Plant Dry Biomass Research Articles

Use of Plant Growth-Promoting Bacteria and Humic Acids for Phytostabilization of Acid-Generating Mining Wastes

An interdisciplinary study was conducted on the effect of application of plant growth-promoting bacteria and humic acids in the reclamation of acid-generating mining wastes through a vegetation cover. The drainage water from the mining waste was characterized by a pH of 3.58 and high concentrations of sulfate, copper, manganese, and zinc. Strains of the Bacillus and Pseudomonas genera and humic substances produced by biotransformation from lignite were applied. The usage of plant growthpromoting bacteria and humic acid in the reclamation of acid-generating mining wastes produced several beneficial effects. The combined application resulted in a significant decrease in Cu, Fe, Zn and sulfate concentrations in a variety of drainage water samples, due to the suppression of pyrite oxidation. Both plant growth-promoting bacteria and humic acid improve plant growth, when used separately. The highest yield of fresh (between 22% and 43 %) and dry biomass of plants (between 31% and 41 %) was observed after combining both treatments, but the effect depended strongly on the dose of application. Yields of fresh and dry biomass in the combined application increased by treating plants with 0.42 g/kg humic acids, but decreased significantly when applying humic acids in a concentration of 0.84 g/kg soil. The treatment with a microbial consortium and humic substances enhanced significantly the uptake of nitrogen, phosphorus, and potassium by the plants. Furthermore, the addition of Bacillus and Pseudomonas bacteria in combination with humic acids to poor soil for reclamation reduced the Cu and Zn uptake.

Biostimulants Promote Plant Development, Crop Productivity, and Fruit Quality of Protected Strawberries

Berries such as strawberries are recognized as a significant constituent of healthy human diets owing to their bioactive secondary metabolites. To improve crop sustainability, yield and berry quality, alternative production systems should be proposed such as organic farming and the use of biostimulants. Thus, we have compared within a complete randomized block design seven biostimulant treatments: 1-control, 2-seaweed extract, 3-Trichoderma, 4-mycorrhiza, 5-mixture of three bacteria, 6-combination of mycorrhiza + bacteria, and 7-citric acid. Strawberry plants were grown in conventional high tunnel (CH), conventional greenhouse (CG) and organic greenhouse (OG). Our results showed that biostimulants did not impact the soil microbial activity (FDA) when compared with the control. Leaf chlorophyll content and photosynthetic leaf performance were not affected by any studied biostimulants. Bacteria, citric acid, and the combination of mycorrhiza + bacteria increased the number of flowering stalks compared with the control in CH, while bacteria increased the crown diameter and all biostimulants increased fresh and dry shoot plant biomass. Citric acid increased leaf Ca content in CG, when all biostimulants increased leaf N content in CH. Studied biostimulants increased berry productivity in CH, while citric acid treatment had the highest yield in CG. The anthocyanins content increased with the use of biostimulants in CH, whereas Trichoderma (CG) and the combination of mycorrhiza + bacteria (OG) increased the Brix, total polyphenols, and anthocyanin contents of the berries compared with the control.

Combination of biochar and AMF promotes phosphorus utilization by stimulating rhizosphere microbial co-occurrence networks and lipid metabolites of Phragmites

Agricultural biochar and arbuscular mycorrhizal fungi were used to promote the growth of Phragmites in the structural damaged and nutritional imbalanced littoral zone soils. Wheat straw biochar played a significant role in improving soil porosity and supplementing available phosphorus to 79.20 ± 3.20 mg/kg, compared with CK at 17.50 ± 0.88 mg/kg. The addition of Diversispora versiformis improved the plant net photosynthetic rate reaching up to 25.66 ± 0.65 μmol·m−2·s−1, which was 36.60 % higher than CK. The combination of biochar and fungi contributed to the whole plant dry weight biomass of 32.30 % and 234.00 % higher than the single biochar or AMF amendment groups, respectively. Meanwhile, the analysis of microbial co-occurrence networks showed the most relevant networks node species were mainly Talaromyces, Chaetomiacea and Gemmatimonadetes etc. Root lipid metabolite of Glycerophospholines further proved that phosphorus utilization was also enhanced endogenously in the rhizosphere soil. These results indicate that the combination of biochar and arbuscular mycorrhizal fungi play synergic role in enhancing phosphorus utilization endogenously and exogenously.

