Growth Of Tomato Plants Research Articles

Characterization of endophytic yeast and its suppressive effect on root rotting fungi of tomato under neem cake soil amendment

BackgroundThe exposure of crops to a variety of fungal and bacterial pathogens leads to huge economic losses. Different strategies are being adapted to control these diseases among which the application of chemicals fungicide is common. However, these chemicals are posing a serious threat to the environment. For biological management of root rot disease of tomato and better fruit quality, studies were conducted on the possible use of endophytic yeast as a biocontrol agent.ResultsEndophytic yeasts were isolated from healthy plants and identified. Identification of selected isolates was confirmed on the basis of 18S rDNA gene sequencing. They were evaluated for suppressive effect on root rotting fungi in vitro and also in vivo on tomato plants, used alone or under neem cake soil amendment. Seventy-six isolates of yeasts were evaluated against root rotting fungi Fusarium oxysporum, F. solani, Rhizoctonia solani and Macrophomina phaseolina using dual culture plate assay. Seventy-five isolates were found to suppress radial growth of F. oxysporum, F. solani and M. phaseolina by producing zones of inhibition or lysing the fungal hyphae. However, none of the isolates was found to inhibit R. solani in vitro. Most of the isolates also caused nematicidal activity at varying degree against Meloidogyne javanica. All test isolates produced indole acetic acid in vitro and solubilized phosphorus. In pots and field plot experiments, test isolates of yeasts were able to suppress root rotting fungi on tomato in natural soil and soil amended with neem cake with enhancement of growth of tomato plants. Yeasts were also found to ameliorate the plant resistance through enhancing polyphenolic contents, salicylic acid and antioxidant activity.ConclusionsEndophytic yeasts were found effective against root rot disease of tomato and could be used as a potential biocontrol agent for the management of soil-borne diseases of tomatoes.

Assessing the Potential Role of Compost, PGPR, and AMF in Improving Tomato Plant Growth, Yield, Fruit Quality, and Water Stress Tolerance

Assessing the Potential Role of Compost, PGPR, and AMF in Improving Tomato Plant Growth, Yield, Fruit Quality, and Water Stress Tolerance

Synergic Effect of Microorganism and Colloidal Biochar-Based Organic Fertilizer on the Growth and Fruit Quality of Tomato

It is well known that carbon-based organic fertilizer can effectively promote crop growth and improve nutrient utilization efficiency. However, little is known about the effect of microorganisms on the nutrient availability of carbon-based organic fertilizer. To elucidate the contribution of microorganisms to the agricultural benefit of colloidal biochar-based fertilizer, a 5-month pot experiment was conducted to study the effect of different combinations of Methyltrophic bacillus, colloidal biochar, and organic fertilizer on physical–chemical properties of soil, plant growth, physiological-biochemical reactions, yield, and quality of tomato. The results show that the addition of Methyltrophic bacillus effectively promoted the availability of soil nutrients (such as nitrate nitrogen and available potassium) and increased soil cation exchange capacity; meanwhile, it significantly increased the content of chlorophyll-a (9.42–27.41%) and promoted the net photosynthetic rate (10.86–13.73%) and biomass of tomato fruit (17.84–26.33%). The contents of lycopene, vitamin C, total sugar, and soluble sugar in the fruits treated by the ternary combination of Methyltrophic bacillus, colloidal biochar, and organic fertilizer increased by 58.40%, 46.53%, 29.45%, and 26.65%, respectively. The above results demonstrate that the addition of beneficial microorganisms could further improve the performance of biochar-based fertilizer on plant growth, yield, and fruit quality of tomato. This information provides evidence for the promising performance of microorganism-supported biochar organic fertilizer in agricultural applications.

Root treatment with a vitamin K3 derivative: a promising alternative to synthetic fungicides against Botrytis cinerea in tomato plants.

