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النتائج 1 - 10 من 12
Global exports draining local water resources: land concentration, food exports and water grabbing in the Ica Valley (Peru) النص الكامل
2026 | 2024
Pronti, A. | Zegarra, E. | Rey Vicario, Dolores | Graves, Anil
The agro-export boom is threatening the sustainability of water resources in many regions around the world. This is the case of the Ica valley in Peru, where in the last decades traditional agriculture has been replaced by big agricultural businesses to meet the growing international food demand. This has led to increasing land concentration by large exporting farms jointly with an increase in groundwater exploitation for irrigation. In this paper, we analyze the effect of land concentration, exporting crop specialization and irrigation intensity on groundwater sustainability using an econometric approach. Our findings highlighted an inverse relation between groundwater sustainability in terms of water withdrawal in the Ica Valley and the intensity of irrigation (drip technology), commodity specialization and concentration of large farms. More research is needed to fully understand the impacts of this very important economic activity on Peru’s natural resources, to ensure its sustainability in the long term. | This research was funded by the UK Natural Environment Research Council (NERC) through the NEXT-AG project (Nexus thinking for sustainable agricultural development in Andean countries) (NE/R015759/1).
اظهر المزيد [+] اقل [-]Enhancing Nitrogen Fertilisation Efficiency by Developing Novel Nitrification Inhibitors for a Greener Agriculture النص الكامل
2026 | 2024
Yildirim, Sibel Cansu | Brüggemann, Nicolas | Knief, Claudia
Nitrogen fertilization in agriculture has serious environmental consequences, including production of the greenhouse gas nitrous oxide (N<sub>2</sub>O), pollution of groundwater with nitrate (NO<sub>3</sub><sup>-</sup>), and river eutrophication. Nitrogen use efficiency can be increased by amending fertilizers with inhibitors to slow microbial nitrification processes, which transform ammonia to NO<sub>3</sub><sup>-</sup>. Unfortunately, commercial inhibitors have failed to perform reliably across various agroecosystems for reasons not well understood. Using a combination of bacterial studies and soil incubations, we demonstrate here that 4-methyl-1-(prop-2-yn-1-yl)-1H-1,2,3-triazole (MPT) exhibits superior nitrification inhibitory properties. Unlike the commercial reversible inhibitors, MPT acts as a mechanistic, irreversible inhibitor of the key enzyme ammonia monooxygenase, enabling effective retention of ammonium (NH<sub>4</sub><sup>+</sup>) and suppression of NO<sub>3</sub><sup>-</sup> and N<sub>2</sub>O production over 21 days in several agricultural soils with pH values ranging from 4.7 to 7.5. A bacterial viability stain and a suite of freshwater and terrestrial ecotoxicity tests did not indicate any acute or chronic toxicity. Real-time quantitative polymerase chain reaction (qPCR) analysis revealed an enhanced inhibitory effect of MPT on both ammonia-oxidizing bacteria and archaea. Thus, MPT outperforms currently available nitrification inhibitors and has great potential for broad application in various agricultural settings.
