Role of calcium nutrition in plant Physiology: Advances in research and insights into acidic soil conditions - A comprehensive review.

Plant mineral nutrition has immense significance for crop productivity and human well-being. Soil acidity plays a major role in determining the nutrient availability that influences plant growth. The importance of calcium (Ca) in biological processes, such as signaling, metabolism, and cell growth, underlines its critical role in plant growth and development. This review focuses on soil acidification, a gradual process resulting from cation leaching, fertilizer utilization, and drainage issues. Soil acidification significantly hampers global crop production by modifying nutrient accessibility. In acidic soils, essential nutrients, such as nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), and Ca become less accessible, establishing a correlation between soil pH and plant nutrition. Cutting-edge Ca nutrition technologies, including nanotechnology, genetic engineering, and genome sequencing, offer the potential to deliver Ca and reduce the reliance on conventional soluble fertilizers. These fertilizers not only contribute to environmental contamination but also impose economic burdens on farmers. Nanotechnology can enhance nutrient uptake, and Ca nanoparticles improve nutrient absorption and release. Genetic engineering enables the cultivation of acid-tolerant crop varieties by manipulating Ca-related genes. High-throughput technologies such as next-generation sequencing and microarrays aid in identifying the microbial structures, functions, and biosynthetic pathways involved in managing plant nutritional stress. The ultimate goal is to shed light on the importance of Ca, problems associated with soil acidity, and potential of emerging technologies to enhance crop production while minimizing the environmental impact and economic burden on farmers.

Production of biochar from tropical fruit tree residues and ecofriendly applications - A review.

Environmental contamination is considered a major issue with the growing urbanization and industrialization. In this context, the scientific society is engaged in searching for a sustainable, safe, and eco-friendly solution. Sustainable materials such as biochar play an important role in environmental contamination. It has some specific properties such as micropores which increase the surface area to bind the pollutants. This review endeavors to analyze the potential of fruit wastes especially tropical fruit tree residues as potential candidates for producing highly efficient biochar materials. The review discusses various aspects of biochar production viz. pyrolysis, torrefaction, hydrothermal carbonization, and gasification. In addition, it discusses biochar use as an adsorbent, wastewater treatment, catalyst, energy storage, carbon sequestration and animal feed. The review put forward a critical discussion about key aspects of applying biochar to the environment.

Valorization of tropical fruits waste for production of commercial biorefinery products - A review.

Tropical fruit wastes (TFW) are considered as the major source of food and nutrition in the topical countries. In the recent years, modernization of agriculture has increased the tropical fruit production. Higher fruit production led to an increasing abundance in the tropical fruit waste. In general, the tropical fruit waste has no economic value and ends up in landfill. But in recent years it was observed that the tropical fruit waste can be valorized to produce value-added products ranging from compost, phytochemicals, and food products to biofuels. The tropical fruit waste has great potential to produce useful products in tropical areas. This review literature is an endeavor to understand the major tropical fruit wastes and their composition. The review presents a detailed investigation on tropical fruit waste composition, its conversion potential, role of microbes in waste valorization, production of commercially valuable products and future perspectives in waste valorization.

Recent advances in lignocellulosic and algal biomass pretreatment and its biorefinery approaches for biochemicals and bioenergy conversion.

As the global demand for sustainable energy increases, lignocellulosic (such as agricultural residues, forest biomass, municipal waste, and dedicated energy crops) and algal (including macroalgae and microalgae) biomass have attracted considerable attention, because of their high availability of carbohydrates. This is a potential feedstock to produce biochemical and bioenergy. Pretreatment of biomass can disrupt their complex structure, increasing conversion efficiency and product yield. Therefore, this review comprehensively discusses recent advances in different pretreatments (physical, chemical, physicochemical, and biological pretreatments) for lignocellulosic and algal biomass and their biorefining methods. Life cycle assessment (LCA) which enables the quantification of the environmental impact assessment of a biorefinery also be introduced. Biorefinery processes such as raw material acquisition, extraction, production, waste accumulation, and waste conversion are all monitored under this concept. Nevertheless, there still exist some techno-economic barriers during biorefinery and extensive research is still needed to develop cost-effective processes.

