Purpose

Greenhouse gases (GHGs) are major reasons for climate change. The intensity of GHGs is continuously increasing in agricultural soils due to intensive practices. Biochar (BC) is an effective measure to mitigate GHGs and improve ecosystem services. However, the efficiency of BC in mitigating nitrous oxide (N₂O) emissions remains debatable. In recent years, BC, when combined with other amendments, has shown promising results in mitigating N₂O emissions. Recently, seaweed-based fertilizers (SBF) have shown promising results in improving crop productivity; however, their role in reducing GHG emissions is still unclear.

Method

This study investigated the impact of BC, SBF, and co-application of BC and SBF on N₂O emissions, soil rejuvenation, canonical ammonia oxidizers, and comammox, bacterial abundance, and rice growth and yield. The study contained different treatments: control, BC (2%), SBF (2%), and BC (1%) + SBF (1%).

Results

The co-application of BC + SBF increased soil pH (> 20%), triggered the transformation of soil nitrogen dynamics, increased soil carbon (92.74%), nosZ genes abundance (107%) and decreased ammonia-oxidizing archaea (AOA) (27%), and ammonia-oxidizing bacteria (AOB) (45%) abundance leading to a significant decrease in N₂O emissions (63.15%). The integrative application of BC and SBF also significantly increased Acidobacteriota, Bacterioidetes, Chloroflexi, Proteobacteria, and Nitrospirae, contributing to a significant decrease in N₂O emissions. Integrative BC and SBF also enhanced rice productivity and quality, which was linked with improved soil nutrient availability, carbon sequestration, and soil enzyme activities.

Conclusion

In conclusion, the BC and SBF blend could be a promising amendment to mitigate N₂O emissions and improve soil fertility, microbial activities, and rice productivity.

This research examines the influence of exogenous indole-3-acetic acid (IAA) on growth parameters and cadmium stress resistance in Sorghum bicolor (L. Moench). The plants were grown in pots, each filled with 4.5 kg of sand. After 21 days, root treatment with indole-3-acetic acid (IAA) was applied using five concentrations (0, 50, 100, 150, and 200 µM) under three cadmium (Cd) levels (0, 40, and 80 ppm). Applied Cadmium stress significantly reduced plant growth, with reductions in root length (12.73–15.88%), shoot length (17.60–19.25%), and plant height (10.62–14.88%). All growth parameters were improved with the application of 200 µM IAA, increasing root length (20.25–28.25%), shoot length (35.68–45.68%), and plant height (20.37%). The highest level of cadmium stress (80 ppm) was the most detrimental, while the 200 µM IAA treatment produced the most favorable results. Under cadmium stress, IAA application reduced the uptake of Na⁺, K⁺, and Ca²⁺ ions by 7.69–9.52%, 3.70–7.31%, and 6.66–7.69%, respectively, as well as Cd²⁺ by 2.50–5.26%. Despite these reductions, IAA application significantly enhanced antioxidant activities, including catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD). At 200 µM IAA, antioxidant enzyme activities were increased by 4.65% (SOD), 8.82% (POD), 10.06% (CAT), and 17.9% ascorbate peroxidase (APX). The treatment also boosted chlorophyll content (17.46–22.85%), while reducing oxidative stress markers such as H₂O₂ (29.4–40.8%) and malondialdehyde (38.9–42.1%). These findings suggest that IAA effectively mitigates cadmium-induced stress by improving growth parameters and physiological responses. Future research should explore the molecular mechanisms underlying IAA-mediated cadmium stress alleviation.

