Pot Study Research Articles

Biochar and Dairy Manure Amendment Effects on Cynodon dactylon Performance and Soil Properties.

Studies have determined the separate effects of biochar (BC) and manure application on forage species and soil, but few examined the effects of BCs made from different feedstock applied along with dairy manure. We compared the effect of wood- and manure-derived feedstock BC as well as dairy manure amendment application on Cynodon dactylon performance and soil properties in sandy loam and clay loam soils in a greenhouse pot study. Plant samples were assayed for herbage and root dry weight as well as herbage and root N and C percent and yield. Soil samples were assayed for macronutrients, micronutrients, metals, pH and conductivity. Data analyses involved variance analysis and Tukey's tests using R in RStudio (the IDE). In general, C. dactylon yields or mineral content were not affected by either manure or BC. However, an increase in the total herbage dry weight (30%) and in herbage N% (55%) was observed for clay loam and sandy loam soil, respectively, due to manure amendment application. There were no alterations in clay loam NO3-N and P due to any treatment; however, in sandy loam, these nutrients were not altered only when wood BC was applied. In sandy loam soil, NO3-N and P increased when manure BC along with dairy manure and when manure BC alone were applied, respectively. Thus, wood BC application should be considered to avoid these nutrient buildups when dairy manure is used as a soil amendment. This research shows a neutral (BC) or positive (dairy manure amendment) impact on C. dactylon performance. BC incorporation increases soil total C, showing potential for C sequestration. Long-term field trials could corroborate plant performance and soil parameters.

Optimizing nutrients from fly ash-amended soil through microbial-assisted phytoremediation using response surface methodology.

Nutrients are vital ingredients to boost plant health. The availability of nutrients is limited in fly ash (FA) waste to properly implement phytoremediation. The research explored the integration of microbes and treated wastewater irrigation in phytoremediation to provide the necessary nutrients for plant growth in fly ash-amended soils. The Box-Behnken method was used to design the experimental layout for the pot study. Response surface methodology (RSM) was applied as the optimization approach to model predictions for nutrient accumulation. The implemented pot study attained the highest morphological indicators with a plastochron index of 33.40, an absolute growth rate of 2.63 cm/day, and a leaf area of 2681.68 cm2 and attained maximum biomass of 24.91 g for the treatments that included a mid-range of the variables. The combination of FA 14.98%, microbial dose 4.07 mL, and treated wastewater as the irrigation source was found to be the optimized combination for nitrogen and phosphorus accumulation of 212.4 and 8.867 mg/L.

Novel use pattern of pendimethalin for annual ryegrass (Lolium rigidum Gaudin) control in wheat and barley

Annual ryegrass (Lolium rigidum Gaudin) is a problematic weed in most of the cropping regions in Australia. Evolved herbicide resistance to multiple modes of action groups, the lack of new herbicidal molecules, and the emergence of late cohorts in winter season crops necessitate the use of existing herbicides in an innovative way to control L. rigidum. Pendimethalin as pre-emergence (PRE) is used for L. rigidum control; however, it is unable to control late cohorts of L. rigidum in winter season crops. Pot studies were conducted from 2019 to 2021 to evaluate the effect of a post-emergence (POST) application of pendimethalin with six doses (0, 220, 440, 880, 1,760, and 3,520 g a.i. ha-1) on L. rigidum control in addition to crop safety in wheat, barley, and sorghum. POST application of pendimethalin was found to be safe for wheat and barley, and the biomass reduction in both crops at varied rates (220 to 3,520 g ha−1) of pendimethalin ranged from 10% to 20%. A dose–response study revealed that the pendimethalin dose required for 50% mortality and growth reduction of L. rigidum was 179 and 144 g ai ha−1, respectively. Pendimethalin at 880 g ai ha−1 completely killed late cohorts of L. rigidum. These results suggest that the POST application of pendimethalin can be used for the effective control of late cohorts of L. rigidum in wheat and barley crops. POST application of pendimethalin suppressed the biomass of sorghum plants compared with the non-treated control treatment, and biomass reduction in sorghum at different pendimethalin doses ranged from 32% to 40%. Results implied that POST applications of pendimethalin in wheat and barley can diversify herbicide programs in managing L. rigidum and may help in delaying the evolution of resistance in this weed.