Agro waste as a potential carbon feedstock for poly-3-hydroxy alkanoates production: Commercialization potential and technical hurdles.

The enormous production and widespread applications of non -biodegradable plastics lead to their accumulation and toxicity to animals and humans. The issue can be addressed by the development of eco-friendly strategies for the production of biopolymers by utilization of waste residues like agro residues. This will address two societal issues - waste management and the development of an eco-friendly biopolymer, poly-3-hydroxy alkanoates (PHAs). Strategies adopted for utilization of agro-residues, challenges and future perspectives are discussed in detail in this comprehensive review. The possibility of PHA properties improvements can be increased by preparation of blends.

Effect of phosphorus-loaded biochar and nitrogen-fertilization on release kinetic of toxic heavy metals and tomato growth.

In this study, we investigate the effect of nitrogen fertilizer application rates with and without phosphorus-loaded biochar (BCP) on the productivity of tomato (Solanum lycopersicum cv GS) planted on a contaminated soil based on pot and incubation experiments. The release kinetic of toxic metals as affected by BCP was also investigated. BCP at rate of 2% (w/w) and nitrogen levels (250 and 500 mg N kg-1) were added to sandy loam soil polluted with Cd, Pb, Zn, and Cu. The experiment consisted of five treatments including: Control (C), nitrogen a rate of 250 (N250), or 500 mg kg (N500), BCP + N250, and BCP + N500. Maximum tomato growth was achieved in the soil that was treated with BCP + N500, followed by BCP + N250, while lowest one was observed in the control. Tomato yield as affected by the BCP and N-fertilization was in the descending order: BCP + N500 > BCP + N250 > N500 = N250 > C. The addition of N250, N500, BCP + N250, and BCP + N500 increased the fruit yield by 24, 31, 35, 58% in comparison with the control. Levels of Zn, Cu, and Pb in tomato fruit was in the descending order: N500> N250 > C > BCP + N500 > BCP + N250. The combined application of BCP and N-fertilization augmented the availability and uptake of essential nutrients and effectively reduced those of toxic ones. The addition of BCP + N250 decreased Zn, Cu, Cd, and Pb content in fruit of tomato by 16, 10, 54, 54, and 58%, respectively, compared to the control soil, while these decreases were 13, 16, 60, 60, and 72% in the case of BCP + N500. BCP succeeded significantly in reducing the release of toxic chemicals, which ultimately may restrict the transfer of toxic chemical to the food chain solution. Novelty statement Tomato grown on metal-contaminated soils contains high levels of toxic metals. Phosphorus-loaded biochar (BCP) reduced the negative effects of high inorganic-N rates by reducing the release of toxic metals to the soil solution. BCP enhanced the soil quality indicators and increased the soil microbe's activity.

Foliar Application of Nano, Chelated, and Conventional Iron Forms Enhanced Growth, Nutritional Status, Fruiting Aspects, and Fruit Quality of Washington Navel Orange Trees (Citrus sinensis L. Osbeck).

Iron (Fe) is required for most metabolic processes, including DNA synthesis, respiration, photosynthesis, and chlorophyll biosynthesis; however, Fe deficiency is common in arid regions, necessitating additional research to determine the most efficient form of absorbance. Nano-fertilizers have characteristics that are not found in their traditional equivalents. This research was implemented on Washington navel orange trees (Citrus sinensis L. Osbeck) to investigate the effect of three iron forms-nano (Fe-NPs), sulfate (FeSO4), and chelated (Fe-chelated)-as a foliar spray on the growth, fruiting aspects, and nutritional status of these trees compared to control. The highest values of the tested parameters were reported when the highest Fe-NPs level and the highest Fe-chelated (EDTA) rate were used. Results obtained here showed that the spraying of the Washington navel orange trees grown under similar environmental conditions and horticulture practices adopted in the current experiment with Fe-NPs (nanoform) and/or Fe-chelated (EDTA) at 0.1% is a beneficial application for enhancing vegetative growth, flower set, tree nutritional status, and fruit production and quality. Application of Fe-NPs and Fe-chelated (EDTA, 0.1%) increased yield by 32.0% and 25% and total soluble solids (TSS) by 18.5% and 17.0%, respectively, compared with control. Spraying Washington navel orange trees with nano and chelated iron could be considered a significant way to improve vegetative growth, fruit production, quality, and nutritional status while also being environmentally preferred in the arid regions.