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

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

ACC Deaminase Containing Plant Growth Promoting Agrobacterium larrymoorie Strain MZ 3-ABF Confers Tolerance to Drought Stress in Chickpea (Cicer arietinum L.) Seedlings

Plant growth-promoting rhizobacteria (PGPR) that produce 1-aminocyclopropane-1-carboxylate (ACC) deaminase can alleviate plant growth constraints caused by water scarcity. In the present study, six PGPR strains were evaluated to produce several plant growth promoting, and ACC deaminase enzyme isolated from the rhizosphere soil of Chickpea (Cicer arietinum) in arid regions of Telangana State, India. According to their 16S rDNA sequencing analysis, only one of the six strains, MZ 3-ABF, belongs to Agrobacterium larrymoorie. A drought tolerance experiment revealed two PGPR strains with high phosphate solubilization, nitrogen fixation, indoleacetic-3-acid (IAA), and ACC deaminase enzyme secretion potential were constrained to only MZ 3-ABF and MZ 5-ABF. One strain MZ 3-ABF was chosen for use in a pot experiment to assess their growth-promoting effects on chickpea under drought conditions. This PGPR strain inoculation into chickpea seedlings was expected to alleviate the overall growth inhibition caused by drought stress. The inoculation was thought to have the greatest growth-promoting effects. Inoculation with strain MZ 3-ABF altered plant height, root length, dry biomass, and net photosynthetic rate of leaves, allowing chickpea seedlings to cope with drought better. They had an indirect effect on the biochemical and physiological properties of chickpea seedlings in order to alleviate drought stress. These findings suggest that the MZ 3-ABF PGPR may be useful for effectively weakening the growth inhibition caused by drought in chickpea. The strain could also be used as effective bioinoculant to maintain pea quality.

Microbial Inoculation Improves Growth, Nutritional and Physiological Aspects of Glycine max (L.) Merr.

Considering a scenario where there is a low availability and increasing costs of fertilizers in the global agricultural market, as well as a finitude of important natural resources, such as phosphorus (P), this study tested the effect of the inoculation of rhizospheric or endophytic microorganisms isolated from Hymenaea courbaril and Butia purpurascens on the growth promotion of Glycine max (L.) Merr. The tests were conducted in a controlled greenhouse system, and the effects of biofertilization were evaluated using the following parameters: dry biomass, nutritional content, and photochemical and photosynthetic performance of plants. Seed biopriming was performed with four bacterial and four fungal isolates, and the results were compared to those of seeds treated with the commercial product Biomaphos®. Overall, microbial inoculation had a positive effect on biomass accumulation in G. max, especially in strains PA12 (Paenibacillus alvei), SC5 (Bacillus cereus), and SC15 (Penicillium sheari). The non-inoculated control plants accumulated less nutrients, both in the whole plant and aerial part, and had reduced chlorophyll index and low photosynthetic rate (A) and photochemical efficiency. Strains PA12 (P. alvei), SC5 (B. cereus), and 328EF (Codinaeopsis sp.) stood out in the optimization of nutrient concentration, transpiration rate, and stomatal conductance. Plants inoculated with the bacterial strains PA12 (P. alvei) and SC5 (B. cereus) and with the fungal strains 328EF (Codinaeopsis sp.) and SC15 (P. sheari) showed the closest pattern to that observed in plants treated with Biomaphos®, with the same trend of direction of the means associated with chlorophyll index, (A), dry mass, and concentration of important nutrients such as N, P, and Mg. We recommend the use of these isolates in field tests to validate these strains for the production of biological inoculants as part of the portfolio of bioinputs available for G. max.

EFFECT OF SUBSTRATES AND FERTIGATION ON GROWTH AND PHOTOSYNTHETIC EFFICIENCY OF MAGUEY PULQUERO PLANTS OF MEZQUITAL VALLEY LANDRACES

