Papaya (Carica papaya L.) is a climacteric fruit, and its quality will rapidly decrease after ripening. Hence, the storage life of its fruit is short. D-limonene is a terpene compound in citrus essential oil and has antibacterial and antioxidant properties. The addition of D-limonene in edible coating can delay volatilization, prevent microorganism and pathogen invasion, decrease water loss, inhibit softening, decrease gas exchange, and extend the storage life of fruits. In this study, 0.25%, 0.5%, and 1% D-limonene nanoemulsion coatings were used for post-harvest immersion treatment of “Tainung No. 2” papayas and its effects on appearance, chlorophyll content, respiration rate, ethylene production, pectin methylesterase, polygalacturonase activity, decay loss, firmness, total soluble solid, titratable acidity, ascorbic acid, and total plate count were investigated. After the papayas were treated with 0.5% D-limonene nanoemulsion coating, polygalacturonase and pectin methylesterase activities decreased, fruit firmness was maintained, and ascorbic acid content was high. On the last day of storage, polygalacturonase and pectin methylesterase activities were 0.01 and 0.02 U/kg FW lower than the control group, respectively; firmness was higher than the control group by 1.75 N, and ascorbic acid content was higher than the control group by 31.97 mg/100 g FW. On Day 2, the treatment showed delay in total soluble solid accumulation and chlorophyll degradation, consequently delaying the color change in fruits. The coating decreased decay loss by 40% on Day 2, decreased respiration rate by 97.0 mg CO₂ kg⁻¹ h⁻¹, and ethylene production by 5.7 µL kg⁻¹ h⁻¹ on Day 2. Simultaneously, the coating decreased the total plate count and resulted in a good appearance. Fruits coated with a 1% D-limonene nanoemulsion coating showed defects in color change. In summary, 0.5% D-limonene nanoemulsion coating delayed “Tainung No. 2” papaya ripening and decreased microbial infection, consequently extending its storage life.

Plant factories offer a promising opportunity for fresh food production due to their minimal land requirements. Among the adjustable factors in the production system of plant factories, light serves as a critical element, significantly influencing both crop yield and quality. Cilantro, a prevalent culinary herb and a traditional flavoring agent, plays a crucial role in Taiwanese gastronomy. This research investigated cilantro plants grown under nine different light treatments with varying red to far-red ratios and green light percentages over a 49-day period. Results demonstrate that maximum fresh and dry biomass accumulation in both shoot and root tissues occurred under treatments with red to far-red ratios of approximately of 1.8 combined with medium green light intensity. Conversely, medium far-red ratios negatively affected lutein and carotenoid concentrations in foliar tissues. Carotenoid biosynthesis exhibited an inverse relationship with green light intensity, with lower green light percentages corresponding to significantly higher carotenoid concentrations. In terms of energy efficiency, a red to far-red ratio of approximately 1.8 yielded the highest energy yield (g kWh⁻¹) and photon yield (g mol⁻¹), indicating optimal energy conversion efficiency under this spectral composition. In conclusion, this study demonstrates that cilantro cultivation under R53G05B13FR29 spectral composition (53% red, 5% green, 13% blue, 29% far-red) with a 49-day production cycle maximizes biomass while optimizing energy utilization efficiency.

Bacterial wilt is a highly destructive disease affecting a wide range of crops, with no effective chemical control methods currently available. Consequently, the development of microbial strategies for disease management has become increasingly important. Among these, plant immunity-intensifying microbes have demonstrated promising efficacy in controlling bacterial wilt. However, the influence of environmental factors, particularly light intensity, on the effectiveness of these microbes remains unclear. Light intensity is a critical regulator of the photosynthetic system and plant biochemical functions, including defense responses. In this study, we specifically utilized Arabidopsis plants grown under distinct light intensities to systematically examine how light conditions affect the induction of plant immune responses and the occurrence of bacterial wilt. Our findings revealed that Arabidopsis grown under high light intensity exhibited significantly stronger immune responses and reduced disease severity, compared to plants grown under low light intensity. Further, application of Bacillus amyloliquefaciens PMB05, a plant immunity-intensifying strain, resulted in more pronounced immune signaling and disease control efficacy under high light conditions. Experiments using salicylic acid (SA)-deficient mutants demonstrated that disruption of the SA pathway abolished the enhanced suppression of bacterial wilt conferred by B. amyloliquefaciens PMB05 under high light intensity, indicating that the SA pathway is indispensable for PMB05-mediated disease resistance. Moreover, the validation experiments in tomato plants supported these results, with B. amyloliquefaciens PMB05 significantly reducing bacterial wilt development under high light intensity. Collectively, our study demonstrates that growing plants under varying light intensities provides critical insights into how environmental conditions modulate the effectiveness of plant immunity-intensifying microbes, offering a potential strategy for integrated disease management in crops.

Bacterial soft rot, caused by Pectobacterium carotovorum subsp. carotovorum, affects numerous vegetable crops. Beneficial microbes like Bacillus amyloliquefaciens PMB05 offer a sustainable alternative to traditional copper- or antibiotic-based controls, which risks the development of pathogen resistance. Bacillus amyloliquefaciens PMB05 enhances disease resistance to soft rot by intensifying PAMP-triggered immunity (PTI). Although our previous research showed that PMB05-intensified PTI correlates with a reduced photosynthetic electron transport rate under high light conditions, it remains unclear whether increasing light intensity can strengthen PMB05-mediated immune signaling to further enhance disease resistance in plant leaves. In this study, Arabidopsis plants were grown under varying light intensities to address this question. Furthermore, expression of the type III elicitor, HrpN protein, was applied to evaluate the impact of PMB05 treatment on immune activation. HrpN acts as a PAMP that can trigger plant defense responses. The results revealed that higher growth light intensity was associated with PMB05-intensified PTI response by increasing reactive oxygen species generation but suppresses callose deposition. In addition, PMB05-facilitated PTI-mediated stomatal closure occurred more rapidly and tightly under high light, thereby restricting pathogen invasion into leaf tissues. Disease assays further confirmed that higher light intensity significantly reduced soft rot severity in A. thaliana, while the combination of high light and PMB05 treatment achieved superior control efficacy. Furthermore, PMB05-associated disease protection under high growth light was not detected in sid2, npr1, and nahG plants, indicating that intact SA-associated functions are required for the detectable protective phenotype under the conditions tested. These findings demonstrate that environmental light management can strategically potentiate immunity-intensifying microbes, establishing a novel paradigm for sustainable disease control through the coordinated manipulation of light conditions and microbial application.