Increasing soil and water salinity threatens global agriculture, particularly affecting rice. This study investigated the residual effects of microbial biochar and nitrogen fertilizer in mitigating salt stress in paddy soil and regulating the biochemical characteristics of rice plants. Two rice varieties, Shuang Liang You 138 (SLY138), a salt-tolerant, and Jing Liang You 534 (JLY534), a salt-sensitive, were grown under 0.4 ds/m EC (S0) and 6.84 ds/m EC (S1) in a glass house under controlled conditions. Three types of biochar—rice straw biochar (BC), fungal biochar (BF), and bacterial biochar (BB)—were applied alongside two nitrogen (N) fertilizer rates (60 kg ha⁻¹ and 120 kg ha⁻¹) in a previous study. The required salinity levels were maintained in respective pots through the application of saline irrigation water. Results showed that residual effects of microbial biochars (BF and BB) had higher salt mitigation efficiency than sole BC. The combination of BB and N fertilizer (BB + N120) significantly decreased soil pH by 23.45% and Na⁺ levels by 46.85%, creating a more conducive environment for rice growth by enhancing beneficial microbial abundance and decreasing pathogenic fungi in saline soil. Microbial biochars (BF and BB) positively improved soil properties (physicochemical) and biochemical and physiological properties of plants, ultimately rice growth. SLY138 significantly had a less severe response to salt stress compared to JLY534. The mitigation effects of BB + N120 kg ha⁻¹ were particularly favorable for SLY138. In summary, the combined residual effect of BF and BB with N120 kg ha⁻¹, especially bacterial biochar (BB), played a positive role in alleviating salt stress on rice growth, suggesting its potential utility for enhancing rice yield in paddy fields.

Mango (Mangifera indica), a nutritionally rich tropical fruit, is significantly impacted by UV-B radiation, which induces oxidative stress and disrupts physiological processes. This study aimed to investigate mango pulp’s molecular and biochemical responses to UV-B stress (96 kJ/mol) from the unripe to mature stages over three consecutive years, with samples collected at 10-day intervals. UV-B stress affected both non-enzymatic parameters, such as maturity index, reactive oxygen species (ROS) levels, membrane permeability, and key enzymatic components of the ascorbate-glutathione (AsA-GSH) cycle. These enzymes included glutathione reductase (GR), gamma-glutamyl transferase (GGT), glutathione S-transferases (GST), glutathione peroxidase (GPX), glucose-6-phosphate dehydrogenase (G6PDH), galactono-1,4-lactone dehydrogenase (GalLDH), ascorbate peroxidase (APX), ascorbate oxidase (AAO), and monodehydroascorbate reductase (MDHAR). Transcriptomic analysis revealed 18 differentially expressed genes (DEGs) related to the AsA-GSH cycle, including MiGR, MiGGT1, MiGGT2, MiGPX1, MiGPX2, MiGST1, MiGST2, MiGST3, MiG6PDH1, MiG6PDH2, MiGalLDH, MiAPX1, MiAPX2, MiAAO1, MiAAO2, MiAAO3, MiAAO4, and MiMDHAR, validated through qRT-PCR. The findings suggest that UV-B stress activates a complex regulatory network in mango pulp to optimize ROS detoxification and conserve antioxidants, offering insights for enhancing the resilience of tropical fruit trees to environmental stressors.

Mango (Mangifera indica) is a highly valuable horticultural crop known for its quality and productivity. This study investigates the dynamic changes in physicochemical properties and glutathione and ascorbic acid metabolic pathways in mango pulp across various growth and development stages over two consecutive years (2021–2022 and 2022–2023) by transcriptomic analysis. Overall, the results demonstrate that during different ripening periods, the pulp shows increased levels of total soluble solids, relative conductivity, glutathione, and enzymes, while titratable acidity, malondialdehyde, reactive oxygen species, and ascorbic acid contents decreased. Moreover, transcriptomic analysis identified key differentially expressed genes from the glutathione and ascorbic acid metabolic pathways and validated them with qRT-PCR. In different comparisons, a total of 1776, 2513, and 828 DEGs were identified in 30 vs. 60, 30 vs. 90, and 60 vs. 90 days after flowering, respectively. Among them, seven DEGs were primarily enriched in relevant pathways, which included ascorbate peroxidase, ascorbate oxidase, glutathione peroxidase, gamma-glutamyl transferase, glutathione transferases, and glucose-6-phosphate dehydrogenase. The upregulation of these genes indicates that glutathione and AsA respond well to scavenging reactive oxygen species and maintain normal functioning in plants. This research sheds light on the molecular mechanisms of glutathione and ascorbic acid dynamic changes in mango pulp, providing valuable insights into the regulation of antioxidant and metabolic pathways during fruit growth and development.

This study investigated the combined effects of microbial-inoculated biochar and nitrogen (N) on rice growth and soil properties under saline conditions. A randomized complete block design with three replications was employed to evaluate three factors: (i) salinity level (non-saline, S0; saline, 0.4% NaCl, S1), (ii) biochar type (20 t/ha BC, BF, BB, and BFB), and (iii) nitrogen application rate (60 and 120 kg ha⁻¹). Soil physicochemical and biological properties, along with rice root development, were assessed. Salinity significantly reduced soil organic matter (OM) by 9%, nitrate nitrogen (NO₃⁻-N) by 16%, ammonium nitrogen (NH₄⁺-N) by 8.18%, and available phosphorus (AP) by 6.81%. Soil enzyme activities, including catalase (CAT), acid phosphatase (ACP), polyphenol oxidase (POX), and β-D-glucosidase (BG), decreased by 32.69%, 29%, 39.18%, and 19.44%, respectively, resulting in suppressed root growth compared with non-saline conditions. The combined treatment of microbial biochar (BFB) and N at 120 kg ha⁻¹ (BFB + N120) markedly improved saline soil quality and rice root performance by maintaining a favorable K⁺/Na⁺ balance in roots. Specifically, BFB+N120 increased OM by 145% and 120% compared with N120 and BC alone, respectively, and enhanced NO₃⁻-N, NH₄⁺-N, and soil enzyme activities (CAT, ACP, POX, and BG). These improvements were strongly associated with enhanced root development. Under saline conditions, BFB+N120 increased root dry mass by 429% and 1185.71%, and root length by 63% and 83%, compared with N120 and BC alone, respectively, in the cultivar Jing Liang You 534. Overall, the results demonstrate that microbial-modified biochar combined with nitrogen fertilizer mitigates salt-induced soil degradation by improving physicochemical and biological properties, thereby enhancing nutrient availability, ionic homeostasis, and root growth. This study provides mechanistic insights into the combined role of microbial biochar and nitrogen in the remediation of saline soils.