Plant Root Activity Research Articles

Effects of Seafood Mushroom Spent Substrate Solid-State Fermentation Combined with PGPR as a Microbial Fertilizer on the Soil Environment and Growth Promotion of Cenchrus fungigraminus

PurposeCareless burning, discarding, or overfertilization of spent mushroom substrate (SMS) is environmentally harmful. The reuse of SMS resources is a matter of concern.MethodsSpent seafood mushroom substrate solid-state fermentation combined with Rhizobium pusense solution was added to soil to evaluate its environmental and Cenchrus fungigraminus seedling growth effects in pot trial experiments.ResultsThe 40% fermented seafood mushroom SMS (fresh weight) with R. pusense treatment had significantly higher total nitrogen (TN), ammonium nitrogen (AMN), organic matter, etc., and decreased soil electrical conductivity (EC) and increased pH compared with other treatment. Soil catalase (CAT), dehydrogenase (DHA), and urease (UE) activities were significantly improved; there were no differences in CAT and UE activities between 40% (T4) and 50% (T5) SMS additions. C. fungigraminus seedling height and leaf length increased gradually and were significantly different from those of the positive control. The 30–50% seafood mushroom SMS treatment increased plant TN by 5.76–10.00% and total phosphorus by 15.44–16.55%. Plant root length and root activity peaked in T4; however, plant split root number and root activity in T5 decreased by 43.96% and 26.97% compared with those in T4. According to Pearson correlation and one-dimensional regression analyses, the seafood mushroom SMS content affected fertility > enzyme activity > plant growth. Principal component analysis and redundancy analysis showed that the effect of the seafood mushroom SMS concentration on the soil environment was mainly reflected in plant aboveground and root activity.ConclusionsUnder an SMS addition amount of 40%, plant growth-promoting rhizobacteria promoted the growth of C. fungigraminus seedlings to a greater extent.

ORGANIC FERTILIZER'S ROLE IN THE IMPROVEMENT OF SOIL MICROFLORA AND BIOMETRIC VALUES IN FRUIT CROPS

Intensive farming has adversely affected soil fertility and ecosystems due to excessive chemicalization in the Kazakhstan Republic. The soil lacks organic matter, leading to declining fertility. Biologization has emerged to address this issue as a solution to improve soil fertility and enhance the growth and development of crop plants. This study aimed to determine the impact of organic fertilizers on the composition of soil microflora and biometric values in cultivating stone and pome fruits. The use of microbiological methods analyzed soil microflora and physiological bacterial groups. The research’s novelty lies in developing a technology that utilizes organic fertilizers and biological products to improve the activities of soil microorganisms and plant roots’ nutrition. Organic fertilizers ‘Bio juice Energy Plus’ and ‘Agroflorin’ positively influenced beneficial bacteria and fungi and significantly contributed to soil enrichment. Organic fertilizers and biological products support soil biological processes and replenish the nutrients, promoting sustainable agricultural productivity and reducing chemical dependency. The current study emphasizes the potential of organic fertilizers and natural products in enhancing soil fertility and supporting plant growth in Kazakhstan. Biologization also offers an eco-friendly approach to agricultural practices, ensuring agronomic productivity and the long-term good health of soils.

Plant development alters the nitrogen cycle in subsurface flow constructed wetlands: Implications to the strategies for intensified treatment performance