Maguey pulquero (Agave spp.) seedling cultivation is an emerging alternative capable of supply the demand of its diverse products. This research aimed to evaluate the growth and maximum quantum yield of Photosystem II (Fv/Fm) of three landraces of maguey pulquero young plants (10 months-old) germinated from seeds, growing under greenhouse within interaction effect of four substrates and four concentration levels of nutrient solution. The hypothesis was that phenotypic variation of young maguey pulquero landraces growing under greenhouse conditions could help to identify genotypes ideal for commercial production and to elucidate its nutrient and substrate requirements. The variables evaluated were: Fv/Fm, number of leaves, length and width (cm) of biggest leaf, and plant dry biomass (g), the results were analyzed by a two-way ANOVA and means comparison by Tukey’s test. The results demonstrated that Penca larga landrace (Agave mapisaga Trel.) had the highest values in all the growth variables evaluated compared to Manso and Xamini landraces (both A. salmiana Otto ex Salm-Dyck). Penca larga exhibited similar growth in the substrate agricultural soil and volcanic scoria mixture (SVM), and substrate agricultural soil alone (S) regardless of the nutrient solution concentration used, while both A. salmiana landraces exhibited total biomass reduction in the maximum nutrient concentration added in the S substrate (S+L4 treatment) compared to their respective effect on SVM substrate without nutrient addition (SVM+L1 treatment). All landraces exhibited growth inhibition in the commercial substrate mixture (CSM) and volcanic scoria alone (VS) without nutrient addition (CSM+L1 and VS+L1), while growth increase of all landraces in those substrates was relative to the increasing nutrient concentration. Photoinhibition was observed in all landraces in the treatment VS+L1. The growth variations observed across the landraces were helpful to identify potential genotypes ideal for commercial production and to set adequate substrates and nutrient requirements for agave cultivation,

Effect of nitrogen application rate under organic and conventional systems on rice (Oryza sativa L.) growth, grain yield, soil properties, and greenhouse gas emissions

The use of appropriate nitrogen (N) rates is important to optimize organic rice yield potential while minimizing environmental impact and input costs. A greenhouse experiment was conducted to identify the optimal N rate for organic and conventional rice and determine its effects on rice yield, soil properties, and greenhouse gas emissions. Six N rates (0, 50, 100, 150, 200, and 250 kg ha−1) and two cropping systems (organic, conventional) were included in this study. Plant dry biomass, panicle number, and yield of conventional rice linearly increased with increasing N rate from 0 to 250 kg ha−1, whereas those of organic rice increased significantly with increasing N rate until 200 kg ha−1. Conventional rice had a significantly taller plant, whereas organic rice had a significantly greater tiller number. At the optimal N rate, the panicle number and yield of organic rice were 77.3% and 92.7% of those of conventional rice, respectively. CO2 and CH4 emissions peaked at the reproductive stage, whereas N2O emissions peaked at the vegetative stage. Global warming potential (GWP) increased with increasing N rate and peaked at 200 and 250 kg N ha−1, respectively, in the organic and conventional system; however, greenhouse gas intensity (GHGI) was not affected by N rate in both systems. Of the measured soil parameters, total microbial biomass (TMB) was significantly correlated to plant growth, yield, and GWP. Our study indicated that the optimal N rate was 200 kg ha−1 for organic rice and 250 kg ha−1 or higher for conventional rice to approach yield potential.

Pemanfaatan Pupuk Hayati-fosfat untuk Meningkatkan Pertumbuhan Tanaman Jagung (Zea mays L.) di Entisol

Entisols are low fertility soils that require high doses of inorganic fertilizers to support plant growth. On the other hand, it was reported that biofertilizers can be applied to support plant growth. The purpose of this study was to examine the ability of bio-phosphate fertilizers to affect plant growth. The greenhouse experiment was arranged according to a completely randomized design, consisting of five treatments of different fertilization and each treatment was repeated four times. Experimental treatments were P1) control; P2) biological-phosphate fertilizer treatment; P3) treatment of NPK fertilizers; P4) integrated fertilizer treatment of 2 combinations of fertilizers (biological-phosphate &amp; NPK); P5) integrated treatment of 3 combinations of fertilizers (biological-phosphate, NPK &amp; organic). The dose of NPK fertilizer is 75% of the recommended dose. The experimental soil has a sandy loam texture, pH-soil 6.01, content of C-organic1.20%, N-total 0.09%, P-available 5.68 ppm and Kdd 0.31cmol/kg. The results showed that the application of a single biological phosphate fertilizer had no significant effect on plant growth compared to the control. A significant effect was obtained on integrated fertilization, both with two combinations of fertilizers (P4) and with three combinations of fertilizers (P5). The highest plant growth rate, with reference to the total dry biomass of plant shoots and roots, was obtained in treatment P5 with plant growth rates reaching 232.14% higher than the single treatment of biological fertilizers (P2), 53.70% higher than the single treatment of NPK fertilizers (P3) and 16.35% higher than the integrated treatment of two combinations of fertilizers (P4).

