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Abiotic Stresses, Biostimulants and Plant Activity

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A special issue of Agriculture (ISSN 2077-0472). This special issue belongs to the section "Crop Production".

Deadline for manuscript submissions: closed (31 October 2022) | Viewed by 51087

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Special Issue Editors

Dr. Daniele Del Buono

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Guest Editor

Associate Professor, Department of Agricultural, Food and Environmental Sciences, University of Perugia, 06121 Perugia, Italy
Interests: biostimulants; plant biochemistry; plant nutrition; heavy metals; oxidative stress; nanoparticles; herbicides; abiotic stress in plants; phytoremediation
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Primo Proietti

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Guest Editor

Department of Agricultural, Food and Environmental Sciences, University of Perugia, 06121 Perugia, Italy
Interests: soil fertility; agriculture environment; plant physiology; sustainable agriculture; biofortification; abiotic stresses; carbon sequestration; fruit quality
Special Issues, Collections and Topics in MDPI journals

Dr. Luca Regni

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Guest Editor

Department of Agricultural, Food and Environmental Sciences, University of Perugia, Borgo XX Giugno, 06121 Perugia, Italy
Interests: in vitro culture; micropropagation; tree crops; agricultural byproduct valorization; sustainable agriculture; C sequestration; salt stress
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Numerous biotic and abiotic stresses can significantly decrease crop growth and yields. In the context of climate change, stresses will be more frequent in the coming years and will have an even more severe impact on agricultural systems. As a result, crop production could be drastically reduced, with the consequences aggravated by the fact that the world’s growing population will require more food production. Furthermore, among abiotic stresses, the salinity of soils and water for agricultural use and the drought particularly impact crops. For these reasons, sustainable measures need to be implemented to maintain/increase crop production and the resilience of agricultural systems.

To this end, biostimulants, materials that can increase crop productivity and the quality profile of end products, are an answer that is finding increasing popularity. The primary function of biostimulants is improving nutrient use efficiency, quality traits, stress tolerance, and bioavailability of nutrients in the soil or rhizosphere.

Therefore, this Special Issue aims to publish research on the effect of biostimulants to help crops to cope with abiotic stresses, focusing on salt and drought stress. In addition, scientific contributions on the use of biostimulants to counteract other abiotic stresses, such as potentially toxic metals and extreme temperatures, are also welcome. New substances with biostimulant action and studies investigating the mechanisms of action of biostimulants and their qualitative, economic, and environmental benefits will also be considered.

Prof. Dr. Daniele Del Buono
Prof. Dr. Primo Proietti
Dr. Luca Regni
Guest Editors

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Keywords

biostimulants
salinity
drought
abiotic stress
plant growth
climate change

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Published Papers (14 papers)

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Editorial

Jump to: Research

5 pages, 188 KiB

Open AccessEditorial

Abiotic Stresses, Biostimulants and Plant Activity

by Daniele Del Buono, Luca Regni and Primo Proietti

Agriculture 2023, 13(1), 191; https://doi.org/10.3390/agriculture13010191 - 12 Jan 2023

Cited by 6 | Viewed by 2423

Abstract

Contemporary agriculture is characterized by a highly intensive nature and productivity [...] Full article

(This article belongs to the Special Issue Abiotic Stresses, Biostimulants and Plant Activity)

Research

Jump to: Editorial

20 pages, 1160 KiB

Open AccessArticle

Effects of Oak Leaf Extract, Biofertilizer, and Soil Containing Oak Leaf Powder on Tomato Growth and Biochemical Characteristics under Water Stress Conditions

by Nawroz Abdul-razzak Tahir, Kamaran Salh Rasul, Djshwar Dhahir Lateef and Florian M. W. Grundler

Agriculture 2022, 12(12), 2082; https://doi.org/10.3390/agriculture12122082 - 4 Dec 2022

