Effect Of Plant Growth Promoting Rhizobacteria Research Articles

Plant Growth Promotion and Heat Stress Amelioration in Arabidopsis Inoculated with Paraburkholderia phytofirmans PsJN Rhizobacteria Quantified with the GrowScreen-Agar II Phenotyping Platform.

High temperatures inhibit plant growth. A proposed strategy for improving plant productivity under elevated temperatures is the use of plant growth-promoting rhizobacteria (PGPR). While the effects of PGPR on plant shoots have been extensively explored, roots-particularly their spatial and temporal dynamics-have been hard to study, due to their below-ground nature. Here, we characterized the time- and tissue-specific morphological changes in bacterized plants using a novel non-invasive high-resolution plant phenotyping and imaging platform-GrowScreen-Agar II. The platform uses custom-made agar plates, which allow air exchange to occur with the agar medium and enable the shoot to grow outside the compartment. The platform provides light protection to the roots, the exposure of it to the shoots, and the non-invasive phenotyping of both organs. Arabidopsis thaliana, co-cultivated with Paraburkholderia phytofirmans PsJN at elevated and ambient temperatures, showed increased lengths, growth rates, and numbers of roots. However, the magnitude and direction of the growth promotion varied depending on root type, timing, and temperature. The root length and distribution per depth and according to time was also influenced by bacterization and the temperature. The shoot biomass increased at the later stages under ambient temperature in the bacterized plants. The study offers insights into the timing of the tissue-specific, PsJN-induced morphological changes and should facilitate future molecular and biochemical studies on plant-microbe-environment interactions.

Exploring plant growth promoting rhizobacteria potential for green agriculture system to optimize sweet potato productivity and soil sustainability in northern Jiangsu, China

The beneficial effects of plant growth-promoting rhizobacteria (PGPR) on crop growth and yield have been widely recognized. However, the application of PGPR in traditional planting systems is often restricted due to the concerns about the incompatibility between PGPR and chemical agricultural inputs. The aim of this study is to test whether the application of PGPR has a beneficial effect on the productivity and sustainability of the green planting system, where the use of low-toxic chemical pesticides and proper amount of chemical fertilizer is allowed. In the current study, field trials of four agriculture systems: green agriculture system, green agriculture system supplemented with beneficial microorganism consortium, organic agriculture system supplemented with the consortium and the control system, were carried out with white, yellow and purple flesh sweet potato varieties. The application of PGPR increased the plant growth and suppressed the stem nematode disease in green system. As a consequence, PGPR increased the yield by 26.44% and raised the farmers’ projected returns in green system on an average of the two-year assessment. Moreover, PGPR promoted the product nutritive quality by 7.51% in soluble sugar and 14.30% in vitamin C content, and also increased the anthocyanin content of the purple sweet potato by 10.73%. Exogenous PGPR significantly retarded the depletion of soil fertility during the crop cultivation, promoted the soil bacterial diversity and altered the bacteria community structure. PGPR treatment increased the relative abundances of Pseudomonas and Lysobacter in the rhizosphere soil, while reduced the amounts of Erwinia and Ralstonia. The changes of soil nutrient and microbes were correlated with the application of exogenous beneficial bacteria regardless of in organic or green agriculture system. Here, we showed the ability of PGPR to efficiently improve the productivity in green agriculture system under the tested condition, and provided evidence for the feasibility of using exogenous PGPR to achieve agricultural sustainability by constructing a positive feedback in crop-soil-microbe interactions.

Growth Promotion of Rice (Oryza sativa L.) Seedlings Using Plant Growth-Promoting Rhizobacteria (PGPR) Isolated from Northwest Ethiopia

Plant growth-promoting rhizobacteria (PGPR) are beneficial soil microorganisms that colonize plant roots and enhance plant growth by a wide variety of mechanisms. In this work, five Bacillus and two Cyanobacteria isolates were successfully isolated and characterized. A pot experiment was conducted to evaluate the effect of PGPR on the growth of three cultivars of rice seedlings. Pots were laid down in a complete random design and 100 ml of spore and Cyanobacteria suspension were poured on the soil surface surrounding each seedling. After 45 days, the seedlings were uprooted and shoot and root parameters were recorded. All the Bacillus and Cyanobacteria isolates showed positive effects on the growth of rice seedlings as compared to control; however, their effectiveness varies from isolate to isolate and also from cultivar to cultivar. Bacterial isolates B3 and B5 showed the highest mean value and statistically significant difference ( P < 0.05 ) in most of the root and shoot parameters of cultivars Jegna and Getachew, respectively, as compared to other bacterial isolates. Both cyanobacterial isolates showed the highest and statistically significant difference ( P < 0.01 ) in almost all the above ground and underground growth parameters compared to other bacterial isolates in all the three cultivars of rice. Similarly, C2 and C1 recorded the highest growth promotion efficacy of shoot and root length (50.07% and 78.27%) on Edget and Getachew cultivars, respectively. Hence, the present study suggests that the use of PGPR isolates such as B3, B5, C1, and C2 as inoculant biofertilizers might be beneficial for rice cultivation as they enhanced the growth of rice seedlings.

