Soil Plant Research Articles

Effects of biochar application on soil properties and the growth of Melissa officinalis L. under salt stress

Soil salinization is one of the world's most seriously ecological issues. The application of biochar may enhance the properties of the soil and lessen the harm that salt stress causes to plants. In this study, we used the cuttings of Melissa officinalis as experimental materials. The method of pot experiment was used to explore to explore the effects of different concentrations of biochar (0, 10 %, and 20 % w/w) on soil properties and plant physiological characteristics under salt stress (0, 0.20 %, and 0.60 % NaCl+Na2SO4). The results indicate that the physicochemical properties of soil and the plant growth were decreased impacted with increasing salinity level, and these negative impacts were decreased traits were improved with the application of biochar. It was discovered that the application of biochar could increase the soil water holding capacity, total porosity, available P and K content, and soil enzyme activity while also decreasing the soil bulk density under salt stress. Biochar addition promoted the accumulation of plant biomass and the acquisition of nutrients, and reduced Na content in plants. With the addition of biochar, malondialdehyde (MDA) content and electrolyte leakage displayed a significant decrease under salt stress. A reduction in the osmotic substances and secondary metabolite accumulation in the leaves was also evident. The presented results reveal that biochar can contribute to protect M. officinalis against salt stress by alleviating the oxidative stress. Among the test samples, the 20 % biochar application had the best performance, suggesting that this is an advantageous method for improving soil properties and lessening the harm caused by salt stress on M. officinalis.

Microbial inoculants using spent mushroom substrates as carriers improve soil multifunctionality and plant growth by changing soil microbial community structure

Peat is typically used as a carrier for microbial inoculants; however, due to its non-renewable nature alternatives need to be identified as reliable and renewable carriers for mineral-solubilizing inoculants. In pot experiments, solid microbial inoculants were comprised of peat (P), biochar (BC), and spent mushroom substrates (SMS) using Medicago sativa L. as experimental materials, and the purpose of this study is to assess the effect of solid microbial inoculants on soil multifunctionality and plant growth. The results revealed that the SMS microbial inoculant had the greatest positive impact on plant biomass and significantly stimulated soil multifunctionality which is typically managed or assessed based on various soil functions or processes that are crucial for sustaining productivity, in contrast to the peat microbial inoculant, particularly at a supply level of 100 g/pot. There was no significant correlation between soil multifunctionality and bacterial/fungal microbial diversity. However, according to the co-occurrence network of bacteria and fungi, soil multifunctionality was intimately correlated with the biodiversity of the main ecological clusters (modules) of bacteria and fungi, rather than to the entire soil microbial community structure. The keystone species of module hubs and connectors play critical roles in maintaining the stability of ecological clusters of microbial co-occurrence networks and linkages between ecological clusters. Soil pH is a major predictor of changes in plant biomass, and leads to changes therein by affecting the major ecological clusters of bacterial and fungal co-occurrence networks. These results suggested that SMS may serve as a good alternative to peat as a carrier of mineral-solubilizing microorganisms to maintain soil multifunctionality and promote plant growth.

Fostering adaptation to climate change among farmers in Pakistan: the influential role of farmers’ climate change knowledge and adaptive capacity

