweet pepper growth and tolerance to salinity stress via modulation of the physiological parameters and antioxidants machinery. Interestingly, proline proved to be the best treatment. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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17 pages, 624 KiB

Open AccessArticle

Screening of Provitamin-A Maize Inbred Lines for Drought Tolerance: Beta-Carotene Content and Secondary Traits

by Aleck Kondwakwenda, Julia Sibiya, Rebecca Zengeni, Cousin Musvosvi and Samson Tesfay

Agronomy 2019, 9(11), 692; https://doi.org/10.3390/agronomy9110692 - 29 Oct 2019

Cited by 7 | Viewed by 3665

Abstract

Provitamin A maize (Zea mays L.) biofortification is an ideal complementary means of combating vitamin A deficiency (VAD) in sub-Saharan Africa where maize consumption is high coupled by high VAD incidences. However, drought remains a major abiotic constraint to maize productivity in [...] Read more.

Provitamin A maize (Zea mays L.) biofortification is an ideal complementary means of combating vitamin A deficiency (VAD) in sub-Saharan Africa where maize consumption is high coupled by high VAD incidences. However, drought remains a major abiotic constraint to maize productivity in this region. Comprehensive drought screening of initial breeding materials before advancing them is important to achieve genetic gain. In this study, 46 provitamin-A inbred lines were screened for drought tolerance in the greenhouse and field under drought and optimum conditions using β-carotene content (BCC), grain yield (GY), and selected morphophysiological and biochemical traits. The results revealed that BCC, morphophysiological and biochemical traits were effective in discriminating among genotypes. Number of ears per plant (EPP), stomatal conductance (Gs), delayed leaf senescence (SEN), leaf rolling (RL), chlorophyll content (CC) and free proline content (PC) proved to be ideal traits to use when indirectly selecting for GY by virtue of having relative efficiency of indirect selection values that are greater than unity and considerable genetic variances under either or both conditions. The findings of this study form the basis of initial germplasm selection when improving provitamin A maize for drought tolerance. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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16 pages, 2146 KiB

Open AccessArticle

Sodium Azide Priming Enhances Waterlogging Stress Tolerance in Okra (Abelmoschus esculentus L.)

by Emuejevoke D. Vwioko, Mohamed A. El-Esawi, Marcus E. Imoni, Abdullah A. Al-Ghamdi, Hayssam M. Ali, Mostafa M. El-Sheekh, Emad A. Abdeldaym and Monerah A. Al-Dosary

Agronomy 2019, 9(11), 679; https://doi.org/10.3390/agronomy9110679 - 25 Oct 2019

Cited by 19 | Viewed by 5156

Abstract

Waterlogging stress adversely affects crop growth and yield worldwide. Effect of sodium azide priming on waterlogging stress tolerance of okra plants was investigated. The study was conducted as a field experiment using two weeks old plants grown from 0%, 0.02%, and 0.05% sodium [...] Read more.

Waterlogging stress adversely affects crop growth and yield worldwide. Effect of sodium azide priming on waterlogging stress tolerance of okra plants was investigated. The study was conducted as a field experiment using two weeks old plants grown from 0%, 0.02%, and 0.05% sodium azide (NaN₃)-treated seeds. The waterlogging conditions applied were categorized into control, one week, and two weeks. Different growth and reproductive parameters were investigated. Activity and expression of antioxidant enzymes, root anatomy, and soil chemical analysis were also studied. Results showed that sodium azide priming inhibited germination. The germination percentages recorded were 92.50, 85.00, and 65.00 for 0%, 0.02%, and 0.05% NaN₃-treated seeds, respectively, nine days after planting. Waterlogging conditions depressed plant height ten weeks after planting. Under waterlogging conditions, NaN₃ promoted plant height and number of leaves formed. NaN₃ also supported the survival of plants and formation of adventitious roots under waterlogging conditions. Waterlogging conditions negatively affected the redox potential, organic C, N, and P concentrations in the soil but enhanced Soil pH, Fe, Mn, Zn, and SO₄. Under waterlogging conditions, NaN₃ increased the average number of flower buds, flowers, and fruits produced in comparison to control. Moreover, NaN₃ highly stimulated the development of aerenchyma which in turn enhanced the survival of okra plants under waterlogging conditions. NaN₃ priming also enhanced the activities and gene expression level of antioxidant enzymes (ascorbate peroxidase, APX; catalase, CAT) under waterlogging conditions. In conclusion, this study demonstrated that NaN₃ priming could improve waterlogging stress tolerance in okra. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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20 pages, 2747 KiB