Cited by 8 | Viewed by 2916

Abstract

Drought stress is one of the most significant abiotic stresses on the sustainability of global agriculture. The finding of natural resources is essential for decreasing the need for artificial fertilizers and boosting plant growth and yield under water stress conditions. This study used a factorial experimental design to investigate the effects of oak leaf extract, biofertilizer, and soil containing oak leaf powder on the growth and biochemical parameters of four tomato genotypes under water stress throughout the pre-flowering and pre-fruiting stages of plant development. The experiment had two components. The first component represented the genotypes (two sensitive and two tolerant), while the second component represented the treatment group, which included irrigated plants (SW), untreated and stressed plants (SS), treated plants with oak leaf powder and stressed (SOS), treated plants with oak leaf powder and oak leaf extract and stressed (SOES), and treated plants with oak leaf powder and biofertilizers and stressed (SOBS). When compared with irrigated or control plants, drought stress under the treatments of SS, SOS, SOES, and SOBS conditions at two stages and their combination significantly lowered shoot length (12.95%), total fruit weight per plant (33.97%), relative water content (14.05%), and total chlorophyll content (26.30%). The reduction values for shoot length (17.58%), shoot fresh weight (22.08%), and total fruit weight per plant (42.61%) were significantly larger in two sensitive genotypes compared with tolerant genotypes, which recorded decreasing percentages of 8.36, 8.88, and 25.32% for shoot length, shoot fresh weight, and total fruit weight per plant, respectively. Root fresh weight and root dry weight of genotypes treated with SS, SOS, SOES, and SOBS, on the other hand, increased in comparison with control plants. Tomato fruits from stressed plants treated with SS, SOS, SOES, and SOBS had considerably higher levels of titratable acidity, ascorbic acid, and total phenolic compounds than irrigated plants during all stress stages. Under water stress conditions, the addition of oak leaf powder to soil, oak leaf extract, and biofertilizer improved the biochemical content of leaves in all genotypes. Furthermore, leaf lipid peroxidation was lower in plants treated with SOES and SOBS, and lower in the two tolerant genotypes than in the two susceptible genotypes. In conclusion, the application of SOS, SOES, and SOBS demonstrated a slight decrease in some morpho-physiological and fruit physicochemical traits compared with SS treatment. However, the application of oak leaf powder and oak leaf extract can be described as novel agricultural practices because they are low-cost, easy to use, time-consuming, and can meet the growing demands of the agricultural sector by providing environmentally sustainable techniques for enhancing plant resistance to abiotic stress. The usage of the combination of leaf crude extract, oak leaf powder, and arbuscular mycorrhizal fungus should be investigated further under stress conditions. Full article

(This article belongs to the Special Issue Abiotic Stresses, Biostimulants and Plant Activity)

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15 pages, 3117 KiB

Open AccessArticle

Aqueous Seaweed Extract Alleviates Salinity-Induced Toxicities in Rice Plants (Oryza sativa L.) by Modulating Their Physiology and Biochemistry

by Kanagaraj Muthu-Pandian Chanthini, Sengottayan Senthil-Nathan, Ganesh-Subbaraja Pavithra, Pauldurai Malarvizhi, Ponnusamy Murugan, Arulsoosairaj Deva-Andrews, Muthusamy Janaki, Haridoss Sivanesh, Ramakrishnan Ramasubramanian, Vethamonickam Stanley-Raja, Aml Ghaith, Ahmed Abdel-Megeed and Patcharin Krutmuang

Agriculture 2022, 12(12), 2049; https://doi.org/10.3390/agriculture12122049 - 29 Nov 2022