IntroductionAdaptation to climate change (ACC) is imperative to avoid deleterious consequences of climate change in agriculture. However, the uptake of adaptation measures has been slow among farmers because of low adaptive capacity (AC) in developing countries, particularly in Pakistan. Farmers and their supporting institutions have been successful in introducing technological innovations to respond and adapt to environmental challenges. The present study intended to determine the impact of farming technologies, along with human, financial, social, physical, natural, and climate information resources that support AC and hence ACC.MethodsThe study collected data from 360 farmers in Punjab through a multi-stage random sampling technique. A binary logit model and odds ratio were used to identify the factors affecting ACC. The study also utilized correlation tests to show the correlation between each pair of variables included in the analysis.ResultsThe results indicated that physical capital such as ownership of tube wells, transportation, and sowing and harvesting tools by the farmers builds farmers’ AC and consequently determines the ACC such as change crop variety (CCV), change crop type (CCT), change planting date (CPD), soil conservation (SC), water conservation (WC), and diversification strategies (DSs). The findings also revealed that human capital (age, education, family size, and labor), financial capital (off-farm employment, access to the marketing of produce, and agricultural credit), social capital (farmers-to-farmers extensions, access to extension services, and the farm association membership), and natural capital (land ownership, tenancy status, and the location of the farm) were importantly related to farm households’ ACC strategies. The odds (likelihood) of adaptation were higher for the users of farm technology as compared to non-users.DiscussionThe analysis conducted in this study showed that climate information resources amplify the adaptation to climate change: technology allows farming to be much more efficient, while climate change knowledge (CCK) self-motivates farmers to adopt more ACC measures. Our findings provide evidence that suggests the need to provide credits and financial support for farming technologies that speed up the ACC in the long run, while in the short run, climate information should be spread among farming communities.

A biochar-based amendment improved cadmium (Cd) immobilization, reduced its bioaccumulation, and increased rice yield

Cadmium (Cd) contamination of soil threatens human health, food security, and ecosystem sustainability. The in situ stabilization of Cd has been recognized as a potentially economical technology for the remediation of Cd-contaminated soil. Recently, biochar (BC) and activated carbon (AC) have received widespread attention as eco-friendly soil amendments that are more beneficial for plant growth, soil health, and remediation of contaminated soil. An experiment was performed in a paddy field to investigate the effects of two different types of BC (maize straw biochar and bamboo biochar) and AC (coconut shell activated carbon) in combination with rape organic fertilizer (R), calcium magnesium phosphate fertilizer (P), and fulvic acid (F), respectively, on soil Cd immobilization, Cd accumulation in rice, and yield. The results indicated that the BC/AC-based amendments reduced soil bioavailable Cd (DTPA-Cd) and brown rice Cd by 9.58%–27.06% and 19.30%–71.77%, respectively. The transformation of exchangeable Cd (Ex-Cd) to carbonate-bound Cd (Ca-Cd), Fe-Mn oxide bond (Ox-Cd), and residual (Re-Cd) in soil accounted for the mitigation of Cd uptake and enrichment by rice. Additionally, BC-/AC-based amendments altered soil physicochemical properties, which significantly increased the soil pH and cation exchange capacity (CEC), total nitrogen (TN), total phosphorus (TP), soil organic carbon (SOC), and dissolved organic carbon (DOC), directly promoting soil health. All BC-/AC-based amendments significantly increased FeIMP and MnIMP concentrations by 47.31%–160.34% and 25.72%–73.09% in the Fe/Mn plaque (IMP), respectively. Maize straw and bamboo biochar-based amendments significantly increased rice yield by 10.46%–20.41% and 9.94%–16.17%, respectively, while coconut shell-activated carbon severely reduced rice yield by 65.06%–77.14%. The correlation analysis revealed that leaf Cd and IMP primarily controlled Cd uptake by rice, and soil pH, Eh, CEC, SOC, IMP, and TP influenced DTPA-Cd in soil. This field study demonstrated that maize straw and bamboo biochar-based amendments not only reduced soil DTPA-Cd in paddy fields but also decreased the accumulation of Cd in brown rice, as well as improved rice yield, which has potential application in Cd-contaminated agriculture fields. Coconut shell-activated carbon severely decreased rice yields, which is not appropriate for rice production.

Closing the gap: examining the impact of source habitat proximity on plant and soil microbial communities in post-mining spoil heap succession.