Botrytis cinerea, the causal agent of gray mold has a great economic impact on several important crops. This necrotrophic fungus causes disease symptoms during vegetative growth and also into postharvest stages. The current method to combat this disease is fungicide application, with high economic costs and environmentally unsustainable impacts. Moreover, there is an increasing general public health concern about these strategies of crop protection. We studied the protection of tomato plants against B. cinerea by previous root treatment with menadione sodium bisulfite (MSB), a known plant defense activator. Root treatment 48 h before inoculation with MSB 0.6 mmol L-1 reduced leaf lesion diameter by 30% and notably cell deaths, compared to control plants 72 h after inoculation. We studied the expression level of several pathogenesis-related (PR) genes from different defense transduction pathways, and found that MSB primes higher PR1 expression against B. cinerea. However, this stronger induced resistance was impaired in transgenic salicylic acid-deficient NahG line. Additionally, in the absence of pathogen challenge, MSB increased tomato plant growth by 28% after 10 days. Our data provide evidence that MSB protects tomato plants against B. cinerea by priming defense responses through the salicylic acid (SA)-dependent signaling pathway and reducing oxidative stress. This work confirms the efficacy of MSB as plant defense activator against B. cinerea and presents a novel alternative to combat gray mold in important crops.

Assessing the effect of P-solubilizing bacteria and mycorrhizal fungi on tomato yield and quality under different crop rotations

Little is known about the effects of inoculation with beneficial microorganisms under diversified crop rotations on agronomic performance of the high-value vegetable crop tomato (Solanum lycopersicum L.). A greenhouse experiment was conducted to evaluate the interactive effect of crop precession with two native species, faba bean (Leguminosae) and barley (Graminaceae), and inoculations with commercial arbuscular mycorrhizal fungi (AMF), and phosphate solubilizing Streptomyces roseocinereus MS1B15 on tomato plant growth, yield, fruit quality and the contents of various mineral nutrients. The overall results revealed that crop inoculation with S. roseocinereus MS1B15 significantly increased tomato growth and yield while crop precession showed no differences among tested treatments. Plant nutrient assimilation was significantly increased by both inoculations and was differentially modulated under faba bean and barley rotations. Furthermore, fruit quality demonstrated significant variations between treatments: whereas the inoculations significantly increased tomato vitamin C, crop rotations increased antioxidant compounds and organic acids. Overall, faba bean rotation combined with S. roseocinereus MS1B15 inoculation showed the best benefits for tomato plants, increasing most of the biometric variables evaluated in this study. Such combinations could be recommended as a sustainable and feasible model for tomato production.

Correction to: Effects of some biological agents on the growth and biochemical parameters of tomato plants infected with Alternaria solani (Ellis & Martin) Sorauer

The effects of three biological control agents (BCAs) including Funneliformis mosseae BEG12 (FM) as arbuscular mycorrhizal fungi (AMF), Bacillus velezensis V40K2 (BV) as plant growth-promoter rhizobacterium (PGPR) and Trichoderma viride NTC2 (TV) as plant growth-promoter fungus (PGPF) against Alternaria solani (Ellis & Martin) Sorauer (AS) were studied. For this purpose, 2.5 g FM (150 spores g−1) was inoculated in the seed bed. After seedling emergence, TV (1 × 106 spor/ml) as well as BV (1 × 108 CFU mL−1) were inoculated. Then, onee week after TV and BV treatments, 1 × 106 spore mL−1 of AS was inoculated by spraying on each plant. It was found that the single, double and triple combinations of these selected biocontrol agents against pathogen generally suppressed the disease severity and stimulated the plant growth. Compared to other treatments without any positive effects, the use of the AM fungal treatment had positive effects on the total phenolic content as well as antioxidant activity. Also, the highest total phosphorus content was observed in FM + TV + AS (7.3%) and AS (8.0%) treatments. No statistically significant difference was observed among the combinations in terms of the AMF colonization rate and soil spore density, which showing that mycorrhizal dependency did not occur in the FM + TV + BV + AS treatment (-6.7). However, compared to the control group, this treatment did not affect on disease suppression and plant growth parameters.

