Contribution of Piriformospora indica on improving the nutritional quality of greenhouse tomato and its resistance against cu toxicity after humic acid addition to soil

Integrated biorefinery process for dual production of fermentable sugars and functional humic acids from lignocellulose

In traditional lignocellulosic biorefineries, lignocellulose undergoes pretreatment followed by enzymatic hydrolysis to produce fermentable sugars, often leaving behind lignin rich residual biomass underutilized. In this study, we present a novel and integrated approach for the comprehensive utilization of lignocellulosic biomass as fermentable sugars and functional humic acids. First, corn stover was subjected to a mild densification pretreatment with Ca(OH)₂ (DLCA(ch)), facilitating efficient enzymatic hydrolysis and yielding 172.09 g/L of sugars at 30 % solid loading. Further, the enzymatic hydrolysis residues were subsequently converted into artificial humic acid (AHA) through a mild artificial humification process at 50 °C, catalyzed by potassium hydroxide (KOH) alone or in combination with urea. This process achieved a high AHA yield of 44.17 %, with a final concentration of 78 g/L. The AHA synthesized with KOH and urea (KU-AHA) predominantly consisted of medium molecular weight fractions (30-100 kDa) and exhibited enhanced nitrogen incorporation due to the involvement of urea. Additionally, KU-AHA demonstrated comparable effectiveness to natural humic acid in promoting plant growth, leading to an 13.40 % increase in plant height, an 11.82 % increase in root length. This integrated approach not only maximizes the utilization of lignocellulosic biomass but also provides a sustainable and efficient pathway for residue valorization.

Production of artificial humic acid from rice straw for fertilizer production and soil improvement

In this study, artificial humic acid (AHA) was produced from rice straw at room temperature. The response surface methodology was used to investigate the response of artificial humic acid to time, liquid-solid ratio, and KOH concentration. The optimal reaction conditions were determined: reaction time of 2 h, liquid-solid ratio of 6, and KOH concentration of 1.5 mol/L. The artificial humic acid content under these conditions was 32.29 g/L, which satisfied the Chinese agricultural industry standard for water-soluble humic acid fertilizers (humic acid content ≥30 g/L). Compared with chemical fertilizers, artificial humic acid fertilizer promoted chard growth and increased soil organic matter and humic acid. The stability of artificial humic acid was better, with a retention rate of 60.47 % in the soil. Water-soluble humic acid fertilizer also promoted chard growth by increasing the relative abundance of growth-promoting bacteria such as Glutamicibacter and Pseudomonas and, as well as growth-promoting fungi such as Mortierella. The application of water-soluble humic acid fertilizers has implications for both soil improvement and the reduction of agricultural carbon emissions.

Piriformospora indica alter root-associated microbiome structure to enhance Artemisia annua L. tolerance to arsenic

Microorganisms in the rhizosphere are crucial allies for plant stress tolerance. Recent research suggests that by interacting with the rhizosphere microbiome, microorganisms can aid in the revegetation of soils contaminated with heavy metal(loid)s (HMs). However, it is unknown that how Piriformospora indica influences the rhizosphere microbiome to mitigate arsenic-toxicity in arsenic-enriched environments. Artemisia annua plants were grown in the presence or absence of P. indica and spiked with low (50) and high (150 µmol/L) concentrations of arsenic (As). After inoculation with P. indica, fresh weight increased by 37.7% and 10% in control and high concentration treated plants, respectively. Transmission electron microscopy showed that cellular organelles were severely damaged by As and even disappeared under high concentration. Furthermore, As was mostly accumulated by 5.9 and 18.1 mg/kg dry weight in the roots of inoculated plants treated with low and high concentrations of As, respectively. Additionally, 16 S and ITS rRNA gene sequencing were applied to analyze the rhizosphere microbial community structure of A. annua under different treatments. A significant difference was observed in microbial community structure under different treatments as revealed by non-metric multidimensional scaling ordination. The bacterial and fungal richness and diversity in the rhizosphere of inoculated plants were actively balanced and regulated by P. indica co-cultivation. Lysobacter and Steroidobacter were found to be the As-resistant bacterial genera. We conclude that P. indica inoculation could alter rhizosphere microecology, thereby mitigating As-toxicity without harming the environment.

