Search Results (10)

Optimizing lighting in plant factory with artificial lighting (PFAL) is essential for balancing lettuce growth and quality. Rapid plant growth in PFAL often induces physiological disorders, especially tipburn, which is associated with calcium deficiency in newly emerging leaves. This study aimed to evaluate the effects of different proportions of green light substitutions on tipburn incidence and the growth of romaine lettuce cultivated in a PFAL. Plants were grown under different proportions of green light at a total light intensity of 200 µmol m⁻² s⁻¹, consisting of 40% (G40), 60% (G60), 80% (G80), and 100% (G100) green light. The results showed that increasing the proportion of green light significantly reduced tipburn incidence from 49% to 25%, while shoot fresh weight declined by 7% and 25% when green light substitution increased to 80% and 100%, respectively. Net CO₂ assimilation of outer leaves remained similar among G40, G60, and G80 but declined by approximately 13% under 100% green light (G100). Higher proportions of green light markedly increased calcium accumulation and chlorophyll content in the inner leaves. These results suggest that higher proportions of green light may improve the inner-leaf light environment, enhance inner-leaf physiological function, and thereby reduce tipburn incidence. Substituting 60% green light achieved a good balance between growth performance and tipburn reduction. This approach offers an effective method to mitigate tipburn and improve lettuce quality in PFALs. Full article

Imaging in controlled agriculture helps maximize plant growth by saving labor and optimizing resources. By monitoring specific plant traits, growers can prevent crop losses by correcting environmental conditions that lead to physiological disorders like leaf tipburn. This study aimed to identify morphometric and spectral markers for the early detection of tipburn in two Romaine lettuce (Lactuca sativa) cultivars (‘Chicarita’ and ‘Dragoon’) using an image-based system with color and multispectral cameras. By monitoring tipburn in treatments using melatonin, lettuce cultivars, and with and without supplemental lighting, we enhanced our system’s accuracy for high-resolution tipburn symptom identification. Canopy geometrical features varied between cultivars, with the more susceptible cultivar exhibiting higher compactness and extent values across time, regardless of lighting conditions. These traits were further used to compare simple linear, logistic, least absolute shrinkage and selection operator (LASSO) regression, and random forest models for predicting leaf fresh and dry weight. Random forest regression outperformed simpler models, reducing the percentage error for leaf fresh weight from ~34% (LASSO) to ~13% (RMSE: 34.14 g to 17.32 g). For leaf dry weight, the percentage error decreased from ~20% to ~12%, with an explained variance increase to 94%. Vegetation indices exhibited cultivar-specific responses to supplemental lighting. ‘Dragoon’ consistently had higher red-edge chlorophyll index (CIrededge), enhanced vegetation index, and normalized difference vegetation index values than ‘Chicarita’. Additionally, ‘Dragoon’ showed a distinct temporal trend in the photochemical reflectance index, which increased under supplemental lighting. This study highlights the potential of morphometric and spectral traits for early detection of tipburn susceptibility, optimizing cultivar-specific environmental management, and improving the accuracy of predictive modeling strategies. Full article

The bunching onion is an important leafy vegetable, prized for its distinctive flavor and color. It is consumed year-round in Japan, where a stable supply is essential. However, in recent years, the challenges posed by climate change and global warming have resulted in adverse effects on bunching onions, including stunted growth, discoloration, and the development of leaf tipburn, threatening both crop quality and yield. Furthermore, as bunching onion belongs to the Allium genus, which includes globally significant vegetables such as onion and garlic, studying the impact of climate change on bunching onion serves as an ideal model. The insights gained can also be applied to other crops and regions. This study investigates the effects of different summer growth conditions on the metabolite profile of heat-tolerant bunching onions with dark green leaf blade coloration and examines their association with leaf tipburn. Pigment compound quantification, functional component analysis, leaf tipburn rate assessment, and widely targeted metabolome profiling were performed across two commercial ${\mathrm{F}}_1$ varieties, one purebred variety, and six Yamaguchi Prefecture-bred ${\mathrm{F}}_1$ lines under different growing conditions. The results obtained were subjected to comparative analyses based on the varieties and groups classified by high and low leaf tipburn rates. The results revealed that $\beta$-carotene accumulation peaked with May sowing and July harvest, while the highest accumulation of other pigment compounds was observed with May sowing and September harvest. Additionally, metabolome analysis related to leaf tipburn rates identified several organosulfur compounds, with gamma-glutamyl-propenyl cysteine sulfoxide emerging as one of the key compounds. Based on the intensity data, the fold change of this metabolite was calculated to be 1.66, indicating an increase in the leaf tipburn group compared to the control group. In the control groups, organosulfur compounds appeared to undergo turnover in preparation for stress response. In contrast, in the leaf tipburn groups, it is hypothesized that organosulfur compounds were converted into precursors of pungency, resulting in inadequate responses to stress. This study aims to elucidate the mechanisms through which organosulfur compounds transition into pungent compounds and to develop varieties with improved resistance to leaf tipburn. Full article