Plant development greatly influences the composition structure and functions of microbial community in constructed wetlands (CWs) via plant root activities. However, our knowledge of the effect of plant development on microbial nitrogen (N) cycle is poorly understood. Here, we investigated the N removal performance and microbial structure in subsurface flow CWs at three time points corresponding to distinct stages of plant development: seedling, mature and wilting. Overall, the water parameters were profoundly affected by plant development with the increased root activities including radial oxygen loss (ROL) and root exudates (REs). The removal efficiency of NH4+-N was significantly highest at the mature stage (p < 0.01), while the removal performance of NO3−-N at the seedling stage. The highest relative abundances of nitrification- and anammox-related microbes (Nitrospira, Nitrosomonas, and Candidatus Brocadia, etc.) and functional genes (Amo, Hdh, and Hzs) were observed in CWs at the mature stage, which can be attributed to the enhanced intensity of ROL, creating micro-habitat with high DO concentration. On the other hand, the highest relative abundances of denitrification- and DNRA-related microbes (Petrimonas, Geobacter, and Pseudomonas, etc.) and functional genes (Nxr, Nir, and Nar, etc.) were observed in CWs at the seedling and wilting stages, which can be explained by the absence of ROL and biological denitrification inhibitor derived from REs. Results give insights into microbial N cycle in CWs with different stages of plant development. More importantly, a potential solution for intensified N removal via the combination of practical operation and natural regulation is proposed.

The Use of rhizobia and vesicular-arbuscular mycorrhiza to improve drought resistance of Kudzu (Pueraria phaseoloides (Roxb.)Benth.) in coastal land

A study was conducted to examine the association between Rhizobium and VAM fungi on the kudzu plant growth and response to drought stress in coastal dry land. The research was carried out in three phases: (1) germination of kudzu seeds; (2) multiplication of VAM and Rhizobia inoculums; and (3) inoculation of fungi and/or bacteria on plants grown at various soil moisture content. At the inoculation phase, the pot experiment was carried out for 8 weeks with a pot experiment arranged based on a 4 x 4 treatment factorial Completely Randomized Design with three replications to test the source of the inoculum and soil moisture content (25%, 50%, 75%, 100%). Observations were made on: (1) Rhizobial infection activity and nodulation; (2) VAM infection activity; (3) plant growth, and 4) population dynamics of rhizobacteria. The results showed that the rhizobia inoculation alone was not able to increase the bacterial infection activity and root nodulation, the VAM fungal infection, and plant growth. Inoculation with VAM fungi alone was able to stimulate infection activity of nodule-forming bacteria and root nodulation, VAM fungal infection activity, and plant growth. The combination of VAM fungal and rhizobial inoculation was able to stimulate fungal infection activity and growth of plant roots and shoots, but not always able to stimulate bacterial infection activity and root nodulation. Inoculation of VAM fungi alone was able to stimulate the plant growth rates even up to a drought stress level of 75%. This means that inoculation of VAM fungi alone was able to increase drought resistance and maintain the plant growth rates at high levels of drought stress.

Fertiliser supplementation with a biostimulant complex of fish hydrolysate, Aloe vera extract, and kelp alters cannabis root architecture to enhance nutrient uptake

Biostimulants are non-nutritive fertiliser additives which have demonstrated improvements to growth outputs of various agricultural crops. As a result, they have gained attention as sustainable components in cultivation practices, particularly in the rapidly emerging cannabis spheres, including medicinal and industrial cannabis cultivation. One point of focus to cannabis cultivators is the plant's efficiency of nutrient utilisation, attributed to the growth vigour and activity of roots. Despite the interest in this topic, due to the concealment of plant roots within substrates, exploration of plant roots is generally challenging and as such has hampered understanding of the impacts of biostimulants to plant root activity and associated nutrient utilisation efficiency. This project aimed to characterise the impacts and modes of action of the biostimulants kelp, Aloe vera extract, and fish hydrolysate to cannabis growth through exploration of their impacts individually, and as a biostimulant complex (BC). To overcome the limitations of root analyses, substrate-free hydroponic growth systems such as aeroponics, deep water culture (DWC), and the Root-TRAPR system were utilized. These systems allowed for the measurement of changes in root architecture and nutrient utilisation induced by the biostimulants. The results demonstrated that application of BC significantly enhanced root development, as indicated by increased root branching (P = 0.038) and increased total length (P = 0.046). In addition, BC treatment resulted in significant increases in the uptake of phosphorous (P = 0.038) and potassium (P = 0.040) by the plant. Metabolite and phytohormone profiling revealed that kelp and Aloe vera extract induced general plant stress-response mechanisms, whilst fish hydrolysate induced mechanisms associated with the plant pathogen defence response. However, when applied together as BC, the induced molecular mechanisms were associated with phosphorous deficiency without induction of general stress response mechanisms, potentially driving the increased uptake of phosphorous observed. These novel characterisations of biostimulant mechanisms and efficacies provide valuable insights to establishing optimised usage of biostimulants within cannabis cultivation, leading to increased production efficiency through sustainable practises.