This study explored the valorization of two carbohydrate rich food wastes, a sugary (spoiled dates, SD) and a starchy (wasted rice, WR) one, for the biotechnological production of α-amylase, biohydrogen (bioH₂), and methane (CH₄). Initially, the bioH₂ and CH₄ production potentials of raw SD and WR were assessed without any pretreatment, via dark fermentation and anaerobic digestion, respectively, to evaluate the need of sacharification of the wastes for achieving efficient yields. For the production of amylolytic enzymes the bacterium Bacillus amyloliquefaciens was used. Aerobic experiments with synthetic media were initially performed to evaluate the effect of carbon and nitrogen sources on microbial growth, substrate uptake and stimulation of α-amylase production. Subsequently a mixture of the SD and WR, supplemented with peptone, was used as a substrate for α-amylase production, achieving a maximum enzymatic activity of 35.7 ± 1.1 AU mL⁻¹. The impact of enzymatic and acid saccharification on biofuel production was then evaluated using commercial α-amylases, crude α-amylase produced in situ by B. amyloliquefaciens, and HCl. Commercial enzymes maximized bioH₂ yields, while crude α-amylase also enhanced production considerably. HCl pretreatment improved WR conversion but reduced bioH₂ yields from SD. Saccharification showed only a limited effect on CH₄ production, with no statistically significant improvements over untreated WR. Overall, SD and WR show strong potential as zero-cost feedstocks for α-amylase and gaseous biofuel production, supporting circular economy principles. Valorization of these carbohydrate-rich wastes could reduce feedstock costs and provide a sustainable approach to enzyme and bioenergy generation.

This study examines the potential inhibitory effects
of extracts of seven Mediterranean macroalgae on the
germination success of two harmful dinoflagellate cysts,
Gymnodinium catenatum and Ostreopsis cf. ovata. The
results revealed that aqueous and methanolic extracts
of these macroalgae showed varying inhibitory effects
on the viability of the cyst germlings, preventing them
from dividing and producing motile vegetative cells.
Among macroalgae, three Cystoseira species (C. compressa,
C. barbata, and C. crinita) exhibited the strongest inhibitory
effects on the germination success of the two cyst types.
The methanolic extracts of these species showed higher
inhibitory effects on O. cf. ovata cysts (% inhibition =
88%–100%) than G. catenatum cysts (83%–95%). Based on
the median inhibitory concentration (IC50), the methanolic
extracts of these macroalgae have exhibited stronger
inhibitory effects on germling viability (IC50 = 0.05–1.5 mg
extract g−1 sediment) than aqueous extracts (IC50 =
0.9–590 mg extract g−1 sediment). The study suggests that
macroalgal materials, specifically Cystoseira species, would
be a promising approach to retard the germination success
of dinoflagellate cysts in constricted coastal areas, hence
limiting the recurrence of harmful algal blooms in the
water column

Macroalgae are known to release allelochemicals that can suppress the growth of their
competitors in the same environment. The present study investigates the potential effects
of aqueous and methanol extracts of two native macroalgae (Cystoseira barbata and Ulva
lactuca) from the southern Mediterranean Sea on the growth and saxitoxin production of
harmful algal bloom-forming dinoflagellate Gymnodinium catenatum. Aqueous extracts of
U. lactuca and C. barbata significantly increased G. catenatum growth by 60–70% as compared
to the control, but they had no discernible effect on toxin production. Conversely,
the methanol extracts of the two macroalgae showed inhibitory effects on G. catenatum
growth, with greater suppression occurring by C. barbata (IC50 = 1.5–50 mg mL−
1) thanU. lactuca ( IC50 = 3.7–214 mg mL− 1). The macroalgal methanol extracts also induced the
toxin production in G. catenatum cells during the first 4 days of incubation, but this production
had dropped to undetectable levels by the end of the experiment. G. catenatum
cells treated with macroalgal methanol extracts sedimented without lysing or releasing toxins
and then transformed to non-viable, nontoxic temporary cysts. Our study suggests that
methanol extracts of these macroalgae could be a viable method to control harmful algal
blooms in confined coastal areas. Nevertheless, ecotoxicological research on the extract’s
possible effects on aquatic life is required before use.