Mechanisms of Chitosan Nanoparticles in the Regulation of Cold Stress Resistance in Banana Plants.

Exposure of banana plants, one of the most important tropical and subtropical plants, to low temperatures causes a severe drop in productivity, as they are sensitive to cold and do not have a strong defense system against chilling. Therefore, this study aimed to improve the growth and resistance to cold stress of banana plants using foliar treatments of chitosan nanoparticles (CH-NPs). CH-NPs produced by nanotechnology have been used to enhance tolerance and plant growth under different abiotic stresses, e.g., salinity and drought; however, there is little information available about their effects on banana plants under cold stress. In this study, banana plants were sprayed with four concentrations of CH-NPs-i.e., 0, 100, 200, and 400 mg L-1 of deionized water-and a group that had not been cold stressed or undergone CH-NP treatment was used as control. Banana plants (Musa acuminata var. Baxi) were grown in a growth chamber and exposed to cold stress (5 °C for 72 h). Foliar application of CH-NPs caused significant increases (p < 0.05) in most of the growth parameters and in the nutrient content of the banana plants. Spraying banana plants with CH-NPs (400 mg L-1) increased the fresh and dry weights by 14 and 41%, respectively, compared to the control. A positive correlation was found between the foliar application of CH-NPs, on the one hand, and photosynthesis pigments and antioxidant enzyme activities on the other. Spraying banana plants with CH-NPs decreased malondialdehyde (MDA) and reactive oxygen species (ROS), i.e., hydrogen peroxide (H2O2), hydroxyl radicals (•OH), and superoxide anions (O2•-). CH-NPs (400 mg L-1) decreased MDA, H2O2, •OH, and O2•- by 33, 33, 40, and 48%, respectively, compared to the unsprayed plants. We hypothesize that CH-NPs increase the efficiency of banana plants in the face of cold stress by reducing the accumulation of reactive oxygen species and, in consequence, the degree of oxidative stress. The accumulation of osmoprotectants (soluble carbohydrates, proline, and amino acids) contributed to enhancing the cold stress tolerance in the banana plants. Foliar application of CH-NPs can be used as a sustainable and economically feasible approach to achieving cold stress tolerance.

The Exogenous Application of Micro-Nutrient Elements and Amino Acids Improved the Yield, Nutritional Status and Quality of Mango in Arid Regions.

The mango is one of the most valuable and appealing tropical fruits due to its color, aroma, tasteful remarkable flavor, and nutritive value; however, improving the yield and quality of mango is an urgent goal in order to combat global population growth. The application of amino acids and a micronutrient mixture might improve the yield and quality features but further research is still required in arid regions. To study the combined effect of a micronutrient mixture (MM) and amino acids (AA) at different rates, twenty-seven Fagri Kalan mango trees (15 years old) were carefully selected. The foliar application effect of MM and AA on vegetative growth, total chlorophyll, leaf chemical constituents, productivity, and the fruit quality of mango trees (cv. Fagri Kalan) was investigated. The findings revealed that the investigated growth measurements and leaf chemical contents, as well as the fruiting aspects and the fruit quality improved significantly due to the application of MM and AA. A higher application rate of the micronutrient mixture (2 g L-1) in combination with the highest amino acid concentration (2 mg L-1) was the most effective combination that increased the yield, total soluble solids (TSS), total sugars (TS), and total carbohydrates by 28.0%, 3.0%, 5.8% and 15.0%, respectively, relative to untreated plants. The relationship between such characteristics revealed a strong positive correlation (0.80-0.95), confirming the importance of these materials in increasing the yield and quality of mangoes. Thus, using doses of MM and AA as a foliar spray four times during each growing season is recommended under similar environmental conditions and horticulture practices used in the current experiment.

