The Growth Promotion of Peppers (Capsicum annuum L.) by Trichoderma guizhouense NJAU4742-Based Biological Organic Fertilizer: Possible Role of Increasing Nutrient Availabilities

Applying bio-organic fertilizer improved saline alkaline soil properties and cotton yield in Xinjiang

Bio-organic fertilizers have demonstrated significant potential in enhancing saline-alkali soil properties, boosting crop yield, and reducing chemical fertilizer dependency. However, the extent of improvement and optimal application rates for varying saline-alkali soil conditions remain unclear. We conducted a 2-year field experiment (2022-2023) to evaluate the effects of different bio-organic fertilizer application rates on soil properties, nutrient availability, and cotton yield across three saline-alkali cotton fields with varying salinity levels 4.58, 9.07, and 12.76 g·kg⁻¹ (T1-T3). Four treatments were implemented, involving chemical fertilizer reductions of 0% (CK), 20% (F1), 40% (F2), and 60% (F3). Results indicated that, compared to CK, bio-organic fertilizer application reduced soil bulk density, salinity, and pH by an average of 15.84%, 53.86%, and 7.5%, respectively. Concurrently, soil moisture content, organic matter, nitrogen, phosphorus, potassium, and cotton yield increased by 36.72%, 58.4%, 59.4%, 77.9%, 88.7%, and 50.32%, respectively. Notably, the improvements in soil properties and cotton yield were more pronounced in 2023 compared to 2022. Principal component analysis revealed that a 60% bio-organic fertilizer application rate was optimal for mild, moderate, and severely salinized cotton fields. These findings provide a scientific basis for reducing chemical fertilizer use while improving the productivity and sustainability of saline-alkali soils.

Current status and future trends of microbial and nematode-based biopesticides for biocontrol of crop pathogens

The increasing public demand to avoid the use of synthetic pesticides and fertilizers in agricultural production systems, causing serious environmental damages, has challenged industry to develop new and effective solutions to manage and control phytopathogens. Biopesticides, particularly microbial-based biopesticides, are a promising new alternative with high biodegradability, specificity, suitability for incorporation into integrated pest management practices, low likelihood of resistance development, and practically no known human health risks. However: expensive production methods, narrow action spectra, susceptibility to environmental conditions, short shelf life, poor storage stability, legislation registry constraints, and general lack of knowledge are slowing down their adoption. In addition to regulatory framework revisions and improved training initiatives, improved preservation methods, thoughtfully designed formulations, and field test validations are needed to offer new microbial- and nematode-based biopesticides with improved efficacy and increased shelf-life. During the last several years, substantial advancements in biopesticide production have been developed. The novelty part of this review written in 2023 is to summarize (i) mechanisms of action of beneficial microorganisms used to increase crop performance and (ii) successful formulation including commercial products for the biological control of phytopathogens based on microorganisms, nematode and/or metabolites.

Trichoderma guizhouense NJAU4742 augments morphophysiological responses, nutrient availability and photosynthetic efficacy of ornamental Ilex verticillata

Winterberry holly (Ilex verticillata [L.] A. Gray), a deciduous shrub producing glossy bright red berries, is a valuable ornamental and medicinal plant with good market prospects. However, the growth and development of I. verticillata are significantly affected by various stresses, and environmentally hazardous agrochemicals are often used to mitigate them. Trichoderma spp., ubiquitous soil-borne eco-friendly plant growth-promoting fungi, are potent biostimulants and biofertilizers and viable alternatives to agrochemicals for healthy and sustainable agriculture. In this study, the temporal efficacy of different dosages of the filamentous fungus Trichoderma guizhouense NJAU4742 in promoting morphophysiological responses of I. verticillata and the physicochemical properties and enzymatic activities of the substrate were investigated. Different concentrations of the strain T. guizhouense NJAU4742 spore suspension (C [0%], T1 [5%, v/m], T2 [10%, v/m] and T3 [15%, v/m]) were injected in the substrate contained in a pot in which 1-year-old I. verticillata was planted for temporal treatment (15, 45 and 75 days) under open-air conditions. The beneficial effects of T2 and/or T3 treatment for a long duration (75 days) were evident on the different root, aerial and photosynthetic traits; total contents of nitrogen (N), phosphorus (P) and potassium (K) in different tissues and the physicochemical properties of the substrate and its enzymatic activities (urease and invertase). Overall, the study revealed the potency of strain T. guizhouense NJAU4742 as a sustainable solution to improve the growth and development and ornamental value of I. verticillata.

