Pot Trial Research Articles

Physiological responses of poplar and willow clones grown in pot trials on soil from landfills

Physiological responses of poplar and willow clones grown in pot trials on soil from landfills

Heavy Metal Co-Resistance with Antibiotics amongst Plant Growth Promoting Bacteria Isolates from Rhizosphere of Nypa Fruticans

Heavy metal co-resistance with antibiotics has the potential to amplify antimicrobial resistance genes in the environment, and this could have an impact on clinical settings. This study aimed to investigate the presence of heavy metal co-resistance with antibiotics among plant growth promoting bacterial isolates from the rhizosphere of Nypa fruticans. The heavy metals content of the water habouring the Nypa fruticans including copper(0.07mg/L), chromium (2.3 mg/L), lead (4.22 mg/L), iron (12.4 mg/L), cadmium (0.45 mg/L), nickel (3.12 mg/L), arsenic (0.47 mg/L) and zinc (5.37 mg/L) were above acceptable limits of WHO. A total of 10 bacteria including Bacillus subtilis, Bacillus cereus, Pseudomonas fluorescens, Klebsiella oxytoca, Serratia marcescens, Achromobacter denitrificans, Bulkholderia vietnamiensis and Azospirrilum brasilense, Azobacter vinelandii and Enterobacter aerogenes were isolated and identified to specie level using 16s RNA gene sequences, which showed above 95 % similarity with reference sequences from GenBank. The isolates showed high resistance to lead, chromium and zinc. Most of the isolates were resistant to streptomycin, ciprofloxacin and augmentin. Also, most of the isolates demonstrated positive growth promoting activities of indole acetic acid production, nitrogen fixation, siderophore production and phosphate solubilization. Pot trials on the effect of heavy metal and antibiotic tolerant bacteria on growth of beans (Phaseolus vulgaris l.) in heavy metal polluted soil revealed that beans treated with consortiumof all the isolates recorded high shoot and root length. Hence these isolates can be used for bioremediation of metal polluted site and as well act as plant growth promoting bacterial in agricultural system.

Effects of Waterlogging at Flowering Stage on the Grain Yield and Starch Quality of Waxy Maize.

Waterlogging is a common abiotic stress in global maize production. Maize flowering stage (from tasseling to silking) is more fragile to environmental stresses, and this stage frequently overlapped the plum rain season in the middle and lower reaches of Yangtze river in China and affect the yield and quality of spring-sown maize severely. In the present study, the soil moisture content under control and waterlogging conditions at the flowering stage was controlled by a negative-pressure water supply and controlling pot device in a pot trial in 2014-2015. The grain yield, starch content, and starch structural and functional properties under two soil moisture levels were compared using Suyunuo5 (SYN5) and Yunuo7 (YN7) as materials, which are the control hybrids of National waxy maize hybrid regional trials in Southern China. The results observed that the grain yield was reduced by 29.1% for SYN5 with waterlogging due to the decreased grain weight and numbers, which was significantly higher than that of YN7 (14.7%), indicated that YN7 was more tolerant to waterlogging. The grain starch content in YN7 was decreased by 9.4% when plants suffered waterlogging at the flowering stage, whereas the content in SYN5 was only decreased in 2014 and unaffected in 2015. The size of starch granules and proportion of small-molecule amylopectin with waterlogging at the flowering stage increased in SYN5 and decreased in YN7 in both years. The type of starch crystalline structure was not changed by waterlogging, whereas the relative crystallinity was reduced in SYN5 and increased in YN7. The pasting viscosities were decreased, and the pasting temperature was unaffected by waterlogging in general. The gelatinization enthalpy was unaffected by waterlogging in both hybrids in both years, whereas the retrogradation enthalpy and percentage in both hybrids were reduced by waterlogging in 2014 and unaffected in 2015. Between the two hybrids, YN7 has high pasting viscosities and low retrogradation percentage than SYN5, indicated its advantages on produce starch for more viscous and less retrograde food. In conclusion, waterlogging at the flowering stage reduced the grain yield, restricted starch accumulation, and deteriorated the pasting viscosity of waxy maize. Results provide information for utilization of waxy maize grain in food production.