Effect of Manure and Compost on the Phytostabilization Potential of Heavy Metals by the Halophytic Plant Wavy-Leaved Saltbush.

This study aimed to use organic fertilizers, e.g., compost and manures, and a halophytic plant [wavy-leaved saltbush (Atriplex undulata)] to remediate an agricultural soil polluted with toxic elements. Compost or manure (1% w/w) was added to a polluted soil in a pot trial. The application of the organic fertilizer, whether compost or manure, led to a significant improvement in the growth of the tested plant. From the physiological point of view, the application of organic fertilizers to polluted soil significantly increased the content of chlorophyll, carotenoid, and proline and, furthermore, led to a clear decrease in malondialdehyde (MDA) in the plant leaves. The highest significant values of organic carbon in the polluted soil (SOC) and cation exchange capacity (CEC) were found for the soil amended by compost and planted with wavy-leaved saltbush. Manure significantly reduced the soil pH to 7.52. Compost significantly decreased Zn, Cu, Cd, and Pb availability by 19, 8, 12, and 13%, respectively, compared to the control. On the other hand, manure increased Zn, Cu, Cd, and Pb availability by 8, 15, 18, and 14%, respectively. Compost and manure reduced the bioconcentration factor (BCF) and translocation factor (TF) of Cd and Pb. Compost was more effective in increasing the phytostabilization of toxic metals by wavy-leaved saltbush plants compared to manure. The results of the current study confirm that the application of non-decomposed organic fertilizers to polluted soils increases the risk of pollution of the ecosystem with toxic elements. The cultivation of contaminated soils with halophytic plants with the addition of aged organic materials, e. g., compost, is an effective strategy to reduce the spreading of toxic metals in the ecosystem, thus mitigating their introduction into the food chain.

Variations in phytoremediation potential and phytoavailability of heavy metals in different Salix genotypes subjected to seasonal flooding.

Climate-related flooding poses a potential challenge to phytoremediation of metal polluted areas. In the present study, uptake, translocation and accumulation of heavy metals (Cd, Zn and Cu), and their phytoavailability in six flood-tolerant Salix genotypes were investigated under simulated seasonal flooding conditions (non-flooding conditions were kept as the control). Plants were cultivated in a greenhouse with open windows using the soil polluted with Cd, Zn and Cu for 110 days. All the control (non-flooded) genotypes did not exhibit visible toxic symptoms, whereas the flooded genotypes showed leaf chlorosis and developed both lenticels and adventitious roots. Biomass production and metal accumulation in tissues varied with Salix genotypes. The flooded genotypes dramatically decreased aerial biomass production compared with corresponding non-flooded genotypes. All the control Salix genotypes showed relatively high accumulation for Cd, Zn and Cu in aerial parts due to high EDTA-extractable metals in the rhizosphere, exhibiting phytoextraction features. In contrast, the flooded genotypes drastically decreased uptake, translocation, accumulation, and extraction capacities for Cd, Zn and Cu in aerial parts, differing with genotypes, and tended to phyto-stabilize them in roots, especially Cu. This study indicated that flooding is a leading factor on phytoremediation efficiency for contaminated sites with willows.

Biochar and compost enhance soil quality and growth of roselle (Hibiscus sabdariffa L.) under saline conditions.

Soil amendments may increase the slate tolerance of plants consequently; it may increase the opportunity of using saline water in agricultural production. In the present pot trial, the effects of biochar (BIC) and compost (COM) on roselle (Hibiscus sabdariffa L.) irrigated with saline water (EC = 7.50 dS m-1) was studied. Roselle plants were amended with biochar (BIC1 and BIC2) or compost (COM1 and COM2) at rates of 1 and 2% (w/w), as well as by a mixture of the two amendments (BIC1+). The experiment included a control soil without any amendments. Biochar and compost significantly enhanced the soil quality and nutrients availability under saline irrigation. Compost and biochar improved the degree of soil aggregation, total soil porosity and soil microbial biomass. BIC1 + COM1 increased the soil microbial biomass carbon and nitrogen over the individual application of each amendments and control soil. BIC1 + COM1 increased the activity of dehydrogenase and phosphatase enzymes. Growth of roselle plants including: plant height, shoot fresh and dry weight, and chlorophyll were significantly responded to the added amendments. The maximum sepal's yield was achieved from the combined application of compost and biochar. All the investigated treatments caused remarkable increases in the total flavonol and anthocyanin. BIC1 + COM1 increased the total anthocyanin and flavonol by 29 and 17% above the control. Despite the notable improvement in soil and roselle quality as a result of the single addition of compost or biochar, there is a clear superiority due to mixing the two amendments. It can be concluded that mixing of biochar and compost is recommended for roselle plants irrigated with saline water.

