Growth Chamber Conditions Research Articles

Root Infection and Minituber Yield Response to Powdery Scab in Plant Growth Chamber Conditions

Powdery scab, caused by the soil borne Plasmodiophorid Spongospora subterranea f. sp. subterranea (Sss), is an increasing concern. Developing resistant varieties with enduring resistance is crucial for sustainable disease management. However, the lack of a consistent infection assay for Sss hindered effective evaluation of disease symptoms, including root gall formation and tuber lesions. This study introduces a reliable method for assessing Sss pathogenicity using a sand/potting mixture in a controlled-environment plant growth chamber. Potato plants were inoculated with three types of inocula sourced from root galls, infested soil, and scab-like tube lesions. All inocula successfully induced root galls and tuber lesions, with the tuber lesion-derived inoculum producing the highest number of root galls. Additionally, the method demonstrated a marked impact on tuber yield, weight, and size in both highly susceptible and moderately susceptible cultivars. These findings underscore the efficacy of this infection assay as a robust tool for evaluating Sss pathogenicity. This method holds promise for screening potato germplasm to develop resistant varieties against powdery scab.

Seed color patterns in domesticated common bean are regulated by MYB-bHLH-WD40 transcription factors and temperature.

Seed colors and color patterns are critical for the survival of wild plants and the consumer appeal of crops. In common bean, a major global staple, these patterns are also essential in determining market classes, yet the genetic and environmental control of many pigmentation patterns remains unresolved. In this study, we genetically mapped variation for several important seed pattern loci, including T, Bip, phbw, and Z, which co-segregated with candidate genes PvTTG1, PvMYC1, PvTT8, and PvTT2, respectively. Proteins encoded by these genes are predicted to work together in MYB-bHLH-WD40 (MBW) complexes, propagating flavonoid biosynthesis across the seed coat as observed in Arabidopsis. Whole-genome sequencing of 37 accessions identified mutations, including seven unique parallel mutations in T (PvTTG1) and non-synonymous SNPs in highly conserved residues in bipana (PvMYC1) and z (PvTT2). A 612 bp intron deletion in phbw (PvTT8) eliminated motifs conserved since the Papilionoideae origin and corresponded to a 20-fold reduction in transcript abundance. In multi-location field trials of seven varieties with partial seed coat pigmentation patterning, the pigmented seed coat area correlated positively with ambient temperature, with up to 11-fold increases in the pigmented area from the coolest to the warmest environments. In controlled growth chamber conditions, an increase of 4°C was sufficient to cause pigmentation on an average additional 21% of the seed coat area. Our results shed light on key steps of flavonoid biosynthesis in common bean. They will inform breeding efforts for seed coat color/patterning to improve consumer appeal in this nutritious staple crop.

Using Fungal and Bacterial Bioagent Formula Antagonists to Combat Fusarium Oxysporum f. sp. Lycopersici Under Greenhouse Conditions

Objective: This study aimed to test fungal and bacterial bioagents as formula antagonists of Fusarium oxysporum f. sp. lycopersici under greenhouse conditions. Methods: The fungal and bacterial formulations' shelf life under different temperatures as well as under growth chamber and greenhouse conditions, as well as their effects on biochemical alterations involved in the induction of plant defense against the causative pathogen were investigated. Results: In-vitro antagonist screening of bacterial and fungal isolates on radial growth, reduction and inhibition percentages revealed that T. harzianum exhibited 45.6% of inhibition followed by B. pumilus with 36.7%. Among the fungal and bacterial bio-agents, the highest effect on disease incidence and efficiency against pathogenic fungus under greenhouse conditions was B. pumilus 27 and 69%, respectively followed by T. harzianum 33 and 62% when applied before pathogen inoculation. Under greenhouse conditions, the effects of bio-fungicides also affected defense enzymes like peroxidase and polyphenol oxidase. The shelf life of the wettable powder formulation of bio-agents under different temperature was very important factor and established that the most suitable temperature for long term storage is 25 ºC for both B. pumilus and T. harzianum. Conclusion: Target application of disease control techniques in tomato plants demonstrated the efficacy of B. pumilus and T. harzianum in reducing Fusarium wilt. These results pave the way for the development of bio-agents that can replace fungicides in agriculture, offering a practical substitute.