Structural properties and dissolution behavior of new generation controlled release phosphate glass fertilizers

In this work, different phosphate glasses in the Na2O–K2O–CaO–P2O5, Na2O–K2O–CaO–Al2O3–P2O5 and Na2O–K2O–CaO–Al2O3–SiO2–P2O5 systems are synthesized by conventional melt quenching technique and investigated in terms of physical, thermal, and structural properties along with long-term dissolution behavior in different solvent media, i.e., deionized water, and 2% citric acid solution simulating the neutral soil environment and pH value of the plant root zone. In addition, the effect of selected glasses (with and without microconstituent doping) on the growth of tomato plants are examined and their potential use as controlled release glass fertilizers is evaluated by linking their chemical durability behavior with structural changes in the glass network. Consequently, studied glass compositions — exhibiting long term (over 90 days) nutrient release during plant growth along with insignificant change in pH and no toxic compound release during dissolution process — are evaluated as promising controlled release fertilizers for tomato plants.

First Report of Protective Activity of Paronychia argentea Extract against Tobacco Mosaic Virus Infection

The widespread use of chemical control agents and pesticides for plant-pathogen control has caused many human health and environmental issues. Plant extracts and biocontrol agents have robust antimicrobial activity against different plant pathogens. However, their antiviral activities are still being investigated. In the present study, the methanol extract of Paronychia argentea was characterized and evaluated for its protective activity against the tobacco mosaic virus (TMV) infection in tomato plants under greenhouse conditions at 21 days post-inoculation. The results showed that the foliar application of P. argentea extract (10 µg/mL) enhanced tomato plant growth, resulting in significant increases in shoot and root parameters and total chlorophyll contents. Moreover, a significant reduction in TMV accumulation level in P. argentea-treated plants of 77.88% compared to non-treated plants was reported. Furthermore, induction of systemic resistance with significant elevation in production of antioxidant enzymes (PPO, CAT, and SOD) and transcriptional levels of the pathogenesis-related proteins (PR-1 and PR-7) and polyphenolic genes (CHS and HQT) were also observed. Out of 16 detected compounds, HPLC analysis revealed that the most abundant polyphenolic compounds found in P. argentea extract were gallic acid (5.36 µg/mL), kaempferol (7.39 µg/mL), quercetin (7.44 µg/mL), ellagic acid (7.89 µg/mL), myricetin (8.36 µg/mL), and ferulic acid (8.69 µg/mL). The findings suggest that the use of P. argentea extract as an effective and safe source for the production of bioactive compounds may offer a solution for a promising approach for the management of plant viral infections. To the best of our knowledge, this is the first report of the protective activity of P. argentea extract against plant viral diseases.

Genomic Analysis Reveals Potential Mechanisms Underlying Promotion of Tomato Plant Growth and Antagonism of Soilborne Pathogens by Bacillus amyloliquefaciens Ba13.

ABSTRACTBacillus amyloliquefaciens Ba13 is a plant beneficial bacterium isolated from loessial soil with notable biological activity. This study clarified potential mechanisms underlying the plant growth-promoting and antipathogenic effects of strain Ba13. A pot experiment was used to verify the plant growth-promoting effects of strain Ba13 on tomato, and the antipathogenic activity was tested in petri dishes. The underlying mechanisms were explored based on whole-genome sequencing of strain Ba13 and liquid chromatography-tandem mass spectrometry (LC-MS/MS) detection of plant hormones and biosynthetic intermediates. The results showed that exposure to strain Ba13 promoted tomato plant growth significantly. Compared with control treatment, bacterial treatment increased plant height and fresh weight by 10.98% and 20.15%, respectively, at 28 days after inoculation. Strain Ba13 exhibited antagonistic activity against all eight plant pathogens tested. The 3,861,210-bp genome of strain Ba13 was predicted to encode antibiotics (e.g., surfactin, bacillaene, bacillomycin D, bacilysin, and bacillibactin) and volatile gaseous compounds (e.g., 2,3-butanediol and acetoin). Genes were also predicted to encode extracellular phytase and β-glucanase that are secreted through the secretory (Sec) system. Strain Ba13 could synthesize indole-3-acetic acid through the indole-3-pyruvic acid pathway. The results of this study indicate that B. amyloliquefaciens Ba13 has multiple effects on tomato plants and associated microorganisms, directly or indirectly promoting plant growth and controlling plant diseases.IMPORTANCE Microbial agents are considered the optimal alternative for chemical agents. Exploring the mechanisms underlying the beneficial effects of microbial agents is essential for rational applications in the field. In this study, we report a functional bacterial strain, Bacillus amyloliquefaciens Ba13, which exhibited plant growth-promoting and antipathogenic effects. The whole genome of strain Ba13 was sequenced, and functional genes of interest were predicted. Strain Ba13 could synthesize indole-3-acetic acid through the indole-3-pyruvic acid pathway.

