This study presents a custom-built, portable multispectral imaging (MSI) system integrated with computer vision for sodium nitrite detection via the Griess reaction on paper-based substrates. The MSI system was used to investigate the absorption characteristics of sodium nitrite at concentrations from 0 to 10 ppm across nine spectral bands spanning 360–940 nm on para-aminobenzoic acid (PABA) and sulfanilamide (SA) substrates. Upon forming azo dyes with N-(1-naphthyl) ethylenediamine (NED), the PABA and SA substrates exhibited strong absorption near 545 nm and 540 nm, respectively, as measured by a spectrometer. This agrees with the 550 nm MSI images, in which higher sodium nitrite concentration regions appeared darker due to increased absorption. A concentration-correlation analysis was conducted for each spectral band. The normalized difference index (NDI), constructed from the most and least correlated bands at 550 nm and 940 nm, showed a stronger correlation with sodium nitrite concentration than the single best-performing band for both substrates. The NDI increased the coefficient of determination (R²) by approximately 19.32% for PABA–NED and 19.89% for SA–NED. This improvement was further confirmed under varying illumination conditions and through comparison with a conventional smartphone RGB imaging approach, in which the MSI-based NDI showed substantially superior performance. The enhancement is attributed to improved contrast, illumination normalization by the NDI, and the narrower spectral bands of the MSI compared with RGB imaging. In addition, the NDI framework enabled effective image segmentation, classification, and visualization, improving both interpretability and usability and providing a practical guideline for developing more robust models with larger training datasets. The proposed MSI system offers strong advantages in portability, sub-minute acquisition time, and operational simplicity, enabling rapid, on-site, and non-destructive chemical analysis.

Radiation beyond Earth’s atmosphere poses a major challenge for space agriculture by affecting seed viability and plant establishment. As a controllable terrestrial analogue of cosmic radiation, gamma (γ) irradiation provides a practical model for evaluating crop resilience. Although rice ( Oryza sativa ) is a promising space crop candidate, germination alone does not ensure developmental or metabolic stability under irradiation stress. Here, eight Thai rice cultivars were screened for radiation tolerance based on early seedling performance following γ-irradiation at 150, 300, and 900 Gy. All cultivars retained high germination capacity (> 90%) across all doses, whereas shoot and root elongation exhibited clear dose-dependent inhibition, with root growth showing greater sensitivity. Based on relative growth maintenance, cultivar 248HT was identified as the most γ-radiation tolerant genotype and selected for in-depth analysis. Untargeted metabolomics of roots and shoots revealed pronounced, tissue-specific metabolic reprogramming in response to irradiation. Roots displayed strong upregulation of metabolites associated with redox homeostasis, including NAD⁺ salvage intermediates and glutathione-related compounds, alongside suppression of nitrogen- and nucleotide-intensive pathways. Targeted phytohormone profiling further demonstrated a consistent reduction in gibberellic acid (GA₃) and accumulation of abscisic acid (ABA), resulting in a lowered GA₃:ABA ratio that aligned with reduced elongation growth. Collectively, these results indicate that radiation tolerance in rice is underpinned by coordinated hormonal recalibration and metabolic shifts that prioritise oxidative stress mitigation, DNA repair, and controlled growth. The superior performance of 248HT highlights it as a promising candidate for further space related radiation stress studies and provides metabolomic markers for selecting or engineering radiation-resilient rice varieties.

Drought stress represents an increasing constraint on rubber tree (Hevea brasiliensis) cultivation under climate change. This study investigated drought responses in a grafted system, where contrasting scion genotypes (RRIM 600 and RRIT 251) systemically influence a shared, seedling-derived rootstock. An integrative framework combining metabolomics, root proteomics, and physiological measurements was applied under progressive soil moisture deficits (85%, 50%, and 30% field capacity). Multivariate analyses of metabolomic data revealed distinct clustering trends associated with drought severity and scion genotype, with more consistent responses observed in RRIT 251, particularly in the roots. Metabolic reprogramming was more pronounced in RRIT 251 roots, highlighted by the strong accumulation of proline, indicating osmoprotective responses. Root proteomics indicated differential stress-associated protein responses between scion types. RRIT 251 showed increased abundance of proteins related to redox regulation and membrane stability, including glutathione S-transferase (7.85-fold) and annexin (4.17-fold), whereas RRIM 600 exhibited a comparatively limited response. Physiological measurements supported these molecular findings, as RRIT 251 maintained higher Photosystem II efficiency and delayed leaf senescence under severe drought. Although based on a limited number of biological replicates, this integrative analysis suggests that RRIT 251 may promote a more coordinated root-associated drought response through scion-mediated systemic regulation. These findings highlight candidate molecular features for future validation and development of drought-resilient rubber tree cultivars.

Ensuring a sustainable source of nutritious food is critical for long-duration space missions. Thai landrace rice 466HM exhibits high nutritional value and stress resilience, making it a promising candidate for space cultivation, yet its response to low Earth orbit (LEO) conditions remains poorly understood. This study compared rice grains maintained under terrestrial conditions with grains stored aboard the Shijian-19 (SJ-19) reusable satellite, orbiting at ~336 km for 13.5 days under microgravity (2⁻⁷ × 10⁻⁷g) and an absorbed radiation dose of ~0.153 rad (Si). Volatile compound profiling, texture analysis of cooked grains, and simulated gastrointestinal digestion followed by peptide mass fingerprinting were performed. LEO-exposed rice grains exhibited a 1.67-fold increase in adhesiveness compared to Earth-based rice (p < 0.01), while hardness remained unchanged between the two groups (p > 0.05), alongside distinct alterations in flavor-related volatile compounds and peptide profiles. Principal component analysis revealed clear separation between Earth and LEO-exposed samples, indicating microgravity-associated shifts in digestible peptide composition. Cytotoxicity assessment using MTT assays in HT-29 and HepG2 cells confirmed the safety of both rice types. These findings demonstrate that orbital conditions influence the compositional, functional, and sensory attributes of rice, providing insights relevant to space agriculture and astronaut nutrition.