Effects of Plant Growth-Promoting Rhizobacteria on the Growth and Soil Microbial Community of Carya illinoinensis.

Plant growth-promoting rhizobacteria (PGPR) are important members of soil microbial communities. In this study, the effects of several PGPR on the growth of Carya illinoinensis plants, the microbial community composition and soil nutrients were investigated by inoculation tests to identify excellent PGPR strains. The experiment showed that after PGPR application, the plant height, ground diameter, and dry weight of C. illinoinensis were significantly increased compared with those of the control group, and Bacillus velezensis YH20 had the most significant effect in promoting growth (p < 0.05). In addition, all the PGPRs used for inoculation promoted plant root growth, and the Brevibacillus reuszeri MPT17 strain had the most significant promoting effect on plant root growth (p < 0.05). The application of PGPRs also affected the nutrient levels in plants and plant rhizosphere soil. For example, compared with the control, the levels of available phosphorus and potassium in rhizosphere soil and the total potassium content in plant roots were significantly increased under Br. reuszeri MPT17 treatment (p < 0.05). The experiment showed that the relative abundance of Mortierella, Dictyophora, and Bacillus in the rhizosphere soil increased significantly after the application of PGPR (p < 0.05). These genera could effectively improve the rate of soil nutrient use, antagonize plant pathogenic bacteria, and promote plant growth. This study provides basic reference data regarding the use of PGPR to improve the microecological environment and promote the growth and development of C. illinoinensis plants.

The key role of indole-3-acetic acid biosynthesis by Bacillus thuringiensis RZ2MS9 in promoting maize growth revealed by the ipdC gene knockout mediated by the CRISPR-Cas9 system

The bacterial biosynthesis of indole-3-acetic acid (IAA) is often related to the beneficial effects of plant growth-promoting rhizobacteria (PGPR) on plant development. In PGPR belonging to the Bacillus genus, the synthesis of IAA may occur through different metabolic pathways that are still poorly understood. B. thuringiensis (Bt) is well known for its insecticidal properties; however, its beneficial features are not limited to pest control. Our group has been studed the beneficial effects of Bt strain RZ2MS9 as growth promoter in a range of plant crops, including soybean, tomato, and maize. We recently demonstrated that bacterial IAA biosynthesis plays an important role in the ability of RZ2MS9 to benefit plant development. However, the molecular involved mechanisms in the IAA biosynthesis by this bacterium in the beneficial interaction with plants remain unclear. Here, we investigated the genetic basis of IAA biosynthesis by RZ2MS9. We knocked out the ipdC gene, involved in IAA biosynthesis via the tryptophan-dependent IPyA pathway, using the CRISPR-Cas9 system. Our results showed that, by disrupting the IPyA pathway, the amount of IAA synthesized by the mutant RZ2MS9 (ΔipdC) in the presence of tryptophan drops 57%. The gene knockout did not affect the bacterial growth, but it did affect its ability to colonize maize. Moreover, deactivating the ipdC gene in RZ2MS9 significantly reduces its ability to promote maize growth. ΔipdC performed worse than RZ2MS9 in almost all evaluated plant parameters, including total root length, projected root area, lateral roots, aerial part dry matter, and germination speed index. Therefore, we demonstrated that tryptophan-dependent IAA biosynthesis via the IPyA pathway by RZ2MS9 is strongly influenced by the ipdC gene. Furthermore, IAA biosynthesis by RZ2MS9 is a major mechanism used by this PGPR to promote maize growth.

The Effect of Plant Growth Promoting Rhizobacteria (PGPRs) on Yield and Some Quality Parameters during Shelf Life in White Button Mushroom (Agaricus bisporus L.).