Fabrication, Characterization, and Evaluation of Eggshells as a Carrier for Sustainable Slow-Release Multi-Nutrient Fertilizers.

Development of environment-friendly fertilizers to adhere to the sustainability in agronomic practices and to overcome the limitations posed by the conventional fertilizers has been an important challenge. In this study, a cost-effective biowaste eggshell (ES) material was utilized as a sustainable support for eco-friendly slow-release multi-nutrient fertilizers (SMFs) by simple impregnation of micro- and macronutrients. The synthesized multi-nutrient composite was characterized by various characterization techniques. The leaching tests were conducted using simulated soil solutions and tap water, which showed slow and steady release patterns of the impregnated nutrients. Also, the water holding and water retention capacity of soil were improved upon addition of ES-SMF. Further, the results of pot experiments showed enhanced plant growth of cucumber (Cucumis sativus) and tomato (Solanum lycopersicum) seedlings that proved the efficiency of ES-SMF to serve as an environment-friendly fertilizer in agriculture to attain sustainability.

Regulation of plant immunity and growth by tomato receptor-like cytoplasmic kinase TRK1.

The molecular mechanisms of quantitative resistance (QR) to fungal pathogens and their relationships with growth pathways are poorly understood. We identified tomato TRK1 (TPK1b Related Kinase1) and determined its functions in tomato QR and plant growth. TRK1 is a receptor-like cytoplasmic kinase that complexes with tomato LysM Receptor Kinase (SlLYK1). SlLYK1 and TRK1 are required for chitin-induced fungal resistance, accumulation of reactive oxygen species, and expression of immune response genes. Notably, TRK1 and SlLYK1 regulate SlMYC2, a major transcriptional regulator of jasmonic acid (JA) responses and fungal resistance, at transcriptional and post-transcriptional levels. Further, TRK1 is also required for maintenance of proper meristem growth, as revealed by the ectopic meristematic activity, enhanced branching, and altered floral structures in TRK1 RNAi plants. Consistently, TRK1 interacts with SlCLV1 and SlWUS, and TRK1 RNAi plants show increased expression of SlCLV3 and SlWUS in shoot apices. Interestingly, TRK1 suppresses chitin-induced gene expression in meristems but promotes expression of the same genes in leaves. SlCLV1 and TRK1 perform contrasting functions in defense but similar functions in plant growth. Overall, through molecular and biochemical interactions with critical regulators, TRK1 links upstream defense and growth signals to downstream factor in fungal resistance and growth homeostasis response regulators.

EFFECT OF SILICON NUTRIENT AND SALINITY (ABIOTIC STRESS) ON TOMATO PLANT (Solanum lycopersicum)

Tomato (Solanum lycopersicum) imports have increased in Malaysia due to high demand. One of the constraints to local production is excessive salinity in soils that leads to toxicity in crops, reduction in soil fertility and reduction of availability of water to tomato plant that is known to be sensitive to high salinity. Nevertheless, silicon nutrient proven could protect plants from abiotic stress. Therefore, the objectives of this study were to determine the plant growth of tomato plant treated with silicon (Si) under salinity stress and to observe the physical changes of stems. A total of ten treatments (T1 – T10) were applied with different concentrations of silicon: 0.5% Si (v/v), 1.5% Si (v/v), 2.5% Si (v/v), potassium silicate as positive control whereas negative control (only water and 0.5% NaCl) and a mixture of equal volumes of the silicon and potassium silicate treatments with 0.5% NaCl. The treatments were applied once a week (40 ml for each plant pot). Throughout this study, plant growth data was collected (plant height, diameter of stems, time of anthesis, number of fruits, and chlorophyll content). Results showed that with 0.5% Si (v/v) and 1.5% Si (v/v) (with 0.5% NaCl), the tomato plants grow well especially in plant height, number of leaves and chlorophyll contents. Furthermore, cross section of stems showed a significant difference (p<0.05) in stem diameter among treated plants [2.5% potassium silicate (T4), 0.5% Si (v/v) + 0.5% NaCl (T6) and 2.5% potassium silicate + 0.5% NaCl (T9)] and control (0.5% NaCl). However, the largest vascular bundle width was recorded in plants treated with 1.5% Si (v/v). This study has proven that tomato plants could uptake silicon and improve the plant growth under salinity stress conditions and giving potential for Si as biostimulant to other Solanaceae family (potato, pepper and eggplant).