Cited by 19 | Viewed by 2883

Abstract

Around the world, salinity a critical limiting factor in agricultural productivity. Plant growth is affected by salt stress at all stages of development. The contemporary investigation focused on Chaetomorpha antennina aqueous extracts (SWEs) to decrease the effects of salt strain on rice germination, growth, yield, and the production of key biological and biochemical characters of the rice, Oryza sativa L. (Poaceae). SWE improved the germination capacities of rice seedlings by promoting their emergence 36.27 h prior to those that had been exposed to saline stress. The creation of 79.647% longer radicles by SWE treatment on salt-stressed seeds which boosted the establishment effectiveness of seeds produced under salt stress longer radicles resulted in plants that were 64.8% taller. SWE treatment was effective in revoking the levels of protein (26.9%), phenol (35.54%), and SOD (41.3%) enzyme levels that were previously constrained by salinity stress. Additionally, SWE were also efficient in retaining 82.6% of leaf water content and enhancing the production of photosynthetic pigments affected by salt exposure earlier. The improvement in plant functionality was evident from the display of increase in tiller numbers/hill (62.36%), grain yield (58.278%), and weight (56.502%). The outcome of our research shows that SWEs protected the plants from the debarring effects of salinity by enhancing the plant functionality and yield by mechanistically enriching their physiological (germination and vegetative growth) and biochemical attributes (leaf RWC, photosynthetic pigments, protein, phenol, and SOD). Despite the increase in TSS and starch levels in rice grain exposed to salinity stress, SWE improved the grain protein content thus cumulatively enhancing rice nutrition and marketability. The current investigation reveals that the extracts of C. antennina can help alleviate rice plants from salt stress in an efficient, eco-friendly, as well as economical way. Full article

(This article belongs to the Special Issue Abiotic Stresses, Biostimulants and Plant Activity)

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10 pages, 3122 KiB

Open AccessArticle

Nitrate Increases Aluminum Toxicity and Accumulation in Root of Wheat

by Yan Ma, Caihong Bai, Xincheng Zhang and Yanfeng Ding

Agriculture 2022, 12(11), 1946; https://doi.org/10.3390/agriculture12111946 - 18 Nov 2022

Cited by 5 | Viewed by 2074

Abstract

Aluminum (Al) toxicity inhibits root growth, while nitrogen is an essential nutrient for plant growth and development. To explore the effects of nitrate (N) on Al toxicity and accumulation in root of wheat, two wheat genotypes, Shengxuan 6 hao (SX6, Al-tolerant genotype) and Zhenmai 168 (ZM168, Al-sensitive genotype), were used in a hydroponic experiment with four treatments (control without N or Al, N, Al, and Al+N, respectively). The results showed that N increased the inhibition of root elongation and aluminum accumulation in root. The Al-sensitive genotype suffered more serious Al toxicity than the Al-tolerant genotype. Histochemical observation clearly showed that Al prefers binding on the root apex 7–10 mm zones, and the Al-sensitive genotype accumulated more Al in these zones. Compared with other treatments, the Al+N treatment had significantly higher O₂⁻, superoxides dismutase (SOD), catalase (CAT), peroxidase (POD) activities, H₂O₂, Evans blue uptake, malondialdehyde (MDA), ascorbic acid (AsA), pectin, and hemicellulose 1 (HC1) contents in both genotypes. Under Al+N treatment, O₂⁻ activity, Evans blue uptake, MDA, and HC1 contents of SX6 were significantly lower than those of ZM168, but SOD, CAT, and POD activities and AsA content exhibited an opposite trend. Therefore, aluminum toxicity and accumulation in root of wheat seedlings were aggravated by nitrate. Full article

(This article belongs to the Special Issue Abiotic Stresses, Biostimulants and Plant Activity)

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23 pages, 4260 KiB

Open AccessArticle

Under Natural Field Conditions, Exogenous Application of Moringa Organ Water Extract Enhanced the Growth- and Yield-Related Traits of Barley Accessions

by Nawroz Abdul-razzak Tahir, Djshwar Dhahir Lateef, Kamil Mahmud Mustafa and Kamaran Salh Rasul

Agriculture 2022, 12(9), 1502; https://doi.org/10.3390/agriculture12091502 - 19 Sep 2022