Influence of Controlled Condition Ice Encasement of Creeping Bentgrass and Annual Bluegrass on Plant Recovery, Gas Evolution, and Metabolites

Two cool-season putting green turfgrass species, annual bluegrass and creeping bentgrass, are differential in ice encasement tolerance. Physiological mechanisms associated with creeping bentgrass ice encasement tolerance and annual bluegrass susceptibility are not understood. The objectives were to evaluate oxygen, ethylene, and CO2 content within the upper soil space of the plants while frozen and immediately after ice melt after 0, 5, 10, 20, and 28 days of ice encasement (2.54 cm of ice) in growth chamber conditions. Following ice melt, plant samples were separated into leaf, crown, and root tissues and used to evaluate carbohydrate and amino acid content. Annual bluegrass exhibited higher damage (slower recovery rates) on most sampling days compared with creeping bentgrass. The organs that were most damaged and exhibited a differential principal component analysis snapshot, were the leaf and crown tissues. Creeping bentgrass may preserve leaf and crown tissues for postwinter recovery whereas significant metabolic changes occur in annual bluegrass leaves and crowns. Creeping bentgrass retained total amino acids in leaves following ice encasement whereas total leaf amino acid levels declined in annual bluegrass. Specific carbohydrates and amino acids such as the ability to maintain high levels of fructose, asparagine, and proline may be important indicators of the tolerance to ice encasement stress. On the basis of more prominent carbohydrate and amino acid loss in leaves and crowns and higher levels of CO2 evolution, annual bluegrass may exhibit a higher metabolism and/or tissue damage during ice encasement compared with creeping bentgrass, which could reduce spring recuperative potential.

Rhizoctonia species, anastomosis groups, and pathogenicity isolated from common bean in Lake Van Basin, Turkiye

Common bean (Phaseolus vulgaris L.) is an important vegetable crop grown in Lake Van Basin. Local genotypes are widely grown in the region. Rhizoctonia root rot induced by Rhizoctonia solani Kühn is an important soilborne plant disease that leads to global economic losses as well as in Turkey. The present study was conducted to determine anastomosis groups and pathogenicity of Rhizoctonia spp. obtained from bean plants in Lake Van Basin in 2013 and 2014. A total of 236 Rhizoctonia isolates in 5 anastomosis groups were obtained from bean plant roots. It was observed that AG- 4 (112) was the most isolated group in beans, followed by AG- 2 (41), AG- 3 (28), AG- 5 (33), and binucleate AG- K (22) isolates. Pathogenicity test conducted in thirty isolates in 5 anastomosis groups was analyzed for A64 (Bitlis/ Adilcevaz), TR68557 genotypes, and Gina (cv.) under growth chamber conditions. The study findings demonstrated that all tested isolates could infect the bean plant with different degrees of severity; however, the most virulent group was AG- 4. It was determined that the most virulent isolate was Isolate No. 19 in the A64 genotype, Isolate No. 2 in TR68557, and Isolate No. 18 in Gina cv. in in vivo tests. The identification and pathogenicity determination of Rhizoctonia isolates are the first steps towards an efficient control strategy for bean diseases caused by Rhizoctonia species. In order to obtain quality and productive products in the Van Lake Basin, where intensive bean production is carried out, precautions should be taken by considering the damage caused by Rhizoctonia spp. on plants.