Nematicidal Activity of Essential Oil from Lavandin (Lavandula × intermedia Emeric ex Loisel.) as Related to Chemical Profile.

Essential oils (EOs) from lavandin are known for a large spectrum of biological properties but poorly and contrastingly documented for their activity against phytoparasitic nematodes. This study investigated the toxicity of EOs from three different lavandin cultivars, Abrialis, Rinaldi Cerioni, and Sumiens, either to juveniles (J2) and eggs of the root-knot nematode Meloidogyne incognita and to infective stages of the lesion nematode Pratylenchus vulnus. The suppressive activity of treatments with EOs from the three lavandin cultivars in soil infested by M. incognita was also investigated in a greenhouse experiment on potted tomato. The compositional profiles of tested EOs were also analyzed by GC-FID and GC-MS. Linalool was the major component of all the three EOs, as accounting for about 66%, 48%, and 40% of total EO from cv Rinaldi Cerioni, Sumiens, and Abrialis, respectively. Linalool acetate was the second most abundant compound in the EOs from cv Abrialis (18.3%) and Sumiens (14.9%), while significant amounts of camphor (11.5%) and 1,8-cineole (12.1%) were detected in cv Rinaldi Cerioni and Sumiens EOs, respectively. The mortality of M. incognita J2 peaked 82.0%, 95.8%, and 89.8% after a 24 h treatment with 100 mg·mL−1 solutions of cv Abrialis, Rinaldi Cerioni, and Sumiens EOs, respectively. Infective specimens of P. vulnus were largely more sensitive than M. incognita J2, as there were peak mortality rates of 65.5%, 67.7%, and 75.7% after 4 h of exposure to Abrialis, Rinaldi Cerioni, and Sumiens EO, respectively. All three lavandin EOs significantly affected also M. incognita egg hatchability, which reduced to 43.6% after a 48 h egg mass exposure to a 100 µg·mL−1 solution of cv Rinaldi Cerioni EO. Soil treatments with the three lavandin EOs strongly reduced, according to a dose–effect relationship, density of M. incognita eggs, and J2 both on tomato roots and in soil, as well as significantly reduced gall formation on tomato roots. Finally, almost all soil treatments with the lavandin EOs also resulted in a positive impact on tomato plant growth.

Bacillus velezensis 83 increases productivity and quality of tomato (Solanum lycopersicum L.): Pre and postharvest assessment.

Bacillus spp. are well known plant growth promoting bacteria (PGPB) and biological control agents (BCA) due to their capacity to synthesize a wide variety of phytostimulant and antimicrobial compounds. B. velezensis 83 is a strain marketed in Mexico as a foliar biofungicide (Fungifree AB™) which has been used for biological control of five different genera of phytopathogenic fungi (Colletotrichum, Erysiphe, Botrytis, Sphaerotheca, Leveillula) in crops of agricultural importance such as mango, avocado, papaya, citrus, tomato, strawberry, blueberry, blackberry and cucurbits, among others. In this work, the potential of plant growth promotion of B. velezensis 83 was evaluated on different phenological stages of tomato plants as well as the biocontrol efficacy of B. velezensis 83 formulations (cells and/or metabolites) against B. cinerea infection on leaves and postharvest fruits. Greenhouse grown tomato plants inoculated with a high concentration (1×108 CFU/plant) of B. velezensis 83 yielded 254 tons/Ha•year of which the 64% was first quality tomato (≥100 g/fruit), while the control plants produced less than 184 tons/Ha•year with only 55% of first quality tomato. Additionally, in vitro assays carried out with leaves and fruits, shown that the B. velezensis 83 cells formulation had an efficacy of control of B. cinerea infection of ∼31% on leaves and ∼89% on fruits, while the metabolites formulation had an efficacy of control of less than 10%. Therefore, it was concluded that spores (not the metabolites) are the main antagonism factor of Fungifree AB™. The high effectivity of B. cinerea control on fruits by B. velezensis 83, opens the possibility for a postharvest use of this biofungicide.