The quantitative and qualitative output of numerous economic crops around the globe is severely limited by
plant-parasitic nematodes (PPNs). The use of synthetic nematicides remarkably causes environmental pollution;
the best alternative for pollution prevention is organic inputs. This study focused on testing nine types of carrots
to determine which carrots are resistant to and susceptible to Meloidogyne javanica. Five weed species were
studied for their effects on Meloidogyne javanica egg masses and second-stage juveniles (J2s). These include
Dipsacus sylvestris (Ds), Euphorbia prostrata (Ep), Malvastrum tricuspidatum (Mt), Lepidium didymum (Ld), Portulaca
oleracea (Po) and Sonchus asper (Sa). In vitro-tested weeds were further utilized against M. javanica in management
(in vivo) experiments with highly susceptible cultivars. The gall index of carrot roots revealed that the
cultivar Golden Rosy was resistant, whereas the cultivar Red Core was highly susceptible to the nematode. In
vitro tests revealed that extracts of certain weeds effectively stopped the second-stage juveniles of M. javanica.
However, only bioactive compounds released from Ld and Sa caused the highest mortality rates (86.8 % and
82.4 %), with LC50 values of 0.016 % and 0.022 %, respectively, and the highest egg hatching inhibition rates
(80.0 % and 78.4 %, respectively) of J2s from M. javanica at a 100 % concentration. This study also used virtual
screening to explore how the chemicals from Meloidogyne javanica, Lemna duckweed (Ld), and Spirodela polyrhiza
(Sa) interact with each other. We used a homology-built receptor protein model for molecular docking. The
phytocompound 4,4-dimethyl-androst-5-ene-3-ol had the best af􀁀nity for binding to key amino acid residues,
with a docking score of 7.5 kcal/mol. The lowest binding af􀁀nity, 􀀀3.9 kcal/mol, was found for 1,8,11-heptadecatriene
(Z,Z) when it contacted the receptor. Among the 33 compounds found in the plants that were tested, 4,4-
dimethyl-androst-5-ene-3-ol and stigmast-5-ene-3-ol were the most effective at preventing M. javanica from
growing in multiple models. The use of leaf powder (5 g) of Ld along with chopped leaves of Ds, Ep, Mt, Po, and
Sa weeds (30 g each) on M. javanica in vivo revealed that all of the treatments had a signi􀁀cant nematicidal effect
on the nematode population, although to different degrees, and helped the carrot plants grow. These 􀁀ndings
support the potential of the above weeds as nematode control agents, suggesting their viability over synthetic
nematicides. This study can help with long-term nematode control plans where phytocompounds, mostly
stigmast-5-ene-3-ol and 4,4-dimethyl-androst-5-ene-3-ol, are used as eco-friendly bionematicides.

Excessive salinity poses serious threats to crop productivity and global food security. Salt stress reduces crop growth and final productivity by inducing ionic, osmotic, and oxidative damage. Applying plant growth hormones is thought to be an efficient method of reducing the negative effects of salinity. Brassinosteroids (BRs) are plant hormones that have demonstrated appreciable effects against different abiotic stresses. BRs can mitigate the deleterious impacts of salt stress by improving water and nutrient uptake, membrane stability, antioxidant activities, and osmolyte synthesis while maintaining the hormonal balance. Furthermore, BRs can also improve the metabolic and molecular responses of plants to help them counter the toxic effects of salinity, and they interact with sugars, proteins, amino acids, and phytohormones to regulate metabolic functioning to increase adaptation against salinity. As vital hormones, BRs are also involved in the signaling pathways of genes, proteins, and enzymes that work to defend plant cells from the toxic effects of salinity. Transgenic plants with improved BR synthesis have shown improved salt tolerance, and genome-wide studies encoding BR genes suggest their roles in plant growth and salt tolerance. The present review discusses the role of BRs in mitigating salinity toxicity through different mechanisms, crosstalk, and the interactions of BRs with other osmolytes and phytohormones. This review will provide knowledge to support the development of salt-tolerant crops and ensure sustainable crop production.