اظهر المزيد [+] اقل [-]Unveiling the Setaria viridis PEPC1 promoter regulatory network in Rice النص الكامل
2026 | 2023
Carvalho, Pedro
More people to feed, reduced arable area, and more extreme environ mental conditions creates constraints never seen before in agricultural systems. In order to feed the increasing world population, plant yield improvement needs to be achieved. Photosynthesis, a process that is tightly related to plant yield, is limited by the efficiency of Rubisco. This enzyme, responsible for the carbon fixation that ulti mately leads to the production of photoassimilates, is limited by its dual role, working as a carboxylase and an oxygenase. When it works as an oxygenase, it produces 2-phosphoglycolate, which needs to be recycled through a process called photorespiration, leading to CO2 and energy losses. To overcome photorespiration, some plants have evolved carbon concentrating mechanisms that allow the increase of CO2 concentration around Rubisco, thus reducing its oxygenase activity. One such mechanisms is C4 photosynthesis. In most C4 plants, two carboxylation reactions take place in two different cell types, mesophyll and bundle sheath. | N/A
اظهر المزيد [+] اقل [-]Territorial embeddedness of sustainable agri-food systems. A systematic review النص الكامل
2026 | 2025
Duarte, Luís | Muñoz-Rojas, José | Rivera, Maria | Gliessmann, Steve
The current food systems require an urgent transition toward more sustainable food landscapes. One key discussion arising is on the potential of territorial approaches to foster the sustainability of agri-food systems, for which this paper provides a review. This systematic literature review is based on bibliometric methods which allowed us to identify in a fairly unbiased manner the most impactful authors, papers, and research trends. Three distinctive scientific fronts are identified, revealing research specializations defined by their distinctive social-territorial approach: sustainable agroecosystems at the farm level; agroecological initiatives at the community level; and transformation of the food system and societal values at the regional/national level. We expect this review will trigger and enrich further discussions about future trends and opportunities for enhancing the sustainability of agri-food systems. This is especially urgent since research on these topics is relatively recent, and conflicting approaches are identified for which an overall understanding of potential solutions is largely missing. Reconciling agricultural and biodiversity sustainability stands on top of current political agendas, and thus providing an overall picture of how territorial approaches confront this problem shall prove key in guiding better-informed land policy and management decisions.
اظهر المزيد [+] اقل [-]Applying an NMR-based metabolomic workflow to unveil strawberry molecular mechanisms in vernalization النص الكامل
2026 | 2025
Fernández Veloso, Andrea | Hiniesta Valero, Jaime | Guerra Castellano, Alejandra | Tomás Gallardo, Laura | Rosa Acosta, Miguel Ángel de la | Díaz Moreno, Irene | Universidad de Sevilla. Departamento de Bioquímica Vegetal y Biología Molecular | Ministerio de Ciencia e Innovación (MICIN). España | European Union (UE)
Nuclear Magnetic Resonance (NMR) is a mature technique in metabolomics due to its non-invasive, highly reproducible, and inherently quantitative nature. However, difficulties in data analysis hinder its standardization in research. Herein, we propose an NMR-based metabolomic workflow that comprises data preprocessing, metabolite annotation, and data analysis. In this work, we apply such workflow to study vernalization, which is a critical process for crop development with largely unknown molecular mechanisms. Our findings suggest that sugar mobility, accessibility, and increased photosynthetic activity support plant viability post-vernalization. In other words, these processes ensure successful transplanting of the plant, highlighting the importance of sufficient cold exposure for flowering, fruiting, and ripening. This study demonstrates that the proposed workflow is suitable to capture metabolic changes in plant development. Such methodology underscores the potential of NMR-based metabolomics as a powerful tool for crop monitoring, aiding in improved agricultural practices and yield optimization.