Combining Willow Compost and Peat as Media for Juvenile Tomato Transplant Production

In 2019–2020, a study was conducted to evaluate the suitability of willow composts as a substrate or substrate component in tomato transplant cultivation. In 2019, 4-year-old chopped willow biomass (mostly chips <2 cm long) was formed into four compost prisms: S0—willow compost without additives; SN—willow compost with the addition of nitrogen; SF—willow compost with the addition of wood-decaying mycelium; and SFN—willow compost with the addition of wood-decaying mycelium and nitrogen. Willow compost was rated as a homogeneous substrate (S0, SN, SF, and SFN) and as a substrate component with peat (P), mixed in willow:peat ratios such as 25:75, 50:50, and 75:25, in the variants S0:P, SN:P, SF:P, and SFN:P. For reference, deacidified peat was used as a homogeneous substrate. The study showed that willow compost could be used as a renewable plant material replacing peat. The best parameters (plant height, leaf span, number of leaves, and especially the highest weight) were found in tomato transplants grown in the SF:P and SFN:P substrates and at a 25:75 ratio. It was found that the addition of nitrogen to the compost, in order to obtain a wide C:N ratio, negatively affected the initial growth of tomato plants.

Response of Hybrid Tomato (Solanum lycopersiucm L) for Calcium Nutrition: Growth, Root Traits and SPAD Index

Aims: To evaluate the effect of various sources and levels of calcium fertilisation in improving the growth and SPAD index of hybrid tomato at different growth stages.
 Study Design: Factorial randomized block design (FRBD) with three replications.
 Place and Duration of Study: A field experiment was conducted in the farmer’s field at Devarayapuram village, Thondamuthur block, Coimbatore from January to April, 2021.
 Methodology: A field experiment was conducted with hybrid tomato (Solanum lycopersiucm L) Shivam by using various organic and inorganic calcium sources viz., calcium sulphate, calcium nitrate, calcium silicate, poultry manure and pressmud applied at different levels (0, 20, 40, 60, 80 kg Ca ha-1) in a factorial randomized block design with three replications. The growth parameters such as plant height, root length, lateral root length, root volume and SPAD index were recorded as per standard protocols at different plant growth stages.
 Results: A linear increase in the plant growth, root traits and SPAD index of hybrid tomato was noted by the addition of organic and inorganic sources of calcium and the highest values were observed with the application of 80 kg Ca ha-1. Higher plant height (93.8 cm), root length (16.8 cm), lateral root length (13.3 g cc-1) and SPAD index (62.0) was registered with poultry manure applied at 80 kg Ca ha-1 which was followed by pressmud applied at the same level. Skipping of calcium in the fertiliser schedule registered the lowest growth response of hybrid tomato at all the growth stages.
 Conclusion: Inorganic Ca fertiliser sources though improved the growth, root traits and SPAD index of hybrid tomato at different growth stages, and it was comparatively lesser than the organic sources such as poultry manure and pressmud as calcium sources. The order of better growth performance was: Poultry manure > Pressmud > Ca silicate > Ca Nitrate > Ca sulphate. The lowest values of all the growth attributes were noted with NPK control. It was concluded that application of poultry manure at 80 kg Ca ha-1 would be effective in improving the growth, root traits and SPAD index of hybrid tomato.