Revegetation of barren substrates is often determined by the composition and distance of the nearest plant community, serving as a source of colonizing propagules. Whether such dispersal effect can be observed during the development of soil microbial communities, is not clear. In this study, we aimed to elucidate which factors structure plant and soil bacterial and fungal communities during primary succession on a limestone quarry spoil heap, focusing on the effect of distance to the adjoining xerophilous grassland. We established a grid of 35 plots covering three successional stages - initial barren substrate, early successional community and late successional grassland ecosystem, the latter serving as the primary source of soil colonization. On these plots, we performed vegetation surveys of plant community composition and collected soil cores to analyze soil chemical properties and bacterial and fungal community composition. The composition of early successional plant community was significantly affected by the proximity of the source late successional community, however, the effect weakened when the distance exceeded 20 m. Early successional microbial communities were structured mainly by the local plant community composition and soil chemical properties, with minimal contribution of the source community proximity. These results show that on small spatial scales, species migration is an important determinant of plant community composition during primary succession while the establishment of soil microbial communities is not limited by dispersal and is primarily driven by local biotic and abiotic conditions.

Conversion of Oil Palm Empty Fruit Bunch Fiber Waste into Green Liquid Organic Fertilizer

Solid wastes generated from the oil palm industry contain valuable nutrients like nitrogen, phosphorus, and potassium that can significantly enhance plant growth and potentially elevate fertilizer production. This study aims to identify the optimal formulation of liquid organic fertilizer (LOF) derived from oil palm empty fruit bunch (OPEFB) fiber waste. Three formulations of LOF were prepared, comprising OPEFB waste, molasses, noni fruit, and cattle urine, designated as Formulation A, B, and C. These formulations underwent a 14-day anaerobic incubation period. The formulated OPEFB LOF was then analyzed for nutrient content, electrical conductivity, and total dissolved solids. This study also examines the soil properties and plant growth outcomes following the application of the formulated OPEFB LOF. The results indicated that Formulation A exhibited the highest nutrient concentrations, specifically 485 ppm nitrogen, 95 ppm phosphorus, and 1007 ppm potassium. In comparison to the other two OPEFB LOF formulations, Formulation A showed the lowest values for total dissolved solids (502 ppm) and electrical conductivity (8.14 dS/m). The findings demonstrated that Formulation A displayed the most favorable growth characteristics in terms of leaf count, plant height, leaf length, and leaf width. This is attributed to the nitrogen-boosting properties of cattle urine, along with the complementary effects of molasses and noni fruit as soil improver and bio-activator. This study confirms the viability of utilizing green organic fertilizer derived from OPEFB substrate in agriculture, replacing conventional inorganic fertilizers.

Optimizing nitrogen fertilization in maize: the impact of nitrification inhibitors, phosphorus application, and microbial interactions on enhancing nutrient efficiency and crop performance.

Despite the essential role of nitrogen fertilizers in achieving high crop yields, current application practices often exhibit low efficiency. Optimizing nitrogen (N) fertilization in agriculture is, therefore, critical for enhancing crop productivity while ensuring sustainable food production. This study investigates the effects of nitrification inhibitors (Nis) such as Dimethyl Pyrazole Phosphate (DMPP) and Dimethyl Pyrazole Fulvic Acid (DMPFA), plant growth-promoting bacteria inoculation, and phosphorus (P) application on the soil-plant-microbe system in maize. DMPFA is an organic nitrification inhibitor that combines DMP and fulvic acid for the benefits of both compounds as a chelator. A comprehensive rhizobox experiment was conducted, employing varying levels of P, inoculant types, and Nis, to analyze the influence of these factors on various soil properties, maize fitness, and phenotypic traits, including root architecture and exudate profile. Additionally, the experiment examined the effects of treatments on the bacterial and fungal communities within the rhizosphere and maize roots. Our results showed that the use of Nis improved plant nutrition and biomass. For example, the use of DMPFA as a nitrification inhibitor significantly improved phosphorus use efficiency by up to 29%, increased P content to 37%, and raised P concentration in the shoot by 26%, compared to traditional ammonium treatments. The microbial communities inhabiting maize rhizosphere and roots were also highly influenced by the different treatments. Among them, the N treatment was the major driver in shaping bacterial and fungal communities in both plant compartments. Notably, Nis reduced significantly the abundance of bacterial groups involved in the nitrification process. Moreover, we observed that each experimental treatment employed in this investigation could select, promote, or reduce specific groups of beneficial or detrimental soil microorganisms. Overall, our results highlight the intricate interplay between soil amendments, microbial communities, and plant nutrient dynamics, suggesting that Nis, particularly DMPFA, could be pivotal in bolstering agricultural sustainability by optimizing nutrient utilization.