Eco-friendly nano-enabled fertilizers derived from date industry waste for sustainable and controlled-release of P, K and Mg nutrients: sorption mechanisms, controlled-release performance and kinetics

Development of nano-enabled fertilizers from green waste is one of the effective options to enhance global agricultural productions and minimize environmental pollution. In this study, novel, eco-friendly and cost-effective nano- enabled fertilizers (NEF) were synthesized using the planetary ball milling procedure. The NEF (nDPF1and nDPF2) were prepared by impregnation of nanostructured date palm pits (nDPP) with (KH2PO4 + MgO) at 1:1 and 3:1 (w/w) ratios respectively. The nDPP, nDPF1 and nDPF2 were extensively characterized. The produced nano-fertilizers enhanced soil water retention capacity with nDPF2 being the most effective. The water retention capacity of nDPF2 treated soil was 5.6 times higher than that of soil treated with conventional fertilizers. In addition, the nDPF2 exhibited superior sustained lower release rates of P, K and Mg nutrients for longer release periods in comparison with the conventional fertilizers. For instance, P cumulative release percentages from conventional fertilizers, nDPF1 and nDPF2 in soil reached 22.41%, 10.82 and 8.9% respectively within 384 h. Findings from FTIR and XPS analyses suggested that hydrogen bonding and ligand exchange were the main interaction mechanisms of PO4-K-Mg ions with nDPP surface. The released kinetics data of the NEF revealed that power function was the best suitable model to describe the kinetics of P, K and Mg release data from NEF in water and soil. Pot study ascertained that the nano-enabled fertilizers (nDPF1 and nDPF2) significantly promoted biomass production and nutrient uptake of maize plants as compared to commercial fertilizer treated plants. The present work demonstrated the potential of NEF to increase nutrients uptake efficiency, mitigate moisture retention problem in arid soils and reduce nutrients loss through leaching and safeguard the environment.Graphical

Drought response and recovery mechanisms of grapevine rootstocks grafted to a common Vitis vinifera scion

As grapevine production is converting into irrigated systems worldwide, understanding rootstock-scion interactions at different stages of moderate drought can help to better manage water resources and the choice of rootstock. This study compared the physio-morphological drought response and recovery of a drought-sensitive (Riparia Gloire (Vitis riparia)) and a drought-tolerant rootstock (Ramsey (Vitis champinii)) grafted with Cabernet Sauvignon (Vitis vinifera), and the self-grafted control in a pot study. Ramsey had lower root-to-shoot ratio but higher performance of the root system under drought, explained by the lower root tissue density and tip suberization and higher VviPIP2;1 aquaporin expression, and faster recovery of root hydraulic conductivity and stomatal conductance after re-watering than Riparia. Riparia maintained better water status under moderate drought by early root suberization, but it was less able to restore water uptake capacity and support scion growth and leaf gas exchange after re-watering. This study shows a suite of rootstock traits that improve scion growth in response to moderate drought. Thus, these results identify traits for breeding programs and the selection of rootstocks for sustainable management of water resources under irrigated production.

Comparative Liming Power of Chicken Manure and Selected Dolomitic Sources on an Acidic High Altitude Burundi Surface Soil

A research initiative was set up to evaluate the comparative liming power of locally available dolomitic products and chicken manure, using an amaranth (Amaranthus viridis L.) test crop. The soil used was acidic, of low % base saturation and risks of Al toxicity, deficient in available P, exchangeable Mg, Ca and K. The experimental setup was a completely randomized design with 11 treatments and 3 replicates which included: a control treatment (equivalent to 100 kg DAP/ha), 4 mineral amendments (Moso Lime, Moso Ground Dolomite, Bubanza Ground Dolomite and Busiga Ground Dolomite) applied at equivalents of 1 T/ha and 2 T/ha, and chicken manure applied at equivalent of 10 and 20 T/ha. The study duration was three months withthree test crop harvests at one-month interval. Monthly measured plant growth and production parameters were plant height, root length, shoot length, root biomass, shoot biomass and their summation (total biomass). Soil pH, available P and exchangeable acidity (Al3++ H+) were assessed at the start and the completion of the pot study. Obtained results could be summarized as follows: (i) the highest available P accumulation was associated with the equivalent of 20 T/ha of chicken manure; (ii) application of equivalents 20 T/ha of chicken manure, 2 T/ha Moso Ground Dolomite and 2 T/ha Moso Lime increased soil pH by 0.2 to 0.5 pH-unitsand reduced exchangeable acdity ; (ii) DAP fertilized treatment was characterised by the lowest pH value and the highest Al3+and H+exchangeable acidity, illustrating the acidifying effect of this NH4+-bearing fertilizer; (iv) amarant growth (root and height) and biomass (root + shoot) production were highest with 20 T/ha chicken manure, 2 T/ha Moso Ground Dolomite and 2 T/haMoso lime. Application rate was only statisticallt detectable for Moso Ground Dolomite (+ 162 %) and chicken manure (+ 182 %). Overall, 20 T/ha chicken manure showed the highest and most stable amaranth root + shoot biomass yields, demonstrating its potential residual effect, which should be evaluated and confirmed under field conditions.