NEMATOCIDAL PROPERTIES OF RED SILK COTTON (Bombax costatum Pellegr. & Vuil.) FLOWER AGAINST ROOT-KNOT NEMATODE, (Meloidogyne javanica (Treub. 1885) CHITWOOD 1949

A study was conducted in Jalingo Nigeria to determine the nematocidal activity of water extract of flower powder of Bombax costatum against the eggs and J2 juveniles of Meloidogyne javanica in the laboratory. For both egg hatch inhibition and juvenile mortality, 15 Petri-dishes were used for each and were arranged in Complete Randomized Design (CRD). For egg hatch inhibition test, 500 suspended in 10 ml distilled water were dispensed into each of 15 Petri-dishes used. Five treatments used included crude extract (stock solution) of B. costatum, 5 ml, 10 ml and 15 ml dilutions and control which were also dispensed into the petri dishes. Hatched nematodes were counted after three days. For juvenile mortality test, 500 J2s suspended in 10 ml distilled water were dispensed into each of 15 Petri-dishes used. The five treatments used included crude extract (stock solution) of B. costatum, 5 ml, 10 ml and 15 ml dilutions and control which were also dispensed into the petri dishes. Dead nematodes were counted after every day for three days. Data collected was analyzed. Results showed that the 100% concentration (crude extract) treatment gave the highest egg hatch inhibition and juvenile mortality of 89.33% and 94.33% respectively. This is an indication of the potential of flower powder of B. costatum to limit these inoculums of M. javanica and therefore reduce their damage potential. Pot and field trials will be needed before can be recommended for wider use.

Detecting the Short-Term Effects of Water Stress on Radiata Pine Physiology Using Thermal Imagery

Despite the utility of thermal imagery for characterising the impacts of water stress on plant physiology, few studies have been undertaken on plantation-grown conifers, including the most widely planted exotic species, radiata pine. Using data collected from a pot trial, where water was withheld from radiata pine over a nine-day period, the objectives of this study were to (i) determine how rapidly key physiological traits change in response to water stress and (ii) assess the utility of normalised canopy temperature, defined as canopy temperature–air temperature (Tc–Ta), for detecting these physiological changes. Volumetric water content remained high in the well-watered control treatment over the course of the experiment (0.47–0.48 m3 m−3) but declined rapidly in the water stress treatment from 0.47 m3 m−3 at 0 days after treatment (DAT) to 0.04 m3 m−3 at 9 DAT. There were no significant treatment differences in measurements taken at 0 DAT for Tc–Ta, stomatal conductance (gs), transpiration rate (E) or assimilation rate (A). However, by 1 DAT, differences between treatments in tree physiological traits were highly significant, and these differences continued diverging with values in the control treatment exceeding those of trees in the water stress treatment at 9 DAT by 42, 43 and 61%, respectively, for gs, E and A. The relationships between Tc–Ta and the three physiological traits were not significant at 0 DAT, but all three relationships were highly significant from as early as 1 DAT onwards. The strength of the relationships between Tc–Ta and the three physiological traits increased markedly over the duration of the water stress treatment, reaching a maximum coefficient of determination (R2) at 7 DAT when values were, respectively, 0.87, 0.86 and 0.67 for gs, E and A. The early detection of changes in tree physiology from 1 DAT onwards suggests that thermal imagery may be useful for a range of applications in field-grown radiata pine.

Plant testing with hemp and miscanthus to assess phytomanagement options including biostimulants and mycorrhizae on a metal-contaminated soil to provide biomass for sustainable biofuel production