Trichoderma asperellum boosts nitrogen accumulation and photosynthetic capacity of wolfberry (Lycium chinense) under saline soil stress

Trichoderma can promote plant growth under saline stress, but the mechanisms remain to be revealed. In this study, we investigate photosynthetic gas exchange, photosystem II (PSII) performance, nitrogen absorption and accumulation in a medicinal plant wolfberry (Lycium chinense) in saline soil supplemented with Trichoderma biofertilizer (TF). Larger nitrogen and biomass accumulation were found in plants supplemented with TF than with organic fertilizer (OF), suggesting that Trichoderma asperellum promoted plant growth and nitrogen accumulation under saline stress. T. asperellum strengthened root nitrogen (N) absorption according to greater increased root NH4+ and NO3- influxes under supplement with TF than OF, while nitrogen assimilative enzymes such as nitrate reductase, nitrite reductase and glutamine synthetase activities in roots and leaves were also stimulated. Thus, the elevated N accumulation derived from the induction of T. asperellum on nitrogen absorption and assimilation. Greater increased photosynthetic rate (Pn) and photosynthetic N-use efficiency under supplement with TF than OF illustrated that T. asperellum enhanced photosynthetic capacity and N utilization under saline stress. Although increased leaf stomatal conductance contributed to carbon (C) isotope fractionation under TF supplement, leaf 13C abundance was significantly increased by supplement with TF rather than OF, indicating that T. asperellum raised CO2 assimilation to a greater extent, reducing C isotope preference. Trichoderma asperellum optimized electron transport at PSII donor and acceptor sides under saline stress because of lower K and J steps in chlorophyll fluorescence transients under supplement with TF than OF. The amount of PSII active reaction centers was also increased by T. asperellum. Thus, PSII performance was upgraded, consistent with greater heightened delayed chlorophyll fluorescence transients and I1 peak under supplement with TF than OF. In summary, TF acted to increase N nutrient acquisition and photosynthetic C fixation resulting in enhanced wolfberry growth under saline soil stress.

Effects of the application of microbiologically activated bio-based fertilizers derived from manures on tomato plants and their rhizospheric communities

Bio-based fertilizers (BBFs) recovered from animal manure are promising products to optimise resources recovery and generate high agricultural yields. However, their fertilization value may be limited and it is necessary to enrich BBFs with microbial consortia to enhance their fertilization value. Three specific microbial consortia were developed according to the characteristics of three different BBFs produced from manure (bio-dried solid fraction, solid fraction of digestate and biochar) to enhance plant growth and product quality. A greenhouse pot experiment was carried out with tomato plants grown with microbiologically activated BBFs applied either as N-organic fertilizers or as an organic amendment. A next generation sequencing analysis was used to characterise the development of each rhizospheric community. All the activated BBFs gave enhanced tomato yields (fresh and dry weight) compared with the non-activated treatments and similar to, or higher than, chemical fertilization. Concerning the tomato fruits' organoleptic quality, lycopene and carotenoids concentrations were improved by biological activation. Metagenomic analysis points at Trichoderma as the main driver of the positive effects, with the effects of added bacteria being negligible or limited at the early stages after fertilization. In the context of the circular economy, the activated BBFs could be used to replace synthetic fertilisers, reducing costs and environmental burdens and increasing production.

Partial substitution of chemical fertilizer by Trichoderma biofertilizer improved nitrogen use efficiency in wolfberry (Lycium chinense) in coastal saline land

A two-year field trial was conducted to investigate the effects of partial substitution of chemical fertilizer (CF) by Trichoderma biofertilizer (TF) on nitrogen (N) use efficiency and associated mechanisms in wolfberry (Lycium chinense) in coastal saline land. As with plant biomass and fruit yield, apparent N use efficiency and plant N accumulation were also higher with TF plus 75% CF than 100% CF, indicating that TF substitution promoted plant growth and N uptake. As a reason, TF substitution stabilized soil N supply by mitigating steep deceases in soil NH4 +-N and NO3 -N concentrations in the second half of growing seasons. TF substitution also increased carbon (C) fixation according to higher photosynthetic rate (Pn) and stable 13C abundance with TF plus 75% CF than 100% CF. Importantly, leaf N accumulation significantly and positively related with Pn, biomass, and fruit yield, and structural equation modeling also confirmed the importance of the causal relation of N accumulation coupled with C fixation for biomass and yield formation. Consequently, physiological and agronomical N use efficiencies were significantly higher with TF plus 75% CF than 100% CF. Overall, partial substitution of CF by TF improved N use efficiency in wolfberry in coastal saline land by stabilizing soil N supply and coupling N accumulation with C fixation.