Cited by 7 | Viewed by 2892

Abstract

Barley (Hordeum vulgare L.) is the preferred crop in arid regions, particularly for farmers with limited agricultural resources and low income. Typically, it is utilized for human consumption, animal feed, and malting. The discovery of natural (organic) sources of biostimulants has attracted a great deal of interest for crop productivity enhancement. Using a randomized complete block design with three main blocks, it was our aim to investigate the effects of foliar moringa (Moringa oleifera L.) organ extract (MOE) on the growth and yield components of a collection of barley accessions grown in Iraq. As indicated by the obtained results, almost all traits associated with barley growth and yield productivity were significantly enhanced by MOE application, relative to the respective control condition. The majority of barley accessions responded positively to the MOE treatment based on all studied traits (with the exception of 1000-kernel weight). According to the results of principal component analysis (PCA), the distribution of accessions on the two components under the MOE application was distinct from the distribution of accessions under control conditions, indicating that accessions responded differently to the MOE application. In addition, the distribution pattern of traits under MOE treatment was comparable to the distribution pattern of traits under the control condition, with the exception of two traits: total yield and 1000-kernel weight. AC5 and AC18 responded positively to the MOE application by possessing the highest total yield and harvest index values. The total yield trait registered the highest increasing value index (37.55%) based on the trait response index, followed by the straw weight (22.29%), tillering number per plant (21.44%), and spike number per plant (21.36%), while the spike length trait registered the lowest increasing value index (0.45%), compared to the traits under control conditions. So far, the results indicate that foliar application of MOE can be utilized effectively as a natural growth promoter to increase the growth and yield productivity of grown barley accessions. Full article

(This article belongs to the Special Issue Abiotic Stresses, Biostimulants and Plant Activity)

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15 pages, 3241 KiB

Open AccessEditor’s ChoiceArticle

Heat Shock Treatment Promoted Callus Formation on Postharvest Sweet Potato by Adjusting Active Oxygen and Phenylpropanoid Metabolism

by Qi Xin, Bangdi Liu, Jing Sun, Xinguang Fan, Xiangxin Li, Lihua Jiang, Guangfei Hao, Haisheng Pei and Xinqun Zhou

Agriculture 2022, 12(9), 1351; https://doi.org/10.3390/agriculture12091351 - 1 Sep 2022

Cited by 17 | Viewed by 2537

Abstract

This study aimed to investigate that rapid high-temperature treatment (RHT) at an appropriate temperature could accelerate callus formation by effectively promoting the necessary metabolic pathways in sweet potato callus. In this study, the callus of sweet potato was treated with heat shock at 50, 65, and 80 °C for 15 min. The callus formation was observed within 1, 3, and 5 days, and the accumulation of intermediates in the metabolism of phenylpropane and reactive oxygen species and changes in enzyme activities were determined. The results showed that appropriate RHT treatment at 65 °C stimulated the metabolism of reactive oxygen species at the injury site of sweet potato on the first day, and maintained a high level of reactive oxygen species production and scavenging within 5 days. The higher level of reactive oxygen species stimulated the phenylalanine ammonia-lyase (PAL), 4-coumarate-CoA ligase and cinnamate-4-hydroxylase activities of the phenylpropane metabolic pathway, and promoted the rapid synthesis of chlorogenic acid, p-coumaric acid, rutin, and caffeic acid at the injury site, which stacked to form callus. By Pearson’s correlation analysis, catalase (CAT), PAL, and chlorogenic acid content were found to be strongly positively correlated with changes in all metabolites and enzymatic activities. Our results indicated that appropriate high-temperature rapid treatment could promote sweet potato callus by inducing reactive oxygen species and phenylpropane metabolism; moreover, CAT, PAL, and chlorogenic acid were key factors in promoting two metabolic pathways in sweet potato callus. Full article

(This article belongs to the Special Issue Abiotic Stresses, Biostimulants and Plant Activity)

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11 pages, 1180 KiB

Open AccessArticle

Effects of Selenium-Methionine against Heat Stress in Ca²⁺-Cytosolic and Germination of Olive Pollen Performance

by Alberto Marco Del Pino, Luca Regni, Alessandro Di Michele, Alessandra Gentile, Daniele Del Buono, Primo Proietti and Carlo Alberto Palmerini