اظهر المزيد [+] اقل [-]Urbanization and temporal shifts in a farmland bumblebee community | Urbanisaatio ja maatalousympäristön kimalaislajiston ajallinen muutos النص الكامل
2026 | 2025
Matikainen, Jenny | Helsingin yliopisto, Maatalous-metsätieteellinen tiedekunta | University of Helsinki, Faculty of Agriculture and Forestry | Helsingfors universitet, Agrikultur-forstvetenskapliga fakulteten
Insects have an essential role in pollinating a wide range of crops and wild flowering plants. To conserve pollinating insects, understanding how they are affected by land-use changes is important. The aim of the thesis was to study what kind of temporal shifts have occurred in a bumblebee community in an agricultural area around which urbanization has increased over time. The study was conducted in Southern Finland, and bumblebees occurring on field margins were surveyed in 2005 and in 2024. The aim was to understand whether bumblebee community composition or species richness changed in 19 years, in parallel with increasing urban land use in the surrounding landscape, and whether the shifts were related to tongue lengths of bumblebee species. In addition, the aim was to understand whether bumblebee abundance and species richness on field margins were affected by the distance from the nearest residential area, the presence of roads, the two study years representing different proportions of build-up area or the local abundance of flowering plants. The results of this study suggest that a significant shift in community composition occurred, and species richness increased in 19 years. Among the new species in the study area, Bombus terrestris Linnaeus showed a rapid increase and became one of the most common bumblebee species in the study area in 19 years. Temporal changes in the mean tongue length were not detected at a community level. Bumblebee abundance and species richness on field margins were not affected by the distance from the nearest residential area, and the presence of roads adjacent to field margins did not reduce bumblebee abundance or species richness. Bumblebee abundance and species richness on field margins were positively associated with the local abundance of flowering plants. The results of this study suggest that bumblebee communities are prone to change, but tongue lengths do not explain temporal changes in the relative abundance of different bumblebee species. Most of the new species observed in the study area are species with southern distributions, and climate change may explain the observed increase in species richness. More research is needed to understand whether the increase in B. terrestris is a threat to native bumblebee species. Based on this study, bumblebee species occurring in an agricultural area can cope with increasing urbanization in the surrounding landscape, and bumblebee species do not avoid the proximity of roads or residential areas. Instead, the abundance of flowering plants is an important factor determining bumblebee abundance and species richness on field margins. | Hyönteisillä on tärkeä rooli monien viljelykasvien ja luonnonkasvien pölytyksessä. Hyönteispölyttäjien suojelemiseksi on tärkeää ymmärtää, miten maankäytön muutokset vaikuttavat niihin. Tämän tutkielman tavoitteena oli tutkia, millaisia ajallisia muutoksia on tapahtunut kimalaisyhteisössä maatalousalueella, jonka ympärillä urbanisaatio on lisääntynyt ajan kuluessa. Tutkimus toteutettiin Etelä-Suomessa, ja pellonpientareilla esiintyviä kimalaisia laskettiin vuosina 2005 ja 2024. Tavoitteena oli ymmärtää, tapahtuiko kimalaisyhteisön koostumuksessa ja lajirikkaudessa muutoksia 19 vuoden aikana urbanisaation lisääntyessä ympäröivässä maisemassa sekä liittyivätkö havaitut muutokset kimalaisten kielten pituuksiin. Lisäksi tavoitteena oli ymmärtää, miten etäisyys lähimpään asuinalueeseen, pellonpientareiden vieressä sijaitsevat tiet, vuosi sekä kukkivien mesikasvien yleisrunsaus vaikuttivat kimalaisten yksilömäärään ja lajirikkauteen pellonpientareilla. Tämän tutkimuksen perusteella kimalaisyhteisön koostumus muuttui merkittävästi ja lajirikkaus kasvoi tutkimusalueella 19 vuoden aikana. Uusista tutkimusalueella havaituista lajeista erityisesti kontukimalaisen (Bombus terrestris Linnaeus) yleistyminen oli nopeaa, ja siitä tuli yksi tutkimusalueen yleisimmistä kimalaislajeista 19 vuodessa. Kimalaisyhteisössä ei kuitenkaan havaittu muutoksia keskimääräisessä kielenpituudessa. Etäisyys lähimpään asuinalueeseen ei vaikuttanut kimalaisten yksilömäärään tai lajirikkauteen pellonpientareilla, eivätkä tiet pellonpientareiden vieressä vähentäneet havaittua yksilö- tai lajimäärää. Sen sijaan kukkivien mesikasvien yleisrunsaudella oli positiivinen yhteys kimalaisten yksilömäärään ja lajirikkauteen pellonpientareilla. Tämän tutkimuksen tulokset viittaavat siihen, että kimalaisyhteisöt ovat alttiita muutoksille, mutta kimalaisten kielten pituudet eivät selitä muutoksia eri kimalaislajien suhteellisessa runsaudessa. Suurin osa uusista tutkimusalueella havaituista lajeista on lajeja, joiden levinneisyysalue painottuu etelään, ja ilmastonmuutos voikin selittää havaittua lajirikkauden nousua tutkimusalueella. Tulevaisuudessa olisi tärkeää tutkia, vaikuttaako kontukimalaisen yleistyminen negatiivisesti alkuperäiseen kimalaislajistoon. Tämän tutkimuksen perusteella maatalousympäristön kimalaislajit eivät ole herkkiä lisääntyvälle urbanisaatiolle maatalousalueen ympärillä, eivätkä ne välttele teiden tai asuinalueiden läheisyyttä. Sen sijaan kukkivien mesikasvien yleisrunsaus on tärkeä tekijä, joka määrittää kimalaisten yksilömäärää ja lajirikkautta pellonpientareilla.