The use of different bacteria that increase yield and quality in plant production has become common since the 1990s. However, effects of plant growth promoting rhizobacterial (PGPR) treatments during the cultivation period of white button mushroom on quality during marketing duration are not known exactly. This study was carried out to determine the effects of different PGPRs in compost medium on mushroom yield and quality. For this reason, Azospillum lipoferum, Bacillus megaterium, Frateuria aurantia and Thiobacillus thiooxidans, for promoting nitrogen, phosphorus, potassium and sulfur transport, respectively, were applied at a 3 mL per m2 concentration on the 12th day of the spawn run period. Control groups were treated with only water. Azospillum lipoferum increased yield at a rate of 33.3% by enhancing mushroom number per unit area. Shelf life characteristics were observed in mushrooms after storage at 1 °C and at 20 ± 1 °C for 2 days. Bacillus megaterium, Frateuria aurantia and Thiobacillus thiooxidans treatments decreased weight loss and loss in cap firmness, total phenolic compounds and antioxidant capacity during shelf life. However, Azospillum lipoferum for increased yield and Frateuria aurantia and Bacillus megaterium for maintaining postharvest quality were promising treatments during shelf life.

Semi-Arid-Habitat-Adapted Plant-Growth-Promoting Rhizobacteria Allows Efficient Wheat Growth Promotion

Plant-growth-promoting rhizobacteria (PGPR) introduced into agricultural ecosystems positively affect agricultural production and constitute an ecological method for sustainable agriculture. The present study demonstrated the effects of two PGPR, Pantoea agglomerans strain Pa and Bacillus thuringiensis strain B25, on seed germination, on the plant growth of two durum wheat varieties, Bousselam and Boutaleb, and on the frequency of the cultivable beneficial bacterial community. The bacterial strains were used as seed primers (individually or in consortia) by coating them with carboxymethyl cellulose (CMC 1%). The effect of PGPR was negligible on germinative ability but improved seed vigor in the Boutaleb variety after inoculation with the Pa strain alone or in combination with the B25 strain. The results showed that the germination capacity depends on the wheat variety. It seemed to be better in the Bousselam variety. Analysis of the results of morphological plant parameters in sterile compost after 75 days under controlled conditions (16 h light, 26/16 °C day/night) showed a significant improvement in plant growth in both wheat varieties with the Pa strain alone or in combination. Chlorophyll (a, and total), carotenoid, and total soluble sugars were significantly increased, while proline and MDA were strongly reduced by inoculation of the Bousselam variety. Bacterial survival of the Pa and B25 strains in the rhizosphere of sterile compost was appreciable (105–107 CFU/g) for both the Pa and B25 strains. Only the Pa strain was endophytic and able to colonize roots. Contrary to sterile compost, the different inoculation treatments in natural soil (after 114 days) significantly improved all morphological parameters and chlorophyll pigments in both wheat varieties. The reduction of proline contents at the leaf level was observed with Pa, mainly in Bousselam. Bacterial densities of the rhizosphere and endophyte cultivable communities did not differ significantly. However, the number of cultivable beneficial bacteria isolated from roots and rhizosphere with multiple PGP traits was significantly increased. Bacterial survival of CMC-coated seed inoculum was appreciable and remained constant, especially for the Pa strain, during 21 months at room temperature. Based on these results, the PGPR used after seed priming would be a feasible and sustainable strategy to improve soil fertility and promote growth of durum wheat in stressful and non-stressful environments.

Effect of Plant Growth Promoting Rhizobacteria on the Growth and Yield of Foxtail Millet (Setaria italica L. Beauv)

The use of plant growth-promoting rhizobacteria (PGPR) is a sustainable way for efficient absorption and utilization of nutrients by crop species to enhance growth and yield and persistence against biotic and abiotic stresses. However, the use of PGPRs in drought tolerant crops such as foxtail millet is limited because of the low adaptability of PGPRs to the low moisture conditions. In this study, PGPRs acclimatised to low moisture conditions, were isolated from the rhizosphere of sorghum and their growth and yield promoting effect on foxtail millet was studied. Four isolates, Pseudomonas putida, Bacillus subtilis, Bacillus cereus, and Pantoea Stewart were isolated from the rhizosphere of sorghum cultivated on black soils. Further their identity was confirmed by sequencing 16S rDNA.&#x0D; Foxtail millet seeds were inoculated with the newly isolated PGPR strains and evaluated for their effect on shoot and root growth under greenhouse conditions. Effect of PGPRs on yield related traits such as ear-head weight, grain weight, fodder weight, and ear-head length were assessed under field conditions. Newly isolated PGPRs boosted average root and shoot length when seeds were inoculated with Bacillus cereus (19.33 cm) and Pseudomonas putida (28.66 cm), respectively. On the other hand, among the four bacterial cultures, Bacillus subtilis enhanced grain weight (40.42%), ear-head weight (30.19%), fodder weight (49.72%) and ear-head length (42.56%) compared to the control group under field conditions. When considered collectively, the empirical evidence suggests that PGPR can improve crop growth and yield under greenhouse and field conditions.