Isolation and characterization of rhizobacteria from lentil for arsenic resistance and plant growth promotion.

Low-cost microbial remediation strategies serve as a viable and potent weapon for curbing the arsenic menace. In the present study, two arsenic-resistant bacteria were isolated from the contaminated lentil rhizosphere in Gangetic plain of eastern India. LAR-21 (Burkholderia cepacia, MW356875) and LAR-25 (Burkholderia cenocepacia, MW356894) could remove 87.6% and 85.9% of arsenite (10mM) from the liquid culture medium in laboratory condition. They were highly resistant to arsenate and arsenite and also had a high arsenite oxidase activity. LAR-21 showed the highest level of minimum inhibitory concentration value of 390mM for arsenate and 31mM for arsenite. The same strain was found to show highest arsenite oxidase activity, i.e., 5.2nMmin-1mg-1of protein. These two strains further possess potential plant growth-promoting characteristics like indole acetic acid production (5-15mMIAAmL-1), 1-aminocyclopropane-1-carboxylate deaminase (8-21nMα-ketobutyratemgprotein-1h-1), nitrogenase activity (3-8.99nMethylenemgcellprotein-1h-1), siderophore production (17-22.1µMdeferoxaminemesylatemL-1), phosphate solubilization (261-453µgmL-1) under arsenic stress condition. The plant growth promotion of the strains was further validated by pot study of lentil by assessing their agronomic and growth-related traits, and potential to recover from arsenic stress (17.2-21.2% arsenic reduction in root and shoot, 16-19.2% in leaf and pod, and 15-23% reduction in seeds). The LAR-21 strain, thus, emerged as the most suited candidate for bioremediation and plant (lentil) growth promotion in arsenic polluted environment.

Resistance mechanisms of cereal plants and rhizosphere soil microbial communities to chromium stress.

Agricultural soils contaminated with heavy metals poison crops and disturb the normal functioning of rhizosphere microbial communities. Different crops and rhizosphere microbial communities exhibit different heavy metal resistance mechanisms. Here, indoor pot studies were used to assess the mechanisms of grain and soil rhizosphere microbial communities on chromium (Cr) stress. Millet grain variety 'Jingu 21' (Setaria italica) and soil samples were collected prior to control (CK), 6 hours after (Cr_6h), and 6 days following (Cr_6d) Cr stress. Transcriptomic analysis, high-throughput sequencing and quantitative polymerase chain reaction (qPCR) were used for sample determination and data analysis. Cr stress inhibited the expression of genes related to cell division, and photosynthesis in grain plants while stimulating the expression of genes related to DNA replication and repair, in addition to plant defense systems resist Cr stress. In response to chromium stress, rhizosphere soil bacterial and fungal community compositions and diversity changed significantly (p<0.05). Both bacterial and fungal co-occurrence networks primarily comprised positively correlated edges that would serve to increase community stability. However, bacterial community networks were larger than fungal community networks and were more tightly connected and less modular than fungal networks. The abundances of C/N functional genes exhibited increasing trends with increased Cr exposure. Overall, these results suggest that Cr stress primarily prevented cereal seedlings from completing photosynthesis, cell division, and proliferation while simultaneously triggering plant defense mechanisms to resist the toxic effects of Cr. Soil bacterial and fungal populations exhibited diverse response traits, community-assembly mechanisms, and increased expression of functional genes related to carbon and nitrogen cycling, all of which are likely related to microbial survival during Cr stress. This study provides new insights into resistance mechanisms, microbial community structures, and mechanisms of C/N functional genes responses in cereal plants to heavy metal contaminated agricultural soils. Portions of this text were previously published as part of a preprint (https://www.researchsquare.com/article/rs-2891904/v1).