The need of biofuels from biomass, including sustainable aviation fuel, without using agricultural land dedicated to food crops, is in constant demand. Strategies to intensify biomass production using mycorrhizal fungi, biostimulants and their combinations could be solutions for improving the cultivation of lignocellulosic plants but still lack well-established validation on metal-contaminated soils. This study aimed to assess the yield of Miscanthus x giganteus J.M. Greef & Deuter and Cannabis sativa L. grown on a metal-contaminated agricultural soil (11 mg Cd, 536 mg Pb and 955 mg Zn kg−1) amended with biostimulants and/or arbuscular mycorrhizal fungi, and the shoot Cd, Pb and Zn uptake. A pot trial was carried out with soil collected from a field near a former Pb/Zn smelter in France and six treatments: control (C), protein hydrolysate (a mixture of peptides and amino acids, PH), humic/fulvic acids (HFA), arbuscular mycorrhizae fungi (AMF), PH combined with AMF (PHxAMF), and HFA combined with AMF (HFAxAMF). Metal concentrations in the soil pore water (SPW), pH and electrical conductivity were measured over time. Miscanthus and hemp shoots were harvested on day 90. Both PH and PHxAMF treatments increased SPW Cd, Pb, and Zn concentrations (e.g. by 26, 1.9, and 22.9 times for miscanthus and 9.7, 4.7, and 19.3 times for hemp in the PH and PHxAMF treatments as compared to the control one, respectively). This led to phytotoxicity and reduced shoot yield for miscanthus. Conversely, HFA and HFAxAMF treatments decreased SPW Cd and Zn concentrations, increasing shoot yields for hemp and miscanthus. Shoot Cd, Pb, and Zn uptakes peaked for PH and PHxAMF hemp plants (in μg plant-1, Cd: 310–334, Pb: 34–38, and Zn: 232–309 for PHxAMF and PH, respectively), while lowest values occurred for PH miscanthus plants mainly due to low shoot yield. Overall, this study suggested that humic/fulvic acids can be an effective biostimulant for increasing shoot biomass production in a metal-contaminated soil. These results warrant further investigations of the HFAxAMF in field trials.

Auxin Production by Bacillus simplex Enhanced the Growth of Zea mays (L.) under In-Vitro and In-Vivo Conditions

In the current study Bacillus simplex was evaluated for its role inimproving the growth of maize (Zea mays (L.)) under lab and natural environmental conditions. Bacterial strains were tested for several biochemical traits and auxin biosynthesis. Maize seeds were surface sterilized and treated with bacterial strains as single and mixed cultures to evaluate the enhancement of maize vegetative growth parameters. All bacterial strains exhibited positive results for catalase, citrate and nitrate while negative for urease, indole, triple sugar iron and oxidase test. Colorimetric analysis revealed significant production of auxin by Z-13 (6.7μg/ml), Z-09 (5.8μg/ml), Z-37 (5.7 μg/ml), Z-38 (5.7μg/ml), Z-02 (5 μg/ml), Z-37 (4.5 μg/ml)and Z-04 (3.5 μg /ml) at 1000μg/ml concentration of L-tryptophan. At 0 μg/ml conc of L-tryptophan, Z-37, Z-13, Z-04, Z-09and Z-38 also manifested significant levels of auxin biosynthesis. In-vitrorooting assay revealed that Z-09, Z-35 and Z-37 showed significant increase in root length i.e., 1.2, 1.18 and 1.11-fold, respectively, as compared to control. Pot trials under natural conditions manifested significant improvements in shoot length by Z-38 (67.1%), Z-13 (51%), and Z-09 (43%), over control. Most significant results for fresh weight (120%) and dry weight (100%) in maize were shown by strain Z-38. Among mixed cultures C-1 (Z-02, Z-04, Z-09) improved shoot length (42%) and fresh weight (45%) with respect to control. Improvement in vegetative growth parameters of maize suggests that B. simplex can be used as an effective biofertilizer.

Physiological tolerance of black locust (Robinia pseudoacacia L.) and changes of rhizospheric bacterial communities in response to Cd and Pb in the contaminated soil.

Woody plants possess great potential for phytoremediation of heavy metal-contaminated soil. A pot trial was conducted to study growth, physiological response, and Cd and Pb uptake and distribution in black locust (Robinia pseudoacacia L.), as well as the rhizosphere bacterial communities in Cd and Pb co-contaminated soil. The results showed that R. pseudoacacia L. had strong physiological regulation ability in response to Cd and Pb stress in contaminated soil. The total chlorophyll, malondialdehyde (MDA), soluble protein, and sulfhydryl contents, as well as antioxidant enzymes (superoxide dismutase, peroxidase, catalase) activities in R. pseudoacacia L. leaves under the 40mg·kg-1 Cd and 1000mg·kg-1 Pb co-contaminated soil were slightly altered. Cd uptake in R. pseudoacacia L. roots and stems increased, while the Pb content in the shoots of R. pseudoacacia L. under the combined Cd and Pb treatments decreased in relative to that in the single Pb treatments. The bacterial α-diversity indices (e.g., Sobs, Shannon, Simpson, Ace, and Chao) of R. pseudoacacia L. rhizosphere soil under Cd and Pb stress were changed slightly relative to the CK treatment. However, Cd and Pb stress could significantly (p < 0.05) alter the rhizosphere soil microbial communities. According to heat map and LEfSe(Linear discriminant analysis Effect Size) analysis, Bacillus, Sphingomonas, Terrabacter, Roseiflexaceae, Paenibacillus, and Myxococcaceae at the genus level were notably (p < 0.05) accumulated in the Cd- and/or Pb-contaminated soil. Furthermore, the MDA content was notably (p < 0.05) negatively correlated with the relative abundances of Isosphaeraceae, Gaiellales, and Gemmatimonas. The total biomass of R. pseudoacacia L. was positively (p < 0.05) correlated with the relative abundances of Xanthobacteraceae and Vicinamibacreraceae. Network analysis showed that Cd and Pb combined stress might enhance the modularization of bacterial networks in the R. pseudoacacia L. rhizosphere soil. Thus, the assembly of the soil bacterial communities in R. pseudoacacia L. rhizosphere may improve the tolerance of plants in response to Cd and/or Pb stress.