Untargeted metabolite profiling to elucidate rhizosphere and leaf metabolome changes of wheat cultivars (Triticum aestivum L.) treated with the plant growth-promoting rhizobacteria Paenibacillus alvei (T22) and Bacillus subtilis.

The rhizosphere is a highly complex and biochemically diverse environment that facilitates plant–microbe and microbe–microbe interactions, and this region is found between plant roots and the bulk soil. Several studies have reported plant root exudation and metabolite secretion by rhizosphere-inhabiting microbes, suggesting that these metabolites play a vital role in plant–microbe interactions. However, the biochemical constellation of the rhizosphere soil is yet to be fully elucidated and thus remains extremely elusive. In this regard, the effects of plant growth-promoting rhizobacteria (PGPR)–plant interactions on the rhizosphere chemistry and above ground tissues are not fully understood. The current study applies an untargeted metabolomics approach to profile the rhizosphere exo-metabolome of wheat cultivars generated from seed inoculated (bio-primed) with Paenibacillus (T22) and Bacillus subtilis strains and to elucidate the effects of PGPR treatment on the metabolism of above-ground tissues. Chemometrics and molecular networking tools were used to process, mine and interpret the acquired mass spectrometry (MS) data. Global metabolome profiling of the rhizosphere soil of PGPR-bio-primed plants revealed differential accumulation of compounds from several classes of metabolites including phenylpropanoids, organic acids, lipids, organoheterocyclic compounds, and benzenoids. Of these, some have been reported to function in plant–microbe interactions, chemotaxis, biocontrol, and plant growth promotion. Metabolic perturbations associated with the primary and secondary metabolism were observed from the profiled leaf tissue of PGPR-bio-primed plants, suggesting a distal metabolic reprograming induced by PGPR seed bio-priming. These observations gave insights into the hypothetical framework which suggests that PGPR seed bio-priming can induce metabolic changes in plants leading to induced systemic response for adaptation to biotic and abiotic stress. Thus, this study contributes knowledge to ongoing efforts to decipher the rhizosphere metabolome and mechanistic nature of biochemical plant–microbe interactions, which could lead to metabolome engineering strategies for improved plant growth, priming for defense and sustainable agriculture.

Phytostimulants in sustainable agriculture

The consistent use of synthetic fertilizers and chemicals in traditional agriculture has not only compromised the fragile agroecosystems but has also adversely affected human, aquatic, and terrestrial life. The use of phytostimulants is an alternative eco-friendly approach that eliminates ecosystem disruption while maintaining agricultural productivity. Phytostimulants include living entities and materials, such as microorganisms and nanomaterials, which when applied to plants or to the rhizosphere, stimulate plant growth and induce tolerance to plants against biotic and abiotic stresses. In this review, we focus on plant growth-promoting rhizobacteria (PGPR), beneficial fungi, such as arbuscular mycorrhizal fungi (AMF) and plant growth-promoting fungi (PGPF), actinomycetes, cyanobacteria, azolla, and lichens, and their potential benefits in the crop improvement, and mitigation of abiotic and biotic stresses either alone or in combination. PGPR, AMF, and PGPF are plant beneficial microbes that can release phytohormones, such as indole acetic acid (IAA), gibberellic acid (GA), and cytokinins, promoting plant growth and improving soil health, and in addition, they also produce many secondary metabolites, antibiotics, and antioxidant compounds and help to combat biotic and abiotic stresses. Their ability to act as phytostimulator and a supplement of inorganic fertilizers is considered promising in practicing sustainable agriculture and organic farming. Glomalin is a proteinaceous product, produced by AMF, involved in soil aggregation and elevation of soil water holding capacity under stressed and unstressed conditions. The negative effects of continuous cropping can be mitigated by AMF biofertilization. The synergistic effects of PGPR and PGPF may be more effective. The mechanisms of control exercised by PGPF either direct or indirect to suppress plant diseases viz. by competing for space and nutrients, mycoparasitism, antibiosis, mycovirus-mediated cross-protection, and induced systemic resistance (ISR) have been discussed. The emerging role of cyanobacterial metabolites and the implication of nanofertilizers have been highlighted in sustainable agriculture.