Nutrient uptake, physiological responses and growth of tobacco (Nicotiana tabacum L.) in soil under composite salt stress

Higher soil salinity imposes osmotic stress and ion toxicity in plants, leading to substantial crop yield loss worldwide. Understanding of the quantitative and dynamic physiological responses to composite soil salinity (CSS) is limited and needs to be expanded. In this study, physiological, nutritional, and biomass yield parameters of tobacco ( Nicotiana tabacum L.) grown in soil with five levels of CSS, basal CSS level (untreated control, CK) and 3 (T 1 ), 6 (T 2 ), 9 (T 3 ), and 12 (T 4 ) times the basal CSS level, grown under greenhouse were determined and studied at 30-, 60-, and 90-d growth periods. Leaf dry biomass was significantly ( P < 0.05) increased by the low salinity levels applied (T 1 and T 2 ) at all three time points, whereas it progressively declined as the CSS level further increased. The leaf physiological and photosynthetic responses were more adversely affected by CSS at the early growth stage (day 30). A path-coefficient analysis demonstrated that leaf proline concentration had the largest direct effect (–0.66), and leaf Cu content had the most significant indirect effect (0.49) on leaf dry biomass of plants. The results suggest that lower CSS levels (T 1 and T 2 ) could stimulate tobacco growth (leaf biomass yield, in particular), and higher leaf proline and Cu levels at the early growth stage may potentially increase the ability of tobacco plants to withstand the adverse effects of salinity, which could be considered for future research and development of salinity management strategies.

Ex Vitro Simultaneous Acclimatization and Rooting of In Vitro Propagated Tamarillo Plants (Solanum betaceum Cav.): Effect of the Substrate and Mineral Nutrition

Plants propagated by seed do not ensure genetic uniformity and are sometimes infected with diseases. In Vitro micropropagation techniques are an alternative method to traditional cloning approaches for producing true-to-type and pathogen-free plants. However, due to the particularities of the in vitro environment, these plants face many challenges, often critical to their survival, to adapt to ex vitro conditions. In this context, four substrates and two types of mineral nutrition (quick-release (QRF) and controlled-release (CRF) fertilizers), as well as their absence were evaluated in the process of acclimatization of Solanum betaceum plants. Stomatal conductance (gs), chlorophyll content index (CCI), and dry biomass of roots, shoots, and entire plants were the parameters analyzed during the acclimatization. The best crop performance (gs, CCI, and dry biomass) were observed in substrates consisting of vermiculite plus the application of mineral nutrients through a CRF, proving that mineral nutrition has the greatest positive impact on the acclimatization process. In these conditions, plants were obtained with a total dry biomass being significantly higher (515.0 mg (QRF) and 635.9 mg (CRF) when compared to the total dry biomass of untreated plants (119.9 mg). The best conditions for this first experiment were replicated in a second test in order to assess the best fertilizer amount suited for plantlet growth. In this case, the best results were obtained with 0.4 g of CRF, in which plants showed a dry biomass of roots (542.7 mg) and a total dry biomass (594.5 mg), which was significantly higher than in the control (183.2 mg and 165.9 mg, respectively) or with other concentrations of CRF (0.8 and 1.6 g). A similar trend was found concerning the CCI (5.3) and gs (72.5 mmol m−2 s−1) in which 0.4 g CRF gave also the best results when compared with the control (without CRF) or with 0.8 g (4.7 and 56.2 mmol m−2 s−1) and 1.6 g (4.7 and 52.2 mmol m−2 s−1) treatments. In general, it was found that tamarillo plantlets acclimatized to 0.4 g of CRF had a faster initial growth and better performance (CCI and gs), with plants ready to go to the greenhouse/field more quickly, thus reducing the time to obtain suitable plants for the market and shortening the production cycle.

Role of Bacterial Consortium and Synthetic Surfactants in Promoting the Phytoremediation of Crude Oil-Contaminated Soil Using Brachiaria mutica