Increased soil bacteria-fungus interactions promote soil nutrient availability, plant growth, and coexistence

Tree species and interkingdom relationships in the belowground metacommunity are key factors in determining soil microbial diversity and community composition. However, how bacterial-fungal interactions mediate soil nutrient and plant growth remains largely unexplored in the coniferous forests. Here, we selected three types of naturally growing coniferous forests on the Loess Plateau—pure stands of Platycladus orientalis, mixed stands of Platycladus orientalis and Pinus tabuliformis, and pure stands of Pinus tabuliformis—to compare the differences in soil properties, microbial diversity and community composition, soil enzymatic activity, and plant growth conditions across these stand types. We found that tree species mixing significantly alters soil microbial community diversity and composition, increasing the positive associations between bacteria and fungi. Compared to pure stands, mixed stands exhibit significantly higher bacterial diversity, whereas fungal diversity shows no significant difference. Additionally, available soil nutrients (ammonium nitrogen and available phosphorus) are significantly increased in mixed stands, along with their associated soil enzymatic activities. The partial least squares path model suggests that higher bacterial diversity enhances bacterial-fungal positive interactions, increasing the relative abundance of ectomycorrhizal fungi and the decomposition rate of organic matter in mixed stands, thereby boosting soil nutrient availability and plant growth. These results highlight the importance of positive bacterial-fungal associations for soil nutrient availability and plant growth, deepen the understanding of the role of soil microbial interactions in mediating plant species coexistence. Most importantly, our results implied a stable coexistence of the pioneer P. orientalis and the late successional species P. tabuliformis in the Loess Plateau region and provided a microbiological interpretation.

Glyphosate application may influence the transfer of trace elements from soils to both soil solutions and plants

Trace elements dynamics in the soil-plant system depends on multiple parameters, including chelating organic compounds from natural or synthetic organic matters. In this study, we evaluated the influence of one of the most common pesticides—glyphosate—on the mobility of trace elements considering contrasted soils (uncontaminated, anthropogenically contaminated, and naturally-enriched) in a greenhouse experiment. Four modalities have been tested: one control without any application, two with different glyphosate doses (1 and 3 times the authorised field dose), and one with compost addition to evaluate its potential ability to mitigate the impact of glyphosate on trace element mobility. Both, trace element and glyphosate concentrations were measured in the soil solutions and trace element contents were determined in plants at the end of the experiment. The results showed that, although glyphosate concentrations rapidly decreased in soil solutions, glyphosate application still influenced the transfer of trace elements to both soil solution (up to 12-times higher) and plant (up to 5.2-times higher). This influence was highly dependent on both the specific elements and the type of soils considered. For instance, in uncontaminated soils, glyphosate especially increased the mobilization of Mn, Co, Zn, Mo, and Pb to soil solution. This effect diminished of 2.5 times on average with increasing soil contamination. A similar trend was observed for the transfer of trace elements from soil to plant (i.e., on average 2.2-times lower in the most contaminated compared to the uncontaminated soil). However, in the naturally-enriched soil, opposing trends were noted between soil solutions and plants. The impact of compost addition on the transfer of trace elements to plants remains unclear: compost enhanced the transfer of trace elements to soil solution in uncontaminated and naturally-enriched soils likely due to trace element input through the compost, but decreased the transfer in anthropogenically-contaminated soils likely due to adsorption processes. Therefore, glyphosate could potentially increase the exposure of trace elements through food consumption and their transfer to the ecosystem, particularly in uncontaminated and weakly contaminated soils. In highly contaminated soils, compost could mitigate the glyphosate-induced enhancement of trace element mobility to soil solutions.