Enhancing Plant Growth: Harnessing the Effectiveness of Artificial Light

This extensive analysis reveals the significant influence of artificial light, especially light-emitting diodes (LEDs), on enhancing plant growth for sustainable agriculture and horticulture optimization. The production of seedlings is an essential component of contemporary agriculture. While study is conducted on the complex relationships between plants and artificial light sources. Controlled light conditions in growth chambers and vertical farming systems are excellent solutions that enable year-round and space-efficient seedling production. It is possible to draw the conclusion that using artificial light can result in increased biomass, faster growth rates, and better crop quality. This review highlights the effects of various light spectra, intensities, and durations on critical physiological processes involved in seed germination, vegetative growth, and overall seedling development during propagation. Apart from that, the new study looks into the complexity of photosynthesis, photomorphogenesis, and photoperiodic reactions, providing useful insights for customising light conditions for different crops and developmental stages.

Control of potato wart disease (Synchytrium endobioticum) by fungicide soil treatments

Synchytrium endobioticum is the causative agent of potato wart disease and can remain in the soil for several years via its sporangia. Effective protection against this disease includes quarantine and the use of disease-resistant potato varieties. However, so far it has not been eradicated. The aim of this study was to determine the effect of fungicides for soil treatment to protect against potato wart. Experiments were conducted with propamocarb hydrochloride 722 SC g/l, metalaxyl M + fludioxonil 10 + 25 g/l, gimexazole 360 g/l, tolklofos methyl + thiram 30 + 30%, dimethomorph + cuproxy chloride 6 + 40WP, famoxadone + cymoxanil 22.5 + 30%, Mandipropamide + Mancoceb 5 + 60%, Zoxamide + Mancoceb 8.3 + 66.7% in the growth chamber and field conditions — showed that Famoxadone + Cimoxanil 22.5 + 30% is able to protect against the disease by 100% in both experimental conditions.

Onion Fusarium Basal Rot Disease Control by Arbuscular Mycorrhizal Fungi and Trichoderma harzianum

Soilborne pathogens reduce 60% of the yield of onion crops. A common fungal pathogen causing wilt disease and severe losses is Fusarium basal rot (FBR). In this study, the combination of Arbuscular Mycorrhizal Fungi (AMF) with Trichoderma harzianum was investigated against FBR. Onion samples were collected from the Ankara–Polatlı region. Among the isolates, isolate S6 was identified as F. oxysporum f. sp. cepae (FOC) using morphological and molecular methods and pathogenicity tests. Different combinations of AMF (Funneliformis mosseae pure strain and the commercial AMF) and T. harzianum were inoculated on susceptible onion cultivars (Seç, Gence, and Şampiyon). The effects of the treatments on FOC biocontrol were studied under growth chamber conditions. The results showed that Şampiyon was the most resistant, while Gence was the most susceptible to basal rot disease. Different colonization rates (8.91–24%), spore densities (16.4–50.4 spore/10 g soil), and the extent to which a plant needs mycorrhizal conditions to grow to its maximum potential (i.e., mycorrhizal dependencies—18.3–51.9%) were recorded by treatment. Both single and combined applications of AMF and Trichoderma applications suppressed FOC. Suppressive effects were more pronounced when the F. mosseae pure strain was used alone (when F. mosseae was used, disease severity decreased from 90 to 68%, p < 0.05). The F. mosseae pure strain also showed the best plant growth promotion and phosphorus content release. The results indicate an interesting potential use of F. mosseae and the combination of AMF with T. harzianum in the management of FOC in onions.

Predicting Floral Bud Progression for Three Peach Cultivars

The prediction of floral bud progression in commercial peach cultivars promotes knowledge about the adaptability of cultivars to the climatic conditions in a specific location under a climatic variability context. Phenology is relevant to improving the scheduling of cultural practices in peach orchards. This research aimed to predict the floral bud progression of three peach cultivars: ‘Harvester’, ‘Red Globe’, and ‘Rubyprince’. Floral bud progression was assessed using one-year-old shoots collected from an orchard located at the Chilton Research and Extension Center, Alabama. Samples were evaluated under laboratory and growth chamber conditions. We recorded the flower developmental stages daily to identify the transition among stages. Daily temperature records were used to estimate the heat requirement in terms of Growing Degree Days (GDD). After dormancy release, samples needed between 23 to 39 and 37 to 42 days to reach the petal fall stage for season 1 and season 2, respectively. In terms of heat requirements, cultivars needed between 425.5 to 721.5 and 684.5 to 777 GDD to end flowering. A logistic curve was adjusted to describe the growth of the different floral stages over time. The results are key to supporting peach growers in crop management practices such as orchard establishment, irrigation, fertilization, freeze and frost protection, and pollination under climate variability scenarios.