Screening of Varieties Resistant to Late-Spring Coldness in Wheat and Effects of Late-Spring Coldness on the Ultrastructure of Wheat Cells

Due to global warming, late-spring coldness affecting wheat (LSCW) is one of the major abiotic adversities affecting wheat production. A combination of field and pot trials were conducted in this study. In the field experiment, 20 wheat varieties from the main wheat-producing areas in China were selected as experimental materials. By exploring the effects of LSCW on the spikelet characteristics and yields of different varieties, the evaluation methods and indexes of wheat varieties’ resistance to LSCW were established. Three varieties with strong resistance to LSCW (Yannong19, Guomai9, and Shannong17) and five varieties sensitive to LSCW (Zhengmai895, Xinmai26, Zhengmai366, Zhengmai8329, and Fanmai5) were screened out. The wheat varieties Yannong19 (YN19), with a strong resistance to LSCW, and Xinmai26 (XM26), with LSCW sensitivity, were selected as the test materials for the pot experiment. The ultrastructure changes in the wheat in different low-temperature treatments during the anther differentiation period were observed using an ultra-low-temperature artificial climate incubator set to 4 °C and −4 °C for 4 h (1:00–5:00 a.m.). The average temperature of the field during the low-temperature treatment was 10 °C, which was the control temperature (CK). The results showed that the cell morphology and chloroplast and mitochondrial structures of the functional leaves, young ears, and internodes below the ears were damaged, and the degree of damage was related to the cell location, the extent of low-temperature stress, and the resistance of the varieties. The degree of damage to the wheat cells was found to occur in the following order: young ears &gt; internode belove young ears &gt; functional leaves. The degrees of damage to the wheat cell, chloroplast, and mitochondrial structures increased with the intensification of the low-temperature stress. The damage to the XM26 variety was obviously greater than that inflicted on the YN19 variety. The anatomical mechanism of YN19 cells makes the cell structure more stable during late-spring coldness.

Marvels of Bacilli in soil amendment for plant-growth promotion toward sustainable development having futuristic socio-economic implications.

Microorganisms are integral components of ecosystems, exerting profound impacts on various facets of human life. The recent United Nations General Assembly (UNGA) Science Summit emphasized the critical importance of comprehending the microbial world to address global challenges, aligning with the United Nations Sustainable Development Goals (SDGs). In agriculture, microbes are pivotal contributors to food production, sustainable energy, and environmental bioremediation. However, decades of agricultural intensification have boosted crop yields at the expense of soil health and microbial diversity, jeopardizing global food security. To address this issue, a study in West Bengal, India, explored the potential of a novel multi-strain consortium of plant growth promoting (PGP) Bacillus spp. for soil bioaugmentation. These strains were sourced from the soil's native microbial flora, offering a sustainable approach. In this work, a composite inoculum of Bacillus zhangzhouensis MMAM, Bacillus cereus MMAM3), and Bacillus subtilis MMAM2 were introduced into an over-exploited agricultural soil and implications on the improvement of vegetative growth and yield related traits of Gylcine max (L) Meril. plants were evaluated, growing them as model plant, in pot trial condition. The study's findings demonstrated significant improvements in plant growth and soil microbial diversity when using the bacterial consortium in conjunction with vermicompost. Metagenomic analyses revealed increased abundance of many functional genera and metabolic pathways in consortium-inoculated soil, indicating enhanced soil biological health. This innovative bioaugmentation strategy to upgrade the over-used agricultural soil through introduction of residual PGP bacterial members as consortia, presents a promising path forward for sustainable agriculture. The rejuvenated patches of over-used land can be used by the small and marginal farmers for cultivation of resilient crops like soybean. Recognizing the significance of multi-strain PGP bacterial consortia as potential bioinoculants, such technology can bolster food security, enhance agricultural productivity, and mitigate the adverse effects of past agricultural activities.