Arbuscular mycorrhizal fungi on the development and copper content in corn and sorghum plants.

The concentration of copper in the soil increased with the intensification of agricultural activities, mainly in grape production areas and orchards as a result of the application of pesticides. Arbuscular mycorrhizal fungi make up the microbial biomass of the soil and appear as an alternative to be researched for the development of plants in an environment contaminated with copper. The purpose of this pot study was to analyze the influence of arbuscular mycorrhizal fungi on the development and content of copper in corn and sorghum plants. Soil treatments were: without inoculum (control) and two arbuscular mycorrhizal (Acaulospora scrobiculata and Rhizoglomus clarum) and five doses of copper (0, 100, 200, 300, and 400 mg Cu kg-1 soil); with seven repetitions. Plant height, stem diameter, number of tillers, root volume, shoot and root dry weight yields, shoot, root and grain Cu concentrations, pseudo-total soil Cu, percentage of mycorrhizal colonization and relative mycorrhizal efficiency index in reducing Cu concentration in root and shoot of corn and sorgum were evaluated. Morphological parameters of sorghum and corn were reduced with at high Cu doses in the soil, and the inoculation with Acaulospora scrobiculata and Rhizoglomus clarum resulted in greater development and lower Cu concentration in the dry mass of the shoot and root parts sorghum and corn plants.

Growth Performance of Soybean (Glycine max L. Merrill) treated with biochar under cadmium Stress

Cadmium (Cd) is a non-essential heavy metal that adversely affects plant growth. Biochar is predicted to facilitate plant growth. Under cadmium stress condition the effects of biochar on Soybean seedling growth, biomass production and SPAD value were poorly understood. In the current pot study Soybean was grown under different biochar and Cd combinations: 0% biochar and no Cd (control), 1.5% biochar, Cd (100 mg kg-1 of soil), Cd (100 mg kg-1 of soil) + 1.5% biochar. The results exhibited that under Cd stress shoot fresh weight (SFW), root fresh weight (RFW), shoot dry weight (SDW), root dry weight (RDW), shoot length (SL), root length (RL), whole plant biomass, stress tolerance index (%) and SPAD value decreased in Soybean, while root and shoot length ratio increased in comparison to control. Application of biochar solely or in addition of Cd enhanced SFW (14.07% with solely and 126.44% with Cd); RFW, SDW, RDW, SL and RL (156.66%, 55.89%, 61.29%, 21.14% and 16.62% with Cd, respectively), whole plant biomass (8.41% with sole biochar and 137.77% with Cd) and SPAD value (34.94% with Cd) in Cd-stressed Soybean. The sole application of biochar or Cd increased stress tolerance index (%) (SFSTI, RFSTI, SDSTI, RDSTI, SLSTI and RLSTIas recorded 114.04%, 92.25%, 104.47%, 105.78%, 100.73% and 99.22%, respectively; SFSTI, RFSTI, SDSTI, RDSTI, SLSTI and RLSTIvalue by 125.90%, 156.67%, 55.79%, 61.31%, 30.16% and 16.62% with Cd, respectively) in Cd-stressed Soybean. These results demonstrate that soil amendment with 1.5% biocharenhanced growth, biomass production and SPAD value of Soybean under Cd stress. It is therefore recommended that biochar can be used as effective tool to mitigate the detrimental effect of Cd stress on Soybean seedlings. South Asian J. Agric., Vol. 9, No.1&amp;2, 2022-‘23: 22-30

Ameliorative Effect of Different Amendments on Nutrients Availability in Sodic Soils