Open AccessArticle

Effect of Heat Stress on Growth and Physiological Traits of Alfalfa (Medicago sativa L.) and a Comprehensive Evaluation for Heat Tolerance

by Misganaw Wassie, Weihong Zhang, Qiang Zhang, Kang Ji and Liang Chen

Agronomy 2019, 9(10), 597; https://doi.org/10.3390/agronomy9100597 - 28 Sep 2019

Cited by 77 | Viewed by 8531

Abstract

Alfalfa (Medicago sativa L.) is a valuable forage legume, but its production is largely affected by high temperature. In this study, we investigated the effect of heat stress on 15 alfalfa cultivars to identify heat-tolerant and -sensitive cultivars. Seedlings were exposed to [...] Read more.

Alfalfa (Medicago sativa L.) is a valuable forage legume, but its production is largely affected by high temperature. In this study, we investigated the effect of heat stress on 15 alfalfa cultivars to identify heat-tolerant and -sensitive cultivars. Seedlings were exposed to 38/35 °C day/night temperature for 7 days and various parameters were measured. Heat stress significantly reduced the biomass, relative water content (RWC), chlorophyll content, and increased the electrolyte leakage (EL) and malondialdehyde (MDA) content of heat-sensitive alfalfa cultivars. However, heat-tolerant cultivars showed higher soluble sugar (SS) and soluble protein (SP) content. The heat tolerance of each cultivar was comprehensively evaluated based on membership function value. Cultivars with higher mean membership function value of 0.86 (Bara310SC) and 0.80 (Magna995) were heat tolerant, and Gibraltar and WL712 with lower membership function value (0.24) were heat sensitive. The heat tolerance of the above four cultivars were further evaluated by chlorophyll a fluorescence analysis. Heat stress significantly affected the photosynthetic activity of heat-sensitive cultivars. The overall results indicate that Bara310SC and WL712 are heat-tolerant and heat-sensitive cultivars, respectively. This study provides basic information for understanding the effect of heat stress on growth and productivity of alfalfa. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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17 pages, 2801 KiB

Open AccessArticle

Transcriptomic Analysis Reveals the Temporal and Spatial Changes in Physiological Process and Gene Expression in Common Buckwheat (Fagopyrum esculentum Moench) Grown under Drought Stress

by Zehao Hou, Junliang Yin, Yifei Lu, Jinghan Song, Shuping Wang, Shudong Wei, Zhixiong Liu, Yingxin Zhang and Zhengwu Fang

Agronomy 2019, 9(10), 569; https://doi.org/10.3390/agronomy9100569 - 20 Sep 2019

Cited by 34 | Viewed by 4133

Abstract

Common buckwheat is a traditional alternative crop that originated from the northwest of China and is widely cultivated worldwide. However, common buckwheat is highly sensitive to drought stress, especially at the seedling stage, and the molecular mechanisms underlying the response to drought stress [...] Read more.

Common buckwheat is a traditional alternative crop that originated from the northwest of China and is widely cultivated worldwide. However, common buckwheat is highly sensitive to drought stress, especially at the seedling stage, and the molecular mechanisms underlying the response to drought stress still remain elusive. In this study, we analyzed the stress phenotypes of buckwheat seedlings under drought condition. The results showed the wrinkled cotyledon due to the decrease of relative water content (RWC) in response to the increased activity of antioxidant enzymes. Transcriptomic analysis was further performed to analyze the regulation patterns of stress-responding genes in common buckwheat cotyledons and roots under drought stress conditions. Characterizations of the differentially expressed genes (DEGs) revealed differential regulation of genes involved in the photosynthesis and oxidoreductase activity in cotyledon, and that they were highly related to the post-transcriptional modification and metabolic process in root. There were 180 drought-inducible transcription factors identified in both cotyledons and roots of the common buckwheat. Our analysis not only identified the drought responsive DEGs and indicated their possible roles in stress adaption, but also primarily studied the molecular mechanisms regulating the drought stress response in common buckwheat. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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18 pages, 4252 KiB