Study on gibberellin and gibberellin-like substances from endophytes and their effect on maize plants

Plant growth promoting endophytes were isolated from the roots of rice, sugarcane, corn, maize, sunflower and chili. The biochemical characterization of those isolated endophytes was carried out according to Bergey's Manual of Determinative Bacteriology. The best gibberellin production of all isolates was found at the concentration of (55.12 ppm, 50 ppm, 38.06 ppm, 90.41 ppm, 58.65 ppm and 63.65 ppm, respectively) on the 12th day of the incubation period. Among all isolates, the A4 isolate produced more GA concentration (90.41 ppm) on the 12th day of the incubation period. In the maize seed germination test, A1, A4, A5 and A6 showed the best results. In the pot trial test, A4, A5 and A6 showed the best results in shoot length (37.5 cm, 35.4 cm and 36.9 cm per ten replicates, respectively). Among them, the A4 isolate was the best GA producing isolate for plant growth promoting activity in maize seedlings. It was found in an average shoot height of 37.5 cm; average shoot fresh weight of 56.7 g and an average shoot dry weight of 7.9 g per ten replicates after one month cultivation which was sprayed by A4 treatment, compared with an average shoot height of 27.80 g, an average shoot fresh weight of 25.08 g, an average shoot dry weight of 3.42 g which were sprayed by water treatment. The qualitative analysis of plant growth regulators (GAs) production of bacterial isolate A4 was determined by using TLC method and FTIR spectroscopy analysis. Chemical fertilizers should not be used not to harm effective endophytes.

Emergence and Early Growth of Four Desmanthus Species in Three Alkaline Clay Soils

Tropical pasture legumes such as Desmanthus are expected to improve pasture productivity in the extensive grazing systems of Northern Australia. However, the soils in these areas are often hostile (e.g., hard-setting and nutrient-deficient), which reduces legume emergence and establishment. Furthermore, these soils are often not ameliorated with amendments such as gypsum or starter fertilisers before planting. A pot trial was conducted to investigate differences in the emergence and early growth of four Desmanthus species. The legumes were grown in three alkaline clay soils that were unamended or amended with either gypsum (1 t CaSO4.2H2O ha−1 equivalent), a starter MAP fertiliser (12 kg P ha−1 equivalent), or both gypsum and the starter fertiliser. Seedling emergence was recorded daily and shoot yield was determined after six weeks’ growth. Final seedling emergence (as a percentage of viable seeds) varied among the Desmanthus species (c.f. D. leptophyllus = 63%, D. pernambucanus = 68%, D. bicornutus = 85%, and D. virgatus = 86%). On average, across the treatments, gypsum increased seedling emergence by 15%, whereas the starter fertiliser had no effect. The shoot yields and shoot phosphorus content of the Desmanthus species generally increased in response to the starter fertiliser. The collective results demonstrated that there were differences in emergence and early growth among the four Desmanthus species, which indicates that Desmanthus cultivar selection may be important in the relatively hostile soils of Northern Australia. Gypsum was an effective amendment for seedling emergence, whereas the starter fertiliser was an effective amendment to increase legume productivity.