Unveiling the potential of nanobubbles in water: Impacts on tomato's early growth and soil properties

Nanobubbles (NBs) in water have been proven to improve plant growth and seed germination, potentially reducing both water and fertilizer consumption. To unravel the promotion mechanism of NBs on plant growth, this study investigated the characteristics of NBs in tap water and their impacts on tomato's early growth, soil chemical properties, enzymatic activity and electrochemical properties of plant roots. Oxygen NBs (ONBs) were found to increase the seed germination by 10 % and plant growth by 30 %–50 % (e.g., stem and diameter), whereas nitrogen NBs (NNBs) only had a significant promotion (7 %–34 %) on plant height. Additionally, compared to control group, irrigation with ONBs increased the peroxidase activities by 500 %–1000 % in tomato leaves, which may increase the expression of genes for peroxidase and promote cell proliferation and plant growth. Moreover, electrical impedance spectroscopy (EIS) revealed that the ONBs could reduce the interfacial impedance due to the increased active surface area and electrical conductivity of root.

The migration and transformation processes of dissolved organic matter in rainwater- drip water- phreatic water of a typical karst spring catchment, in South China

The dissolved organic matter (DOM) migration and transformation in karst aquifer are of great significance for geochemical processes but remain poorly understood. In this study, we selected the Guilin Yaji Karst Experimental Site as a natural laboratory and collected rainwater (RW), drip water (DW), and phreatic water (PW) from September 2019 to September 2021 to study the DOM migration and transformation in a typical bare karst spring catchment. Hydrochemical and stable hydrogen and oxygen isotopes were applied to study the water cycle of the aquifer. Absorbance and fluorescence spectroscopy were used to characterize the DOM quality. Three-dimensional fluorescence combined with fluorescence regional integration was used for identifying the DOM compositions. The RW DOM had a weak humification degree and strong terrestrial characteristics. It was affected by the monsoon and showed higher humification in the dry season than in the wet season. The higher rainfall intensity had a dilution effect on the DOM fluorescence components levels when the rain intensity was>10 mm/day (not the threshold value). Continuous rain events led to the continuous dilution effect on RW DOM in the dry season, but such a phenomenon was not obvious in the wet season. The DW DOM inherited weak humification characteristic that was close to RW DOM but was altered by the hydrogeology conditions and plant root and microbial activities intensities of the upper vadose zone. The higher humification degree of PW DOM may be related to the higher degree of microbial processing caused by the longer groundwater residence time. The humic and hydrophobic degree of DOM for fissure PW was weaker than that for conduit PW because fissure media provides a superior condition for DOM to adsorb to the mineral surface. In the wet season, when the preferential channel of the aquifer was activated, the PW DOM showed similar characteristics to RW DOM, indicating a significant hydrologic effect on the PW DOM. Our results provide a valuable reference to advance understanding of DOM behavior in karst aquifer and highlight the importance of hydrogeologic conditions and hydrologic processes on DOM migration and transformation.

Growth rate is a dominant factor predicting the rhizosphere effect.