Efektifitas Azotobacter sp. dan Pseudomonas sp. sebagai Plant Growth promoting Rhizobacteria (PGPR) terhadap tanaman Tomat (Lycopersicum esculentum Mill.) pada Andisol-Lembang

The concept of balanced fertilization application is appropriate for tomato plant cultivation. However, most farmers still apply inorganic fertilizers excessively, which negatively impacts the environment and plant productivity. Alternative efforts can be made to reduce the usage for inorganic fertilizers through effective plant growth-promoting rhizobacteria (PGPR) application. This research studied the characteristics of the PGPR inoculants effectiveness (Azotobacter sp. and Pseudomonassp.) combined with NPK towards tomato in Lembang Andisol. The experimental design used was randomized block design, with three replications: A (Control), B (1 PGPR + 0 NPK), C (1 PGPR + NPK), D (1 PGPR + NPK), E (1 PGPR + NPK), F (1 PGPR + 1 NPK), G (1 PGPR + 1 NPK), H (2 PGPR + 1 NPK), I (0 PGPR + 1 NPK), J (½ PGPR +1 NPK). The results showed the treatments of C, F, and J resulted in higher total soil N content than the control treatment. Meanwhile, C and D treatment increased plant N uptake compared to control. Nitrogen uptake increased with the decrease of NPK dose application. All of the PGPR inoculation treatments with NPK combination did not increase Azotobacter sp. population and tomato yield. The yield of tomatoes per hectare showed that the PGPR inoculation at a dose of 3 l/ha (1 PGPR + NPK) increased yield by 28.7% compared to 1 NPK (150 kg/ha of Urea, 100 kg SP-36 and 50 kg/ha KCl) dose. Application of 3 l/ha of PGPR inoculant can save up to 75% of NPK usage

Enhancing productivity of perennial aromatic grasses on marginal lands through plant growth promoting rhizobacteria

AbstractThe cultivation of perennial aromatic grasses on marginal lands is a socio‐economically and ecologically sustainable approach. However, the studies on assessment of the potential efficacies of consortium of plant growth promoting rhizobacteria (PGPR) in enhancing the productivity of perennial aromatic grasses on marginal lands are rare. In this study, therefore, we studied the effect of PGPR consortium (Pseudomonas protegens and two strains of Bacillus paramycoides) on yield and economics of four perennial aromatic grasses (Vetiveria zizanioides, Cymbopogon citratus, C. martinii, and C. winterianus) in slightly alkaline (pH &gt;8.50) soil. A field experiment was established in a complete randomized block design with two treatments (i.e. with PGPR consortium and without PGPR consortium) and three replications. The changes in growth (height, number of slips, and leaf area index), productivity (fresh shoot‐root biomass and oil yield), quality (important secondary metabolites), and economics (cost of cultivation, gross, and net return) in response to PGPR were observed at three harvests. The species‐specific effects of PGPR were found on the growth and productivity of perennial aromatic grasses. On an average, the highest increase in growth and productivity with the effect of PGPR was found in V. zizanioides followed by other grasses. The highest oil yield 16.38, 71.14, 53.13, and 49.49 kg ha−1 were recorded at third harvest in PGPR consortium treated plots for V. zizanioides, C. citratus, C. martinii, and C. winterianus, respectively. The agronomical economics show the highest net return of 2094.95 $US in the cultivation of V. zizanioides with the application of PGPR.

Moisture- and period-dependent interactive effects of plant growth-promoting rhizobacteria and AM fungus on water use and yield formation in dryland wheat

PurposeIn drought-prone soils, plant growth-promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungus (AMF) might positively affect water uptake and crop yield via rhizosphere interactions.MethodsSole and combined additions of Bacillus amyloliquefaciens producing 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase and Rhizophagus irregularis into rhizospheric soils were performed under well-watered (WW; 80% field water capacity), moderate water stress (MWS; 50% FWC) and severe water stress (SWS; 35% FWC) in pot-cultured wheat (Triticum aestivum L.).ResultsIn moderate and severe drought stress, water use efficiency (WUEB) was increased by 27.9–34.3% in PGPR and 20–22.1% in AMF treatments, respectively, and grain yield was improved by 20.03–30.77% in PGPR and 12.13–34.34% in AMF treatments, respectively, compared with control (CK). Importantly, the co-inoculation of AMF and PGPR significantly promoted WUEB by 11.12–27.77% and grain yield by 18.26–21.68% compared to the average value of two sole inoculations in MWS and SWS treatments, respectively. WUEY and biomass production followed a similar trend as WUEB and yield. Particularly, the above parameters were significantly enhanced with the prolonged developmental stages (p < 0.05). ACC deaminase significantly reduced ACC accumulation in MWS and SWS, enhanced AMF root colonization, and promoted rhizosphere microbial biomass carbon and nitrogen levels across all three developing stages. Furthermore, AMF-PGPR co-inoculation enhanced chlorophyll and carotenoid contents during anthesis while reducing them during pre-harvesting. Enhanced water uptake and root activities upsurged photosynthetic traits throughout the growing season.ConclusionAMF-PGPR co-inoculation acted as a promising solution to cope with the droughted environment via root activities for stronger water capture.