Recent innovations in fertilization with treated digestate from food waste to recover nutrients for arid agricultural fields

This study aims to explore the development of sustainable fertilizers from waste materials of a biogas plant and a brewery. These wastes, rich in organic carbon and nitrogen, were processed with sulfuric(VI) and phosphoric(V) acid mixture, facilitating the production of free amino acids and achieving waste sanitization. This treatment produced by-products, which extended the range of possible applications. The highest concentration of free amino acids (360 mg/l) was achieved through hydrolyzing with a 40% concentration medium over 24 h. In this case, the maximum levels were recorded for beta-alanine (69.3 mg/l), glycine (46.8 mg/l), isoleucine (43.5 mg/l), proline (36.2 mg/l), and valine (31.5 mg/l). The study presents two fertilizer technologies, with and without micronutrients, that satisfy European Parliament Regulation 2019/1009 (Ntot > 2%, Norg > 0.5%, Corg > 3%). Bioavailability of nutrients in the formulations ranged from 60 to 100%. The efficacies of these fertilizers were evaluated in 30-day pot trials with various plant species, with both single application and fertigation tested. Multielement analysis confirmed high nutrient transfer in the soil-plant system, and the inclusion of micronutrients led to biofortification of plant biomass in Cu (48.3 ± 7.2 mg/kg), Mn (249 ± 37 mg/kg), Zn (164 ± 25 mg/kg), and Fe (211 ± 32 mg/kg). These sustainable fertilizers present an alternative to traditional, non-renewable fertilizers and offer promising solutions for precision agriculture and environmentally conscious production.Graphical abstract

Bio-management of Fusarium wilt of tomato (Fusarium oxysporum f.sp. lycopersici) with multifacial Trichoderma species

Fusarium oxysporum f.sp. lycopersici (FOL), the incitant of the Fusarium wilt of tomato, is a highly damaging and prevalent disease in the majority of tomato growing areas. Keeping into consideration of high disease occurrence and incidence of FOL in tomato crop, the present investigation was undertaken to develop an effective bio-management approach to combat this disease. Initially, the studies were conducted to evaluate six multi-facial biocontrol isolates of Trichoderma species viz., Trichoderma harzianum AMUTH-1, T. harzianum AMUTH-2, T. harzianum AMUTH-3, T. asperellum (= T. viride) AMUTV-1, T. asperellum AMUTV-3 and T. virens (= Gliocladium virens) AMUTS-1 against FOL in vitro. Among these antagonists, T. harzianum AMUTH-1 and T. asperellum AMUTV-3 exhibited the maximum inhibitory effect while T. virens AMUTS-1 was recorded as the least effective Trichoderma isolate against FOL in vitro. Interestingly, T. harzianum AMUTH-1 and T. asperellum AMUTV-3 were found to produce indole acetic acid, siderophore and possess high enzymatic activities (cellulase, chitinase, ligninase and protease) in vitro. Further, pot trials were conducted and the chemical fungicide, carbendazim was used to compare the effectiveness of Trichoderma isolates. Pot trials also verified the efficacy of T. harzianum AMUTH-1 with 9–28% enhancement in the plant-growth parameters and 15–21% biomass production, and 88% decrease in the soil population of FOL. The effect of T. harzianum AMUTH-1 was also at par with fungicides, carbendazim.

A facile strategy to fabricate lignocellulose-based slow-release fertilizers via a high-performance treatment of rice straw using deep eutectic solvents

Lignin-based slow-release fertilizers (SRFs) have attracted widespread attention due to their ability to enhance nutrient utilization efficiency and reduce environmental pollution in agricultural production. However, the extraction and separation processes of lignin from biomass sources are intricate, involving substantial quantities of non-reusable toxic reagents. Here, a sustainable and eco-friendly approach using deep eutectic solvents (DES) was employed to treat rice straw, effectively dissolving the lignin present. Subsequently, the in-situ lignin regeneration was facilitated through the addition of a zinc chloride solution. The regenerated lignin was tightly wrapped around and connected to cellulose micro/nanofibers, forming a homogeneous slurry. A simple coating technique was employed to uniformly coat urea particles with the lignocellulosic slurry, yielding lignocellulose-based SRFs. Results revealed that the nutrient release of the lignocellulose-based coated fertilizers in water exceeded 56 days. A pot trial demonstrated that the application of lignocellulose-based SRFs significantly promoted the growth of rice and improved grain yield (by 10.7 %) and nitrogen use efficiency (by 34.4 %) compared to the urea treatment in rice production. Furthermore, the DES demonstrated consistently high efficiency in biomass processing even after four cycles of reuse. This green strategy offers a novel approach for the preparation of SRFs coating materials, promoting agricultural sustainability.