Open AccessArticle

Changes in Root Anatomy of Peanut (Arachis hypogaea L.) under Different Durations of Early Season Drought

by Nuengsap Thangthong, Sanun Jogloy, Tasanai Punjansing, Craig K. Kvien, Thawan Kesmala and Nimitr Vorasoot

Agronomy 2019, 9(5), 215; https://doi.org/10.3390/agronomy9050215 - 27 Apr 2019

Cited by 19 | Viewed by 7298

Abstract

Changes in the anatomical structure of peanut roots due to early season drought will likely affect the water acquiring capacity of the root system. Yet, as important as these changes are likely to be in conferring drought resistance, they have not been thoroughly [...] Read more.

Changes in the anatomical structure of peanut roots due to early season drought will likely affect the water acquiring capacity of the root system. Yet, as important as these changes are likely to be in conferring drought resistance, they have not been thoroughly investigated. The objective of this study was to investigate the effects of different durations of drought on the root anatomy of peanut in response to early season drought. Plants of peanut genotype ICGV 98305 were grown in rhizoboxes with an internal dimension of 50 cm in width, 10 cm in thickness and 120 cm in height. Fourteen days after emergence, water was withheld for periods of 0, 7, 14 or 21 days. After these drought periods, the first and second order roots from 0–20 cm below soil surface were sampled for anatomical observation. The mean xylem vessel diameter of first- order lateral roots was higher than that of second- order lateral roots. Under early season drought stress root anatomy changes were more pronounced in the longer drought period treatments. Twenty-one days after imposing water stress, the drought treatment and irrigated treatment were clearly different in diameter, number and area of xylem vessels of first- and second-order lateral roots. Plants under drought conditions had a smaller diameter and area of xylem vessels than did the plants under irrigated control. The ability of plants to change root anatomy likely improves water uptake and transport and this may be an important mechanism for drought tolerance. The information will be useful for the selection of drought durations for evaluation of root anatomy related to drought resistance and the selection of key traits for drought resistance. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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11 pages, 2426 KiB

Open AccessArticle

A LEA Gene from a Vietnamese Maize Landrace Can Enhance the Drought Tolerance of Transgenic Maize and Tobacco

by Bui Manh Minh, Nguyen Thuy Linh, Ha Hong Hanh, Le Thi Thu Hien, Nguyen Xuan Thang, Nong Van Hai and Huynh Thi Thu Hue

Agronomy 2019, 9(2), 62; https://doi.org/10.3390/agronomy9020062 - 31 Jan 2019

Cited by 12 | Viewed by 5410

Abstract

Maize (Zea mays) is a major cereal crop worldwide, and there is increasing demand for maize cultivars with enhanced tolerance to desiccation. Late embryogenesis abundant (LEA) proteins group 5C is involved in plants’ responses to various osmotic stresses such as drought [...] Read more.

Maize (Zea mays) is a major cereal crop worldwide, and there is increasing demand for maize cultivars with enhanced tolerance to desiccation. Late embryogenesis abundant (LEA) proteins group 5C is involved in plants’ responses to various osmotic stresses such as drought and salt. A putative group 5C LEA gene from Z. mays cv. Tevang 1 was isolated, named ZmLEA14tv, and cloned into a T-DNA for expression in plants. The deduced amino acid of ZmLEA14tv showed a conserved Pfam LEA_2 domain and a high proportion of hydrophobic residues, characteristic of group 5C LEA proteins. Transgenic tobacco and maize plants expressing ZmLEA14tv were generated. During drought simulation conditions, the ZmLEA14tv-expressing plants of tobacco showed improved recovery ability, while those of maize enhanced the seed germination in comparison with the non-transgenic control plants. In addition, the survival rate of ZmLEA14tv transgenic maize seedlings was twice as high as the control. These results indicated that ZmLEA14tv might be involved in the drought tolerance of plants and could be a candidate gene for developing enhanced drought-tolerant crops. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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20 pages, 3493 KiB

