Trichoderma-mediated rice straw compost promotes plant growth and imparts stress tolerance

Enhancing rice ecological production: synergistic effects of wheat-straw decomposition and microbial agents on soil health and yield

Aims

This study evaluated the impact of wheat straw return and microbial agent application on rice field environments.

Methods

Using Rice variety Chuankangyou 2115 and a microbial mix of Bacillus subtilis and Trichoderma harzianum. Five treatments were tested: T1 (no straw return), T2 (straw return), T3, T4, and T5 (straw return with varying ratios of Bacillus subtilis and Trichoderma harzianum).

Results

Results indicated significant improvements in rice root length, surface area, dry weight, soil nutrients, and enzyme activity across T2-T5 compared to T1, enhancing yield by 3.81-26.63%. T3 (50:50 microbial ratio) was optimal, further increasing root dry weight, soil enzyme activity, effective panicle and spikelet numbers, and yield. Dominant bacteria in T3 included MBNT15, Defluviicoccus, Rokubacteriales, and Latescibacterota. Higher Trichoderma harzianum proportions (75% in T5) increased straw decomposition but slightly inhibited root growth. Correlation analysis revealed a significant positive relationship between yield and soil microorganisms like Gemmatimonadota and Firmicutes at the heading stage. Factors like dry root weight, straw decomposition rate post-jointing stage, and elevated soil enzyme activity and nutrient content from tiller to jointing stage contributed to increased panicle and spikelet numbers, boosting yield.

Conclusion

The optimal Bacillus subtilis and Trichoderma harzianum ratio for straw return was 50:50, effectively improving soil health and synergizing high rice yield with efficient straw utilization.

Desilification of phytolith exacerbates the release of arsenic from rice straw

Arsenic (As) turnover in rice paddy agro-ecosystems has received much attention because As can enter the food chain through its accumulation in rice, thereby affecting human health. Returning straw to soil is a common practice to retain nutrients for soil and crops, but it also cycles As within the rice paddy field ecosystems. However, there is still a lack of detailed understanding of the fate of As in rice straw, and how or to what extent it is recycled back into the soil environment. This study aims to elucidate the relationship between the microstructure of rice straw and the release of As during rice straw decomposition. The microstructure of rice straw was found to comprise both organic and silica (phytolith) components. These two constituents are inter-embedded to form a composite-like structure that contains up to 6.48 mg As Kg-1. The 30-day batch experiments revealed that the biochemical release of As simultaneously depends upon the decomposition of the organic component and the desilicification of the silica component. Accompanying the release of As was the release of other elements such as Fe, Al, P and S. These elements can further interact with As to form less mobile compounds. The introduction of either Trichoderma harzianum or Bacillus velezensis was expected to accelerate the decomposition of rice straw, and enhance the silica dissolution, hence contributing to an increase in the As release. Despite these expectations, our observations showed the opposite effects. Microorganisms presumably have facilitated the change in solution chemistry or the inclusion of As into the newly-formed precipitates. The biochemical decomposition process can reduce straw particle size, while the negatively-charge surface will involve microsized straw particles in the electrostatic interaction, thereby favoring the dispersibility state. Therefore, the co-transport of micro-sized straw particles with As under field conditions should not be neglected.

Titanium biogenic nanoparticles to help the growth of Trichoderma harzianum to be used in biological control

BACKGROUND

The biogenic synthesis of metallic nanoparticles is a green alternative that reduces the toxicity of this nanomaterials and may enable a synergy between the metallic core and the biomolecules employed in the process enhancing biological activity. The aim of this study was to synthesize biogenic titanium nanoparticles using the filtrate of the fungus Trichoderma harzianum as a stabilizing agent, to obtain a potential biological activity against phytopathogens and mainly stimulate the growth of T. harzianum, enhancing its efficacy for biological control.

RESULTS

The synthesis was successful and reproductive structures remained in the suspension, showing faster and larger mycelial growth compared to commercial T. harzianum and filtrate. The nanoparticles with residual T. harzianum growth showed inhibitory potential against Sclerotinia sclerotiorum mycelial growth and the formation of new resistant structures. A great chitinolytic activity of the nanoparticles was observed in comparison with T. harzianum. In regard to toxicity evaluation, an absence of cytotoxicity and a protective effect of the nanoparticles was observed through MTT and Trypan blue assay. No genotoxicity was observed on V79-4 and 3T3 cell lines while HaCat showed higher sensitivity. Microorganisms of agricultural importance were not affected by the exposure to the nanoparticles, however a decrease in the number of nitrogen cycling bacteria was observed. In regard to phytotoxicity, the nanoparticles did not cause morphological and biochemical changes on soybean plants.