Edible vegetables grown in the vicinity of electronic wastes: A study of potential health risks and DNA damage in consumers

There has been a growing concern on the health effect of edible plants growing near/on/within the vicinity of dumpsites. This study investigated two edible vegetables: Amarathus hybridus and Talinum triangulare (Jacq) grown in the vicinity of a major informal dumpsite of electronic waste in Nigeria. The levels of polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and heavy metal concentrations in the vegetables were measured. The health risks of consuming the vegetables were assessed using the hazard index (HI), lifetime cancer risk (LCR), estimated daily intake (EDI), and hazard quotient (HQ). Using the Ames Salmonella fluctuation test on Salmonella typhimurium (TA100 and TA98) and the SOS chromo test on Escherichia coli (PQ37), the mutagenicity and genotoxicity of the vegetables were evaluated. The two vegetables have elevated levels of heavy metals, PBDEs, PCBs, and hazardous PAHs. Compared to A. hybridus, T. triangulare was more contaminated. The amounts of organic constituents and heavy metals in the vegetables correlated favorably. The levels of the HQ, HI, and LCR were above the suggested guideline values, indicating a significant risk of both carcinogenic and non-carcinogenic consequences, particularly in children. The two vegetables were mutagenic even at 50 % concentration in the Ames test. This was corroborated with SOS-chromo test results showing that the two vegetables were indeed genotoxic. This study demonstrated the harmful effects of growing food crops close to dumpsites; therefore, sufficient measures should be implemented to stop farmers and individuals from utilizing dirt from dumps as fertilizer or from planting in soil that has been used as a dump in the past or present.

Influence of indole acetic acid and trehalose, with and without zinc oxide nanoparticles coated urea on tomato growth in nitrogen deficient soils

Nitrogen deficiency in low organic matter soils significantly reduces crop yield and plant health. The effects of foliar applications of indole acetic acid (IAA), trehalose (TA), and nanoparticles-coated urea (NPCU) on the growth and physiological attributes of tomatoes in nitrogen-deficient soil are not well documented in the literature. This study aims to explore the influence of IAA, TA, and NPCU on tomato plants in nitrogen-deficient soil. Treatments included control, 2mM IAA, 0.1% TA, and 2mM IAA + 0.1% TA, applied with and without NPCU. Results showed that 2mM IAA + 0.1% TA with NPCU significantly improved shoot length (~ 30%), root length (~ 63%), plant fresh (~ 48%) and dry weight (~ 48%), number of leaves (~ 38%), and leaf area (~ 58%) compared to control (NPCU only). Additionally, significant improvements in chlorophyll content, total protein, and total soluble sugar, along with a decrease in antioxidant activity (POD, SOD, CAT, and APX), validated the effectiveness of 2mM IAA + 0.1% TA with NPCU. The combined application of 2mM IAA + 0.1% TA with NPCU can be recommended as an effective strategy to enhance tomato growth and yield in nitrogen-deficient soils. This approach can be integrated into current agricultural practices to improve crop resilience and productivity, especially in regions with poor soil fertility. To confirm the efficacy of 2mM IAA + 0.1% TA with NPCU in various crops and climatic conditions, additional field studies are required.

Ammonium nutrition enhances rhizosphere mobilization and uptake of silicon in white lupin grown in low phosphorus soil

Abstract Background and Aims While nitrogen (N) supply can enhance plant silicon (Si) accumulation, the mechanisms by which different forms of N affect Si mobilization in the rhizosphere are not well understood. This study aims to elucidate how pH changes induced by ammonium (NH4+) and nitrate (NO3−) affect Si availability in the rhizosphere, especially under low phosphorus (P) conditions. Methods White lupin (Lupinus albus) plants were grown in non-fertilized low-P soil, supplied with a low dose of N, either as NH4+ or NO3−, with or without supply of monosilicic acid. We measured Si levels in various rhizosphere soil pools, along with different plant and rhizosphere soil parameters. Results The addition of NH4+ significantly lowered rhizosphere pH and decreased both Si adsorbed to pedogenic Fe/Mn oxides and amorphous phytogenic Si, resulting in higher concentrations of plant available Si in the white lupin rhizosphere. This led to greater Si uptake and improved plant growth compared to both the –N and + NO3− treatments. The supply of Si further enhanced these effects, with NH4+ showing a consistently different pattern of influence compared to NO3−. Additionally, –N white lupin plants accumulated more P than those treated with N, while Si supply significantly improved P acquisition across all treatments. Conclusions Our study demonstrates that rhizosphere acidification induced by NH4+ nutrition can significantly enhance Si mobilization from the rhizosphere soil in the absence of Si supply and reduce Si adsorption when Si is applied. These findings may have practical implications for improving both Si mobilization in the rhizosphere and the effectiveness of Si fertilizers.