The decreased quality of leafy vegetables and tipburn caused by inappropriate light intensity are serious problems faced in plant factories, greatly reducing the economic benefits. The purpose of this study was to comprehensively understand the impact of light intensity on the growth and quality of different crops and to develop precise lighting schemes for specific cultivars. Two lettuce (Lactuca sativa L.) cultivars—Crunchy and Deangelia—and one spinach (Spinacia oleracea L.) cultivar—Shawen—were grown in a plant factory using a light-emitting diode (LED) under intensities of 300, 240, 180, and 120 μmol m⁻² s⁻¹, respectively. Cultivation in a solar greenhouse using only natural light (NL) served as the control. The plant height, number of leaves, and leaf width exhibited the highest values under a light intensity of 300 μmol m⁻² s⁻¹ for Crunchy. The plant width and leaf length of Deangelia exhibited the smallest values under a light intensity of 300 μmol m⁻² s⁻¹. The fresh weight of shoot and root, soluble sugar, soluble protein, and ascorbic acid contents in the three cultivars increased with the increasing light intensity. However, tipburn was observed in Crunchy under 300 μmol m⁻² s⁻¹ light intensity, and in Deangelia under both 300 and 240 μmol m⁻² s⁻¹ light intensities. Shawen spinach exhibited leaf curling under all four light intensities. The light intensities of 240 and 180 μmol m⁻² s⁻¹ were observed to be the most optimum for Crunchy and Deangelia (semi-heading lettuce variety), respectively, which would exhibit relative balance growth and morphogenesis. The lack of healthy leaves in Shawen spinach under all light intensities indicated the need to comprehensively optimize cultivation for Shawen in plant factories to achieve successful cultivation. The results indicated that light intensity is an important factor and should be optimized for specific crop species and cultivars to achieve healthy growth in plant factories. Full article

This study evaluated the effects of fish farm wastewater from the production of hybrid sturgeon (Acipenser gueldenstaedtii Brandt × Acipenser baeri Brandt) on the growth and quality parameters of romaine lettuce (Lactuca sativa var. longifolium cv. “Elizium”). The tested combinations were fish farm wastewater, fish farm wastewater enriched with one of the three microbiological consortia, and fish farm wastewater supplemented with minerals. The best growth parameters of romaine lettuce plants were obtained in the combination of wastewater from fish farming supplemented with mineral nutrients. The application of fish farm wastewater and beneficial microbiological consortia positively influenced the fresh weight of lettuce leaves and the number of leaves per plant. However, plants fed with wastewater supplemented with minerals were characterized by the strongest symptoms of leaf tip-burn and the lowest commercial value. By comparison, plants fed only with fish farm wastewater or wastewater with microorganisms were characterized by a high, similar commercial value. After the application of increased doses of minerals, there was evidence of greater activity of microorganisms involved in nutrient cycling in aquaponic lettuce cultivation. The application of the microbiological consortia and minerals significantly increased the numbers and activity of the bacteria in the culture liquids 7, 14, and 21 days after inoculation. Full article

Chinese cabbage tipburn is characterized by the formation of necrotic lesions on the margin of leaves, including on the insides of the leafy head. This physiological disorder is associated with a localized calcium deficiency during leaf development. However, little information is available regarding the molecular mechanisms governing Ca-deficiency-triggered tipburn. This study comprehensively analysed the transcriptomic comparison between control and calcium treatments (CK and 0 mM Ca) in Chinese cabbage to determine its molecular mechanism in tipburn. Our analysis identified that the most enriched gene ontology (GO) categories are photosynthesis, thylakoid and cofactor binding. Moreover, the KEGG pathway was most enriched in photosynthesis, carbon metabolism and carbon fixation. We also analyzed the co-expression network by functional categories and identified ten critical hub differentially expressed genes (DEGs) in each gene regulatory network (GRN). These DEGs might involve abiotic stresses, developmental processes, cell wall metabolism, calcium distribution, transcription factors, plant hormone biosynthesis and signal transduction pathways. Under calcium deficiency, CNX1, calmodulin-binding proteins and CMLs family proteins were downregulated compared to CK. In addition, plant hormones such as GA, JA, BR, Auxin and ABA biosynthesis pathways genes were downregulated under calcium treatment. Likewise, HATs, ARLs and TCP transcription factors were reported as inactive under calcium deficiency, and potentially involved in the developmental process. This work explores the specific DEGs’ significantly different expression levels in 0 mM Ca and the control involved in plant hormones, cell wall developments, a light response such as chlorophylls and photosynthesis, transport metabolism and defence mechanism and redox. Our results provide critical evidence of the potential roles of the calcium signal transduction pathway and candidate genes governing Ca-deficiency-triggered tipburn in Chinese cabbage. Full article