Comparative Metabolic Profiling in Pulp and Peel of Green and Red Pitayas (Hylocereus polyrhizus and Hylocereus undatus) Reveals Potential Valorization in the Pharmaceutical and Food Industries.

Pitaya (Hylocereus genus) is a popular plant with exotic and nutritious fruit, which has widespread uses as a source of nutrients and raw materials in the pharmaceutical industry. However, the potential of pitaya peel as a natural source of bioactive compounds has not yet fully been explored. Recent advances in metabolomics have paved the way for understanding and evaluating the presence of diverse sets of metabolites in different plant parts. This study is aimed at exploring the diversity of primary and secondary metabolites in two commercial varieties of pitaya, i.e., green pitaya (Hylocereus undatus) and red pitaya (Hylocereus polyrhizus). A total of 433 metabolites were identified using a widely targeted metabolomic approach and classified into nine known diverse classes of metabolites, including flavonoids, amino acids and its derivatives, alkaloids, tannins, phenolic acids, organic acids, nucleotides and derivatives, lipids, and lignans. Red pitaya peel and pulp showed relatively high accumulation of metabolites viz. alkaloids, amino acids and its derivatives, and lipids. Differential metabolite landscape of pitaya fruit indicated the presence of key bioactive compounds, i.e., L-tyrosine, L-valine, DL-norvaline, tryptophan, γ-linolenic acid, and isorhamnetin 3-O-neohesperidoside. The findings in this study provide new insight into the broad spectrum of bioactive compounds of red and green pitaya, emphasizing the valorization of the biowaste pitaya peel as raw material for the pharmaceutical and food industries.

Improving quality of metal-contaminated soils by some halophyte and non-halophyte forage plants.

Toxic elements cause degradation in agricultural land quality. Phytoremediation of polluted sites is the safest technique to sustain ecosystem. Field trial was established to examine the performance of two Atriplex species (A. numularia and A. amnicola) and two traditional forage plants (pearl millet and cowpea) cultivated on polluted sandy soil and clean one. The studied contaminated soil was irrigated with untreated sewage wastewater for more than 60 years and contained Zn, Cu, Pb and Cd levels excessed the permissible limits. The growth of Atriplex plants was not affected by the soil pollution, while the traditional forage plants lost 40-50% of their biomass. The roots biomass of Atriplex plants was higher by 54% than those of cowpea and pearl millet plants. The crude protein (CP) and chlorophyll in the tested species were reduced as a result of soil pollution, but the reduction was higher in pearl millet and cowpea than Atriplex plants. CP in Atriplex plants that were grown in the contaminated soil was reduced by 10%, while in the case of pearl millet and cowpea; the reduction was more than 20%. Atriplex plants were more effective in reducing the metal bioavailability than pearl millet and cowpea. Atriplex plants were able to protect the photosynthesis process in the presence of toxic elements; moreover, they produced some substances that increasing the resistance of toxic metal stress such as proline. The cultivation of metal-contaminated soil with Atriplex plants enhanced the soil quality and increased the aggregation and porosity of soil; besides, it reduced the soil salinity and concentration of toxic elements. Cultivation of halophyte and traditional fodder plants in contaminated lands is a good strategic management of the ecosystem, and the resulting plant may be used to feed animals due to their low content of pollutants or be recycled to soil organic amendments.

Recycling of sugar crop disposal to boost the adaptation of canola (Brassica napus L.) to abiotic stress through different climate zones.