A pot house experiment was conducted at the Net House, Regional Research Station, AAU, Anand during rabi season of 2018-19 on Wheat (GW-496) as a indicator crop. Total four amendments i.e. A0(control), A1(Gypsum @ 50% GR), A2(Vermi-compost @ 4.0 t ha-1) and A3 (sulphur @ 50 kg ha-1) and six soils type (S1 to S6) were selected under Factorial CRD. Pot study results indicated that the soil amendments significantly decreased the pH, EC and ESP of sodic soils. The order of decrease in pH of sodic soils from 8.75 to 7.89 by application of amendments remained as: vermin-compost &gt; sulphur &gt; gypsum. The EC of sodic soils significantly decreased due to application of vermin-compost and gypsum by 20.48% and 10.84%, respectively over control. The application of vermin-compost, gypsum and sulphur significantly lowered down Exchangeable Sodium Percentage (ESP) from 18.45 to 12.44, 13.00 and 13.57, respectively, and the effect of gypsum was found at par with sulphur in decreasing soil ESP. Application of vermin-compost (4.0 t ha-1) significantly influenced CEC (28.28 Cmol (P+) kg-1) over control (no amendment). Irrespective of amendments, soil S5 recorded the highest pH (8.39), EC (0.92 dSm-1), ESP (16.48) and the lowest was in soil S6 (pH 7.99, EC 0.64 dSm-1). The interaction of soil x amendment treatments showed significant effects on pH, EC and ESP of sodic soils. The application of amendments showed significant effect on available nutrients in soil after harvest of wheat and the highest OC (0.73%), available P2O5 (65.71 kg ha-1), available K2O (207.1 kg ha-1) content in soil was recorded when vermin-compost applied at 4.0 t ha-1 followed by sulphur at 50 kg ha-1 and gypsum at 50% GR but available S (16.33 mg kg-1) was recorded the highest due to sulphur application at 50 kg ha-1 followed by gypsum and vermi-compost.

Impact of water stress during reproductive development on seed dormancy in Bromus diandrus Roth and Lolium rigidum Gaudin

Context Bromus diandrus Roth and Lolium rigidum Gaudin are important weeds of cereal-based cropping systems of Australian agriculture. Adaptation to environmental stresses, protracted seed germination and herbicide resistance have made these weeds serious threats to crop production. Aims Studies were undertaken to determine the impact of moisture stress during reproductive development on the extent of seed dormancy and the expression of genes involved with gibberellic acid and abscisic acid synthesis. Methodology A pot study was undertaken at two locations, with two populations each of B. diandrus and L. rigidum. Water stress was applied from either the GS31 or GS60 stage until seed maturation, along with a well-watered treatment. Seeds of stressed vs well-watered treatments were assessed for seed dormancy and the expression of ABA1 and GA20ox genes using quantitative polymerase chain reaction. Results The seeds from GS31 treatment, where plants experienced the longest water stress, were most dormant in both weed species. Water stress treatments altered the expression of the GA20ox gene, which was correlated with the level of dormancy in seeds of B. diandrus and L. rigidum. Conclusions This investigation has provided clear evidence of the impact of water stress on seed dormancy and on expression of genes involved in regulating seed dormancy in these weed species. Implications As spring rainfall in the Australian agricultural landscape is highly variable, weeds are likely to experience variable levels of water stress during reproductive development, which in turn is likely to influence seed dormancy, weed seedling emergence and effectiveness of pre-sowing weed management next season.

Efficacy of bokashi-composting methods and quality assessment of organic fertilizers on spinach (Spinacia oleracea L.)

Raw materials of corn stalk and Japanese watercress at four volumetric ratios of 4:1, 3:1, 2:1, 1:2 were composted for 40 days using compost (PP compost) and bokashi (PP bokashi) methods. The quality of organic fertilizer products as solid (RComp) and liquid (LComp &amp; LBoka) was analyzed for physico-chemical properties and initially evaluated for spinach (Spinacia oleracea L.) in a pot study. The single-factor experiment was arranged in a completely randomized design with seven treatments and three replications. The treatments differed in application rates, types and dilution of liquid organic fertilizers. The PP compost had a thermophilic phase (t &gt; 40oC) lasting for 15 days, which was three times longer than the PP bokashi. Accordingly, RComp(2:1) had a high EC (electrical conductivity) value (3.8 mS/cm) and organic matter (77.7%), and macronutrient concentrations of total N, available phosphorus and potassium were 26.3 g/kg, 13.6 g P2O5/kg and 63.0 g K2O/kg, respectively. Total aerobic plate counts in LComp(2:1) reached 2.5 × 107 CFU/mL. Meanwhile, L Boka(1:2) had an EC value of 19.8 mS/cm, and nutrient concentrations of total N, available phosphorus and potassium were 0.35 g N/kg, 0.09 g P2O5/kg and 9.93 g K2O/kg, respectively. Total humic and fulvic acids in LBoka(1:2) reached 2,300 mg/kg. The results of the trial rate of 0.5 kg RComp/m2 as a single or combined application with LComp(2:1) and LBoka(1:2) at diluted concentrations of total dissolved solids (TDS) 500 ppm gave a similar performance of plant heights, number of leaves, and yields of 1,278.9 - 1,425.7 g/m2, and were significantly different from those of the control treatment (526.8 g/m2).