The root microbiome is shaped by plant root activity, which selects specific microbial taxa from the surrounding soil. This influence on the microorganisms and soil chemistry in the immediate vicinity of the roots has been referred to as the rhizosphere effect. Understanding the traits that make bacteria successful in the rhizosphere is critical for developing sustainable agriculture solutions. In this study, we compared the growth rate potential, a complex trait that can be predicted from bacterial genome sequences, to functional traits encoded by proteins. We analyzed 84 paired rhizosphere- and soil-derived 16S rRNA gene amplicon datasets from 18 different plants and soil types, performed differential abundance analysis, and estimated growth rates for each bacterial genus. We found that bacteria with higher growth rate potential consistently dominated the rhizosphere, and this trend was confirmed in different bacterial phyla using genome sequences of 3270 bacterial isolates and 6707 metagenome-assembled genomes (MAGs) from 1121 plant- and soil-associated metagenomes. We then identified which functional traits were enriched in MAGs according to their niche or growth rate status. We found that predicted growth rate potential was the main feature for differentiating rhizosphere and soil bacteria in machine learning models, and we then analyzed the features that were important for achieving faster growth rates, which makes bacteria more competitive in the rhizosphere. As growth rate potential can be predicted from genomic data, this work has implications for understanding bacterial community assembly in the rhizosphere, where many uncultivated bacteria reside.

Solid and modified biochars mitigate root cell lignification and improve nutrients uptake in mint plants under fluoride and cadmium stresses

Lignification is a physiological process that reduces pollutants' entrance into plant root cells via blocking apoplastic pathways. The closure of apoplastic pathways can also decrease the nutrients’ uptake by roots. Application of biochar as an efficient soil amendment might be useful in increasing nutrients influx into root cells by decreasing lignification. Therefore, this experiment was performed to examine the conceivable effects of biochar forms [solid and chemically altered biochars with H2O2, KOH and H3PO4 (25 g biochar forms kg−1 soil)] on modifying lignification process and nutrients uptake by mint (Mentha crispa L.) plants under toxicity of cadmium and fluoride. The biochar treatments boosted plant root growth and activity as well as the real content and maximum sorption capacity of Zn, Fe, Mg, and Ca under stressful conditions. In contrast, biochar treatments increased root cell viability and reduced fluoride and cadmium contents, and oxidative damages under stressful conditions. The biochar treatments decreased the activity of phenylalanine ammonia-lyase and peroxidase enzymes under toxic conditions, which led to a decrease in the contents of lignin and its monomers (p-hydroxybenzaldehyde, guaiacyl, and syringaldehyde) in the roots. Solid biochar was less effective than engineered biochars in reducing root cell lignification. Therefore, addition of biochar forms to the soil could be an effective way to reduce root cell lignification and enhance nutrients uptake by plants under cadmium and fluoride toxicities.

Root vertical spatial stress: A method for enhancing rhizosphere effect of plants in subsurface flow constructed wetland

The depth of the substrate of subsurface flow (SSF) constructed wetlands (CWs) is closely related to their cost and operation stability. To explore the physiological regulation mechanism of wetland plants and pollutant removal potential of SSF CWs under “vertical spatial stress of roots” (by greatly reducing the depth of the substrate in SSF CWs to limit the vertical growth space of roots, VSSR), the physiological response and wetland purification effect of a 0.1 m Canna indica L. CW under VSSR were studied compared with conventional SSF CWs (0.6 m, 1.2 m). The results demonstrated that VSSR significantly enhanced the dissolved oxygen (DO) concentration (p < 0.05) within the SSF CWs, with the DO in 0.1 m CW remaining stable at over 3 mg/L. Under the same hydraulic retention time (HRT), VSSR significantly improved the removal effect of pollutants (p < 0.05). The removal rates of COD, NH4+-N, and total phosphorus (TP) remained above 87%, and the mean removal rates of total nitrogen (TN) reached 91.71%. VSSR promoted the morphological adaptation mechanisms of plants, such as significantly increased root-shoot ratio (p < 0.05), changed biomass allocation. Plants could maintain the stability of the photosynthetic mechanism by changing the distribution of light energy. The results of microbial community function prediction demonstrated that aerobic denitrification was the main mechanism of N transformation in the 0.1 m CW under VSSR. VSSR could induce the high root activity of plants, augment the concentration of root exudates, enhance the redox environment of the plant rhizosphere, further foster the enrichment of aerobic denitrifying bacteria, and strengthen the absorption efficiency of wetland plants and substrate, thus achieving an efficient pollutant removal capacity. Studies showed that VSSR was an effective means to enhance the rhizosphere effect of plants and pollutant removal in SSF CWs.