We need to produce higher foods even under declining natural resources to feed the projected population of 9 billion by 2050 and to sustain food security and nutrition. Abiotic stress has adversely affected canola crop and oil quality especially in sandy soils. To combat this stress, adaptation at the farm level using new and cost-effective amendments are required. Field trials were conducted in two different climatic zones to determine the efficacy of cane molasses, bagasse ash, sugar beet factory lime, and their compost mixtures to improve soil quality and heat stress-adapting canola. The results showed a significant improvement in bulk density, hydraulic conductivity, organic matter content, and available macronutrients of sandy soil and subsequent canola growth, yield, quality and water productivity due to the application of the tested soil amendments, particularly those mixed with compost. Despite the estimated reduction of yield by 18.5% due to heat stress, application of sugar beet lime and compost mixture not only compensated for this reduction but also increased the seed yield by 27.0%. These findings highlight the value of recycling compost-based sugar crop disposal as a cost-effective technology to boost crop tolerance to abiotic stress, ensuring sustainable agriculture and food security in arid environments.

A vermicompost and deep tillage system to improve saline-sodic soil quality and wheat productivity.

Land degradation due to soil salinity and sodicity is a serious concern in arid ecosystems. Despite the importance of conservation tillage in carbon sequestration and improving soil properties, its effect on saline-sodic soils under amendment application remains unknown. Therefore, the present study aimed to explore the combined effects of inorganic (sulfuric acid and gypsum) and organic (vermicompost) soil amendments and tillage systems (zero, reduced and deep tillage) on saline-sodic soil properties and wheat productivity. Deep tillage with vermicompost application significantly improved soil physical and chemical properties compared with control. Interestingly, integration between deep tillage and vermicompost decreased soil salinity and sodicity by 37% and 34%, respectively, compared with zero tillage and unamended soils. The application of vermicompost surpassed chemical amendments in the improvement of saline-sodic soils and consequently increased the growth and yield of wheat, provided that deep tillage was used as a suitable tillage system. Although deep tillage reduced soil organic carbon, application of vermicompost not only compensated this reduction, but also significantly increased soil organic carbon. This confirms the potential of combined deep tillage and vermicompost as a method for environmentally reclaiming saline-sodic soils.

Combined Transcriptome and Metabolome analysis of Pitaya fruit unveiled the mechanisms underlying Peel and pulp color formation.

BACKGROUND: Elucidating the candidate genes and key metabolites responsible for pulp and peel coloration is essential for breeding pitaya fruit with new and improved appeal and high nutritional value. Here, we used transcriptome (RNA-Seq) and metabolome analysis (UPLC-MS/MS) to identify structural and regulatory genes and key metabolites associated with peel and pulp colors in three pitaya fruit types belonging to two different Hylocereus species. RESULT: Our combined transcriptome and metabolome analyses suggest that the main strategy for obtaining red color is to increase tyrosine content for downstream steps in the betalain pathway. The upregulation of CYP76ADs is proposed as the color-breaking step leading to red or colorless pulp under the regulation by WRKY44 transcription factor. Supported by the differential accumulation of anthocyanin metabolites in red pulped pitaya fruit, our results showed the regulation of anthocyanin biosynthesis pathway in addition to betalain biosynthesis. However, no color-breaking step for the development of anthocyanins in red pulp was observed and no biosynthesis of anthocyanins in white pulp was found. Together, we propose that red pitaya pulp color is under the strict regulation of CYP76ADs by WRKYs and the anthocyanin coexistence with betalains is unneglectable. We ruled out the possibility of yellow peel color formation due to anthocyanins because of no differential regulation of chalcone synthase genes between yellow and green and no detection of naringenin chalcone in the metabolome. Similarly, the no differential regulation of key genes in the carotenoid pathway controlling yellow pigments proposed that the carotenoid pathway is not involved in yellow peel color formation. CONCLUSIONS: Together, our results propose several candidate genes and metabolites controlling a single horticultural attribute i.e. color formation for further functional characterization. This study presents useful genomic resources and information for breeding pitaya fruit with commercially attractive peel and pulp colors. These findings will greatly complement the existing knowledge on the biosynthesis of natural pigments for their applications in food and health industry.

