Bernard Dell

Drought stress, exacerbated by climate change, is a serious threat to global food security. This review examines the synergistic potential of plant growth-promoting rhizobacteria (PGPR) and biochar as a sustainable strategy for enhancing crop drought resilience. Biochar’s porous structure creates a protective “charosphere” microhabitat, enhancing PGPR colonization and survival. This partnership, in turn, induces multifaceted plant responses through: (1) the modulation of key phytohormones, including abscisic acid (ABA), ethylene (via 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity), and auxins; (2) improved nutrient solubilization and uptake; and (3) the activation of robust antioxidant defense systems. These physiological benefits are orchestrated by a profound reprogramming of the plant transcriptome, which shifts the plant’s expression profile from a stressed to a resilient state by upregulating key genes (e.g., Dehydration-Responsive Element-Binding protein (DREB), Light-Harvesting Chlorophyll B-binding protein (LHCB), Plasma membrane Intrinsic Proteins (PIPs)) and downregulating stress-senescence markers. To realize a climate-resilient farming future, research must be strategically directed toward customizing biochar–PGPR combinations, validating their long-term performance in agronomic environments, and uncovering the molecular bases of their action.

Soil and irrigation salinity continue to have a major impact on the world's agriculture and horticulture, and loss of plant production is likely to worsen with global warming and climate change. Efforts to mitigate salinity stress and breed better salt-tolerant plants rely on our knowledge of plant response to abiotic stress at the physiological and molecular levels. Salinity usually leads to the accumulation of free and conjugated polyamines (PAs) in plant tissues. Putrescine (Put), and its derivatives spermine (Spm) and spermidine (Spd), perform critical functions by activating biochemical, physiological and molecular defense systems, thus reducing damage caused by salinity stress. Promoting endogenous levels of PAs can improve the salt tolerance of plants. Furthermore, the application of exogenous PAs has been shown to effectively mitigate salt stress across a range of commercially important plant species. This review critically examines the biosynthesis of PAs and their associated physiological, phytochemical, and molecular responses in plants under saline conditions. In addition, it evaluates the potential of PAs as a strategic tool for enhancing salinity tolerance. The review also highlights key gaps in current knowledge and proposes directions for future research to optimize the use of PAs in salinity stress management.

Dalbergia tonkinensis (Yellow rosewood) is a rare timber species with high economic value in Vietnam and China. It was assessed as Vulnerable under criteria A1cd in IUCN Red List of Threatened Species and in the Vietnamese decree 84/2021/ND-CP to control illegal harvesting. The seed sources of this species are low in genetic diversity because few mature trees exist in natural populations. In the last decade, efforts have been made to study the market and use of the species, morphological characteristics, phenology, pests and diseases, and gene conservation in Vietnam. A study of morphological variation among provenances of D. tonkinensis in Vietnam revealed significant differences in traits such as total height, bark colour, stem form, fruit shells, and seed size. The species is propagated easily via seeds and cuttings. Seeds from plus trees have been safely stored in seed and field gene banks. Provenance/progeny tests in three field gene banks showed notable genetic variations in growth, form, and disease resistance. High individual heritability (0.33–0.49) and additive variation were observed for growth traits. Results highlight superior gene sources for early plantation growth and recommend conserving genetic diversity. Comprehensive information on D. tonkinensis has been reviewed in this chapter.

Regeneration will determine the success of forest restoration and affect the sustainability of future forest ecosystems. Research has been conducted to evaluate the characteristics of the regeneration storey and their spatial distribution on the ground. The study has established 10 plots (100 m x 100 m) for secondary forests, 10 plots for old-growth forests. Sub-plots (2 m x 2 m) were set up systemically to investigate the regeneration. The results showed that 148 species in secondary forest and 130 species in old-growth forest were found. The number of families in the secondary forest was lower than in the old-growth forest by 3 families. The Simpson index of both forest states was high (0.9769 and 0.9799 respectively). Canonical correspondence analysis exposed that species composition of both species and families between the two types of stages was significant dissimilar. There were clear groups of species and families appeared together with similar frequency in plots proved by hierarchical classification. In both stages, the height frequency distribution was inverse-J shape forms. And these distributions were different in studied types. The good regeneration in two studies states of forests were 67.9% and 55.7%. Regeneration quality was significant associated with height and light classes. The number of regenerating trees generated in each 1-hectare plot of the secondary forest was almost twice that of the old-growth forest. In the secondary forest, most plots illustrated that the spatial pattern was random at all scales. Contrary, in the old-growth forest, the patterns were much more complicated.

Fire is a distinctive factor in forest ecosystems. While uncontrolled wildfires can cause significant damage, prescribed burning is widely used as a management tool. However, despite the growing threat of forest water stress under climate change, there is a lack of concrete evidence on the impact of fire on water stress in forest ecosystems. This study utilized Landsat time-series remote sensing data combined with the Infrared Canopy Dryness Index (ICDI) to monitor changes in canopy dryness patterns across the eucalyptus-dominated Northern Jarrah Forest of southwestern Australia. The forest was chosen due to its exposure to a changing climate characterized by decreasing rainfall and more frequent droughts, signs of water stress in otherwise drought-resilient trees, and its well-documented fire management history. Analysis of ICDI patterns over the period from 1988 to 2024 revealed a clear overall trend of increasing water stress, coinciding with a small overall decline in annual rainfall in the 10,000 km2 study area. Furthermore, by examining five prescribed burns and five wildfires, we found that NDVI-assessed canopy cover recovered rapidly in fire-affected areas, typically within one to three years, depending on fire severity. However, ICDI water stress levels were reduced for approximately 7–8 years following low-severity prescribed burns and more than 20 years after high-severity wildfires. These findings suggest the potential of prescribed burning as a tool to mitigate water stress in vulnerable forest landscapes, particularly in regions prone to drought and climate change. Additionally, the study underscores the effectiveness of the ICDI in monitoring forest water stress and its potential for broader applications in forest management and climate adaptation strategies.