Agriculture 2022, 12(6), 826; https://doi.org/10.3390/agriculture12060826 - 8 Jun 2022

Cited by 1 | Viewed by 2117

Abstract

Climate change (CC), which causes temperatures to rise steadily, is causing global warming. Rising temperatures can reduce plant yield and affect pollen characteristics. In particular, heat stress strongly influences pollen viability for its sensitivity to this extreme environmental condition. This work evaluated the effect of heat stress on olive pollen after in vitro incubation at different temperatures (20, 30, and 40 °C). Furthermore, the potential of selenium-methionine (Se-met) in mitigating the detrimental effects of heat stress on olive pollen was investigated. In particular, how thermal stress can affect pollen was evaluated by testing the effect of temperature on pollen germinability and morphology and cytosolic Ca²⁺ content. The results suggest that the heat stress at 40 °C caused a marked reduction in the germination rate, changes in the morphology of the external pollen wall, and a decreased response to Ca²⁺-agonist agents. On the contrary, in vitro treatment of pollen with Se-met improved the germination rate and Ca²⁺-cytosolic homeostasis under heat stress conditions and confirmed the protective role of this compound in containing the hydrogen peroxide (H₂O₂) toxicity. Therefore, this study revealed that organic selenium could play a crucial role in promoting heat tolerance in olive tree pollen. Full article

(This article belongs to the Special Issue Abiotic Stresses, Biostimulants and Plant Activity)

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16 pages, 5008 KiB

Open AccessArticle

Green-Synthesized Zinc Oxide Nanoparticles Mitigate Salt Stress in Sorghum bicolor

by Tessia Rakgotho, Nzumbululo Ndou, Takalani Mulaudzi, Emmanuel Iwuoha, Noluthando Mayedwa and Rachel Fanelwa Ajayi

Agriculture 2022, 12(5), 597; https://doi.org/10.3390/agriculture12050597 - 24 Apr 2022

Cited by 48 | Viewed by 4548

Abstract

Salinity is an abiotic stress that is responsible for more than 50% of crop losses worldwide. Current strategies to overcome salinity in agriculture are limited to the use of genetically modified crops and chemicals including fertilizers, pesticides and herbicides; however these are costly and can be hazardous to human health and the environment. Green synthesis of nanoparticles (NPs) is an eco-friendly and cost-effective method, and they might serve as novel biostimulants. This study investigated for the first time the efficiency of ZnO NPs, synthesized from Agathosma betulina to mitigate salt stress in Sorghum bicolor. Hexagonal wurtzite ZnO NPs of about 27.5 nm, were obtained. Sorghum seeds were primed with ZnO NPs (5 and 10 mg/L), prior to planting on potting soil and treatment with high salt (400 mM NaCl). Salt significantly impaired growth by decreasing shoot lengths and fresh weights, causing severe deformation on the anatomical (epidermis and vascular bundle tissue) structure. Element distribution was also affected by salt which increased the Na⁺/K⁺ ratio (2.9). Salt also increased oxidative stress markers (reactive oxygen species, malondialdehyde), enzyme activities (SOD, CAT and APX), proline, and soluble sugars. Priming with ZnO NPs stimulated the growth of salt-stressed sorghum plants, which was exhibited by improved shoot lengths, fresh weights, and a well-arranged anatomical structure, as well as a low Na⁺/K⁺ ratio (1.53 and 0.58) indicating an improved element distribution. FTIR spectra confirmed a reduction in the degradation of biomolecules correlated with reduced oxidative stress. This study strongly suggests the use of green-synthesized ZnO NPs from A. betulina as potential biostimulants to improve plant growth under abiotic stress. Full article

(This article belongs to the Special Issue Abiotic Stresses, Biostimulants and Plant Activity)