اظهر المزيد [+] اقل [-]Path Analysis and correlation between quantitative traits in cultivated sugar beet germplasms (Beta vulgaris L.), under rhizomania disease conditions in Miandoab النص الكامل
2026
Mousa Arshad | Behzad Ghanbari taghi abad | Hamid Hatami Maleki | Keivan Fotuhi
Extended Abstract Background: Sugar beet (Beta vulgaris L.) is one of the most important root crops and the main source of sugar. It has the greatest ability to be cultivated in the temperate regions of Iran. One of the main centers for cultivating this crop in Iran is West Azerbaijan Province, which accounts for a major share of its production in the country. Rhizomania disease is among the most important factors limiting the growth and reducing the yield of sugar beet. Given that the use of some agricultural methods, such as planting date, irrigation methods, crop rotation, chemical methods, and biological methods, are not very useful in fighting the disease, the use of resistant cultivars is suggested as the best and only way to fight this disease. So far, several studies have been conducted on obtaining disease-resistant cultivars. The first prepared and cultivated hybrid, called Rizor, was a relatively resistant monogerm diploid hybrid that significantly increased the yield of sugar beet in contaminated fields. Studies on the genetic diversity of this strategic plant help breeders identify genetic resources resistant to rhizomania disease with breeding objectives, including yield and yield components. It is crucial to be aware of the differences and diversity between different genotypes of sugar beet and the associations of these differences with their potential performance in improving the yield of new cultivars. Since there are mutual effects among the variables in multivariate regression, a variable may be significant next to some variables, but not significant next to some other variables. For this reason, it is necessary to select important variables that have a significant effect on yield. In this regard, this research aimed to evaluate domestic and imported modified varieties of sugar beet under the presence of rhizomania disease in the climatic conditions of Miandoab City. Methods: An experiment in the form of a completely randomized block design with four replications was conducted at the Miandoab Agricultural and Natural Resources Research Center in the geographic location of 46° 90' E and 36° 58' N with at an altitude of 1314 m above sea level. The experimental materials included 12 sugar beet genotypes (10 domestic genotypes with one imported resistant genotype and 1 domestic sensitive genotype). In this study, the studied genotypes were exposed to the natural infection of the region. After determining the percentage of cultivars, the level of resistance and sensitivity of each genotype was determined based on the percentage of infection. Before the experiment, land preparation operations included plowing, disking, leveling, and plotting the field in the same way. Phosphorus and potash fertilizers were applied based on the results of the soil decomposition test at the time of land preparation, and nitrogen fertilizer was used as a starter in the form of plant feet. The seed distances between and on the rows were 60 cm and 15 cm, respectively. The size of each plot included three planting lines with a length of 8 m. Agricultural operations, including irrigation, pest and disease control, and cultivator application, were carried out as needed. Root yield traits, pure sugar percentage by the polarimetric method, gross sugar percentage, pure sugar yield, gross sugar yield, extraction percentage, and molasses sugar percentage were measured after harvest. Results: Based on the results of variance analysis of data, significant differences were observed between genotypes in terms of all traits. According to the results of comparing the average traits, genotype 31914 (domestic number) with 11.97% was the least infected and, at the same time, the most resistant variety, and genotype SBSI010 (susceptible-domestic control) with 79.37% was the highest contamination and the most sensitive variety to rhizomania disease among the studied genotypes. In this study, the correlation coefficients of the infection percentage index had negative and significant relationships with root yield traits, gross sugar percentage, pure sugar percentage, gross sugar yield, pure sugar yield, and the extraction coefficient at the probability level of 1%. However, this