Gaps have a significant influence on forest structure and development. This study analysed characteristics of gaps between secondary and old–growth forests in Kon Ka Kinh National Park, Gia Lai Province, Vietnam. One hectare inventory plots were established in each forest stage. Data on gap size, coordinates, average height of surrounding trees, slope and directions of main axes were recorded. Results showed that the secondary forest had slightly higher number of gaps, compared to old–growth forest. However, the average size of gaps was smaller. Frequency distributions were significantly different between the two forest stages. The size of the gaps correlated with the height of the surrounding forest canopy but there was no correlation with slope. The length direction of gaps was most concentrated at East–North–East in both forest types. The distribution of gaps were regular at a scale of 0 to about 15 m, but were random at larger distances. The gap size spatial distribution was random in the secondary forest, but 60% of plots in the old–growth forest were affected by neighbouring gaps. The findings suggest that assisted natural regeneration, enrichment planting and gap–size extension should be undertaken in these secondary forests to increase forest quality.

Ceracris kiangsu (Tsai) (Orthoptera: Acrididae) is a severe pest of the bamboo Dendrocalamus barbatus Hsuch & D.Z. Li that is widely grown in plantations in Vietnam. A biocontrol option to manage this pest is a priority for the forest sector. This study evaluates whether there are potential biocontrol candidates within the C. kiangsu population. Bacteria were isolated from C. kiangsu nymphs that were parasitized in the field. In a nursery experiment, three Bacillus bombysepticus Wang isolates (FPRC17, FPRC23 and FPRC30) caused 63-68% mortality of C. kiangsu nymphs 9 days after spraying, and the results were similar to applying a commercial Bacillus thuringiensis product. In a field trial, feeding damage from a C. kiangsu infestation was reduced by over 70% at 15 days after spraying these isolates. This finding reveals the potential for the development of a natural biopesticide for bamboo locust management in Vietnam.

Bacterial leaf blight disease of rice caused by Xanthomonas oryzae pv. oryzae (Xoo) impairs grain yield and is difficult to control. Therefore, we investigated the antibacterial activity of 100 bacterial isolates, obtained from plant tissues and agricultural soils, against Xoo strain E. Bacteria were grown in modified Wickerhams Antibiotic Test Medium (WATM), cell-free supernatants were collected, and their activity was evaluated using the agar well diffusion assay. The most inhibitory strain was TBRC 16324, isolated from Fragaria x ananassa roots, and its antimicrobial activity was further investigated. Ethyl acetate crude extracts were subjected to Sephadex LH-20 column chromatography followed by TCL-bioautographic assays. Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (LCESI-MS) analysis of combined fraction 1 (with biological activity) showed that the pseudomolecular ion ( m/z 1036.6919) closely matched the pseudomolecular ion of surfactin (m/z 1036.6928 [M + H]+). As the ethyl acetate crude extract was non-toxic to mammals using the L-929 mouse fibroblast assay, an in vivo experiment was undertaken. TBRC 16324 live cells and crude extract slightly reduced Xoo disease severity in Phitsanulok 2 rice seedlings in a screen-house. These findings suggest that TBRC 16324 may be a suitable candidate for further evaluation in field trials.

Plants possess a complex signaling system that enables them to sense and adapt to various environmental stressors, including abiotic factors like extreme temperatures, drought, salinity, and toxic heavy metals. While the roles of hormones and signaling molecules in plant stress responses are well established, the involvement of neurotransmitters—traditionally linked to animal nervous systems—in plant stress physiology is a relatively underexplored area. Recent findings indicate that neurotransmitters such as gamma-aminobutyric acid, glutamate, serotonin, and dopamine play crucial roles in several physiological processes within plants. They regulate ion channels, adjust stomatal movements, modulate the production of reactive oxygen species, and influence gene expression. Evidence suggests that these neurotransmitters enhance antioxidant defense mechanisms and regulate stress-responsive pathways vital for plant stress tolerance. Additionally, under stressful conditions, neurotransmitters have been shown to impact plant growth, development, and reproductive activities. This review aims to illuminate the emerging understanding of neurotransmitters as key biomediators in plant responses to abiotic stress.

This study examines the harvest and trade of wild edible Russula griseocarnosa in north Vietnam. Russula griseocarnosa is an edible forest mushroom, but there is no reliable information on harvesting practices and trade in this species in Vietnam. This study aims to provide ethnomycological and marketing knowledge for this mushroom. Semi-structured interviews were conducted with mushroom collectors and traders over 2 years; harvest yields were obtained from local officials; and policy settings were sought from forest managers. About 85% of mushroom collectors were women of the Dao, Lo Ursula, Muong, Nung, Mong, San Chi, San Diu, and Tay ethnicities. The collecting season was bimodal, with the wet season beginning (May) and ending (September). The traders were Hoa, Kinh, Nung and Tay, and 57% were women. Fresh mushrooms sold for 9.1-10.5 US$/kg on dry days and 7.0-7.9 US$/kg on wet days. The best grade of dried product fetched 70.4-83.3 US$/kg. A number of interim policies have been established to encourage local people to protect forests and to help create a sustainable edible wild mushroom market. Our study provides the first detailed account of the role of edible wild mushrooms in northeast Vietnam, and this will inform the co-development of rural livelihood and sustainable forest management plans.