A transcriptomic study reveals salt stress alleviation in cotton plants upon salt tolerant PGPR inoculation

Soil salinity is a major constraint for reducing crop productivity worldwide. To combat this situation, the current project was aimed to examine the effect of plant growth-promoting rhizobacteria (PGPR) inoculation on the growth of cotton ( Gossypium hirsutum, var. Jin668) plants during salt stress and to identify salt stress-responsive genes in cotton plants. For this purpose, two bacteria, Bacillus subtilis and Bacillus pumilus were selected among the 20 strains isolated from the cotton rhizosphere under the salt stress (200 mM NaCl) and identified by 16 S rRNA sequencing. B. subtilis and B. pumilus were applied to Jin668 plants under salt stress which enhanced resistance to salt stress (leaf and root growth) compared to only salt-treated plants and control plants. Transcriptomic analysis revealed 556 differentially expressed genes (481 up-regulated and 75 down-regulated) in the B. subtilis + Salt versus Salt treatments and 943 (536 up-regulated and 407 down-regulated) genes in the B. pumilus + Salt versus Salt treatments. KEGG analysis of B. pumilus + Salt versus Salt and B. pumilus + Salt versus Salt revealed the pathways plant-pathogen interaction and plant hormone signal transduction were expressed in both treatments, while ascorbate and aldarate metabolism pathways and glyoxylate and dicarboxylate metabolism pathways were uniquely expressed in the B. pumilus + Salt versus Salt comparison, and the pentose and glucuronate interconversions pathway was uniquely expressed in the B. pumilus + Salt treatment versus Salt comparison. These data showed that B. subtilis and B. pumilus significantly enhance salt stress tolerance in cotton plants during salt stress conditions. • Two Bacteria, Bacillus subtilis and Bacillus pumilus were selected from the cotton rhizosphere under the salt stress. • B. subtilis and B. pumilus were applied to cottonplants under salt stress which enhanced resistance to salt stress. • Transcriptomic analysis revealed 556 DEGs in the B.subtilis vs Salt and 943 DEGS in the B.pumilus vs Salt treatments. • KEGG analysis of B. subtilis and B. pumilus versus Salt revealed the variouspathways were expressed in both treatments. • In conclusion, B. subtilis and B. pumilus significantly enhancetolerance in cotton plants during salt stress conditions.

Effects of plant growth-promoting rhizobacteria (PGPR) and different fertilizer combinations on yield and quality properties in cauliflower (Brassica oleracea L. var. botrytis)

Purpose: This study was carried out to determine the influence of plant growth promoting rhizobacteria (PGPR) (Paenibacillus polymyxa RC14, Bacillus subtilis RC63 and Pseudomonas fluorescens RC77), organic chicken manure (OCM) (4000 kg/da), 3 levels of mineral fertilizer [(NPK1 (80 kg/ha N+50 kg/ha P+80 kg/ha K), NPK2 (160 kg/ha N+75 kg/ha P+160 kg/ha K) and NPK3 (200 kg/ha N+100 kg/ha P+200 kg/ha K)] and combination of these applications on growth, yield and quality of cauliflower under field conditions. Materials and Methods: Field experiments were conducted in randomized complete block design with four replications. Treatments were 1. Control (No Fertilizer Application; 0 kg /ha NPK), 2. NPK1 (80-50-80 kg / ha NPK), 3. NPK2 (160-75-160 kg /ha NPK), 4. NPK3 (200-100-200 kg /ha NPK), 5. PGPR, 6. Organic Chicken Manure (OCM), 7. PGPR + OCM, 8. NPK1+PGPR, 9. NPK2+PGPR, 10. NPK3+PGPR, 11. NPK1+ OCM, 12. NPK2+ OCM, 13. NPK3+ OCM, 14. NPK1+PGPR+ OCM, 15. NPK2+PGPR+ OCM, 16. NPK3+PGPR+ OCMResults: The highest curd weight and marketable yield were observed in NPK2+ OCM in 2014 while in NPK1+PGPR+OCM and NPK2+PGPR+OCM in 2015. NPK2+ OCM elevated the curd weight and marketable yield by 300% compared to the control in 2014. NPK1+PGPR+OCM increased the curd weight and marketable yield by 200% compared to the control in 2015. The highest TSS was observed in the control in 2014 whereas NPK1+PGPR+OCM gave the highest value. NPK treatments elevated the NO3 content of cauliflower curds. In 2014 the highest ascorbic acid content was determined in PGPR while the control gave the highest content in 2015. The highest oxalic acid contents were observed in NPK treatments. Furthermore, PGPR and OCM treatments generally reduced the oxalic acid contents of the cauliflower. Conclusion: NPK with OCM and PGPR applications could be advisable for the yield and quality parameters of cauliflower. Furthermore, the PGPRxOCM combination was advisable for efficiently using in organic agricultural production.