Agrobacterium-mediated transfer of the Fusarium graminearum Tri6 gene into barley using mature seed-derived shoot tips as explants

Key messageWe transferred the Tri6 gene into the elite barley GemCraft via new transformation method through shoot organogenesis and identified the rearrangements of transgenes and phenotypic variations in the transgenic plants.Despite its agronomic and economic importance, barley transformation is still very challenging for many elite varieties. In this study, we used direct shoot organogenesis to transform the elite barley cultivar GemCraft with the RNAi constructs containing Tri6 gene of Fusarium graminearum, which causes fusarium head blight (FHB). We isolated 4432 shoot tips and co-cultured these explants with Agrobacterium tumefaciens. A total of 25 independent T0 transgenic plants were generated including 15 events for which transgene-specific PCR amplicons were observed. To further determine the presence of transgenes, the T1 progenies of all 15 T0 plants were analyzed, and the expected PCR products were obtained in 10 T1 lines. Droplet digital (dd) PCR analysis revealed various copy numbers of transgenes in the transgenic plants. We determined the insertion site of transgenes using long-read sequencing data and observed the rearrangements of transgenes. We found phenotypic variations in both T1 and T2 generation plants. FHB disease was evaluated under growth chamber conditions, but no significant differences in disease severity or deoxynivalenol accumulation were observed between two Tri6 transgenic lines and the wildtype. Our results demonstrate the feasibility of the shoot tip transformation and may open the door for applying this system for genetic improvement and gene function research in other barley genotypes.

The Effects of Mycorrhiza and Seaweed Applications on Seedling Growth Parameters: Tomato and Pepper

ABSTRACT The use of mycorrhiza and seaweed are becoming significant and complementary applications in different production systems because organisms increased quality of seedlings and crop yield. This study has been conducted under growth chamber conditions to determine some of the seedling growth parameters (length (cm), stem diameter (mm), fresh weight (g plant −1), dry weight (g plant −1), root fresh weight (g plant −1), root dry weight (g plant −1), leaf area (cm2 plant−1), SPAD, photosynthesis rate (%) and color parameters). As a plant material, Cuma F1 and Mert F1 genotype seeds were sown. Endo Roots Soluble (Mycorrhiza (ERS)) and MC-Extra (Seaweed) were applied in different doses (0, 250 and 500 mg kg−1) to seedling growing vessels at a rate of 10 ml per plant. Treatment effects in tomato were found statistically significant (p ≤.01**) on stem diameter, fresh weight, dry weight. Seedling length, leaf area and SPAD results were also statistically significant (p ≤.01**), and the results of these parameters were higher in ERS. ERS increases the leaf area and SPAD measurements in tomato seedlings. The results of pepper measurements were found to be statistically significant at p ≤.05* on root fresh weight, SPAD and photosynthesis rate. The highest values of root fresh weight, SPAD were obtained from 250 mg kg−1 doses of ERS; the highest value of photosynthesis rate was measured from 500 mg kg−1 doses of ERS on pepper. The effect of 500 mg kg−1 ERS on seedling growth was found statistically significant in pepper.

Early detection of Kentucky bluegrass and perennial ryegrass responses to drought stress by measuring chlorophyll fluorescence parameters