DISCOVERING THE POTENTIAL IMPACT OF SELENIUM TO ALLEVIATE DROUGHT STRESS IN BARLEY (HORDEUM VULGARE L.) VIA PHYSIOLOGICAL INTERFERENCES

Drought stress is a significant environmental issue that directly impacts plant growth and development by limiting water availability and affecting the overall health of plants. However, innovative solutions are needed to protect plant health and productivity against this significant environmental issue by using all available techniques. By considering this major issue, the pot study aimed to check the potential of foliar application of selenium @ 10mM on various morphological, physiological, and yield aspects of two barley cultivars viz. Jau-17 and Sultan-17 under three different field capacities, including 100%, 75%, and 50% FC, respectively. The results showed maximum plant growth reduction was noticed at 50% FC in both barley cultivars. Interestingly, selenium helped to boost proline content, relative water content (RWC), SPAD chlorophyll, leaf area index (LAI) while it helped to decrease excised leaf water lose (ELWL), membrane thermostability index (MTSI) under drought stress conditions. In addition, various plant morphological and yield-related components were improved by selenium application under drought conditions. Among cultivars, Jau-17 gave the best results in stress tolerance. Conclusively, it is suggested to check the potential of selenium in field conditions under drought stress, especially in rainfed areas.

Growth response of cowpea (Vigna unguiculata L.) exposed to Pseudomonas fluorescens, Pseudomonas stutzeri, and Pseudomonas gessardii in lead contaminated soil

Lead (Pb) is a major contaminant among heavy metals in the soil environment that has negative impacts on the growth of plants, which ultimately cause health risk via entering into the food chain. In this regard, plant growth promoting rhizobacteria (PGPR) might improve plant growth by counteracting the harmful effects of Pb stress. Therefore, the present pot study was conducted to evaluate the role of PGPR in improving the growth of cowpea in Pb-contaminated soil. Three different concentrations of Pb (250, 350, and 750 mg kg−1) were applied alone (control) and in combination with bacterial inoculums [S1 (Pseudomonas fluorescens), S2 (Pseudomonas stutzeri) and S3 (Pseudomonas gessardii)] using completely randomized design each with three replicates. Results showed that plant fresh weight, plant dry weight, shoot length, root length, and chlorophyll contents of cowpea plants were improved significantly (P ≤ 0.05) by applying bacterial isolates as compared to the un-inoculated contaminated control. Among bacterial isolates, S3 performed better as compared to other bacterial isolates. The maximum increase in plant fresh weight, plant dry weight, shoot length, root length, and chlorophyll content was observed under S3 bacterial strain. Bacterial inoculation also enhanced the Pb concentration in the plant and the maximum uptake was recorded under S3 bacterial strain at 750 mg kg−1. Consequently, it has been concluded that PGPR has the great potential to enhance the plant growth and physiological characteristics of cowpea in Pb-contaminated sites and can also be used for bioremediation purposes.

Assessment of the Suitability of Extractants for Predicting Plant Available Arsenic in Some Tropical Rice Growing Inceptisols of Eastern India

ABSTRACT The complex behavior of arsenic (As) in soil in conjunction to crop mediated transfer through the food chain necessitates a thorough evaluation of its phyto-availability. In this pretext, the present experiment has been conducted to determine the best chemical extractant for plant available As under the As-prone, rice-dominant agro-ecosystems of Gangetic West Bengal, India. Based on the tube-well arsenic data (JPOA, UNICEF), surface soil samples from high, medium, low and uncontaminated As sites have been collected. A pot study with rice cv. IR-36, exposed to varying levels of As (0, 0.1, 0.2, 0.3 and 0.4 mg L−1) was conducted. Ten chemical extractants were used in this study. The As extraction pattern followed the pattern of (HCl+H2SO4)>; (NH4-oxalate+Ascorbic acid)>; (Malic+Citric)> NaOH> KH2PO4> NaHCO3>; (H2O2+HNO3)> NH4F> NH4Cl> NH4OAc. On the 85th day after sowing, the rice plants were harvested keeping in mind that the maximum uptakes of heavy metals like As occurs during the peak vegetative growth (panicle initiation) stage. The soil As correlated with rice dry matter As accumulation as: NH4-oxalate+ascorbic acid (r = 0.729**)> NH4Cl (r = 0.698**)> H2O2+HNO3 (r = 0.697**)> NH4F (r = 0.693**)>Malic+Citric (r = 0.666**)> KH2PO4 (r = 0.615**)> HCl+H2SO4 (r = 0.608**)> NaOH (r = 0.589**)> NaHCO3 (r = 0.571**)> NH4OAc (r = 0.533*). Statistical analyses through correlation sum and stepwise multiple regression modeling revealed that NH4-oxalate+ascorbic acid had the best relationship with all other extractants, As fractions and soil physicochemical characters and therefore emerged as the best suited extractant of As for the wide-scale experimental locations under rice cultivation system.