Open AccessArticle

Silicon and the Association with an Arbuscular-Mycorrhizal Fungus (Rhizophagus clarus) Mitigate the Adverse Effects of Drought Stress on Strawberry

by Narges Moradtalab, Roghieh Hajiboland, Nasser Aliasgharzad, Tobias E. Hartmann and Günter Neumann

Agronomy 2019, 9(1), 41; https://doi.org/10.3390/agronomy9010041 - 21 Jan 2019

Cited by 88 | Viewed by 8813

Abstract

Silicon (Si) is a beneficial element that alleviates the effects of stress factors including drought (D). Strawberry is a Si-accumulator species sensitive to D; however, the function of Si in this species is obscure. This study was conducted to examine the effect of [...] Read more.

Silicon (Si) is a beneficial element that alleviates the effects of stress factors including drought (D). Strawberry is a Si-accumulator species sensitive to D; however, the function of Si in this species is obscure. This study was conducted to examine the effect of Si and inoculation with an arbuscular mycorrhizal fungus (AMF) on physiological and biochemical responses of strawberry plants under D. Plants were grown for six weeks in perlite and irrigated with a nutrient solution. The effect of Si (3 mmol L⁻¹), AMF (Rhizophagus clarus) and D (mild and severe D) was studied on growth, water relations, mycorrhization, antioxidative defense, osmolytes concentration, and micronutrients status. Si and AMF significantly enhanced plant biomass production by increasing photosynthesis rate, water content and use efficiency, antioxidant enzyme defense, and the nutritional status of particularly Zn. In contrast to the roots, osmotic adjustment did not contribute to the increase of leaf water content suggesting a different strategy of both Si and AMF for improving water status in the leaves and roots. Our results demonstrated a synergistic effect of AMF and Si on improving the growth of strawberry not only under D but also under control conditions. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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Review

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22 pages, 1321 KiB

Open AccessReview

What Has Been Thought and Taught on the Lunar Influence on Plants in Agriculture? Perspective from Physics and Biology

by Olga Mayoral, Jordi Solbes, José Cantó and Tatiana Pina

Agronomy 2020, 10(7), 955; https://doi.org/10.3390/agronomy10070955 - 2 Jul 2020

Cited by 12 | Viewed by 35820

Abstract

This paper reviews the beliefs which drive some agricultural sectors to consider the lunar influence as either a stress or a beneficial factor when it comes to organizing their tasks. To address the link between lunar phases and agriculture from a scientific perspective, [...] Read more.

This paper reviews the beliefs which drive some agricultural sectors to consider the lunar influence as either a stress or a beneficial factor when it comes to organizing their tasks. To address the link between lunar phases and agriculture from a scientific perspective, we conducted a review of textbooks and monographs used to teach agronomy, botany, horticulture and plant physiology; we also consider the physics that address the effects of the Moon on our planet. Finally, we review the scientific literature on plant development, specifically searching for any direct or indirect reference to the influence of the Moon on plant physiology. We found that there is no reliable, science-based evidence for any relationship between lunar phases and plant physiology in any plant–science related textbooks or peer-reviewed journal articles justifying agricultural practices conditioned by the Moon. Nor does evidence from the field of physics support a causal relationship between lunar forces and plant responses. Therefore, popular agricultural practices that are tied to lunar phases have no scientific backing. We strongly encourage teachers involved in plant sciences education to objectively address pseudo-scientific ideas and promote critical thinking. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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32 pages, 1378 KiB

Open AccessReview

Adaptation of Plants to Salt Stress: Characterization of Na⁺ and K⁺ Transporters and Role of CBL Gene Family in Regulating Salt Stress Response

by Toi Ketehouli, Kue Foka Idrice Carther, Muhammad Noman, Fa-Wei Wang, Xiao-Wei Li and Hai-Yan Li

Agronomy 2019, 9(11), 687; https://doi.org/10.3390/agronomy9110687 - 28 Oct 2019

Cited by 77 | Viewed by 10794

Abstract

Salinity is one of the most serious factors limiting the productivity of agricultural crops, with adverse effects on germination, plant vigor, and crop yield. This salinity may be natural or induced by agricultural activities such as irrigation or the use of certain types [...] Read more.