PhytOC sequestration characteristics and phytolith carbon sink capacity of the karst grasslands in southwest China

Grassland is an important component of terrestrial ecosystems and plays a crucial role in the global carbon cycle. PhytOC (phytolith-occluded organic carbon) is an extremely important long-term and stable carbon pool in terrestrial ecosystems. Southwest China karst soil exhibits obvious characteristics of alkalinity, high silicon content, and rich calcium, which can significantly influence the characteristics and mechanisms of PhytOC sequestration in vegetation. To elucidate the sequestration characteristics and mechanisms of PhytOC in the karst grasslands, three typical karst grasslands of tropical shrub tussock (TST), warm-temperate shrub tussock (WST), and mountain meadow (MM) from Guizhou province of southwest China were studied. The following results and conclusions were obtained that: 1) the range of PhytOC content of aboveground plant parts, underground roots, and soil in the karst grasslands was 4.03–16.54 g·kg−1, 10.67–33.92 g·kg−1, and 0.63–1.89 g·kg−1, respectively. The underground roots are an important site for phytolith carbon sequestration in grassland ecosystems, and the PhytOC content of underground roots may be higher than that of the aboveground parts. 2) The PhytOC sequestration rate of vegetation was 7.34–15.93 kg·ha−1·yr−1, and the annual sequestration amount of PhytOC of the whole grasslands in southwest China could reach 0.48 × 103–1.48 × 103 t CO2. Compared to grasslands in non-karst regions of China, karst grasslands in southwest China have a higher sequestration rate of PhytOC in vegetation and a greater capacity for phytolith carbon sequestration. 3) Soil available silicon, pH, and stoichiometric characteristics of C, N and P nutrients significantly affected the phytolith carbon sequestration of vegetation and the soil accumulation of PhytOC in the karst grasslands. The research results are of great significance for estimating the phytolith carbon sequestration capacity of grassland ecosystems and for grassland construction and management based on enhancing carbon sequestration.

Effects of short-term nitrogen addition on the recovery of alpine grassland in the Tianshan Mountains of Xinjiang, China.

The restoration of alpine grasslands has garnered significant attention across various sectors. Historically, natural restoration has been the primary approach for grassland recovery, characterized by its prolonged duration. To expedite the recovery of degraded grasslands, it is essential to identify the limiting factors of restoration, enabling efficient and rapid recovery. Appropriate nitrogen (N) addition levels have been considered a potential strategy to enhance the recovery of grassland ecosystems and augment their ecological benefits. However, the effectiveness of N addition in alpine grassland restoration remains debated. This study investigated the impact of five N addition levels (CK: control [0 g/m2]; LN: low N [5 g/m2]; MN: medium N [10 g/m2]; HN: high N [15 g/m2]; SN: severe N [20 g/m2]) and two experimental approaches (N addition once per year [NPY] and three times per year [NTY] at the same dosages) on plant and soil properties and the maximum restoration capacity of alpine meadows. Our findings reveal three key insights: The level of N addition was the primary factor influencing aboveground plant biomass and coverage. Plant diversity decreased under the NTY regime and increased with NPY in the Bayinbruck grassland. N addition significantly altered soil properties, including pH, salinity, soil organic carbon (SOC), soil-available phosphorus (AP), and soil total phosphorus (TP). Notably, soil TP, total nitrogen (TN), and AP substantially impacted plant community structure and diversity. Based on structural equation model (SEM) and analysis of variance (ANOVA), optimal grassland restoration was achieved with the HN (15 g/m2) treatment under NPY and the MN and HN (10 and 15 g/m2) treatments under NTY. Overall, our study offers crucial insights into the conservation, management, and restoration of grassland ecosystems on the Bayinbruck Plateau. It underscores the significance of N addition effects on plant communities, vegetation restoration, and soil properties.