Biochar loaded with bacteria enhanced Cd/Zn phytoextraction by facilitating plant growth and shaping rhizospheric microbial community

Biochar and metal-tolerant bacteria have been widely used in the remediation of heavy metal contaminated soil. However, the synergistic effect of biochar-functional microbes on phytoextraction by hyperaccumulators remains unclear. In this study, the heavy metal-tolerant strain Burkholderia contaminans ZCC was selected and loaded on biochar to produce biochar-resistant bacterial material (BM), and the effects of BM on Cd/Zn phytoextraction by Sedum alfredii Hance and rhizospheric microbial community were explored. The results showed that, BM application significantly enhanced the Cd and Zn accumulation of S. alfredii by 230.13% and 381.27%, respectively. Meanwhile, BM alleviated metal toxicity of S. alfredii by reducing oxidative damage and increasing chlorophyll and antioxidant enzyme activity. High-throughput sequencing revealed that BM significantly improved soil bacterial and fungal diversity, and increased the abundance of genera with plant growth promoting and metal solubilizing functions such as Gemmatimonas, Dyella and Pseudarthrobacter. Co-occurrence network analysis showed that BM significantly increased the complexity of the rhizospheric bacterial and fungal network. Structural equation model analysis revealed that soil chemistry property, enzyme activity and microbial diversity contributed directly or indirectly to Cd and Zn extraction by S. alfredii. Overall, our results suggested that biochar- B. contaminans ZCC was able to enhance the growth and Cd/Zn accumulation by S. alfredii. This study enhanced our understanding on the hyperaccumulator-biochar-functional microbe interactions, and provided a feasible strategy for promoting the phytoextraction efficiency of heavy metal contaminated soils.

Solid-State Fermentation: Applications and Future Perspectives for Biostimulant and Biopesticides Production

With the expansion of the green products market and the worldwide policies and strategies directed toward a green revolution and ecological transition, the demand for innovative approaches is always on the rise. Among the sustainable agricultural approaches, microbial-based products are emerging over time as effective and feasible alternatives to agrochemicals. However, the production, formulation, and commercialization of some products can be challenging. Among the main challenges are the industrial production processes that ensure the quality of the product and its cost on the market. In the context of a circular economy, solid-state fermentation (SSF) might represent a smart approach to obtaining valuable products from waste and by-products. SSF enables the growth of various microorganisms on solid surfaces in the absence or near absence of free-flowing water. It is a valuable and practical method and is used in the food, pharmaceutical, energy, and chemical industries. Nevertheless, the application of this technology in the production of formulations useful in agriculture is still limited. This review summarizes the literature dealing with SSF agricultural applications and the future perspective of its use in sustainable agriculture. The survey showed good potential for SSF to produce biostimulants and biopesticides useful in agriculture.

Organic Amendments: Direct Application and Residual Effects on Vegetative and Reproductive Growth of Hot Pepper

The high production potential of coffee and animals in the Gedeo zone that could produce huge amounts of coffee pulp and animal manure wastes has been polluting the environment. In this sense, this study was aimed at averting pollution and managing plant and animal wastes, focusing on the effect of coffee pulp and animal manure in the form of vermicompost, biochar, and ordinary compost on hot pepper vegetative and reproductive growth. A 15 ton per hectare of each treatment was applied in a randomized complete block design replicated three times. Vegetative and reproductive growth parameters (plant height, leaf number, number of branches, days to 50% flowering, total fresh biomass, number of fruits per plant, single fruit length, and fruit yield per hectare) were recorded, and the statistical difference was determined at 5% significance level using R-program. The result showed that there was a significant difference among treatments. Coffee pulp vermicompost prepared using Eisenia fetida earthworm had significantly ( $P<0.05$ ) higher results in plant height, leaf number, number of branches, total fresh biomass, number of fruits per plant, single fruit length, and total yield, while the minimum values were recorded in topsoil (control treatment) and animal manure compost. The direct and residual effects of vermicompost and biochar organic amendments were the potential organic fertilizers for hot pepper fast growth and to produce enormous yield, which might be due to their nature in improving soil physicochemical and biological properties as well as nutrient uptake.