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21 pages, 1724 KiB

Open AccessArticle

Individual and Interactive Effects of Multiple Abiotic Stress Treatments on Early-Season Growth and Development of Two Brassica Species

by Akanksha Sehgal, Kambham Raja Reddy, Charles Hunt Walne, T. Casey Barickman, Skyler Brazel, Daryl Chastain and Wei Gao

Agriculture 2022, 12(4), 453; https://doi.org/10.3390/agriculture12040453 - 23 Mar 2022

Cited by 2 | Viewed by 3059

Abstract

Potential global climate change-related impacts on crop production have emerged as a major research priority and societal concern during the past decade. Future changes, natural and human-induced, projected in the climate have implications for regional and global crop production. The simultaneous occurrence of several abiotic stresses instead of stress conditions is most detrimental to crops, and this has been long known by farmers and breeders. The green leafy vegetables of the Brassicaceae family have especially gained attention due to their many health benefits. However, little information is available about abiotic stress’s effects on Brassica vegetables’ growth and development. An experiment was conducted on two Brassica species: B. oleracea L. var. acephala WINTERBOR F1 (hybrid kale) and B. juncea var. GREEN WAVE OG (mustard greens). Seven treatments were imposed on the two brassica species in soil–plant–atmosphere–research (SPAR) units under optimum moisture and nutrient conditions, including a control treatment (optimal temperature and UV-B conditions at ambient CO₂ levels), and six treatments where stresses were elevated: CO₂, UV-B, temperature (T), CO₂+UV-B, CO₂+T, and CO₂+UV-B+T. Above- and below-ground growth parameters were assessed at 26 d after sowing. Several shoot and root morphological and developmental traits were evaluated under all the treatments. The measured growth and development traits declined significantly under individual stresses and under the interaction of these stresses in both the species, except under elevated CO₂ treatment. All the traits showed maximum reductions under high IV-B levels in both species. Leaf area showed 78% and 72% reductions, and stem dry weight decreased by 73% and 81% in kale and mustard, respectively, under high UV-B levels. The increased CO₂ concentrations alleviated some deleterious impacts of high temperature and UV-B stresses. The results of our current study will improve our understanding of the adverse effects of environmental stresses on the early-season growth and development of two Brassica species. Full article

(This article belongs to the Special Issue Abiotic Stresses, Biostimulants and Plant Activity)

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21 pages, 2236 KiB

Open AccessArticle

Drought Stress Amelioration in Maize (Zea mays L.) by Inoculation of Bacillus spp. Strains under Sterile Soil Conditions

by Muhammad Azeem, Muhammad Zulqurnain Haider, Sadia Javed, Muhammad Hamzah Saleem and Aishah Alatawi

Agriculture 2022, 12(1), 50; https://doi.org/10.3390/agriculture12010050 - 1 Jan 2022

Cited by 56 | Viewed by 7892

Abstract

The aim of the present study was to promote plant growth characteristics including mineral uptake and various phytohormone production by indigenously isolated Bacillus spp. strains. Plants subjected to normal and water stress conditions were collected after 21 days to measure physiological parameters, photosynthetic pigment estimation, biochemical attributes, lipid peroxidation and antioxidant enzyme response modulation. Our results correlated with drought stress amelioration with the inoculation of Bacillus spp. strains BEB1, BEB2, BEB3 and BEB4 under sterile soil condition. Inoculated plants of both maize cultivars showed increases in fresh (56.12%) and dry (103.5%) biomass, plant length (42.48%), photosynthetic pigments (32.76%), and biochemical attributes with enhanced nutrient uptake. The overall maize antioxidant response to bacterial inoculation lowered the malonaldehyde level (59.14%), generation of hydrogen peroxide (45.75%) and accumulation of flavonoid contents in both control and water stress condition. Activity of antioxidant enzymes, catalase (62.96%), peroxidase (23.46%), ascorbate peroxidase (24.44%), and superoxide dismutase (55.69%) were also decreased with the application of bacterial treatment. Stress amelioration is dependent on a specific plant–strain interaction evident in the differences in the evaluated biochemical attributes, lipid peroxidation and antioxidant responses. Such bacteria could be used for enhancing the crop productivity and plant protection under biotic and abiotic stresses for sustainable agriculture. Full article