Crude oil is causing widespread pollution in both aquatic and terrestrial environments. Phytoremediation, which is an emerging technology, involves the efficient use of plant species to remove, detoxify, and/or immobilize contaminants in the soil through natural processes. For this study, Para grass (Brachiaria mutica) inoculated with a previously isolated and characterized bacterial consortium was grown in a pot containing crude oil-contaminated soil. The effects of different concentrations (0.01, 0.1, and 1% of 10% detergent solution in ultrapure water) of nonionic surfactant (Triton X-100) on the degradation of crude oil in contaminated soil were observed. After 4-month experimentation, the maximum growth of the plant root length (28.57 cm), shoot length (65.73 cm), and dry biomass of root and shoot (92.42 g) in the pot having an application of surfactants of 0.1% augmented with the bacterial consortium (T7) was observed. Increasing the concentration of Triton X-100 from 0.01 to 1% augmented with a bacterial consortium led to the maximum removal of total petroleum hydrocarbons ranging between 6 and 40%. This is an indication of the inhibiting effect of Triton X-100 above 0.1% on the growth of plants. Furthermore, the hydrocarbon degradation was confirmed by the FTIR study that can be attributed to the adopted plant species' ability to degrade crude oil contamination, and it is evident through the FTIR results after 120 days of experimentation that the different functional groups are responsible for petroleum hydrocarbons present in soil samples. The current study concludes that the application of integrated treatment of crude oil-contaminated soil by using Triton X-100 and augmented with microbes can help to restore polluted soils for agricultural use. Future strategies such as bioaugmentation of contaminated soil with PGPR and the use of genetically modified (GMO) plants may result in amplifying plant tolerance and ultimately lower the level of soil pollutants for better soil health and boost plant yield.

Application of zinc oxide nanoparticles to promote remediation of nickel by Sorghum bicolor: metal ecotoxic potency and plant response

Nickel (Ni) is one of the most toxic metals in human health. Its bioaccumulation in gluten-free crops limits the progressing demand of safe foods for allergic people to gluten. Nanoparticles have shown promising results in enhancing the crop yield and reducing the risk of heavy metal uptake. However, their nanotoxicity has been raised environmental concerns. This study investigated the environmental behavior of Ni (II) with the co-presence of Zinc Oxide Nanoparticles (ZnO-NPs) in sorghum bicolor. The plants were exposed to different treatments of Ni, ZnO-NPs, or their coexistence. The uptake experiments were carried out within nine treatments consisting of 1 or 5 ppm Ni alone or in coexistence with 50 or 100 ppm ZnO-NPs. The physiological impacts on plants as potential fingerprints for nanotoxicity were recorded and assessed in a phenotypic spectrum. The total Ni or Zn contents were quantified using atomic absorption. NPs significantly altered the bioavailability of Ni. The results revealed that at 5 ppm Ni contamination, 50 and 100 ZnO-NPs significantly reduced the Ni uptake by ∼43% and 47%, respectively. Further, the results showed at 50 ppm NPs, the phytotoxicity effects of both Ni and NPs may reduce, leading to higher plant dry biomass yield. Novelty statement Characterization of zinc oxide nanotoxicity threshold by developing a phenotypic spectrum. Also, the study revealed the phytoremediation potential of ZnO nanoparticle in mitigating the nickel uptake in a gluten-free crop (sorghum bicolor).

Application of natural and synthetic growth promoters improves the productivity and quality of quinoa crop through enhanced photosynthetic and antioxidant activities

Modern agriculture is primarily concerned with enhanced productivity of field crops linked with maximum resources use efficiency to feed the increasing population of the world. Exogenous application of biostimulants is considered a sustainable and ecofriendly approach to improve the growth and productivity of agronomic and horticultural field crops. The present study was carried out to explore the comparative growth enhancing potential of plant biostimulants (moringa leaf extract at 3% and sorghum water extract at 3%) and synthetic growth promoters (ascorbic acid at 500 μM and hydrogen peroxide at 100 μM) on growth, productivity and quality of quinoa crop (cultivar UAF-Q7) because it has gained significant popularity among agricultural scientists and farmers throughout the world due to its high nutritional profile. A field experiment was carried out at the Research Area of Directorate of Farms, University of Agriculture, Faisalabad, Pakistan during quinoa cultivation season of 2016–2017 and repeated during next year (2017–2018). All the foliar treatments enhanced the physiological, biochemical, quality, growth and yield attributes of quinoa as compared to control group. However, maximum improvement was observed in chlorophyll a and b contents, photosynthesis and respiration rates, and water use efficiency by moringa leaf extract (MLE) application. MLE application was also found more responsive regarding the improvement in activities of peroxidase, catalase, superoxide dismutase, phenolics and glycine betaine as compared to other treatments. Mineral elements i.e. K, Ca and N in root as well as in shoot were found the highest in response to MLE application. Similarly, growth (plant fresh and dry biomass, plant length and grain yield) and grain quality parameters (protein, K and Ca) were also significantly enhanced. Application of MLE was found to be a viable approach to improve the growth and quality of produce as compared to synthetic compounds.