parameter showed a positive and significant relationship with the molasses sugar trait at the probability level of 1%. Moreover, the infection severity index showed a positive and significant relationship with the yield traits, namely pure sugar, molasses sugar, potash, and harmful nitrogen at the level of 1%. Based on the results of step-by-step regression analysis, the percentages of root infection, sugar extraction, and gross sugar explained 68.7% of the changes in pure sugar yield. Besides, the percentage of root infection had a negative direct effect and the percentages of sugar extraction and gross sugar had a positive direct effect on the yield changes of white sugar. Conclusion: Although genotype SBSI030 showed the maximum quantitative and qualitative traits in this study, the lowest percentage of root infection was recorded for genotype 31914. After additional tests, genotype 31914 can be used as a genetic source resistant to rhizomania. This investigation showed that gross sugar percentage had the most positive effect on white sugar yield. Thus, selecting genotypes with a high gross sugar percentage can lead to obtaining cultivars with high white sugar yield.
اظهر المزيد [+] اقل [-]Genetic Diversity and Relationship Analysis of Different Local and International Cultivars and some Strawberry Clones (Fragaria× ananassa Duch) النص الكامل
2026
Masume Abedi | Mehdi Hadadinejad | Kamran Ghasemi | Ghafar Kiani
Extended Abstract Background: Strawberry (Fragaria × ananassa) is a perennial shrub of the Rosaceae family that has become one of the most significant fruits globally due to its unique characteristics, ease of care, and delicious flavor. This plant thrives particularly well in temperate regions, although it can also be cultivated as an annual. These traits have made strawberries popular not only in home gardens but also in commercial agriculture. It has emerged as an important economic crop in many countries because of its tasty and nutritious fruits. Given the economic and nutritional significance of strawberries, it is crucial to assess their genetic diversity and identify various genotypes. Genetic diversity in this plant enables researchers to develop newer, higher-quality varieties that are more resistant to pests and diseases while yielding greater outputs. Therefore, the use of morphological markers is highly beneficial in distinguishing and identifying different strawberry cultivars and populations. Consequently, this study was conducted to investigate genetic diversity and identify relationships between domestic and imported strawberry genotypes and clones. Methods: The present study was carried out in Mazandaran Province, Sari City, from November 2020 to June 2021. Transplants of imported cultivars were sourced from the Kurdistan Agricultural and Natural Resources Research Center. This selection was made due to the high diversity of cultivars and their specific characteristics, allowing for an accurate assessment of their yields and quality. The plants were grown in pots filled with a substrate of cocopeat and perlite in a 70:30 ratio. Due to its favorable physical and chemical properties, this substrate promotes better root growth and enhances the absorption of water and nutrients, thereby providing optimal conditions for plant growth. The comparison stage of cultivars was conducted through detailed studies at the Sari University of Agricultural Sciences and Natural Resources, aiming to investigate genotypic and phenotypic diversity. The experiment utilized a completely randomized design with 23 treatments, including mother cultivars in three replications and daughter cultivars in four replications, all within a hydroponic medium. Measurements were taken on fertile plants, and various data points, including growth habit, leaf density, and growth vigor based on international descriptors, as well as traits such as leaf length and width, leaf area, the number of individual flowers, the number of inflorescences, and total flower count, were analyzed quantitatively. Results: The examined genotypes exhibited significant differences in reproductive and vegetative traits. The highest genetic diversity coefficient was associated with the number of fruits per plant, the number of flowers per plant, and plant yield, all of which showed variations exceeding 50%. In contrast, a narrower range of variation was noted in traits related to vegetative growth, likely due to environmental influences and cultivation