(This article belongs to the Special Issue Abiotic Stresses, Biostimulants and Plant Activity)

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18 pages, 911 KiB

Open AccessFeature PaperArticle

Assessment of Drought Tolerance of Miscanthus Genotypes through Dry-Down Treatment and Fixed-Soil-Moisture-Content Techniques

by Tzu-Ya Weng, Taiken Nakashima, Antonio Villanueva-Morales, J. Ryan Stewart, Erik J. Sacks and Toshihiko Yamada

Agriculture 2022, 12(1), 6; https://doi.org/10.3390/agriculture12010006 - 22 Dec 2021

Cited by 5 | Viewed by 3158

Abstract

Miscanthus, a high-yielding, warm-season C₄ grass, shows promise as a potential bioenergy crop in temperate regions. However, drought may restrain productivity of most genotypes. In this study, total 29 Miscanthus genotypes of East-Asian origin were screened for drought tolerance with two methods, a dry-down treatment in two locations and a system where soil moisture content (SMC) was maintained at fixed levels using an automatic irrigation system in one location. One genotype, Miscanthus sinensis PMS-285, showed relatively high drought-tolerance capacity under moderate drought stress. Miscanthus sinensis PMS-285, aligned with the M. sinensis ‘Yangtze-Qinling’ genetic cluster, had relatively high principal component analysis ranking values in both two locations experiments, Hokkaido University and Brigham Young University. Genotypes derived from the ‘Yangtze-Qinling’ genetic cluster showed relatively greater photosynthetic performance than other genetic clusters, suggesting germplasm from this group could be a potential source of drought-tolerant plant material. Diploid genotypes showed stronger drought tolerance than tetraploid genotypes, suggesting ploidy could be an influential factor for this trait. Of the two methods, the dry-down treatment appears more suitable for selecting drought-tolerant genotypes given that it reflects water-stress conditions in the field. However, the fixed-SMC experiment may be good for understanding the physiological responses of plants to relatively constant water-stress levels. Full article

(This article belongs to the Special Issue Abiotic Stresses, Biostimulants and Plant Activity)

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14 pages, 13582 KiB

Open AccessArticle

Biostimulant Effects of an Aqueous Extract of Duckweed (Lemna minor L.) on Physiological and Biochemical Traits in the Olive Tree

by Luca Regni, Daniele Del Buono, Begoña Miras-Moreno, Biancamaria Senizza, Luigi Lucini, Marco Trevisan, Diletta Morelli Venturi, Ferdinando Costantino and Primo Proietti

Agriculture 2021, 11(12), 1299; https://doi.org/10.3390/agriculture11121299 - 20 Dec 2021

Cited by 15 | Viewed by 5448

Abstract

Biostimulants are becoming increasingly popular in agriculture for their ability to induce beneficial effects in crops, paving the way towards the identification of new materials with biostimulant potential. This study evaluated the potential of different concentrations of an aqueous extract (0.25%, 0.50%, and 1.00%, dry weight/water volume, respectively) obtained from duckweed (Lemna minor L.) to stimulate olive plants. Leaf net photosynthesis (Pn), leaf transpiration rate (E), stomatal conductance (gs), sub-stomatal CO₂ concentration (Ci), chlorophyll content and other plant growth parameters were investigated. As a result, the extract improved Pn, gs, Ci, chlorophyll content and plant biomass production (leaf fresh and dry weight). Furthermore, the duckweed extract generally increased the uptake of nitrogen (N), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe) and zinc (Zn), while it did not influence the content of sodium (Na), manganese (Mn) and copper (Cu). The untargeted metabolomic profiling of the extract revealed the presence of signalling compounds (including phytohormones), phenolics and glutathione. Such broad diversity of bioactives may support the stimulatory potential observed in olive. In summary, this study revealed for the first time that duckweed could be seen as a promising species to obtain extracts with biostimulant properties in olive trees. Full article