Heterologous overexpression of strawberry bZIP11 induces sugar accumulation and inhibits plant growth of tomato

Consumers and breeders value strawberry fruit with high sugar content and sweetness. However, many factors negatively affect this trait. bZIP-S1 subfamily was closely correlated with the carbohydrate metabolism. Moreover, it can regulate plant development and growth, and respond to various stress. In the present study, a total of four bZIP-S1 members were identified in strawberry. Quantitative RT-PCR analysis showed a member of this subfamily, designated as bZIP11, most highly expressed in different tissues of strawberry. Especially, it had a significant transcript accumulation during the fruit development and ripening. Constitutive expression of FvbZIP11 in tomato caused severe plant growth retardation which was accompanied by wrinkled and curly leaves. The leaf yellowish and chlorotic patches were reflected in decrease of chlorophyll. Meanwhile, epidermal cells were smaller in leaves of transgenic plant. In addition, the total soluble solid and soluble sugar content of the fruit was significantly higher than WT during the fruit ripening. Taken together, the heterologous overexpression of strawberry bZIP11 induced sugar accumulation and hindered plant growth in tomato, which provided more information for improving strawberry fruit quality.

Effects of some biological agents on the growth and biochemical parameters of tomato plants infected with Alternaria solani (Ellis & Martin) Sorauer

Effects of some biological agents on the growth and biochemical parameters of tomato plants infected with Alternaria solani (Ellis & Martin) Sorauer

Introduction of probiotic bacterial consortia promotes plant growth via impacts on the resident rhizosphere microbiome.

Plant growth depends on a range of functions provided by their associated rhizosphere microbiome, including nutrient mineralization, hormone co-regulation and pathogen suppression. Improving the ability of plant-associated microbiomes to deliver these functions is thus important for developing robust and sustainable crop production. However, it is yet unclear how beneficial effects of probiotic microbial inoculants can be optimized and how their effects are mediated. Here, we sought to enhance tomato plant growth by targeted introduction of probiotic bacterial consortia consisting of up to eight plant-associated Pseudomonas strains. We found that the effect of probiotic consortium inoculation was richness-dependent: consortia that contained more Pseudomonas strains reached higher densities in the tomato rhizosphere and had clearer beneficial effects on multiple plant growth characteristics. Crucially, these effects were best explained by changes in the resident community diversity, composition and increase in the relative abundance of initially rare taxa, instead of introduction of plant-beneficial traits into the existing community along with probiotic consortia. Together, our results suggest that beneficial effects of microbial introductions can be driven indirectly through effects on the diversity and composition of the resident plant rhizosphere microbiome.

Dose-Dependent Application of Straw-Derived Fulvic Acid on Yield and Quality of Tomato Plants Grown in a Greenhouse.

Fulvic acids are organic compounds widely distributed in soils, and the application of fulvic acids is thought to increase crop yield and quality. However, the effects vary among various sources and doses of fulvic acids and environmental and growth conditions of crops. Here, we investigated the effects of bioresource-derived (corn straw) fulvic acids on plant production and quality of tomato plants and soil chemical properties in soil cultures while experiments on seed germination and hydroponics were conducted to explore the underlying mechanism. Base dressing with 2.7 g kg–1 increased the yield of tomato by 35.0% at most as increased fruit number. Fulvic acids increased the concentrations of minerals, such as Ca, Fe, and Zn and the concentrations of citric, malic, and some amino acids in berries of tomato but did not affect the concentrations of soluble sugars and aromatic substances in tomato fruits. Similarly, fulvic acids at 80–160 mg L–1 increased germination rate, growth vigor, and radicle elongation of tomato seeds while it increased plant biomass, concentrations of nutrients, and root length of tomato plants in hydroponics to the greatest extent in general. The increases in yield and quality can be attributed to the improvement in root growth and, thus, increased nutrient uptake. In addition, the base application of fulvic acids improved soil cation exchange capacity and soil organic matter to an extent. In conclusion, base dressing and the addition into solution of fulvic acids at moderate doses facilitate root growth and nutrient uptake and, thus, vegetable production and quality; therefore, fulvic acids can be an effective component for designing new biofertilizers for sustainable agricultural production.