Arbuscular mycorrhizal fungus Rhizophagus irregularis alleviates drought stress in soybean with overexpressing the GmSPL9d gene by promoting photosynthetic apparatus and regulating the antioxidant system

Drought is the most destructive abiotic stress and negatively affects crop growth and productivity. Modern breeding efforts have produced numerous cultivars with distinct genetic traits that improve crop growth and drought stress tolerance. Arbuscular mycorrhizal fungi (AMF) can enhance drought tolerance in soybean plants by directly providing nutrients to plants, promoting photosynthesis, or influencing interspecific plant interactions in natural communities. However, the interactions between AMF and wild and transgenic soybean genotypes remain unclear. Therefore, in the present study, we evaluated the effect of arbuscular mycorrhizal fungi on the growth performance of drought-stressed transgenic soybean lines (ZXOE-11 and ZXOE-13) overexpressing GmSPL9d gene and their wild soybean Tianlong 1 (TL1) at the seedling stage (45 d after sowing). The results showed that colonization of wild and transgenic soybean with Rhizophagus irregularis significantly decreased the adverse effects of drought on plant growth. AMF inoculation significantly increased plant biomass, root activity, chlorophyll metabolism, photosynthesis, and chlorophyll fluorescence in wild-type and transgenic plants under both control and drought stress conditions. Drought causes the production of ROS, such as hydrogen peroxide, which enhances MDA, thereby decreasing the membrane stability index (MSI). However, AMF-inoculated plants exhibited decreased ROS accumulation and increased MSI. Moreover, AMF treatment significantly improved osmolyte, nitrogen, and nitrate reductase activity under control and drought conditions, which increased the relative water content. Furthermore, AMF treatment enhanced the antioxidant systems of drought-stressed plants by increasing the activities of peroxidase, superoxide dismutase, catalase, and ascorbate peroxidase. AMF improved the growth performance, photosynthesis, and antioxidant activity of transgenic plants under drought stress conditions. The present findings indicate that the AMF contribution to soybean seedling drought tolerance was more significant for the transgenic plants than for the wild plants under drought conditions. The current findings emphasize the possibility of growth and photosynthetic variation in the degree of AMF-associated drought resistance in soybean plants. Our findings suggest that future crop breeding challenges include developing cultivars for sustainable production and maximizing crop cultivar and fungal species (AMF) combinations in drought-stressed regions.

Towards a better and more complete understanding of microbial nitrogen transformation processes in the rhizosphere of subsurface flow constructed wetlands: Effect of plant root activities

Plant rhizosphere is the most active hotspot for microbial nitrogen (N) removal in constructed wetlands (CWs), but the effects of plant root activities (i.e., radial oxygen loss, ROL and root exudates, REs) on different microbial N transformation processes, including nitrification, denitrification, anaerobic ammonia oxidation (anammox) and dissimilatory nitrate reduction to ammonia (DNRA) have not been comprehensively studied. In this study, N removal performance and transformation processes in the rhizosphere of CWs were investigated using rhizobox, planar optode system, and metagenomic approaches. Results suggested nitrification was promoted in the rhizosphere, due to the high dissolved oxygen (DO) concentration caused by ROL and the humic acid-like substance in REs, making the rhizosphere a higher removal efficiency of NH4+-N than in the nonrhizosphere. Out of expectation, the denitrification process was not promoted by the REs, the potential “carbon source”, but inhibited by the high DO concentration in the rhizosphere and the phenol-like substance (a kind of biological denitrification inhibitor) in REs. In addition, both anammox and DNRA processes were, for the first time, found to be inhibited in the rhizosphere. The humic acid-like substance in REs and ammonia-oxidation production hydroxylamine inhibited the activity of anammox microorganisms and genes, and there was a symbiotic relationship between anammox microorganisms and DNRA microorganisms. This study provides better and more complete insights into the biogeochemical cycle of N occurred in the rhizosphere of CWs.