conditions. The correlation analysis of the growth habit trait revealed that a more erect plant positively impacted the growth of leaf components, which in turn enhanced fruit length and width. This is a crucial discovery as it can aid in the selection and breeding of superior cultivars. Factor analysis successfully identified several main factors representing qualitative and quantitative traits, facilitating a better understanding of the relationships among these traits. The Camarosa cultivar, the predominant cultivar in Mazandaran Province, along with the cultivars Merck, Tan Beauty, Missionary, and Queen Eliza, demonstrated positive vegetative growth but negative reproductive growth. However, the selected clone from Ghaemshahr excelled in both vegetative and reproductive growth, placing it in the fourth quadrant and positive section. The evaluated values for strawberry traits indicated that phenotypic variance surpassed genotypic variance, highlighting the environmental impact on the studied traits. The maximum phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) were attributed to plant yield (67.25 and 65.67), followed by leaf area (38.92 and 39.47), respectively. Furthermore, high heritability was observed in the traits of leaf area (97.3%), plant yield (95.35%), and the number of flowers per inflorescence (90.59%). Conclusion: The results of the correlation of morphological traits indicate that the plant's growth habit has a positive and significant correlation with various traits, including leaf length, leaf width, leaf area, petiole length, and fruit length and width. The correlation results for the descriptive trait of growth habit in three forms (erect, semi-erect, and creeping) demonstrate that a more erect plant positively influences the growth of leaf components, leading to improvements in both fruit length and width. Additionally, the correlation findings suggest that an increase in shoot density and leaf number can negatively and significantly impact the plant's growth habit. Therefore, shoot density may decrease as the plant grows, resulting in a more open structure with fewer leaves. Finally, considering the genetic distance among the cultivars, it appears that crossing these genotypes could yield greater heterosis, which can be leveraged to produce new cultivars and enhance orchard yields. Utilizing genetic and phenotypic diversity and incorporating these traits into breeding programs can significantly improve the quality and yields of strawberries in Iran.
اظهر المزيد [+] اقل [-]Future precipitation scenarios in Portugal using high-resolution WRF simulations based on a global model from CMIP6 | Cenários futuros de precipitação em Portugal usando simulações WRF de alta resolução com base num modelo global do CMIP6 النص الكامل
2026 | 2024
Barbosa, David Emanuel São Marcos | Vaz, Susana Cardoso Pereira Firmino | Carvalho, David João da Silva
The context of global climate change, exacerbated by human activity, justifies the need for detailed regional climate projections, particularly for vulnerable regions like Portugal. This study aims to assess changes in precipitation in Portugal under three future scenarios (SSP2-4.5, SSP3-7.0, and SSP5-8.5) for the future periods of 2046-2065 and 2081-2100, compared to the reference period 1995-2014. For this purpose, WRF model simulations with a spatial resolution of 6 km based on a CMIP6 global model were used. These simulations were validated with the WRF simulation of ERA5 data, and a statistical analysis of the data was performed, including differences in the annual and seasonal precipitation medians and various precipitation indices. The results indicate a general trend of reduced annual precipitation, more pronounced in summer and in the southern region, as well as a lower frequency of rainy days, in the SSP2-4.5 and SSP3-7.0 scenarios, with significant impacts on agriculture, water resources, and ecosystems. In the SSP5-8.5 scenario, a significant increase in annual precipitation is projected, more pronounced in winter, along with a greater concentration of intense precipitation events over shorter periods, leading to an intensification of extreme events. This study underscores the importance of using high-resolution models to capture regional climate variations and the need for specific adaptation policies. These projections underline the importance of proactive climate adaptation in Portugal, including sustainable water resource management, diversification