AbstractKentucky bluegrass (Poa pratensis L.; drought resistant) and perennial ryegrass (Lolium perenne L.; drought sensitive) are economically important grass species contrasting in drought stress resistance. This study determined the optimal chlorophyll fluorescence parameters to indicate drought incidence and whether the parameters differentiate intra‐ and interspecies variations in drought stress. For each species, nine cultivars were exposed to well‐watered or drought (water withheld) conditions in growth chambers containing high‐throughput photosynthetic imagers to track real‐time responses of maximum quantum efficiency of photosystem II (Fv/Fm), quantum yield of photosystem II (ΦII), non‐photochemical quenching (NPQ), energy‐dependent quenching (qE), and photoinhibition‐associated quenching (qI). Soil moisture content and relative water content of leaf tissues were evaluated. Due to drought, Fv/Fm and ΦII decreased for cultivars of both species but earlier for perennial ryegrass compared to Kentucky bluegrass. The NPQ, qI, and qE values exhibited more dynamic and earlier changes due to drought compared to Fv/Fm and ΦII and allowed for early, mid, and late drought responses to be illustrated. Drought induced an increase in NPQ, qI, and qE values, which corresponded to activation of photoprotection mechanisms, and was exhibited earlier for perennial ryegrass compared to Kentucky bluegrass. As the drought treatment progressed, a decrease or stabilization of low values of NPQ, qI, and qE was observed, and the lowest values were associated with the most drought‐sensitive cultivars. These results indicate important stress tolerance protection mechanisms for grass species and will broadly impact basic and applied grass research as a nondestructive phenotyping tool.

First Occurrence of Coffee Leaf Rust Caused by Hemileia vastatrix on Coffee in Saudi Arabia

Coffee leaf rust (CLR) is a major disease of Arabica coffee caused by the biotrophic fungus Hemileia vastatrix. Jazan region in Saudi Arabia has long been one of the last coffee-producing regions in the world free of this disease. In August 2023, CLR was initially observed in coffee plantations located in Fyfa district one of the main coffee-producing mountains of Jazan region. The source of the infection is unknown, however CLR could have entered Jazan from the nearest coffee-producing locations that haven the pathogen. During a scheduled survey in August 2023, symptoms were observed including yellowish-orange lesions that frequently combined to form chlorotic lesions and exhibited the powdery appearance of yellow uredospores on the abaxial surface of leaves. The uredospores and teliospores were microscopically examined and their morphology matched the previously published description for H. vastatrix. The identity of H. vastatrix specimens was further confirmed based on PCR amplification and sequencing of ITS, sharing a 99–100% identity with previously published sequences, as belonging to H. vastatrix. The pathogenicity of H. vastatrix specimens was investigated on Coffee arabica plants under growth chamber conditions, and all were pathogenic relative to control, with 100% of disease incidence, therefore fulfilling Koch’s postulates. Based on our findings, this is the first documentation of H. vastatrix causing CLR in Saudi Arabia.

Phenotypic evaluation of USDA peanut (Arachis hypogaea L.) mini-core collection for resistance against stem rot caused by Sclerotium rolfsii Sacc.

Sclerotium rolfsii is a necrotrophic fungus that causes devastating stem rot disease on peanuts under high temperature and humidity conditions. Developing more resistant stem rot varieties is a better disease management strategy from an economic and environmental point of view. In this study, 105 peanut accessions from the USDA mini-core collection were screened for resistance against stem rot under growth chamber and greenhouse conditions at the New Mexico State University Agricultural Science Center in Clovis, NM, USA. The accessions were inoculated with a virulent isolate of S. rolfsii, and disease development was monitored and scored at 5, 7, 9, 11, and 17-days post-inoculation (DPI). Mean disease score, lesion length and broad sense heritability were calculated, and cluster analysis was performed. Though the accessions were not significantly different for the mean disease parameters, numerical differences were observed in disease score and lesion length among the accessions at 17-DPI. Eleven accessions showed moderate resistance and performed better than stem rot resistant commercial cultivar, ‘G03L’, and ninety-four accessions were susceptible based on mean disease scores under both growing conditions. Low broad-sense heritability for disease score (0.05 to 0.06) and lesion length (0.03 to 0.06) under different environments indicates that most of the variance for these traits is due to environmental effects, and that stem rot resistance can be a complex trait. The identified resistant accessions can be used for genotyping and finding major QTLs through genome-wide association mapping to dissect genetic basis of stem rot resistance in peanuts. This information would be helpful to the peanut breeding program to develop more resistant varieties.