Enhanced Nutrients Removal from Eutrophic Water by Aerobic Denitrifiers Assisting Floating Plants

Accelerated eutrophication is one of the most serious problems confronting freshwater systems worldwide. More effective methods to reduce nutrients from eutrophic water with high nitrogen but low carbon source are now urgently needed. In this study, the methods of floating plant remediation and aerobic denitrification were combined for seeking an effective strategy. Four aerobic denitrifying bacteria were adopted. Each strain was co-cultured with Eichhornia crassipes, and then the effects of different combinations on the removal of nitrogen and phosphorus were compared. Meanwhile, their impacts on the growth and physiological characteristics of plants were also measured. The results showed that the association of aerobic denitrifying bacteria with E. crassipes was effective in enhancing the simultaneous removal of nitrogen and phosphorus. E. crassipes helped bacteria to eliminate the accumulation of nitrites under the condition of limited carbon sources. Cooperation between Rhizobium rosettiformans and E. crassipes exhibited the best remediation performance. The four aerobic denitrifying bacteria increased the plant growth and phosphorus content, and had different effects on the plant root activity, leaf chlorophyll, leaf soluble sugar and leaf soluble protein concentration. Although the overall nutrients removal efficiency was greatly improved by the synergic association, the percentage contribution of plant uptake remained constant.

Study on the water level ecological amplitude of the wetland plant Triarrhena lularioriparia

Water level plays an important role in the growth and development of wetland plants. To study the ecological responses of the growth and physiology of Triarrhena lularioriparia under different water levels, seedlings were used as the study materials and in 13 water level gradient treatment groups, −67, −54, −42, −34, −29, −16, −3.5, 10, 20, 30, 40, 50, 60 cm. The results showed that (1) the plant height, leaf number and root activity of T. lularioriparia first increased and then decreased with the increment of the water level gradient, and the highest values appeared at a water level of approximately 0 cm; (2) the concentrations of chlorophyll a (Chl a), chlorophyll b (Chl b), chlorophyll (a + b) (Chl a + b) and biomass first increased and then decreased with the increment of the water level gradient. The malondialdehyde (MDA) and antioxidant enzyme concentrations of T. lularioriparia first increased and then decreased, and both reached their maximums at a water level of approximately 20 cm. The soluble protein decreased and then increased with the change in the water level gradient and reached its lowest value at 31 cm; soluble protein increased slightly at 30–40 cm but showed a stable trend after the waterlogging depth exceeded 40 cm. (3) The water level ecological amplitude of T. lularioriparia was [−38.62, 41.07 cm], and the optimum water level ecological amplitude was [−11.04, 20.15 cm]. This study demonstrates that T. lularioriparia could adapt to drought and flooding stress to a certain extent, but it could be stressed if the water level exceeded the suitable range.

Effects of the dual inoculation of dark septate endophytes and Trichoderma koningiopsis on blueberry growth and rhizosphere soil microorganisms.

Blueberry is a shallow root plant in which the absorption of nutrients is inefficient, resulting in slow growth under artificial cultivation conditions. Endophytes play an important role in promoting plant growth; however, the effects of Trichoderma spp. and dark septate endophytes (DSEs) on host plant growth and soil microorganisms are still debatable. We isolated two endophytic fungal species, Trichoderma koningiopsis (TK) and a DSE (Amesia nigricolor; AN), from blueberry roots, which can solubilize insoluble phosphorus and produce amylase and cellulase to promote plant growth. We found that under dual inoculation, the colonization rate and colonization intensity of TK were higher than they were under single inoculation with TK, while the colonization rate and colonization intensity of AN were lower under dual inoculation than under single inoculation with AN. The plant nutrients, root activity, available potassium, and parts of soil phosphatase activities were highest under dual inoculation. TK inoculation resulted in the highest diversity and richness in the soil fungi and bacteria, followed by dual inoculation. The abundance of Ascomycota, Acidobacteriae, Firmicutes, and Actinobacteriota increased significantly, resulting in Trichoderma and Vicinamibacteria inoculated with TK, Chaetomium and Alicyclobacillales inoculated with AN, and Hypocreales and Burkholderiaceae with dual inoculation enriched in the soil.

