Nickel (Ni) is extremely toxic to plants at high concentrations. Phytoliths have the potential to sequester the heavy metals absorbed by plants and act as a detoxification mechanism for the plant. The authors of the present study aimed to evaluate the effects of Ni on the growth and phytolith yield of grasses in two artificially contaminated soils. Two experiments separated by soil types (Typic Quartzipsamment and Rhodic Hapludox) were conducted in a completely randomized design in a 2 × 4 factorial scheme with three replications. The factors were two species of grass (Urochloa decumbens and Megathyrsus maximus) and three concentrations of Ni (20, 40, and 120 mg kg⁻¹) and control treatment. The grasses were influenced by the increase in Ni rates in the soils. Ni exerted a micronutrient function with the addition of 30 mg kg⁻¹ of Ni in soils, but this concentration caused toxicity in grasses. Such a level is lower than the limits imposed by the Brazilian environmental legislation. Higher Ni availability in Typic Quartzipsamment promoted Ni toxicity, with reduced growth and increased phytolith yield in the shoot, increased Ni in the shoot, and Ni occlusion in phytoliths by grasses, in comparison with Rhodic Hapludox. The yield and Ni capture in phytoliths by grasses in Ni-contaminated soils are related to the genetic and physiological differences between grasses and Ni availability in soils. Ni capture by phytoliths indicates that it may be one of the detoxification mechanisms of Urochloa decumbens to Ni contamination, providing additional tolerance. Megathyrsus maximus may be a future grass for the phytoremediation technique in Ni-contaminated soils.

Phytoremediation is a technique with high viability due to its low cost and minimal environmental impact. However, there are a few results regarding the use of tropical grasses in the phytoremediation of manganese (Mn), and there is no clear definition of which extractor is more suitable for assessing Mn availability in soils. The objective of this study was to evaluate the growth potential and phytoremediation of five tropical grasses in Mn‐contaminated soil, as well as to assess the efficiency of four extractors in Mn extraction. The grass cultivars evaluated included Aruana and Tanzânia of Megathyrsus maximus, Xaraés and Marandu of Urochloa brizantha, and Basilisk of Urochloa decumbens grown in Typic Hapludox (Oxisol) amended with 0, 50, 150, and 450 mg of Mn per kg⁻¹ of soil. The experiment was conducted in a greenhouse, using a completely randomized experimental design in a 5 × 4 factorial scheme, with five replications. The experimental period lasted for 90 days. The dry matter of the shoot and root of the grasses was evaluated. Mn concentration in dry matter and its availability in soil were extracted by Mehlich‐1 and DTPA pH 7.3, while the semitotal concentration was determined by USEPA 3051 and total Mn by USEPA 3052 method. Tropical grasses showed reduced growth with increasing Mn rates in the soil, with the following sequence in the reduction in growth: Aruana > Basilisk > Marandu > Xaraés and lastly the Tanzânia. The Aruana cultivar showed greater potential for phytoextraction due to its higher ability to accumulate Mn in its biomass, followed by the Basilisk cultivar. The four different evaluated extractors were efficient in measuring Mn concentrations in the soil, with higher toxicity critical levels for the USEPA 3051 method due to the semitotal extraction nature and USEPA 3052 due to total Mn extraction. The growth of tropical grasses is reduced with increasing Mn rates applied to the soil. The Aruana of M. maximus grass has greater potential for phytoextraction of Mn‐contaminated soils, followed by Basilisk of Urochloa decumbens, Xaraés and Marandu of U. brizantha, and Tanzânia of M. maximus. The Mehlich‐1, DTPA pH 7.3, USEPA 3051, and 3052 extractors were efficient in extracting and evaluating Mn availability in soil for tropical grasses. The USEPA 3051 and 3052 methods presented higher toxicity critical levels.

Fungi of the genus Trichoderma are known for their activity as plant growth promoters. This study aimed to evaluate the morphological responses of Eucalyptus plants inoculated with Trichoderma harzianum UFT-25. The experiment was developed in a completely randomized design with two treatments: non-inoculated (control) plants and plants inoculated with T. harzianum UFT-25 with ten replicates. The isolate was developed in 50 mm Petri dishes containing a potato, dextrose, and agar (PDA). All plates were incubated in a biochemical oxygen demand (BOD) chamber at 25 ± 2 ºC with a photoperiod of 12 h for seven days. Plants were inoculated by spraying the fourth, fifth, and sixth fully expanded leaves with a suspension of T. harzianum UFT-25 conidia. Control plants received an application of autoclaved distilled water containing 0.02% (v/v) Tween 80. Analysis of the results revealed a significant difference between the treatments in terms of height, diameter, leaf and branch numbers, dry mass, and chlorophyll. T. harzianum UFT-25 stimulated greater growth in the inoculated plants than control plants at 15, 30, 45, and 60 d. The inoculated plants have been shown an increase of 16.19% in the shoot dry mass and 51.65% in the root dry mass. These results open new avenues for exploring the potential of T. harzianum UFT-25, proving its efficiency in promoting the growth of Eucalyptus plants. Thus, the use of this fungus can contribute to the reduction of inputs, such as fungicides and fertilizers, promoting greater sustainability in forestry production.

The aim of this study was to evaluate the effects of Trichoderma asperellum, Rhizolex-T (a chemical fungicide), and their combinations with Fusarium equiseti on fruit yield and disease inhibition in plants. Trichoderma asperellum and Fusarium equiseti were isolated from the soil surrounding robust tomato roots in various parts of Brazil, and molecularly identified by 5.8S-ITS region sequencing. The biocontrol agent T. asperellum exhibited strong antagonistic activity, surpassing the efficacy of the chemical fungicide Rhizolex-T. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analysis confirmed that most T. asperellum exhibited potent antagonistic activity in terms of mechanistic insights. Fresh fruit weight increased by 14.70%, dry fruit weight increased by 14.81%, fruit size increased by 3.75%, and the number of fruits per plant increased by 12.50% as a consequence of the application of T. asperellum (T). Additionally, antioxidant activity and total phenol contents increased in response to T. asperellum treatment. These results highlight the potential of T. asperellum as a sustainable, eco-friendly alternative to chemical fungicides for managing Fusarium wilt in tomatoes. The study advocates for the integration of biocontrol agents into disease management strategies to reduce chemical inputs and promote sustainable agriculture.

Plant endophytic bacteria play crucial roles in the prevention and control of crop diseases. Yam (Dioscorea opposita), an important tuber and root crop, is renowned for its rich vegetable and medicinal values. However, the black-spot disease is relatively prevalent during its cultivation process, and there are no reports on using endophytes to control this disease. In this study, we aimed to investigate the biological control of black spot disease caused by Alternaria alternata in Dioscorea opposita using the endophytic bacterium Bacillus sp. E-Do8. An endophytic bacterium that strongly antagonized Alternaria alternata, the pathogen causing yam black-spot disease, was isolated from Tiegun yam leaves, and it was identified as a strain of Bacillus and named E-Do8. Further investigations revealed that the E-Do8 fermentation broth could significantly inhibit the spore germination and mycelial growth of A. alternata, and the mycelia showed uneven thickness, swelling, and irregular entanglement. Moreover, the ability of A. alternata to penetrate cellophane was weakened when cultured with the E-Do8 fermentation broth, which could also significantly inhibit the pathogenicity of A. alternata. In addition, the UHPLC-Orbitrap Exploris 240 system was employed to analyze the active ingredients in the E-Do8 fermentation broth that inhibit A. alternata, and it was found that E-Do8 only produced surfactin-type compounds, C14-surfactin and surfactin.