Chemical and mechanical coating of sulfur on baby corn biochar and their role in soil Pb availability, uptake, and growth of tomato under Pb contamination

In recent ages, industrial revolution and natural weathering processes have been increasing lead (Pb) contamination in agricultural soils, therefore, green remediation technologies are becoming attractive and cost-effective. In the current pot study, 1% and 2% (w/w) application rates of sulfur (S) alone and novel chemo-mechanically S-modified baby corn biochars (CSB and MSB) were applied in a Pb-contaminated (500 mg/kg) soil to evaluate tomato (Lycopersicon esculentum L.) growth, Pb uptake and its soil availability. The results from SEM-EDS and XRD patterns confirmed the S enrichment on the surface of baby-corn biochar. Further, Pb treatment alone imposed a significant reduction in biomass accumulation, photosynthetic pigments, antioxidative mechanism, root traits, and Pb-tolerance index because of increased soil Pb availability and its uptake, translocation and biological accumulation in various tissues of tomato. However, incorporation of lower rate of elemental S (1%) and higher rates of biochars, especially chemically S-modified biochar, CSB (2%) significantly improved dry biomass production, Pb-tolerance index, physiological attributes and antioxidative defense system of tomato plants. These results might be due to a prominent decrease in soil Pb availability by 37.5%, Pb concentration in shoot by 66.7% and root by 58.3%, soil to root transfer by 33.8%, and root to shoot transfer by 20.2% in tomato plants under 2% application rate of CSB, as compared with the Pb treatment without any amendment. Moreover, sulfur treatment induced a significant impact in reduction of soil pH (from 8.97-7.47) as compared to the biochar treatments under Pb-toxicity. The current findings provided an insight that 2% chemically S-modified biochar (CSB) has significant potential to improve the tomato growth by reducing Pb bioavailability in the Pb-contaminated soil, compared to the S alone and MSB amendments.

Effect of Biochar Application and Mineral Fertilization on Biomass Production and Structural Carbohydrate Content in Forage Plant Mixture

Biochar, a fine-grained porous material, exhibits properties that improve soil quality on agricultural land. Biochar, in combination with mineral fertilizers in perennial mixed crops, has so far not been studied for its effect on biomass production and feed value. The study, conducted in 2021 and 2022, aims to investigate the impact of different biochar application rates (alone and in combination with high and low NPK (nitrogen, phosphorus, potassium) fertilizer dosages) on the yield and structural carbohydrate content in grass–legume mixtures. Thus, a two-factorial pot study consisting of 36 pots was established in 2021. The study was set up in a randomized block design with nine fertilization treatments in four replicates. The factors studied were the rate of biochar (0, 5, and 10 Mg ha−1) and the rate of NPK mineral fertilizer application (0, 105, and 185 kg ha−1). First, biochar was applied and then the grass–legume mixture was sown, consisting of Lolium perenne L., Festuca arundinacea Schreb., Dectylis glomerata L., Lolium multiflorum Lam., Phleum pratense L., Festuca rubra L., Festuca ovina L., Poa pratensis L., Trifolium repens L., and Medicago sativa L. In both years of the study, during the growing season, plant biomass was harvested three times to assess biomass production and structural carbohydrate content. In the collected samples, neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) were examined, and, based on these, dry matter digestibility (DDM), dry matter intake (DMI), and relative feed value (RFV) were calculated. Compared to the control, the biochar addition increased the biomass production by 6.7–14.4% in the first year and by 49–59% in the second year after application. The addition of biochar in combination with NPK fertilization caused an increase in biomass production—22–45% in the first year and 71–136% in the second year after application. The structural carbohydrate content in the mixture depended neither on the biochar dose nor on fertilization. On the other hand, the most significant differences for the studied parameters were observed due to different harvest dates.