of agricultural practices, and the implementation of environmental conservation policies to mitigate the impacts of projected climate changes. | O contexto das mudanças climáticas globais, exacerbadas pela atividade humana, justifica a necessidade de projeções climáticas regionais detalhadas, particularmente para regiões vulneráveis como Portugal. Este estudo tem como objetivo avaliar as mudanças na precipitação em Portugal sob três cenários futuros (SSP2-4.5, SSP3-7.0, e SSP5-8.5) para os períodos futuros de 2046-2065 e 2081-2100, comparando com o período de referência 1995-2014. Para isso foram utilizadas simulações do modelo WRF com uma resolução espacial de 6 km baseadas num modelo global do CMIP6. Estas simulações foram validadas com a simulação WRF dos dados ERA5 e foi realizada uma análise estatística dos dados, como as diferenças das medianas da precipitação anual e sazonal e de vários índices de precipitação. Os resultados indicam uma tendência geral de redução da precipitação anual, mais pronunciada no verão e na região sul e de uma menor frequência de dias chuvosos, nos cenários SSP2-4.5 e SSP3-7.0, com impactos significativos para a agricultura, recursos hídricos e ecossistemas. No cenário SSP5-8.5, projeta-se um aumento significativo da precipitação anual, mais pronunciada no inverno e uma maior concentração de eventos de precipitação intensa em períodos mais curtos, levando a uma intensificação dos eventos extremos. Destaca-se com este estudo a importância da utilização de modelos de alta resolução para captar variações climáticas regionais e a necessidade de políticas de adaptação específicas. Estas projeções sublinham a importância de uma adaptação climática proativa em Portugal, que inclua a gestão sustentável dos recursos hídricos, a diversificação das práticas agrícolas, e a implementação de políticas de conservação ambiental para mitigar os impactos das mudanças climáticas projetadas. | Mestrado em Ciências do Mar e da Atmosfera
اظهر المزيد [+] اقل [-]The Effect of Chitosan Priming on Germination and Biochemical Characteristics of Black Seed (Nigella sativa L.) under Cadmium Stress النص الكامل
2026
Ellahe Arab | Leila Ahangar | Abbas Biabani
Extended Abstract Background: Black seed (Nigella sativa L.) from the Ranunculaceae family is one of the natural useful antioxidants, and the oil prepared from its seeds has various medicinal properties, including anti-cancer, anti-microbial, anti-hypertensive, anti-diabetic and increased immunity has been reported. Nigella sativa, like other plants, is constantly exposed to abiotic or biotic stresses. The main abiotic stresses that plants are exposed to include extreme temperature, drought, high salinity and heavy metals. Environmental pollution caused by heavy metals is increasing. Among heavy metals, cadmium is one of the most toxic elements for living organisms, which has received much attention due to its increase in the environment in recent decades. This element is toxic to most plants even in very low concentrations, while in concentrations higher than five to ten micrograms per gram of dry leaf weight, it can lead to the death of the plant. The presence of this element in the growth environment of plants causes a lot of poisoning, including disruption of water-plant relations, disruption of chlorophyll biosynthesis and formation of free ions. Therefore, it is necessary to adopt appropriate environmental methods to reduce or eliminate the negative and irreparable effects of this metal in agriculture. Seed priming is known to be an effective method to improve plant performance by increasing plant tolerance to stress. One of the types of priming methods is the use of chemicals such as chitosan. Chitosan is a non-toxic and environmentally adaptive substance that is very important due to its antioxidant activity in dealing with oxidative damage resulting from environmental stress. Therefore, in this study, the effect of chitosan priming on reducing the harmful effects of cadmium on germination and biochemical characteristics of black seed was investigated. Methods: In this study, in order to investigate the effect of chitosan priming on cadmium chloride stress on the germination and biochemical characteristics of Nigella sativa, the experiment was carried out as a factorial design based on completely randomized design with 4 replications in sterile petri dishes in the laboratories of Gonbadkavos Agricultural University in 2023. For seed priming with