APLIKASI BIANG PGPR (PLANT GROWTH PROMOTING RHIZOBACTERIA) DARI AKAR BAMBU TERHADAP PERTUMBUHAN DAN HASIL TANAMAN PARE (Momordica charantia L)

Paria (Momordica charantia L) is one of the plants from the Cucurbitaceae tribe or the pumpkin tribe, including lowland vegetables, and is classified as a herbaceous plant aged one year or more, growing creeping and climbing. PGPR (Plant Growth Promoting Rhizobacteria) bamboo roots are bacteria that live around the roots of bamboo plants. The purpose of this study was to determine the effect of PGPR from bamboo roots and the right concentration on the growth and yield of pariah plants. This research was conducted in Kelapa Lima village, South Banggai District, Banggai Laut Regency from August 2021 to November 2021. This study used a one-factor randomized block design (RBD) method. This study consisted of 5 levels of treatment, namely: P0 = control, P1 = concentration of 12.5 ml/liter of water, P2 = concentration of 15 ml/liter of water, P3 = concentration of 17.5 ml/liter of water and P4 = concentration of 20 ml / liter of water. Each treatment was repeated five times so that there were twenty-five experimental units. The results showed that the application of PGPR from bamboo roots had a significant effect on plant height at 5 WAP, 7 WAP, and 8 WAP, significantly affected the number of leaves at 3 WAP, 5 WAP, 7 WAP, and 8 WAP, very significant effect on fruit weight, fruit length, and fruit diameter and had no significant effect on the number of pariah fruit.

Impact of Plant Growth-Promoting Rhizobacteria Inoculation on the Physiological Response and Productivity Traits of Field-Grown Tomatoes in Hungary

Drought-tolerant plant growth-promoting rhizobacteria (PGPR) may promote plant development under limited water supply conditions, when plant’s water demand is not completely satisfied under rain-fed conditions or when irrigation water availability is limited. The aim of this study was to examine the effects of two inoculation treatments (B2: Alcaligenes sp. 3573, Bacillus sp. BAR16, and Bacillus sp. PAR11 strains and B3: Pseudomonas sp. MUS04, Rhodococcus sp. BAR03, and Variovorax sp. BAR04 strains) and compare those to a control (B0) without artificial inoculation on chlorophyll fluorescence, leaf chlorophyll content (SPAD value), canopy temperature, and the yield of the processing tomato cultivar H-1015 F1 grown under field conditions. The young seedlings of the hybrid tomato variety H-1015 F1 were immersed in 1% of B2 or B3 products (BAY-BIO, Szeged Hungary) for 5 min. Inoculated and untreated seedlings were grown under three irrigation treatments [regular irrigation (RI), deficit irrigation (DI), and no irrigation (I0)], to reveal the effect of PGPR under different levels of water stress. In the dry year (2018), higher canopy temperature and chlorophyll fluorescence (Fv/Fm) were measured during flowering in plants treated with bacteria than in untreated plants. In the stage of flowering and fruit setting, the B3 treatment led to a significant decrease in the Fv/Fm value, canopy temperature remained high, and the SPAD value was statistically the same in all treatments. Under limited water supply, in most cases, PGPR led to a significantly greater total yield but more unripe green berries compared to untreated plants. Under moderate water shortage (dry year + deficit irrigation), the B3 treatment resulted in 26% more ripe, marketable fruit and 49% less unripe fruit compared to the B2 treatment. On the other hand, in the wet year (2020), the bacterial treatments generally did not affect physiological properties, though the B2 treatment produced a higher marketable yield while the amount of green and diseased fruits did not differ statistically, compared to the B3 treatment under deficit irrigation. Based on our study, we recommend the application of the B3 PGPR product as it positively affected key physiological processes, leading to a higher marketable yield particularly under water shortage.