Life-Cycle Multiomics ofRice Shoots Reveals Growth Stage-Specific Effects ofDrought Stress andTime-Lag Drought Responses.

Field-grown rice plants are exposed to various stresses at different stages of their life cycle, but little is known about the effects of stage-specific stresses on phenomes and transcriptomes. In this study, we performed integrated time-course multiomics on rice at 3-d intervals from seedling to heading stage under six drought conditions in a well-controlled growth chamber. Drought stress at seedling and reproductive stages reduced yield performance by reducing seed number and setting rate, respectively. High temporal resolution analysis revealed that drought response occurred in two steps: a rapid response via the abscisic acid (ABA) signaling pathway and a slightly delayed DEHYDRATION-RESPONSIVE ELEMENT-BINDING PROTEIN (DREB) pathway, allowing plants to respond flexibly to deteriorating soil water conditions. Our long-term time-course multiomics showed that temporary drought stress delayed flowering due to prolonged expression of the flowering repressor gene GRAIN NUMBER, PLANT HEIGHT AND HEADING DATE 7 (Ghd7) and delayed expression of the florigen genes HEADING DATE 3a (Hd3a) and RICE FLOWERING LOCUS T 1 (RFT1). Our life-cycle multiomics dataset on rice shoots under drought conditions provides a valuable resource for further functional genomic studies to improve crop resilience to drought stress.

Tandem Expression of a Mobile RNA and Its RNA-Binding Protein(s) Enhances Tuber Productivity in Potato

A significant number of discoveries in past two decades have established the importance of long-distance signaling in controlling plant growth, development, and biotic and abiotic stress responses. Numerous mobile signals, such as mRNAs, proteins, including RNA-binding proteins, small RNAs, sugars, and phytohormones, are shown to regulate various agronomic traits such as flowering, fruit, seed development, and tuberization. Potato is a classic model tuber crop, and several mobile signals are known to govern tuber development. However, it is unknown if these mobile signals have any synergistic effects on potato crop improvement. Here, we employed a simple innovative strategy to test the cumulative effects of a key mobile RNA, StBEL5, and its RNA-binding proteins, StPTB1, and -6 on tuber productivity of two potato cultivars, Solanum tuberosum cv. Désirée and subspecies andigena, using a multi-gene stacking approach. In this approach, the coding sequences of StBEL5 and StPTB1/6 are driven by their respective native promoters to efficiently achieve targeted expression in phloem for monitoring tuber productivity. We demonstrate that this strategy resulted in earliness for tuberization and enhanced tuber productivity by 2–4 folds under growth chamber, greenhouse, and field conditions. This multi-gene stacking approach could be adopted to other crops, whose agronomic traits are governed by mobile macromolecules, expanding the possibilities to develop crops with improved traits and enhanced yields.

Production of bioactive and aroma volatile compounds of Lawsonia inermis L. cultivated under different growth conditions

The present study aimed to investigate the influence of different growing conditions on the amount of leaf pigments (chlorophylls, carotenoids), bioactive metabolites, such as polyphenols, flavonoids, lawsone and volatile organic compounds (VOCs) of Lawsonia inermis L. (henna) plants. Young henna plants were cultivated for two months in a growth chamber (GC) and in open-air conditions during summer under the Mediterranean climate (OF), and leaves were analysed to evaluate their adaptive responses. The different growth conditions modified the carbon allocation priorities, increasing antioxidant metabolites (e.g. phenolic and flavonoid compounds) while decreasing lawsone in GC conditions. Quali-quantitative changes were observed for VOCs. This study revealed that GC conditions permit an alternative use of Lawsonia cultivation, because of the increase in the endogenous content of bioactive secondary metabolites with many potential biological activities.

Effects of measurement methods and growing conditions on phenotypic expression of photosynthesis in seven diverse rice genotypes.