different concentrations of chitosan (0.2, 0.4, 0.6, 1.0%), the seeds were immersed in the desired solutions for 3 hours under dark conditions and after drying, they were placed in Petri dishes on Whatman paper bed. Then 5 ml of solutions prepared with different concentrations of cadmium chloride (control, 1000, 750, 500, 250 μmol) were added to them. Distilled water was used for control treatment. Finally, the samples were placed for 10 days in the germinator in dark conditions with a temperature of 25±1 oC. At the end of the experiment, the characteristics of germination percentage, germination rate, seedling vigor index, root and shoot length were measured. Then the biochemical traits of seedlings such as catalase, peroxidase, phenol, soluble sugar and proline were measured after 14 days. Statistical analysis of data was done using SAS 9.1 and MSTAT-C software. Results: The results of analysis of variance indicated the significant simple effects of priming with chitosan and cadmium stress on all investigated traits. Also, the interaction effects of priming × cadmium stress were also significant for all traits at the 1% level. The comparison of average data showed that with the increase of cadmium concentration, germination rate and percentage, radicle length and seedling vigor index decreased significantly, so that the highest amount of these traits was in the control and 250 μmol cadmium and the lowest amount of these traits was observed at a concentration of 1000 μmol cadmium. The external application of chitosan in the form of priming improved germination traits, root and shoot length and seedling vigor index in 0.2 and 0.4% chitosan treatments compared to the control, while with the increase in the percentage of chitosan (0.8 and 1 percent) the amount of these traits decreased significantly. The results of the comparison of average traits under the interaction of chitosan ×cadmium showed that seed priming with chitosan was able to reduce the negative effects of cadmium chloride stress on the traits of percentage germination, root and shoot length and seedling vigor index. Thus, the highest amount of these traits was observed in the treatment of 0.2 and 0.4% chitosan and 250 and 500 μmol cadmium stress. Also, the results of the present study showed that increasing the concentration of cadmium chloride causes an increase in the activity of antioxidant enzymes such as catalase and peroxidase and non-enzymatic antioxidants such as proline and phenol. So that peroxidase enzyme at the treatment of 750 μM of cadmium (0.0053 μmol per gram of fresh tissue) with an increase of 178.2% compared to the control and phenol in the treatment of 1000 μM of cadmium (3.2 mg/g of extract) with an increase of 211.7 % compared to the control showed the highest level of activity. Also, the use of seed priming technique with chitosan could significantly increase the content of these proteins in plants under cadmium stress. So that, the highest amount of peroxidase enzyme is observed in the treatment of 500 μM cadmium in the priming treatment with 0.4% chitosan (0.0083 μmol Bergam of fresh tissue) and in the tratment of 750 μM cadmium chloride in the priming treatment 0.2% chitosan (0.0082 μmol Bergam) fresh tissue). That this amount was about 64 and 57.6% more than their controls, respectively. Conclusion: The results of this research showed that cadmium stress leads to a decrease in germination characteristics and weakens the plant's defense system. To deal with these changes and reduce the adverse effects of the produced ROS, the plant increased the activity of antioxidant enzymes, but the adverse effects of cadmium had an inhibitory effect on these changes. Conversely, the use of chitosan in the form of priming prevented the harmful effects of cadmium and increased the activity of antioxidant enzymes and protected the germination process against the toxicity of this heavy metal. Although the application of chitosan up to 0.6% improved these mechanisms, its beneficial effects decreased with the increase in the concentration of this substance. Based on the results of the present study, it can be stated that the application of chitosan caused the activation of some biochemical and physiological mechanisms in the black seed plant under cadmium stress. Therefore, seed priming with chitosan can be suggested as an effective strategy to increase Nigella sativa tolerance to cadmium stress.
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