Divergent apparent temperature sensitivity of forest-floor respiration across a managed boreal forest landscape

Understanding the apparent temperature sensitivity (Q10) of forest floor respiration (Q10Rff) and its plant autotrophic (Q10Ra) and soil heterotrophic (Q10Rh) components is critical for determining the strength and direction of forest carbon cycle-climate feedbacks. However, the spatial variability of Q10Rff and its controlling factors across the spatially heterogeneous boreal forest landscape remains poorly understood. In this study, we used chamber-based respiration measurements conducted on paired natural and trenching plots over three growing seasons (2016–2018) to determine Q10Rff, Q10Rh and Q10Ra to soil temperature across 50 diverse forest stands (ranging 5–211 years old) in a managed landscape in northern Sweden. Additionally, we estimated ecosystem- and landscape-scale Q10 based on conventional and tall tower eddy covariance measurements, respectively, conducted over the same landscape. Our results suggest manifold variations (i.e., 10th to 90th percentiles) of Q10Rff (1.7 to 6.6), with Q10Ra (0.9 to 7.4) showing a greater range than Q10Rh (1.6 to 5.3). Forest-floor understory biomass was the main control of variations in Q10Ra, whereas soil properties explained best those of Q10Rh. Furthermore, a seasonal hysteresis of Q10Rff was observed, with higher values mostly occurring during the late growing season. The magnitude of this hysteresis scaled with stand age in response to concurrent changes in net primary production. The Q10Rff to air temperature declined with increasing stand age, which was attributed to the increased decoupling of air and soil temperatures with canopy development. Despite the considerable stand-level variations, when averaged over the 50 forest stands, Q10Rff to air temperature converged with that of both ecosystem- and landscape-scale respiration. In conclusion, our study highlights the complexity of Q10Rff, which needs to be considered in predictions of the interactions of climate change and management with the carbon cycle of managed boreal forests.

Streptomyces improves sugarcane drought tolerance by enhancing phenylalanine biosynthesis and optimizing the rhizosphere environment

Drought stress is a common hazard faced by sugarcane growth, and utilizing microorganisms to enhance plant tolerance to abiotic stress has become an important method for sustainable agricultural development. Several studies have demonstrated that Streptomyces chartreuses WZS021 improves sugarcane tolerance to drought stress. However, the molecular mechanisms underlying tolerance at the transcriptional and metabolomic levels remain unclear. We comprehensively evaluated the physiological and molecular mechanisms by which WZS021 enhances drought tolerance in sugarcane, by performing transcriptome sequencing and non-targeted metabolomics; and examining rhizosphere soil properties and plant tissue antioxidant capacity. WZS021 inoculation improved the rhizosphere nutritional environment (AP, ammonia, OM) of sugarcane and enhanced the antioxidant capacity of plant roots, stems, and leaves (POD, SOD, CAT). Comprehensive analyses of the transcriptome and metabolome revealed that WZS021 mainly affects plant drought tolerance through phenylalanine metabolism, plant hormone signal transduction, and flavonoid biosynthesis pathways. The drought tolerance signaling molecules mediated by WZS021 include petunidin, salicylic acid, α-Linoleic acid, auxin, geranylgeraniol and phenylalanine, as well as key genes related to plant hormone signaling transduction (YUCCA, amiE, AUX, CYPs, PAL, etc.). Interestingly, inoculation with WZS021 during regular watering induces a transcriptome-level response to biological stress in sugarcane plants. This study further elucidates a WZS021-dependent rhizosphere-mediated regulatory mechanism for improving sugarcane drought tolerance, providing a theoretical basis for increasing sugarcane production capacity.