The integrated effect of salinity, organic amendments, phosphorus fertilizers, and deficit irrigation on soil properties, phosphorus fractionation and wheat productivity.

Soil degradation due to global warming, water scarcity and diminishing natural resources negatively impacts food security. Soil fertility deterioration, particularly phosphorus (P) deficiency, remains a challenge in the arid and semi-arid regions. In this study, field experiments were conducted in different geographical locations to investigate the effects of organic amendments coupled with P fertilization and irrigation on soil physical-chemical properties, and the growth, yield and quality of wheat. Application of P fertilizers combined with organic amendments mitigated soil salinity, increased organic matter content, available water, hydraulic conductivity and available macronutrients, but decreased soil bulk density. Application of organic amendments slightly increased total Cd, Ni and Pb in soil, but Cd and Ni concentration was below allowable limits whilst Pb reached a hazardous level. Soil P fractions were significantly increased with the combined application of mineral P and organic amendments irrespective of salinity and irrigation. Crop growth yield and quality of wheat improved significantly in response to the integrated application of mineral P and organic amendments. In conclusion, the combination of mineral P sources with organic amendments could be successfully used as a cost-effective management practice to enhance soil fertility and crop production in the arid and semi-arid regions stressed with water scarcity and natural resource constraints.

Interactions between cadmium and zinc in uptake, accumulation and bioavailability for Salix integra with respect to phytoremediation.

The willow (Salix spp.) is a potential accumulator of cadmium (Cd)/zinc (Zn), and the interaction between Cd and Zn is an important factor influencing their phytoextraction potentials. In this study, interactions between Cd and Zn in uptake, accumulation and bioavailability for Salix integra clone SI63 were investigated through nutrient solution and soil culture methods. The result of the soil culture showed that Cd had additive effects for Zn-caused biomass reduction. The result from nutrient solution indicated that added Zn showed antagonistic (low Cd level) or synergistic (moderate and high Cd levels) effects on shoot Cd accumulation and antagonistic effects on root Cd accumulation. Irrespective of nutrient solution or soil culture experiment, Cd addition always had antagonistic effects on Zn accumulation in both shoots and roots. Under Cd10Zn50 condition, the clone accumulated higher Cd and Zn concentrations (95 µg g-1 Cd and 165 µg g-1 Zn) in shoots. Cd slightly increased bioavailable Zn in the rhizosphere, and EDTA well predicted bioavailable Cd and Zn in the rhizosphere. Interactions of Cd-Zn markedly changed their respective phytoextraction potentials, especially for Zn. This result will provide a new insight into improving phytoextraction potentials of both Cd and Zn using willows through applying metal interactions.

Differences in uptake and accumulation of copper and zinc by Salix clones under flooded versus non-flooded conditions.

The climate-driven flooding poses a challenge for phytoremediation of contaminated soil, and the willow (Salix spp.) is a promising candidate coping with climate change and environmental pollution. In this study, uptake and accumulation of copper (Cu), zinc (Zn) and their bioavailability in the rhizosphere across the Salix clones under flooded versus non-flooded (control) conditions were investigated using a pot experiment. The tested Salix clones grew well without showing any toxic symptoms under non-flooded soil condition; in contrast, the clones showed 100% survival for long-term flooding with the development of hypertrophied lenticels and adventitious roots. There were wide clonal variations in biomass production and accumulation of Cu and Zn under flooded and non-flooded conditions. Flooded treatments dramatically decreased aboveground biomass across the Salix clones to different extents compared to the control. The non-flooded clones exhibited relatively high accumulation capacities of Cu and Zn in aerial parts. However, the flooded clones resulted in more substantial reductions in Cu and Zn accumulation in aerial parts, and most of Cu and Zn were limited in roots. EDTA-extractable Cu and Zn predicted well bioavailability of Cu and Zn to the Salix clones under the current condition. It was concluded that the Salix clones exhibited Cu and Zn phytoextraction traits (non-flooding) or phytostabilization traits (flooding), which provides a valuable insight into phytomanagement of contaminated soils by willows subjected to flooding stress.