PBAT/PLA humic acid biodegradable film applied on solar greenhouse tomato plants increased lycopene and decreased total acid contents

This work aims to resolve residual film pollution in farmlands and improve tomato quality. The mechanical properties and degradation of PBAT/PLA lignin (MZS) and PBAT/PLA humic acid (FZS) composite biodegradable film were analyzed, and its effect on soil temperature and humidity, soil microorganisms, soil physical and chemical properties, tomato yield, and quality was studied. Polyethylene film (PE) was used as a control. The results demonstrate a higher degradation degree of FZS film than of MZS film. The degradation degree of FZS and MZS films reached level 2 and level 1, respectively, after 131 days of film covering. The weight loss rate of FZS and MZS films reached 52.74 % and 57.82 %, respectively, when buried for 160 days. Compared to the coverings of PE and MZS films, FZS film could significantly increase the soil's electric conductivity and organic matter content (p < 0.05). The relative abundance of soil fungi Chaetomium also increased. The yield, soluble solids, vitamin C (Vc), soluble sugar, and lycopene of tomato plants covered with FZS film significantly increased by 6.74 %, 8.75 %, 15.41 %, 8.30 %, and 27.27 % compared to plants covered with PE film, and the total acid and hardness significantly decreased by 24.95 % and 8.46 %, respectively (p < 0.05). Using 10 μm PBAT/PLA humic acid biodegradable film for tomato cultivation in autumn and winter increased the lycopene and decreased the total acid content by changing the soil's physical and chemical characteristics and increasing the content of Chaetomium soil.

Impact of Piriformospora indica on various characteristics of tomatoes during nickel nitrate stress under aeroponic and greenhouse conditions

As an essential nutrient for plant growth, nickel's (Ni) requirement is very low, and its augmented level causes environmental pollution and toxicity. Being a root endophytic fungus, Piriformospora indica (P. indica) can be beneficial to many plants under stress and non-stress conditions, particularly in terms of their improved growth performance. P. indica, as evidenced, enhances tolerance and resistance in most plants once they experience a range of stresses caused by biotic and abiotic factors, e.g., diseases and heavy metals. Against this background, the positive effects of P. indica on the tomato plants under Ni-induced stress (300, 600, and 900 mg L^-1) were analyzed in three experiments at labs, at greenhouses, and via aeroponics in this study. The growth traits of the tomato plants, such as root length (RL) and root dry weight (RDW), were accordingly found to be positively boosted in the cases treated with P. indica compared to the non-treated ones. Treating with P. indica also thwarted the negative effects of Ni on some biochemical traits, including anthocyanin (Anth), proline (Pro), catalase (CAT), and glutathione peroxidase (GPx), while significantly minimizing the adverse impacts of this heavy metal at different levels on hydrogen peroxide (H₂O₂). Despite this, the Ni-stressed plants indicated much better traits in the presence of this fungus, compared with the non-treated ones, in most of the cases measured. Moreover, the photosynthetic pigments, i.e., chlorophyll a and b (Chl a & b) and carotenoid content (Carrot), were significantly higher in the tomato plants treated with P. indica under high Ni-induced stress as compared with the non-treated ones under non-Ni conditions, in which these pigments were low. The pro-production was further observed all through the P. indica inoculation, which could aid the treated plants in becoming Ni-stress-tolerant. Finally, the current study contributed to a better understanding of how to use the P. indica symbiosis to induce heavy metal tolerance in tomato plants, such as Ni, to meet the goals of sustainable agriculture.

Serendipita indica-A Review from Agricultural Point of View

Fulfilling the food demand of a fast-growing population is a global concern, resulting in increased dependence of the agricultural sector on various chemical formulations for enhancing crop production. This leads to an overuse of chemicals, which is not only harmful to human and animal health, but also to the environment and the global economy. Environmental safety and sustainable production are major responsibilities of the agricultural sector, which is inherently linked to the conservation of the biodiversity, the economy, and human and animal health. Scientists, therefore, across the globe are seeking to develop eco-friendly and cost-effective strategies to mitigate these issues by putting more emphasis on the use of beneficial microorganisms. Here, we review the literature on Serendipita indica, a beneficial endophytic fungus, to bring to the fore its properties of cultivation, the ability to enhance plant growth, improve the quality of produced crops, mitigate various plant stresses, as well as protect the environment. The major points in this review are as follows: (1) Although various plant growth promoting microorganisms are available, the distinguishing character of S. indica being axenically cultivable with a wide range of hosts makes it more interesting for research. (2) S. indica has numerous functions, ranging from promoting plant growth and quality to alleviating abiotic and biotic stresses, suggesting the use of this fungus as a biofertiliser. It also improves the soil quality by limiting the movement of heavy metals in the soil, thus, protecting the environment. (3) S. indica's modes of action are due to interactions with phytohormones, metabolites, photosynthates, and gene regulation, in addition to enhancing nutrient and water absorption. (4) Combined application of S. indica and nanoparticles showed synergistic promotion in crop growth, but the beneficial effects of these interactions require further investigation. This review concluded that S. indica has a great potential to be used as a plant growth promoter or biofertiliser, ensuring sustainable crop production and a healthy environment.