(This article belongs to the Special Issue Abiotic Stresses, Biostimulants and Plant Activity)

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13 pages, 2634 KiB

Open AccessArticle

Hydropriming with Moringa Leaf Extract Mitigates Salt Stress in Wheat Seedlings

by Talaat Ahmed, Ahmed Abou Elezz and Muhammad Fasih Khalid

Agriculture 2021, 11(12), 1254; https://doi.org/10.3390/agriculture11121254 - 10 Dec 2021

Cited by 20 | Viewed by 4158

Abstract

Salinity is the major constraint that decreases the yield and production of crops. Wheat has a significant value in agricultural food commodities. The germination and growth of wheat seedlings are a big challenge in salt-affected soils. The seed priming technique is used to mitigate salt stress and enhance the germination and growth of the crops. Therefore, the current study was conducted to evaluate the hydropriming of natural plant extract (moringa leaf extract) and water on wheat seeds and grown under different saline (0, 0.05, 0.1, 0.15, and 0.2 M NaCl) environments. The germination attributes (germination percentage, germination index, mean germination day, coefficient of variance, vigor index) and seedling growth (fresh weight, dry weight, root length, shoot length) were enhanced in the plants primed by moringa leaf extract. The germination percentage was observed 10% more at 0.2 M NaCl stress in seeds treated with moringa leaf extract than seeds treated with water. The nutrient (K, Ca, Mg, P, S, Fe, B, Mn, Zn, Cu) uptake was also observed more in the shoots and roots of wheat seedlings soaked in moringa leaf extract as compared to soaked in water. Controlled plants showed higher concentrations of toxic ions (Na) and reactive oxygen species (H₂O₂) in shoots and roots of wheat seedlings. The use of moringa leaf extract for priming wheat seeds will enhance their germination and growth by maintaining efficient nutrient uptake and restricting the toxic ions and reactive oxygen species accumulation. Full article

(This article belongs to the Special Issue Abiotic Stresses, Biostimulants and Plant Activity)

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13 pages, 6653 KiB

Open AccessArticle

Effects of Different Water Table Depth and Salinity Levels on Quality Traits of Bread Wheat

by İsmail Sezer, Hasan Akay, Zeki Mut, Hakan Arslan, Elif Öztürk, Özge Doğanay Erbaş Köse and Mehmet Sait Kiremit

Agriculture 2021, 11(10), 969; https://doi.org/10.3390/agriculture11100969 - 6 Oct 2021

Cited by 10 | Viewed by 2472

Abstract

Abiotic stress factors encountered in production lands influence both the yield and the quality traits of bread wheat. This study investigated the effects of three different water table depths (30, 55, and 80 cm) and four different groundwater salinity levels (0.38, 2.0, 4.0, and 8.0 dSm⁻¹) on some quality traits of bread wheat under irrigated and unirrigated conditions. The experiments were conducted in the 2018 and 2019 growing seasons in randomized blocks—factorial (three factors) experimental design with three replications under controlled conditions. The hectoliter weight, fat ratio, starch ratio, protein content, Zeleny sedimentation, wet gluten content, ash ratio, acid detergent fiber (ADF), and neutral detergent fiber (NDF) values were investigated. The hectoliter weights varied between 66.1% and 77.8 kg, fat ratios between 1.49% and 1.70%, starch ratios between 61.9% and 67.8%, protein contents between 11.9% and 13.8%, Zeleny sedimentation values between 23.5 and 28.0 mL, wet gluten contents between 25.0% and 28.8%, ash ratios between 1.43% and 1.75%, and ADF values between 2.85% and 4.12%. The quality traits were positively influenced by increasing the water table depths. With increasing the groundwater salinity levels, the hectoliter weight, fat ratio, starch ratio, and NDF values decreased, while the protein ratio, sedimentation value, wet gluten content, ash ratio, and ADF values increased. Full article

(This article belongs to the Special Issue Abiotic Stresses, Biostimulants and Plant Activity)

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