Malaysian Nuclear Agency

The Asia–Pacific region encompasses hydrologically diverse and climate-vulnerable systems, where groundwater security is increasingly threatened by over-exploitation, climate change, urbanization, and salinization. This regional synthesis, developed under the IAEA Technical Cooperation Project RAS7040, integrates environmental isotopes (δ¹⁸O, δ²H, d-excess, ³H), hydrochemical indicators, and numerical modeling to delineate groundwater recharge processes, surface–groundwater interactions, and salinization mechanisms across contrasting hydroclimatic settings, including coastal, urban, alpine, riverine, and arid basins. Multi-country case studies from Lao PDR, Pakistan, Mongolia, China, Bangladesh, Indonesia, Vietnam, Australia, and the Philippines demonstrate the robustness of isotope-based diagnostics for resolving complex groundwater systems. Across the region, results consistently identify local meteoric precipitation as the dominant recharge source, while revealing pronounced contrasts in recharge timing, aquifer vulnerability, and salinity evolution governed by climate variability, land use, and geological framework. In densely populated coastal plains, such as Bangladesh, shallow aquifers exhibit active seawater intrusion, clearly traced by diagnostic Cl⁻–δ¹⁸O mixing relationships, whereas deeper confined aquifers commonly contain isolated paleo-salinity or remain largely protected from modern marine ingress. In high-altitude glacier-fed catchments (e.g., the Mingyong Basin, China), isotope-based hydrograph separation quantifies increasing seasonal meltwater contributions to river discharge, highlighting climate-driven shifts in runoff generation and long-term water storage. In Mongolia’s Kherlen River Basin, groundwater and surface water plot close to the Global Meteoric Water Line, indicating minimal evaporative modification prior to recharge. Strong seasonal contrasts in precipitation isotopes—from highly depleted winter values (δ¹⁸O ≈ −30‰) to enriched summer rainfall (δ¹⁸O ≈ −12‰)—demonstrate that groundwater recharge is dominated by warm-season precipitation, with clear isotopic evidence of river–groundwater exchange in alluvial reaches. In arid to semi-arid regions of Pakistan, stable isotopes are critical for quantifying evaporation losses, identifying recharge zones, and distinguishing irrigation return flow from natural recharge in intensively managed aquifer systems. In Australia, isotope (δ¹⁸O, δ²H, ³H) and hydrochemical investigations of the Thirlmere Lakes conclusively identify evaporation as the dominant mechanism driving lake-level decline, with a secondary, multi-decadal groundwater recharge component. Urban aquifers in major cities (e.g., Hyderabad, Metro Manila, Karachi) show heightened vulnerability to anthropogenic contamination and reduced recharge, diagnosed through isotopic enrichment patterns and complementary tracers such as nitrate isotopes. In the riverine systems of Lao PDR and Vietnam, isotopic apportionment clarifies Mekong and Red River connectivity with adjacent alluvial aquifers, providing essential insights for transboundary water management. When coupled with Bayesian mixing models and variable-density flow simulations, the integrated isotope–geochemical approach effectively differentiates modern seawater intrusion from relic salinity, quantifies river–aquifer interactions, and constrains recharge source elevations and catchment domains. This synthesis underscores the value of regional scientific coordination to harmonize methodologies, identify transboundary groundwater linkages, and upscale local findings. Overall, it demonstrates that isotope-based evidence is indispensable for science-informed policy, supporting managed aquifer recharge, regulation of abstraction, and early-warning systems for salinization and water-quality degradation, thereby advancing climate-resilient water governance across the Asia–Pacific region. Key words: Isotope Hydrology, Groundwater Recharge, Seawater Intrusion, Aquifer Vulnerability, Water Resource Management, Asia–Pacific Region

Abstract Rice blast disease, caused by the pathogenic fungus Magnaporthe oryzae , poses a significant threat to global rice production, particularly impacting the high-value Mahsuri variety cultivated in Malaysia. Despite the extensive genetic diversity within Oryza sativa germplasm that offers potential source of resistance, genome-level variations in distinguished resistant and susceptible Mahsuri genotypes remain unexplored. Addressing this gap, the present study employed whole-genome resequencing to elucidate the molecular basis of blast resistance in Mahsuri rice. Whole-genome sequences of a blast-resistant Mahsuri Mutant and its susceptible parent genotype were generated, a total of 116 million reads, with sequencing coverage of 23.91X and 21.76X, respectively. Bioinformatic analyses using SAMtools identified single nucleotide polymorphisms (SNPs) and insertions and deletions (InDels) between the two rice lines, with comparative genomic analysis against the Japonica reference genome revealing a higher variant count in the Mahsuri mutant (4,096,071) than in the parent (4,024,223). Notably, 178,622 SNPs were detected within exonic regions, underscoring their potential impact on protein function and their association with enhanced blast resistance observed in the mutant line. Further genomic analysis identified unique SNPs in several key candidate genes associated with blast resistance, including Pit , Pi64 , Pish , Pi21 , Piz , Pikm and Pi-ta , providing valuable molecular markers for marker-assisted selection. This comprehensive genomic analysis deepens our understanding of the genetic architecture underlying blast resistance in the Mahsuri rice, facilitating more precise and efficient identification of candidate genes to accelerate breeding programs aimed at developing resilient rice varieties for sustainable cultivation in Malaysia and beyond.