Organic amendment plus inoculum drivers: Who drives more P nutrition for wheat plant fitness in small duration soil experiment.

Functioning of ecosystems depends on the nutrient dynamics across trophic levels, largely mediated by microbial interactions in the soil food web. The present study investigated the use of phosphate solubilizing bacteria (PSB) and poultry manure (PM) for maintaining labile P in the soil for an extensive fertility enhancement and as a substitution of chemical fertilizers. Based on the different P solubilizing capabilities of Bacillus and Pseudomonas, a quadruple consortium of Bacillus subtilis, Bacillus cereus, Bacillus thuringiensis and Pseudomonas fluorescens, and their grazer nematodes (soil free living) supplemented with PM were studied. This study was carried out on the trophic levels of soil communities to assess the growth and availability of P to the wheat plants. Experiment was performed for 90 days. Comparing the unamended and amended predator results showed that nematode addition beyond bacterial treatment substantially increased the net available P by ≈2 times, and alkaline phosphatase (ALP) activity by 3.3 times. These results demonstrated the nematodes association with increasing nutrient availability or P mineralization. The interactive effect of PM as substrate and biological drivers was more noticeable on plant dry biomass (1.6 times) and plant P concentration (3.5times) compared to the similar unamended treatment. It is concluded that the biological drivers significantly enhanced the soil ALP and available P while the substrate and biological drivers enhanced dry biomass and plant P concentration. Bacterivore nematodes enhanced the effect of PSB for P mineralization via microbial loop and could be used for the enhancement of wheat production.

Silicon increases the production and quality of cherry tomato under different electrical conductivity levels

The addition of high nutrient concentrations to irrigation water increases its electrical conductivity by contributing to its salinity, resulting in crop yield losses. However, in cases where stress conditions are not observed, silicon can act as a biostimulant and promote vegetative growth, fruit quality, and fruit production. From this perspective, this study aimed to evaluate the effect of fertigation with different electrical conductivity levels associated with potassium silicate on the production parameters of cherry tomatoes grown in a protected environment. The study was conducted in Bom Jesus - PI, and arranged in a randomized block design with four replications and a 6 x 2 factorial corresponding to six electrical conductivity levels (1.0, 2.0, 3.0, 4.0, 5.0, and 6.0 dS m-1) in the absence and presence of silicon (2 mmol L-1). The variables analyzed were the number of fruits per plant, fresh and dry fruit biomass, dry biomass of stem, leaves, bunches, root, shoot, and whole plant; and chemical quality of fruits (pH, total soluble solids, titratable acidity, and the ratio of total soluble solids to titratable acidity. Silicon supplementation increased the root and shoot dry masses and improved fruits quality, thus increasing cherry tomato production (Sweet Heaven hybrid) regardless of the electrical conductivity levels.

Mutation breeding of Aspergillus niger by atmospheric room temperature plasma to enhance phosphorus solubilization ability.

BackgroundPhosphorus (P) is abundant in soils, including organic and inorganic forms. Nevertheless, most of P compounds cannot be absorbed and used by plants. Aspergillus niger v. Tiegh is a strain that can efficiently degrade P compounds in soils.MethodsIn this study, A. niger xj strain was mutated using Atmospheric Room Temperature Plasma (ARTP) technology and the strains were screened by Mo-Sb Colorimetry with strong P-solubilizing abilities.ResultsCompared with the A. niger xj strain, setting the treatment time of mutagenesis to 120 s, four positive mutant strains marked as xj 90–32, xj120–12, xj120–31, and xj180–22 had higher P-solubilizing rates by 50.3%, 57.5%, 55.9%, and 61.4%, respectively. Among them, the xj120–12 is a highly efficient P solubilizing and growth-promoting strain with good application prospects. The growth characteristics such as plant height, root length, and dry and fresh biomass of peanut (Arachis hypogaea L.) increased by 33.5%, 43.8%, 43.4%, and 33.6%, respectively. Besides available P, the chlorophyll and soluble protein contents also vary degrees of increase in the P-solubilizing mutant strains.ConclusionsThe results showed that the ARTP mutagenesis technology can improve the P solubilization abilities of the A. niger mutant strains and make the biomass of peanut plants was enhanced of mutant strains.