The study examined the influence of light quality on the growth and nutritional status of romaine lettuce grown in deep water culture with a floating raft system using two different nutrient solutions. Four spectra of LED light were used with different ratios of R, G, and B lights (80:10:10, 70:10:20, 60:10:30, and 70:18:12). Two nutrient solutions with a low (A) and moderately high (B) nutrient content were used. Regardless of the nutrient solution, the RGB 70:18:12 light promoted the production of leaf biomass as well as inhibited the accumulation of K and Mg in the leaves. Moreover, those plants were characterized by a low Nitrogen Balance Index (NBI) and a high flavonol index. In the last week of cultivation, there was a strong decrease in K, P, and nitrates in the nutrient solution, and an increase in Ca. In the final stage of growth, symptoms of withering of the tips of young leaves (tipburn) were observed on the plants. The most damage was observed on the plants growing under 70:10:20, 70:18:12, and with the higher concentration of minerals in the solution (B). Full article

Cultivated lettuce (Lactuca sativa L.) is one of the most important leafy vegetables in the world, and most of the production is concentrated in the Mediterranean Basin. Hydroponics has been successfully utilized for lettuce cultivation, which could contribute to the diversification of production methods and the reduction of water consumption and excessive fertilization. We devised a low-cost procedure for closed hydroponic cultivation and easy phenotyping of root and shoot attributes of lettuce. We studied 12 lettuce genotypes of the crisphead and oak-leaf subtypes, which differed on their tipburn resistance, for three growing seasons (Fall, Winter, and Spring). We found interesting genotype × environment (G × E) interactions for some of the studied traits during early growth. By analyzing tipburn incidence and leaf nutrient content, we were able to identify a number of nutrient traits that were highly correlated with cultivar- and genotype-dependent tipburn. Our experimental setup will allow evaluating different lettuce genotypes in defined nutrient solutions to select for tipburn-tolerant and highly productive genotypes that are suitable for hydroponics. Full article

Tipburn is an important disorder caused by a calcium deficiency that affects the marketability of endives. Genotype, air relative humidity, and temperature are directly involved in tipburn occurrence. Our study aimed to investigate the effect of cropping systems and relative humidity on the marketable yield, nitrate accumulation, and incidence of tipburn in endives. Two cultivars were evaluated in pots (‘Cuartana’ and ‘Natacha’), two cropping systems (greenhouse and open-field), and in two different air humidity levels (high level: plants under a plastic tunnel with an extra supply of humidity with micro-sprinklers, and low level: plants without an extra supply of humidity and outside of a plastic tunnel) during two years (2013 and 2014) in different growing seasons. Nitrate content was determined by reflectometry, and tipburn was evaluated using a qualitative scale. Results showed that tipburn was favored under greenhouse with low humidity levels, with 40–60% plants affected. ‘Natacha’ was more susceptible to tipburn (>20% plants affected) than ‘Cuartana’ (<20% plants affected). Leaf nitrate accumulation was favored by the highest temperatures (greenhouse). It is concluded that in our conditions, tipburn incidence in endives depends on the interaction of genotype and the environmental conditions. Nitrate content was more influenced by the temperature than by the cultivars used. Full article

For the treatment of wastewater containing organic pollutants and metals in constructed wetlands (CWs), phytoindicators may help in guiding management practices for plants and optimizing phytoremediation processes. Hairy willow-herb (Epilobium hirsutum L.) is a fast growing species commonly found in European CWs that could constitute a suitable phytoindicator of metal toxicity. E. hirsutum was exposed for 113 days in microcosm CWs, to a metal and metalloid mixture (MPM, containing Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sn, Zn), an organic pollutant mixture (OPM, containing hydrocarbonsC₁₀-C₄₀, phenanthrene, pyrene, anionic detergent LAS) and an organic pollutant and metal and metalloid mixture (OMPM), separately and at concentration levels mimicking levels of industrial effluents. Analyses of metal and As concentrations in biomass, and different biometric and physiological measurements were performed. Results showed that metal uptake patterns were affected by the type of pollutant mixture, resulting in variation of toxicity symptoms in E. hirsutum plants. Some of them appeared to be similar under MPM and OMPM conditions (leaf chlorosis and tip-burning, decrease of green leaf proportion), while others were characteristic of each pollutant mixture (MPM: Decrease of water content, increase of phenol content; OMPM: reduction of limb length, inhibition of vegetative reproduction, increase of chlorophyll content and Nitrogen balance index). Results emphasize the potential of E. hirsutum as a bioindicator species to be used in European CWs treating water with metal, metalloid and organic pollutants. Full article