Salinity is one of the most serious factors limiting the productivity of agricultural crops, with adverse effects on germination, plant vigor, and crop yield. This salinity may be natural or induced by agricultural activities such as irrigation or the use of certain types of fertilizer. The most detrimental effect of salinity stress is the accumulation of Na⁺ and Cl⁻ ions in tissues of plants exposed to soils with high NaCl concentrations. The entry of both Na⁺ and Cl⁻ into the cells causes severe ion imbalance, and excess uptake might cause significant physiological disorder(s). High Na⁺ concentration inhibits the uptake of K⁺, which is an element for plant growth and development that results in lower productivity and may even lead to death. The genetic analyses revealed K⁺ and Na⁺ transport systems such as SOS1, which belong to the CBL gene family and play a key role in the transport of Na⁺ from the roots to the aerial parts in the Arabidopsis plant. In this review, we mainly discuss the roles of alkaline cations K⁺ and Na⁺, Ion homeostasis-transport determinants, and their regulation. Moreover, we tried to give a synthetic overview of soil salinity, its effects on plants, and tolerance mechanisms to withstand stress. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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19 pages, 1191 KiB

Open AccessReview

Physiological Responses of Selected Vegetable Crop Species to Water Stress

by Eszter Nemeskéri and Lajos Helyes

Agronomy 2019, 9(8), 447; https://doi.org/10.3390/agronomy9080447 - 13 Aug 2019

Cited by 101 | Viewed by 12804

Abstract

The frequency of drought periods influences the yield potential of crops under field conditions. The change in morphology and anatomy of plants has been tested during drought stress under controlled conditions but the change in physiological processes has not been adequately studied in [...] Read more.

The frequency of drought periods influences the yield potential of crops under field conditions. The change in morphology and anatomy of plants has been tested during drought stress under controlled conditions but the change in physiological processes has not been adequately studied in separate studies but needs to be reviewed collectively. This review presents the responses of green peas, snap beans, tomatoes and sweet corn to water stress based on their stomatal behaviour, canopy temperature, chlorophyll fluorescence and the chlorophyll content of leaves. These stress markers can be used for screening the drought tolerance of genotypes, the irrigation schedules or prediction of yield. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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13 pages, 1234 KiB

Open AccessReview

Phytohormone-Mediated Stomatal Response, Escape and Quiescence Strategies in Plants under Flooding Stress

by Kazi Khayrul Bashar, Md. Zablul Tareq, Md. Ruhul Amin, Ummay Honi, Md. Tahjib-Ul-Arif, Md. Abu Sadat and Quazi Md. Mosaddeque Hossen

Agronomy 2019, 9(2), 43; https://doi.org/10.3390/agronomy9020043 - 22 Jan 2019

Cited by 56 | Viewed by 9838

Abstract

Generally, flooding causes waterlogging or submergence stress which is considered as one of the most important abiotic factors that severely hinders plant growth and development. Plants might not complete their life cycle even in short duration of flooding. As biologically intelligent organisms, plants [...] Read more.

Generally, flooding causes waterlogging or submergence stress which is considered as one of the most important abiotic factors that severely hinders plant growth and development. Plants might not complete their life cycle even in short duration of flooding. As biologically intelligent organisms, plants always try to resist or survive under such adverse circumstances by adapting a wide array of mechanisms including hormonal homeostasis. Under this mechanism, plants try to adapt through diverse morphological, physiological and molecular changes, including the closing of stomata, elongating of petioles, hollow stems or internodes, or maintaining minimum physiological activity to store energy to combat post-flooding stress and to continue normal growth and development. Mainly, ethylene, gibberellins (GA) and abscisic acid (ABA) are directly and/or indirectly involved in hormonal homeostasis mechanisms. Responses of specific genes or transcription factors or reactive oxygen species (ROS) maintain the equilibrium between stomatal opening and closing, which is one of the fastest responses in plants when encountering flooding stress conditions. In this review paper, the sequential steps of some of the hormone-dependent survival mechanisms of plants under flooding stress conditions have been critically discussed. Full article

(This article belongs to the Special Issue Physiological and Molecular Characterization of Crop Resistance to Abiotic Stresses)

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