Soil Amendment with Biochar Reduces the Magnitude of Drought Stress in Soybean

Drought stress severely affects plant growth and causes huge economic losses worldwide. The beneficial effect of biochar to improve soil properties and plant growth is well discussed nowadays. To investigate biochar’s potential for drought stress mitigation, a two-factorial pot experiment was conducted. Factor one was drought stress (100% Field capacity (FC), 70% FC, and 40% FC) and another was biochar treatment. Cow dung biochar (CDB) and poultry manure biochar (PMB) was applied at three rates (0, 4 and 8 g pot−1). The experiment was designed following a completely randomized design with four replicates. The results showed that drought deteriorated all the studied parameters whereas biochar application significantly improved all the parameters compared to control treatment. The chlorophyll concentration was maximum at the application of CDB as 8 g pot−1 followed by PMB as 8 g pot−1 at both drought conditions (70% FC and 40% FC). Biochar application significantly improved plant height at 28 and 42 days after sowing and the highest plant height was found at the application CDB as 8 g pot−1 followed by PMB as 8 g pot−1. The highest leaflet number was found at the application of CDB at a rate of 8 g pot−1. On average, the root length and biomass at 70% and 40% FC was the highest at the application of 8 g CDB pot−1 which was 28.66% and 61.59% higher, respectively over control. The application of CDB at a rate of 8 g pot−1 increased the shoot biomass by 45.35 and 69.52% compared to control at 70% FC and 40% FC, respectively. Therefore, application of biochar could be an option to reduce drought stress in plants. J Bangladesh Agril Univ 22(3): 317-325, 2024

DIGITAL TOOLS FOR MONITORING AND MANAGEMENT IN AGRICULTURAL PRODUCTION

The digitalization of agricultural production has led to the widespread use of mobile technologies for monitoring and managing agricultural processes. Applications and devices such as drones and satellites allow you to receive real-time data on soil conditions, humidity, plant growth, and pest threats. This data helps farmers to make quick decisions on irrigation, fertilization, and crop forecasting. Modern mobile solutions such as AgroMonitor integrate with various data sources and provide accurate information, which increases the efficiency of resource management and reduces production risks. The introduction of these technologies not only helps to increase yields but also ensures the sustainable development of agricultural operations, minimizing the impact of external factors. Thus, digital tools are becoming an important element of the modernization of the agro-industrial sector, contributing to its competitiveness at the global level.

Transport, pollution, and health risk of heavy metals in “soil-medicinal and edible plant-human” system: A case study of farmland around the Beiya mining area in Yunnan, China

Heavy metals (HMs) pose a significant threat to soil quality, plant growth, and human health. However, the impacts (transport, pollution, and health risk) of HMs in medicinal and edible plants with rich value growing in high background soil for a long time remain unclear. So the effects of HMs on the “soil-medicinal and edible plant-human” system were comprehensively studied. Houttuynia cordata Thunb. (HCT) and growing soil were collected from the farmland around Beiya mining area located in Three Parallel Rivers of Yunnan Protected Areas, China. The transport, pollution, and health risks of HMs in the system were investigated by determining the content of active ingredients, HMs, and physicochemical properties in HCT and soil. The results of comprehensive analysis using various measurement and analysis methods showed that Zn, Cu, Mn, and Co in soil could affect the contents of available nutrients (available P (AP), available K (AK), and organic matter (OM)), while AP, OM, pH, Co, and Fe in soil were closely related to the formation of HCT quality. Cr and Fe had the strongest transport capacity in stems and leaves of HCT, respectively. Furthermore, it is worth noting that Cr, Pb, and Cu had caused serious pollution to HCT in the area. Pb and Cu are tolerable levels for human health and may pose a carcinogenic risk. Our study demonstrates that HCT is expected to be a marker of heavy metal pollution in the area and provides a scientific basis for making effective regulations on HMs control and scientific planting.

Accumulation and Distribution of Heavy Metals in Soils and Medicinal Plants in the Impact Zone of Novocherkassk Power Station

Accumulation and Distribution of Heavy Metals in Soils and Medicinal Plants in the Impact Zone of Novocherkassk Power Station