Light response curves are widely used to quantify phenotypic expression of photosynthesis by measuring a single sample and sequentially altering light intensity within a chamber (sequential method) or by measuring different samples that are each acclimated to a different light level (non-sequential method). Both methods are often conducted in controlled environments to achieve steady-state results, and neither method involves equilibrating the entire plant to the specific light level. Here, we compare sequential and non-sequential methods in controlled (greenhouse), semi-controlled (plant grown in growth chamber and acclimated to field conditions 2-3 days before measurements), and field environments. We selected seven diverse rice genotypes (five genotypes from the USDA rice minicore collection: 310588, 310723, 311644, 311677, 311795; and 2 additional genotypes: Nagina 22 and Zhe 733) to understand (1) the limitations of different methods, and (2) phenotypic plasticity of photosynthesis in rice grown under different environments. Our results show that the non-sequential method was time-efficient and captured more variability of field conditions than the sequential method, but the model parameters were generally similar between two methods except the maximum photosynthesis rate (Amax). Amax was significantly lower across all genotypes under greenhouse conditions compared to the growth chamber and field conditions consistent with prior work, but surprisingly the apparent quantum yield (α) and the mitochondrial respiration (Rd) were generally not different among growing environments or measurement methods. Our results suggest that field conditions are best suited to quantify phenotypic differences across different genotypes and nonsequential method was better at capturing the variability in photosynthesis.

Bacillus velezensis and Paenibacillus peoriae Strains Effective as Biocontrol Agents against Xanthomonas Bacterial Spot

Gram-negative bacteria belonging to the Xanthomonas genus include plant pathogens representing a major challenge in the field of agriculture for a wide variety of economically important crops, such as tomato, pepper, and lettuce. Due to the massive usage of agrochemicals, Xanthomonas spp. are developing resistance to copper pesticides typically used to control microbial infections. An interesting alternative approach to control bacterial phytopathogens consists of using eco-friendly biocontrol agents, often beneficial microorganisms. Here, following the targeted, broad-spectrum screening of thousands of microorganisms isolated from different environmental locations, we isolated Bacillus velezensis strain 71 and Paenibacillus peoriae strain To99 displaying potent antagonistic activity against Xanthomonas spp. We found that oxydifficidin and polymyxin A secreted by B. velezensis 71 and P. peoriae To99, respectively, are mainly responsible for the anti-Xanthomonas activity. We further evaluated the performance of cell suspensions and cell-free supernatants of these isolates in controlling tomato bacterial spot disease in growth chamber and greenhouse conditions to validate the in vitro results. The overall results demonstrate the potential of treatments based on the secondary metabolites from both isolates and their cells as an alternative to copper-based chemicals to control leaf spot diseases caused by Xanthomonas spp. phytopathogens.

Energy-Efficient IoT-Based Light Control System in Smart Indoor Agriculture.

Indoor agriculture is emerging as a promising approach for increasing the efficiency and sustainability of agri-food production processes. It is currently evolving from a small-scale horticultural practice to a large-scale industry as a response to the increasing demand. This led to the appearance of plant factories where agri-food production is automated and continuous and the plant environment is fully controlled. While plant factories improve the productivity and sustainability of the process, they suffer from high energy consumption and the difficulty of providing the ideal environment for plants. As a small step to address these limitations, in this article we propose to use internet of things (IoT) technologies and automatic control algorithms to construct an energy-efficient remote control architecture for grow lights monitoring in indoor farming. The proposed architecture consists of using a master-slave device configuration in which the slave devices are used to control the local light conditions in growth chambers while the master device is used to monitor the plant factory through wireless communication with the slave devices. The devices all together make a 6LoWPAN network in which the RPL protocol is used to manage data transfer. This allows for the precise and centralized control of the growth conditions and the real-time monitoring of plants. The proposed control architecture can be associated with a decision support system to improve yields and quality at low costs. The developed method is evaluated in emulation software (Contiki-NG v4.7),its scalability to the case of large-scale production facilities is tested, and the obtained results are presented and discussed. The proposed approach is promising in dealing with control, cost, and scalability issues and can contribute to making smart indoor agriculture more effective and sustainable.