Phytoremediation of Zinc and Lead from Polluted Soils Using Sunflower

Phytoremediation is a new, cost-effective remediation technique. Sunflower, a plant grown in Pb- and Zn-contaminated soils, underwent pot trials to examine its biomass and determine how well may remove the metals. According to the findings, the fresh and dry weights of the developing plants gradually reduced, as the amount of heavy metals in the soil increased. The fresh weights of the shoot and root were decreased by the application of 835 mg/kg soil of Pb and 598 mg/kg Zn. The maximum concentration of lead and zinc in the shoot (146.27and 277.83 mg/kg) and roots (589.77 and 287.97 mg/kg, respectively) was recorded in the plant cultivated in contaminated soil. The root growing on soil treated with 835 mg/kg had the maximum bioaccumulation of lead. The control soil had the longest plant shoot and root lengths, averaging 75.67 cm and 9.5 cm, respectively. Under a soil Pb concentration of 835 mg/kg, the shortest plants had shoots that measured 58.5 cm and roots that measured 6 cm. Similarly, when the soil was treated with 598 mg/kg soil zinc, the plant?s shoot and root decreased dramatically by 55.67 cm and 7 cm, respectively. As a result, the study shows that sunflower plants were better at absorbing lead and zinc, and we recommend using them to clean up soil that has been contaminated with these metals. . KEYWORDS :Sunflower, Heavy Metals, Lead, Phytoremediation, Zinc

English

The canola is an important oilseed crop of the world and Pakistan that grows in a substantial area, but the required quality and yield of canola oil is still not enough to meet the country’s need. Iron (Fe) and Zinc (Zn) are important human nutrients and biofortification of these elements in canola oil is a challenge especially under alkaline calcareous soil conditions owing to less bioavailability of these metal ions in soil. With the same objective, the present investigation was conducted in 2 experiments (Pot and Field trials) with 7 treatments (Control, So-200 kg ha-1, Iron-3 kg ha-1, Zinc-6 kg ha-1, S+Fe, S+Zn and S+Fe+Zn) under pot and filed conditions, separately. The application of S, Fe and Zn resulted in a significant increment in canola crop growth, yield, improved plant physiology and enhanced Fe and Zn uptake and accumulation. The elemental S alone was found to be affecting these properties significantly and combined application with Fe, Zn, and Fe+Zn resulted in further increment in growth, yield, oil percentage and shoot/grain elemental components. For Fe distribution, S application with Fe enhanced its shoot and grains accumulation 16% and 14% compared to alone Fe control under pot settings while 16% and 15% higher shoot and grain Fe was observed under field trial. The shoot and grains’ Zn contents were also found to be significantly improved (10% and 9% higher Zn in shoot and grain of pot-grown canola plants while 19% and 10% increment was observed under filed investigation compared with respective controls).

Endophytic bacteria Klebsiella spp. and Bacillus spp. from Alternanthera philoxeroides in Madiwala Lake exhibit additive plant growth-promoting and biocontrol activities

BackgroundThe worldwide increase in human population and environmental damage has put immense pressure on the overall global crop production making it inadequate to feed the entire population. Therefore, the need for sustainable and environment-friendly practices to enhance agricultural productivity is a pressing priority. Endophytic bacteria with plant growth-promoting ability and biocontrol activity can strongly enhance plant growth under changing environmental biotic and abiotic conditions. Herein, we isolated halotolerant endophytic bacteria from an aquatic plant, Alternanthera philoxeroides, from the polluted waters of Madiwala Lake in Bangalore and studied their plant growth promotion (PGP) and biocontrol ability for use as bioinoculant. ResultsThe isolated bacterial endophytes were screened for salt tolerance ranging from 5 to 15% NaCl concentration. Klebsiella pneumoniae showed halotolerant up to 10% NaCl and Bacillus amyloliquefaciens and Bacillus subtilis showed up to 15%. All three strains demonstrated good PGP abilities such as aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, phosphate solubilization, ammonia production, and nitrogen fixation. In addition, K. pneumoniae also exhibited high indoleacetic acid (IAA) production (195.66 ± 2.51 µg/ml) and potassium solubilization (2.13 ± 0.07 ppm). B. amyloliquefaciens and B. subtilis showed good extracellular enzyme production against cellulase, lipase, protease, and amylase. Both the isolates showed a broad spectrum of antimicrobial activity against the tested organisms. The optimization of IAA production by K. pneumoniae was done by the response surface methodology (RSM) tool. Characterization of IAA produced by the isolate was done by gas chromatography-mass spectrometry (GCMS) analysis. The enhanced plant growth-promoting ability of K. pneumoniae was also demonstrated using various growth parameters in a pot trial experiment using the seeds of Vigna unguiculata. ConclusionThe isolated bacterial endophytes reported in this study can be utilized as PGP promotion and biocontrol agents in agricultural applications, to enhance crop yield under salinity stress. The isolate K. pneumoniae may be used as a biofertilizer in sustainable agriculture and more work can be done to optimize the best formulations for its application as a microbial inoculant for crops.