Application of plant growth-promoting rhizobacteria combined with compost as a management strategy against Verticillium dahliae in tomato

This study aimed to evaluate the effect of plant growth-promoting rhizobacteria (PGPR) and compost, applied alone or in combination, on tomato resistance to vascular wilt caused by Verticillium dahliae. Improved management of vascular wilt is important for enhanced productivity of greenhouse-grown susceptible tomato plants. The application of compost and PGPR resulted in a reduction in infection parameters compared with untreated plants inoculated with the pathogen, as well as activation of plant defence mechanisms. In the presence of the pathogen, compost application significantly improved the total fresh and dry weights by 97% and 71%, respectively, compared with pathogen-inoculated controls. The combination of compost with PGPR significantly increased chlorophyll fluorescence and stomatal conductance compared with the infected-control. In addition, the combination of compost and PGPR reduced the accumulation of stress markers such as malondialdehyde and hydrogen peroxide by 48% and 77%, respectively, and promoted the activity of antioxidant enzymes. Fruit yield and quality were also significantly improved relative to the control. The results suggest that compost applied alone or in combination with PGPR helps to suppress vascular wilt and to improve the yield and quality of tomatoes.

Co-application of spent mushroom substrate and PGPR alleviates tomato continuous cropping obstacle by regulating soil microbial properties

Continuous cropping of tomato (Solanum lycopersicum L.) in China has contributed to the decline of crop quality and yield. The aims of this study were to evaluate the integrated effect of plant growth-promoting rhizobacteria (PGPR) Bacillus sp. HW27 and spent mushroom substrate (SMS) on tomato plant growth and microbiological properties of rhizosphere soil. Bacillus sp. HW27 showed indole-3-acetic acid (IAA) and siderophore production, phosphate solubilization, and root colonization capacity in vitro assays. A pot experiment was carried out with four treatments: (1) CK: unamended control, (2) PGPR, (3) SMS, and (4) PGPR + SMS: combined application of strain HW27 and SMS. The enzyme activities, the abundances of beneficial microbes Bacillus and Pseudomonas and soil-borne pathogenic Fusarium oxysporum (using real-time PCR), the microbial functional diversity (using Biolog Ecoplates), and microbial community (using phospholipid fatty acid (PLFA) analysis) in rhizosphere soil were studied 20, 40 and 60 days after transplantation. At the end of the 60-day pot experiment, the results showed that the PGPR + SMS treatment performed best in improving tomato plants growth, which significantly (p < 0.05) increased the shoot length, root length, shoot dry weight and root dry weight by 34.4, 78.4, 93.5 and 82.4%, respectively, compared to the CK treatment. The enzyme activities of β-1,4-glucosidase, β-d-cellobiosidase, β-1,4-N-acetyl-glucosaminidase, protease and acid phosphatase were higher in the SMS and/or PGPR application treatments than in the CK treatment in the order PGPR < SMS < SMS + PGPR. The SMS + PGPR treatment showed the highest abundances of Bacillus and Pseudomonas, and the lowest abundance of Fusarium oxysporum. Furthermore, the application of SMS and/or PGPR stimulated microbial functional diversity and microbial growth (total PLFAs, bacterial, and Gram (+) and Gram (−) bacterial PLFAs), in which SMS + PGPR treatment had the greatest effect. Consequently, this study showed that co-application of PGPR and SMS expressed synergistic effect to increase tomato plant growth, enzyme activities and microbial biomass in continuous cropping greenhouse soil.

Effects of Plant Growth-Promoting Rhizobacteria and Trichoderma sp. on Potato Growth on Medium Plains

The potato is a horticultural commodity with a high economic value and a consistent selling price. Indonesian potato production, however, remains lower than that of other Asian countries. One reason for this is that environmental sustainability has influenced the expansion of potato cultivation on a plateau, so medium plains have become an alternative. Aside from high-quality seeds, using plant growth-promoting rhizobacteria (PGPR) and Trichoderma sp. as an organic fertilizer is a strategic effort to boost potato yields on medium plains. The focus of this research was to examine how PGPR and Trichoderma sp. affect the growth of potatoes on medium plains. This study was carried out in Temanggung and Sawangan, Magelang, Jawa Tengah, at an altitude of 480 m.a.s.l, using the a complete random design with four different treatments: P0 = control, Treatment P1 = PGPR 20 ml/10 liter water, Treatment P2 = PGPR 40 ml/10 liter water, Treatment P3 = Trichoderma 80 gram/10 liter water, Treatment P4 = Trichoderma 150 gram/10 liter water, and Treatment P5 = PGPR 20 ml/10 liter water + Trichoderma 80 gram/10 liter water. The study found that a combination of PGPR and Trichoderma sp. treatment resulted in better growth than a single PGPR treatment.&#x0D; Keywords: biopesticide, organic fertilizer, PGPR