Silicon enhances plant resistance to Fusarium wilt by promoting antioxidant potential and photosynthetic capacity in cucumber (Cucumis sativus L.).

Fusarium wilt, caused by Fusarium oxysporum f. sp. cucumerinum (Fo), is a severe soil-borne disease affecting cucumber production worldwide, particularly under monocropping in greenhouses. Silicon (Si) plays an important role in improving the resistance of crops to Fusarium wilt, but the underlying mechanism is largely unclear. Here, an in vitro study showed that 3 mmol·l-1 Si had the best inhibitory effect on the mycelial growth of F. oxysporum in potato dextrose agar (PDA) culture for 7 days. Subsequently, the occurrence of cucumber wilt disease and its mechanisms were investigated upon treatments with exogenous silicon under soil culture. The plant height, stem diameter, root length, and root activity under Si+Fo treatment increased significantly by 39.53%, 94.87%, 74.32%, and 95.11% compared with Fo only. Importantly, the control efficiency of Si+Fo was 69.31% compared with that of Fo treatment. Compared with Fo, the activities of peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) significantly increased by 148.92%, 26.47%, and 58.54%, while the contents of H2O2, , and malondialdehyde (MDA) notably decreased by 21.67%, 59.67%, and 38.701%, respectively, in roots of cucumber plants treated with Si + Fo. Compared with Fo treatment, the net photosynthesis rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), maximum RuBisCO carboxylation rates (Vcmax), maximum RuBP regeneration rates (Jmax), and activities of ribulose-1,5-bisphosphate carboxylase (RuBisCO), fructose-1,6-bisphosphatase (FBPase), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and the expression of FBPA, TPI, SBPase, and FBPase in Si+Fo treatment increased significantly. Furthermore, Si alleviated stomatal closure and enhanced endogenous silicon content compared with only Fo inoculation. The study results suggest that exogenous silicon application improves cucumber resistance to Fusarium wilt by stimulating the antioxidant system, photosynthetic capacity, and stomatal movement in cucumber leaves. This study brings new insights into the potential of Si application in boosting cucumber resistance against Fusarium wilt with a bright prospect for Si use in cucumber production under greenhouse conditions.

EFFECT OF RICE PLANT ROOT TTC-REDUCING ACTIVITY ON THE CHEMICAL FORM OF IODINE IN CULTIVATED SOIL SOLUTIONS

Abstract This study aimed to evaluate the effect of rice plant root activity on the chemical form of stable iodine (I) in a cultivated soil solution. Concentrations of I−, IO3− and organic-I were analyzed 4 days after exposure I− or IO3− solutions to each of the cultivated soil surface. When exposed to I−, its concentration in the cultivated soil was approximately the same as that in the non-planted soil. When the rhizosphere was exposed to IO3−, the I− concentration in the soil increased under cultivation conditions. IO3− remained undetected in the soil solution. The organic-I concentration in the cultivated soil solution was higher than that in the non-cultivated soil. Concentrations of organic-I increased under IO3− addition compared to I− addition. A weak positive correlation was observed between the TTC-reducing activity of plant roots, and the total and organic-I concentrations in the soil solution. It was suggested that the amount of organic I formed from IO3− was determined by the reducing activity of the roots.