CONCLUSION

The production of biogenic nanoparticles was an essential factor in stimulating or maintaining structures that are important for biological control, showing that this may be an essential strategy to stimulate the growth of biocontrol organisms to promote more sustainable agriculture.

A review of additives use in straw composting

Straw composting is not only a process of decomposition and re-synthesis of organic matter, but also a process of harmless treatment, avoiding air pollution caused by straw burning. Many factors, including raw materials, humidity, C/N, and microbial structure, may determine the composting process and the quality of final product. In recent years, many researches have focused on composting quality improvement by adding one or more exogenous substances, including inorganic additives, organic additives, and microbial agents. Although a few review publications have compiled the research on the use of additives in composting, none of them has specifically addressed the composting of crop straw. Additives used in straw composting can increase degradation of recalcitrant substances and provide ideal living surroundings for microorganism, and thus reduce nitrogen loss and promote humus formation, etc. This review's objective is to critically evaluate the impact of various additives on straw composting process, and analyze how these additives enhance final quality of composting. Furthermore, a vision for future perspectives is provided. This paper can serve as a reference for straw composting process optimization and composting end-product improvement.

Fungi That Promote Plant Growth in the Rhizosphere Boost Crop Growth

The fungi species dwelling in the rhizosphere of crop plants, revealing functions that endeavor sustainability of the plants, are commonly referred to as 'plant-growth-promoting fungi' (PGPF). They are biotic inducers that provide benefits and carry out important functions in agricultural sustainability. The problem encountered in the agricultural system nowadays is how to meet population demand based on crop yield and protection without putting the environment and human and animal health at risk based on crop production. PGPF including Trichoderma spp., Gliocladium virens, Penicillium digitatum, Aspergillus flavus, Actinomucor elegans, Podospora bulbillosa, Arbuscular mycorrhizal fungi, etc., have proven their ecofriendly nature to ameliorate the production of crops by improving the growth of the shoots and roots of crop plants, the germination of seeds, the production of chlorophyll for photosynthesis, and the abundant production of crops. PGPF's potential mode of action is as follows: the mineralization of the major and minor elements required to support plants' growth and productivity. In addition, PGPF produce phytohormones, induced resistance, and defense-related enzymes to inhibit or eradicate the invasion of pathogenic microbes, in other words, to help the plants while encountering stress. This review portrays the potential of PGPF as an effective bioagent to facilitate and promote crop production, plant growth, resistance to disease invasion, and various abiotic stresses.

A review on recent eco-friendly strategies to utilize rice straw in construction industry: pathways from bane to boon

With the growing demand, a large amount of paddy has been harvested by growers leaving behind the stubble (left over rice straw), which is being a big burden on the farmers for its management. For the easy access, the burning of stubble has been opted which in turn results in the deterioration of the environment. To mitigate this problem, rice straw utilization strategies should be opted. Therefore, in this review article, the strategies of utilizing rice straw in fiber or ash form to manufacture construction materials have been summarized. The manuscript also considers the method of productions, variability in raw materials, and various mechanical/physical properties of construction materials targeted. Further, the financial aspects related to utilization of rice straw and rice straw ash are also encoded at last. This review will be helpful to expedite the research in this field and may also be used for startups related to various product development using straw in the local areas, which may depreciate the burning of straw in the field and its environmental effects.

Rhizosphere inoculation of Nicotiana benthamiana with Trichoderma harzianum TRA1-16 in controlled environment agriculture: Effects of varying light intensities on the mutualism-parasitism interaction

Trichoderma spp., a genus of fast-growing and highly adaptable fungi that form symbiotic relationships with plant roots, rendering them ideal for practical use in controlled environment agriculture. Herein, this paper aims to understand how the Nicotiana benthamiana with inoculation of Trichoderma harzianum strain TRA1-16 responds to light intensity variation. Pot experiments were conducted under low and high light intensities (50 and 150 μmol·m^-2·s^-1, respectively) and microbial treatments. Plant growth, physio-biochemical attributes, activities of antioxidant enzymes, and phytohormones regulation were investigated. The results showed that for non-inoculated plants, the reduction in light intensity inhibited plant growth, nitrogen (N) and phosphorus (P) uptake, chlorophyll a/b, and carotenoid content. Trichoderma inoculation resulted in 1.17 to 1.51 times higher concentrations of available N and P in the soil than the non-inoculated group, with higher concentrations at high light intensity. Plant height, dry weight, nutrient uptake, and antioxidant activity were significantly increased after inoculation (p<0.05). However, the growth-promoting effect was less effective under low light conditions, with lower plant height and P content in plants. We suggested that when the light was attenuated, the mutualism of the Trichoderma turned into parasitism, slowing the growth of the host plant. The application of fungal inoculation techniques for plant growth promotion required coordination with appropriate light complementation. The mechanisms of coordination and interaction were proposed to be incorporated into the biological market theory.