Effective and durable systemic wheat-induced resistance by a plant-growth-promoting rhizobacteria consortium of Paenibacillus sp. strain B2 and Arthrobacter spp. strain AA against Zymoseptoria tritici and drought stress

For a sustainable environment, plant-growth-promoting rhizobacteria (PGPR) are natural resources considering as one of the most important fungicides’ alternatives inducing resistance to plant diseases.The aim of the present work is to investigate the synergistic promotion effect of a PGPR mixture composed of Paenibacillus sp. strain B2 (PB2) and Arthrobacter spp. strain AA (AA), referred hereafter as Mix-2, on the wheat growth, resistance to Zymoseptoria tritici (teleomorph Mycosphaerella graminicola), the causal agent of Septoria tritici blotch (STB) and drought stress.The results of the quantitative real-time polymerase chain reaction (qPCR) showed a helpful effect of AA for wheat-root external and internal colonization with PB2. Interestingly, in non-stress conditions, the inoculation of wheat grains with Mix-2 (PB2:AA, 1:1), at sowing, showed an increase in almost all tested cultivars for foliar and root dry biomasses. Under drought stress, contrarily to PB2 in single inoculation, Mix-2 induced a significant tolerance in all tested cultivars for plant dry biomass and root length. On the other hand, both PB2 alone and Mix-2 induced resistance against Z. tritici with at least 50% of protection efficiency in all tested cultivars. However, Mix-2-root colonization and -induced resistance were observed at the most mature wheat growth stage. Moreover, Mix-2-induced resistance is characterized by the upregulation of gene markers of the basal defense, defense and cell rescue, reactive oxygen species, jasmonic acid, and phenylpropanoids & phytoalexins pathways. Pathogenesis-related protein 1 (PR1), chitinase, glucanase, and flavonoides are possible gene markers for wheat resistance selection to STB.To conclude, the endophyte PGPR’ consortium of AA and PB2 is a wheat growth promoter and inducer of a durable-systemic resistance to Z. tritici and genotype-independent tolerance to drought stress.

The influence of low-density polyethylene on the development of soybean and vetch plants, and on the formation of root nodules

The introduction of low-density polyethylene (LDPE, 1-5 g/kg) into a poorly humified Typical chernozem resulted in negative effects on the growth of soybean plants and formation of nodules on their roots. At the same time this toxic impact from LDPE was completely neutralized after the soybean seeds had been bacterized with the Rhizobium japonicum RD2 strain – there were no statistical differences in the plant growth parameters and root nodule number observed between the parallel cases where the bacterized seeds were grown in soil with and without LDPE. The introduction of LDPE into soil had a significant stimulating effect in the case of vetch plants: the plant dry biomass increased by 39,3-64,3%, and the number of root nodules – by 2,4-2,8 times. As a result, it was demonstrated that soybean and vetch plants possess a phytoremediation potential for the cases of soil pollution by LDPE. Further research is recommended to evaluate and implement this potential.

The performance of sweet pepper cultivars under different nitrogen levels in a semi-arid environment

Nitrogen is the most important and widely applied nutrient in sweet pepper production as it improves vegetative growth as well as fruit production. Therefore, the present research was aimed to evaluate promising sweet pepper cultivars as a function of different nitrogen fertilizer levels for semi-arid conditions of Pakistan during 2018 and 2019. Four nitrogen levels (75, 100, 125 and 150 kgha−1) and three sweet pepper cultivars (Ganga, Winner and Savio) were adopted in this study. Vegetative growth as well yield attributes were found highest during the cropping season of 2019 as compared with 2018. Plant height, stem diameter, canopy diameter, fresh and dry biomass of sweet pepper enhanced by the increased application of nitrogen from 75 to 125 kgha−1. All the yield contributing traits including number of fruits per plant, fruit fresh weight per plant and fruit yield per hectare were found the highest with nitrogen application of 150 kgha−1. In most of the crop traits, application of 125 kg Nha−1 and 150 kg Nha−1 produced statistically similar results. Cultivars respond differently to the nitrogen application. Ganga and Savio behaved similarly in response to nitrogen application. They had a quadratic response to nitrogen application; maximum growth and yield were at 125 kg Nha−1 and then decreased at 150 kg Nha−1. In contrast, Winner showed a somewhat linear response to nitrogen application and maximum growth, biomass and yield were recorded at 150 kg Nha−1. Planting a pepper cultivar with improved nitrogen use efficiency can result in maximum yield in a semi-arid region.