Increasing phosphorus rate alters microbial dynamics and soil available P in a Lixisol of Zimbabwe.

Soil phosphorus (P) deficiency is a major challenge to food security in most parts of sub-Saharan Africa, including Zimbabwe, where farmers largely depend on local organic nutrient resources as fertilizer in the production of crops. Soil microorganisms can contribute to synchronous availability of soil P to plants through regulating immobilization and mineralization cycles of soil P pools but their activity may be influenced by antecedent soil P, P fertilizer application regimes and P uptake by plants. Using soils collected from plots where Crotalaria juncea (high quality), Calliandra calothyrsus (medium quality), cattle manure (variable quality), maize stover and Pinus patula sawdust (both low quality) were applied at the rate of 4 t C ha-1 with 16 kg P ha-1 at the start of every season over 16 seasons. A pot study was conducted to evaluate the influence of increasing inorganic P fertilizer rates (26 and 36 kg P ha-1) on soil microbial dynamics, soil P pools, and maize P uptake. Results indicated that nineteen (19) fungal and forty-two (42) bacterial colonies were identified over the study period. Fungi dominated bacteria on day one, with Aspergillus niger showing a 30-98% abundance that depends on organic resource quality. Overall, microbial diversity peaked activity characterized succession on day 29, which coincided with a significant (P<0.05) increase in P availability. Increasing P rate to 26 kg P ha-1 amplified the microbial diverse peak activity under medium-high quality resources while under the control the peak emerged earlier on day 15. Mucor and Bacillus had peak abundances on day 43 and 57, respectively, across treatments regardless of P rates. Treatment and P rate had a significant (P<0.01) effect on microbial P. Bacteria were more responsive to added P than fungi. Increasing P to 36 kg P ha-1 also stimulated an earlier microbial diverse peak activity under maize stover on day 15. Addition of P alone, without supplying complementary nutrients such as N, did not have a positive effect on maize P uptake. Farmers need to co-apply medium-high quality organic resources with high fertilizer P rates to increase microbial diversity, plant available P and maize growth on sandy soils (Lixisols). Our results suggest that there is a need to reconsider existing P fertilizer recommendations, currently pegged at between 26 and 30 kg P ha-1, for maize production on sandy soils as well as develop new fertilizer formulations to intensify crop production in Zimbabwe.

Investigation of the Impact of Mycogenic Titanium and Selenium Nanoparticles on Fusarium Wilt Infection of Tomato Plant

We applied biosynthesized titanium and selenium nanoparticles, prepared using a fungal water extract of Trichoderma harzianum (T. harzianum), to eradicate tomota wilt infection. Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Energy Dispersive X-Ray analysis, and Transmission electron microscopy/X-ray diffraction (TEM/XRD) techniques were used to characterize the spherical metal nanoparticles, whose diameters were 16.0 nm for selenium nanoparticles (SeNPs) and 50.0 nm for titanium nanoparticles (TiNPs). This confirmed the efficient biosynthesis of the nanoparticles. Under greenhouse conditions, the effectiveness of TiNPs and SeNPs produced by nonpathogenic fungi (T. harzianum) against the pathogen responsible for the tomato wilt disease, Fusarium oxysporum (F. oxysporum), was studied. Based on the results, the most efficient method for combating the pathogen that causes tomato wilt was used in open fields, whereas pot studies were conducted in greenhouse conditions. All tested treatments considerably lowered tomato plant wilt disease in both the greenhouse and the open field. The disease severity was reduced by 20.4% using TiNPs at high concentrations of 150 ppm and by 41.5% using SeNPs. Compared to conventional antibiotics, the antibacterial activity assessment of the biosynthesized TiNPs and SeNPs revealed a significant effect versus pathogenic bacteria and fungi, with a negligible influence on the examined human and animal microflora. The findings showed that biosynthesized TiNPs and SeNPs can be applied to suppress the plant pathogen F. oxysporum in a way that is safe for the microflora of humans and animals. This is the first instance where the nanocidal activity of biological TiNPs and SeNPs has been used against the pathogen that causes tomato wilt.