Seaweed Fertilizer Prepared by EM-Fermentation Increases Abundance of Beneficial Soil Microbiome in Paddy (Oryza sativa L.) during Vegetative Stage

Excessive use of chemical fertilizer could potentially decrease soil productivity by decreasing soil microbiome diversity. In this study, we evaluated the effects of fermented seaweed fertilizer in the soil microbial community of paddy plants (Oryza sativa L.). The paddy seedlings were divided into five groups, control (C0), chemical fertilizer (CF), seaweed fertilizer (SF), chemical and seaweed fertilizer combination 50:50 (CFSF1), and chemical and fertilizer combination 75:25 (CFSF2). The CFSF1 combination showed to be the most effective in inducing plant height (83.99 ± 3.70 cm) and number of tillers (24.20 ± 4.08). After 8 weeks after transplantation, the isolated DNA from each soil treatment were subjected to 16S rRNA (v3–v4 region) next-generation sequencing. The beneficial Acidobacteriota was most abundant in CFSF1. At genus level, the nitrifying bacteria MND1 was seen to be abundant in CFSF1 and also present in other SF treatments. The genus Chujaibacter is highly abundant in CF, which potentially plays a role in denitrification resulting in soil degradation. In addition, the CFSF1-treated soils show significantly higher diversity of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA). The current results could potentially contribute to the utilization of SF as a bioremediator and promoting green agriculture practice by reducing the amount of CF usage.

Waste-Derived NPK Nanofertilizer Enhances Growth and Productivity of Capsicum annuum L

Waste generation is a global issue that necessitates effective management for both human and animal health as well as environment. There are several ways to reduce waste, but recycling appears to be the best choice. By recycling, not only will the problem of pollution be resolved, but valuable compounds could be generated to be used as nutrients for plants. In this study, eco-friendly methods were established to produce α- and β-chitosan (CS) (as a source of nitrogen) with different degrees of deacetylation from shrimp shells and squid pin waste, phosphorous through degreasing and calcination of bovine bone and potassium from evaporation of banana peels Kolakhar. The waste bulk products were physically characterized and dry-milled into nano-powders. Different concentrations of the produced nano-NPK fertilizer (10%, 25%, 50% and 100%) were foliar-applied to Capsicum annum L. cv. Cordoba plants and compared to commercial chemical fertilizer and untreated control plants. The obtained results revealed that the nano-composite NPK with 25% concentration significantly promoted growth, yield and harvest of C. annuum as compared with the control and chemical fertilizer-treated plants. This study demonstrated that the use of an eco-friendly preparation of waste NPK composites, with a low concentration, could be applied as foliar fertilizer over chemical fertilizer to enhance the growth and productivity of Capsicum.

Effect of Colonization of Trichoderma harzianum on Growth Development and CBD Content of Hemp (Cannabis sativa L.)

Trichoderma harzianum, as a natural endophytic biocontrol agent, can ameliorate plant development, nutrient uptake, and resistance to biotic and abiotic stresses. This study aimed to investigate the effect of Trichoderma harzianum inoculation on agronomical and quality characteristics of two monoecious hemp (Cannabis sativa L.) varieties, Fedora 17 and Felina. A greenhouse pot experiment was conducted in a completely randomized design of two treatments of Trichoderma harzianum with a low and high dose of the fungus (T1 and T2). The significance of differences between treatments was estimated by using a Fisher’s test with a significance level p = 0.05. The root density of both varieties was significantly affected by treatments, and higher values were recorded in Fedora 17 (2.32 mm cm⁻³). The Arbuscular Mycorrhizal Fungi (AMF) colonization of the root system and the soil emission of CO₂ were higher after the inoculation of Trichoderma harzianum. The highest values of plant height and dry weight were noticed for T2, especially in variety Felina. Trichoderma harzianum positively influenced characteristics of inflorescences such as their number, fresh weight moisture, and compactness in both varieties, while the dry weight, length, and dry yield of inflorescences were not improved. Finally, the fertigation of Trichoderma harzianum in hemp plants was beneficial by increasing the cannabidiol (CBD) content, especially in T2 treatment (4 × 10¹² CFU kg⁻¹).