Fate of carbamazepine and its effect on physiological characteristics of wetland plant species in the hydroponic system

Plants play a cardinal role in removing various pollutants through the synergistic interaction with filling materials and microbes of constructed wetlands (CWs). However, the information regarding the selection of plant species to remove pharmaceutically active compounds (PhACs) is not adequate. The present study attempted to select an appropriate plant species for CWs, considering their characteristics and physiological response to PhACs. In this regard, batch hydroponics studies were carried out to assess the removal, fate, and antioxidative response of carbamazepine (CBZ) in four wetland plant species (Canna indica, Colocasia esculenta, Phragmites australis, and Chrysopogon zizanioides). The specific uptake potential of CBZ (in terms of plant dry biomass) was found to be in the order: C. indica (14.48 mg/g) >P. australis (11.71 mg/g) >C. esculenta (8.67 mg/g) >C. zizanioides (6.04 mg/g). The results showed that exposure to CBZ (0–30 days) caused an accumulation of reactive oxygen species (ROS) in the plant tissues, causing a decline in chlorophyll content, root activity, and increased oxidative stress. However, the selected plants could recover from the oxidative damages to a certain extent in the recuperation phase (31–60 days). C. indica exhibited relatively lesser ROS accumulation and oxidative damage during the experimental phase than other selected plants. The study also showed that plant biomass, transpiration rate, chlorophyll content, root exudates, and root activity influenced the removal of CBZ by various plants (r – 0.76 to 0.98, P < 0.05). The mass balance analysis indicated that a significant proportion of CBZ (49.2 to 72.7 %) underwent metabolism in the plant tissues. Apart from higher removal, lesser accumulation, and lower oxidation stress, multi-criteria decision analysis showed that C. indica is a potential plant species for the removal of CBZ.

Phytoremediation of bauxite wastewater potentiality by Jatropa curcas.

Bauxite wastewater creates soil contamination and produces toxic effects on human health such as respiratory and skin rash problems. In this study, we investigated the phytoremediation ability of Jatropha curcas to remove bauxite wastewater from soil. Pot experiments were conducted to investigate the bauxite wastewater on the phytoremediation potential of J. curcas grown in contaminated soils. J. curcas exhibited a significant increase in plant growth leaf, root activity, plant height, and plant shoot when grown in bauxite contaminated soils compared with J. curcas grown in uncontaminated soils after 30 d treatment. Under bauxite exposure, a higher aluminium removal (88.5%) was observed in soils planted with J. curcas than unplanted soils (39.6%). The bioconcentration factor was also found to be 5.62, indicating that J. curcas have great tolerance and hyperaccumulator of aluminium under high aluminium concentrations and are capable of phytoextraction of soil contaminated with bauxite wastewater.

Phytoremediation of chromium, iron and nickel by Indian Rice Plant (Oryza sativa L.): An opportunity for management of multi-metal contaminated tannery wastewaterPhytoremediation of chromium, iron and nickel by Indian Rice Plant (Oryza sativa L.): An opportunity for management of multi-metal contaminated tannery wastewater

India is the largest producer of leather and leather products. Tannery industries use a large number of synthetic chemicals for the processing of leather and generate a huge amount of wastewater containing a large amount of potentially toxic heavy metals (PTHMs) making them problematic for next-door soil and water system. Currently, phytoremediation is an inexpensive green technology used to move, eradicate, and stabilized heavy metal contamination from contaminated sludge, soil, and wastewater. In this study, the accumulation and distribution of PTHMs found in tannery wastewater and their physio-biochemical effects on Oryza sativa L. have been studied by ICP-MS, GC-MS, and biochemical analysis. The plant was grown in the soil spiked with a mixture of metals (Cr, Fe and Ni) and their five-level of treatment T1 (25mg/kg); T2 (50mg/kg); T3 (100mg/kg); T4 (200mg/kg) and T5 (400mg/kg). During the experiments, various morphological attributes, oxidative stress, enzymatic activities, chlorophyll, and protein content at the different stage was measured. Further, metal accumulation pattern in different parts of plants was also measured. Results of the study revealed that plant root, shoot length, chlorophyll content, and enzymatic activities were significantly reduced after the treatment with 200 mg/kg PTHMs; whereas oxidative stress was increase compared to control levels. Further, treatment of PTHMs suggested that the rice plant (Oryza sativa L.) is well adapted to tolerate and accumulate a high level of heavy metals (up to 200mg/kg) in the root and shoot of the treated plants. If it is treated above this, then seeds were also affected and not safe for human consumption.