Acute and chronic gamma irradiations (ACGIs) has facilitated generation of new varieties that can withstand abiotic and biotic stresses. This study examined the impact of ACGI doses on the regenerative ability of in vitro embryogenic tissues into complete plants. Tissues from nine genotypes (Alado, NASE 13, NASE 19, NAROCASS 1, CV_193, CV_98/0505, CV_60444, BAO, and reference Ubi Putih) were subjected to acute gamma irradiation (AGI) across six dose levels (0, 5, 10, 15, 20, 25, 35 Gy). Five genotypes (Ubi Putih, CV_60444, Alado, NASE 13, NAROCASS 1) were exposed to chronic gamma irradiation (CGI) for one to four weeks. Ten explants per genotype per dose were evaluated. Mean shoot length was used to calculate the growth reduction dose (GR50), and cell structure changes were analyzed using hematoxylin and eosin staining. Exposure of tissues to AGI and CGI enhanced shoots, roots, leaf regeneration as well as shoot length at dose rates of 5-20 Gy (AGI) and 46 Gy (CGI) at twoweeks. The calculated GR50 varied across genotypes and irradiation types. Histological analysis confirmed that distinct structural changes in cell and tissue morphology were linked to irradiation exposure. These results demonstrate that ACGIs can induce accelerated regeneration and structural variation in embryogenic cassava tissues, revealing the potential to develop novel varieties with improved stress resilience. The study underscores ACGIs as a viable biotechnological tool in mutation breeding and genetic improvement of root crops.

Electron beam irradiation has emerged as a powerful technique for modifying material properties at the atomic level, offering vast potential for advanced applications in nanotechnology and material science. This study investigates the impact of electron beam irradiation on graphene oxide (GO) thin films, focusing on structural, chemical, and electrical modifications. GO was synthesized using Hummer’s method. GO solution was drop-casted onto ITO substrate and dried. The GO thin film was then irradiated at varying doses (25 kGy to 200 kGy) using 3 MeV electron beam. Characterization was made using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with energy-dispersive X-ray (SEM EDX), x-ray photoelectron spectroscopy (XPS), and conductive atomic force microscopy (C-AFM). XRD analysis indicated notable changes in crystallinity, pointing to structural rearrangements induced by irradiation. At the 175 kGy dose, the irradiated graphene oxide achieved the best conductivity, and the C-AFM analysis showed a particle size of approximately 9.5 nm. The XPS and EDX analyses revealed a 0.81% reduction in oxygen concentration at an irradiation GO of 100 kGy compared to unirradiated dose. This reduction trend continues to be observable up to 175 kGy, indicating progressive deoxygenation. Among tested doses, 100 kGy appears to be the most optimal for achieving significant oxygen reduction, whereas higher doses, particularly at 175 kGy, are more favorable for enhancing the material’s conductivity. At 175 kGy, the material recorded an ideality factor of 8.92 is based on C-AFM measurements. FTIR spectra confirmed significant modifications in chemical bonding, providing evidence of functional group transformations. These findings collectively demonstrate that electron beam irradiation serves a versatile tool for tuning the physiochemical properties of GO thin films, enabling precise control over the structure and functionality. The irradiation-induced alteration of GO leads to a more conductive reduced graphene oxide (rGO) with lower oxygen content.

Malaysia’s electricity sector faces mounting pressures from renewable energy integration, evolving load profiles, and sustainability imperatives. Demand Response (DR) offers a viable, cost-effective strategy to enhance grid flexibility and consumer participation. This study proposes a phased DR implementation roadmap tailored to Malaysia’s regulatory and market context, underpinned by a Single Aggregator Model and supported by enabling technologies such as DERMS and AMI. Economic modeling projects RM 50 million in annual gross system benefits from a modest 100 MW DR deployment—via avoided peaking plant costs and reduced reserve requirements—with full investment payback within three years. Unlike previous global reviews, this paper presents original modeling calibrated to Malaysia’s system characteristics, informed by a dedicated feasibility study. International benchmarks from France, Japan, Taiwan, and the U.S. are analyzed and adapted to local constraints. The study concludes with a proposed pilot framework, regulatory reform priorities, and a 2040 DR integration roadmap. Future research should focus on consumer behavior modeling, multi-aggregator market structures, and AI-enabled DR dispatch optimization in Southeast Asian power systems.

Vanilla planifolia is a commercially valued crop as it yields the natural vanilla flavour. However, due to its limited genetic diversity, hybrid production is difficult in V. planifolia. A feasible means to improve the V. planifolia genome is using gamma (γ) radiation. The M1V1 (10 Gy; First generation) ex vitro plant has improved increased vanillin concentration (μM) significantly (P<0.05) compared to control (0 Gy) in its leaves. Therefore, the objective of this study was to investigate the effect of γ radiation on the morphology of in vitro-generated M1V3 (mutation 1 in the third vegetative generation) V. planifolia plantlets. Initially, V. planifolia cuttings were exposed to four doses of gamma radiation (10, 30, 40, and 50 Gy) each with five replicates, and propagated ex vitro to generate M1V1 (first generation) and M1V2 (second generation) plants, followed by micropropagation of M1V2 explants. Morphological growth parameters like shoot height, root length, and number of leaves were recorded. There was only a significant difference (p < 0.05) in shoot height among the cultures at 10 days after culture (DAC), after which the height was not significantly different (p > 0.05) amongst the treatments throughout the experiment; 10 Gy was slightly higher. The increase in root per 10 DAC was significantly reduced in 10 Gy, while 30 Gy had the highest but insignificant compared to 0 Gy. Also, leaf number was significantly (p < 0.05) reduced in both 30 Gy and 10 Gy at 100 DAC. Summarily, lower-dose γ radiation has a mild effect on the M1V3 V. planifolia morphology of in vitro plantlets. To our knowledge, this is the first report on in vitro studies of M1V3 V. planifolia.