Accumulation of Health-Promoting Compounds in Upland Black Rice by Interacting Mycorrhizal and Endophytic Fungi.

There is an increasing interest in finding eco-friendly and safe approaches to increase agricultural productivity and deliver healthy foods. Arbuscular mycorrhizal fungi (AMF) and endophytic fungi (EPF) are important components of sustainable agriculture in view of their ability to increase productivity and various plant secondary metabolites with health-promoting effects. In a pot experiment, our main research question was to evaluate the additive and synergistic effects of an AMF and four root-endophytic fungi on plant performance and on the accumulation of health-promoting secondary compounds. Plant growth varied between the treatments with both single inoculants and co-inoculation of an AMF and four EPF strains. We found that inoculation with a single EPF positively affected the growth and biomass production of most of the plant-endophyte consortia examined. The introduction of AMF into this experiment (dual inoculation) had a beneficial effect on plant growth and yield. AMF, Rhizophagus variabilis KS-02 co-inoculated with EPF, Trichoderma zelobreve PBMP16 increased the highest biomass, exceeding the growth rate of non-inoculated plants. Co-inoculated R. variabilis KS-02 and T. zelobreve PBMP16 had significantly greater beneficial effects on almost all aspects of plant growth, photosynthesis-related parameters, and yield. It also promoted root growth quality and plant nutrient uptake. The phenolic compounds, anthocyanin, and antioxidant capacity in rice seeds harvested from plants co-inoculated with AMF and EPF were dramatically increased compared with those from non-inoculated plants. In conclusion, our results indicated that EPF and AMF contributed to symbiosis in Maled Phai cultivar and were coordinately involved in promoting plant growth performance under a pot trial.

Bacterial Inoculation and Extracts of Opuntia Rackets or Marine Algae Trigger Distinct Proline Balances in Tomato Salt Stress Alleviation

High salt levels in soil can severely limit plant development and diminish the positive effect of plant-growth-promoting rhizobacteria (PGPR). However, extracts of organisms adapted to high salinity, such as Opuntia ficus-indica (OFI) and Enteromorpha intestinalis (EI), can restore the growth of PGPR. Therefore, we used OFI or EI extracts and their combination with the PGPR Achromobacter xylosoxidans BOA4 to evaluate salt stress relief in tomato (Solanum lycopersicum). The experimental setup consisted of a plant pot trial under greenhouse conditions with 12 treatments: control, irrigation with OFI extract; EI extract; BOA4-inoculated plus OFI extract and BOA4-inoculated plus EI extract under no salinity or salinity conditions (150 mM NaCl). The percentage of germination, and plant’s fresh and dry weight were registered 30 and 46 days after sowing. At 46 days, the ratio between proline and glutamic acid concentration (PR/GA) was determined, expecting high PR/GA ratios in plants more responsive to salt stress since proline is an osmolyte mainly synthesized from glutamate. The results showed that 52% of the control seeds under salt stress germinated, a figure that was increased to 92% in OFI-treated seeds. Tomato plants were shown to be very sensitive to salt stress since the dry weight was ca. one fourth that of the plants grown without salinity. However, EI or BOA4 plus EI stimulated plant biomass by ca. 3 times compared to the control with salt, restoring plant biomass to values comparable to those of control plants grown without salinity. The joint treatments with BOA4 and EI or OFI caused distinct PR/GA levels in plant tissues. An inverse relationship between the sum of relative shoot proline and glutamic acid contents and shoot biomass accumulation was observed, namely in treatments accumulating more biomass under no salinity and salinity conditions. This indicates that the proline/glutamate pathway represents a carbon sink that is needed to fight stress and is competing with the carbon flow used for growth.