Greenhouse Conditions Research Articles

Effect of Plant Growth Regulators on Germination and Seedling Growth of Passiflora alata and Passiflora edulis

The yellow (Passiflora edulis) and sweet (Passiflora alata) passion fruit plants hold significant economic importance in tropical fruit cultivation, valued not only for the quality of their fruit but also for their medicinal properties. Conventional propagation through seeds faces challenges due to irregular and slow germination, affecting the time required for seedling formation and the viability and uniformity of plantations. The use of plant growth regulators has been explored as a strategy to overcome these barriers, improving both the rate and uniformity of seed germination. This study aimed to evaluate the influence of seed imbibition with plant growth regulators on the germination and subsequent growth of yellow and sweet passion fruit seedlings. Gibberellic acid (GA3) and GA4+7 combined with 6-benzyladenine (GA4+7+6BA) were applied in five different concentrations (0, 250, 500, 750, and 1000 mg L−1 a.i.). The experiments were conducted in both laboratory and greenhouse conditions, following a completely randomized design with a 2 × 5 factorial scheme. The varieties tested were ‘BRS Mel do Cerrado’ for sweet passion fruit and ‘IAC-275’ for yellow passion fruit. Quantitative parameters, such as germination percentage, germination speed index, fresh and dry biomass of roots and shoots, and enzymatic activity, were assessed. The results indicated that GA3, at higher concentrations, significantly enhanced both germination percentage and speed index in both Passiflora alata and Passiflora edulis when compared to the control. Additionally, seedlings treated with GA3 showed a marked increase in shoot and root biomass, particularly at concentrations of 500 and 750 mg L−1. Enzymatic assays revealed heightened catalase and peroxidase activities in treated seedlings, indicating improved stress tolerance. In contrast, the GA4+7+6BA treatment showed less pronounced effects on seedling growth. Overall, GA3 was more effective in enhancing germination and seedling growth in both species, suggesting its potential application in improving the propagation of passion fruit.

Hyperspectral imaging for pest symptom detection in bell pepper

BackgroundThe automation of pest monitoring is highly important for enhancing integrated pest management in practice. In this context, advanced technologies are becoming increasingly explored. Hyperspectral imaging (HSI) is a technique that has been used frequently in recent years in the context of natural science, and the successful detection of several fungal diseases and some pests has been reported. Various automated measures and image analysis methods offer great potential for enhancing monitoring in practice.ResultsIn this study, the use of hyperspectral imaging over a wide spectrum from 400 to 2500 nm is investigated for noninvasive identification and the distinction of healthy plants and plants infested with Myzus persicae (Sulzer) and Frankliniella occidentalis (Pergande) on bell peppers. Pest infestations were carried out in netted areas, and images of single plants and dissected leaves were used to train the decision algorithm. Additionally, a specially modified spraying robot was converted into an autonomous platform used to carry the hyperspectral imaging system to take images under greenhouse conditions. The algorithm was developed via the XGBoost framework with gradient-boosted trees. Signals from specific wavelengths were found to be associated with the damage patterns of different insects. Under confined conditions, M. persicae and F. occidentalis infestations were distinguished from each other and from the uninfested control for single leaves. Differentiation was still possible when small whole plants were used. However, application under greenhouse conditions did not result in a good fit compared to the results of manual monitoring.ConclusionHyperspectral images can be used to distinguish sucking pests on bell peppers on the basis of single leaves and intact potted bell pepper plants under controlled conditions. Wavelength reduction methods offer options for multispectral camera usage in high-grown vegetable greenhouses. The application of automated platforms similar to the one tested in this study could be possible, but for successful pest detection under greenhouse conditions, algorithms should be further developed fully considering real-world conditions.

Tissue ontogeny and chemical composition influence bacterial biodiversity in the wood and shoot tip of Populus nigra.

Plant-microbe interactions significantly influence plant growth dynamics and adaptability. This study explores the impact of metabolites on microbial biodiversity in shoot tips and wood of Populus nigra under greenhouse conditions, using high-throughput sequencing and metabolite profiling. Branches from P. nigra were harvested, rooted, and transplanted into pots for growth. After 3 months, tissue samples from shoot tips and wood were collected, and metabolites extracted and analysed using GC-MS and LC-MS. Genomic DNA was extracted and subjected to high-throughput sequencing for bacterial biodiversity profiling. Both datasets were analysed using bioinformatic and statistical pipelines. Metabolite profiling indicated that shoot tips had a higher relative abundance of primary and secondary metabolites, including sugars, fatty acids, organic acids, phenolic acid derivatives and salicinoids, while wood was enriched in flavonoids. Bacterial biodiversity also differed significantly between these tissues, with Clostridiales, Bacteroidales and Bacillales dominating in shoot tips, associated with rapid growth and anaerobic fermentation, while wood tissues were characterized by diazotrophs from Rhizobiales, Sphingomonadales and Frankiales. PCoA clustering confirmed tissue-specific microbial differences. Functional analysis revealed an enrichment of fundamental cellular processes in shoot tips, while wood exhibited pathways related to degradation and mortality. Metabolite profiling revealed significant variations in primary and secondary metabolites, highlighting their influence on microbial biodiversity across plant tissues. The dominance of specific bacterial orders and distinct functional pathways in each tissue suggests a tailored microbial response to the unique environments of shoot tips and wood.

Iodine-Enriched Urea Reduces Volatilization and Improves Nitrogen Uptake in Maize Plants

Urea is the primary source of nitrogen (N) used in agriculture. However, it has a high N loss potential through volatilization. Various mechanisms can be employed to reduce N volatilization losses by inhibiting urease. When added to urea, iodine (I) has high potential for this purpose. Thus, this study aimed to determine whether adding I to urea reduces volatilization losses and increases N uptake in maize plants. Maize plants were cultivated in greenhouse conditions for 36 days. Urea treatments were applied at 15 days of testing, including iodine-enriched urea, conventional urea, and no urea application. Additionally, a study concerning N volatilization from urea was conducted using the same treatments under the same environmental conditions. Iodine was incorporated and adhered to urea, at an I concentration of 0.2%, using potassium iodate (KIO3). Under controlled conditions and over a short period of time, it was observed that the application of iodine-enriched urea increased the chlorophyll b content, root N accumulation, and total N accumulation in maize plants compared with conventional urea. Moreover, iodine-enriched urea reduced N losses from volatilization by 11% compared with conventional urea. The reduction in N volatilization correlated positively with the increased chlorophyll b, total chlorophyll, root N accumulation, and total N accumulation favored by the iodine-enriched urea treatment. Our findings demonstrated that adding I to urea is an efficient and promising strategy to reduce N losses and increase N uptake in plants.

Pennisetum glaucum in reducing ecotoxicity in soil with tebuthiuron, thiamethoxam and vinasse

The purpose of this study was to evaluate the ecotoxicological effects on soils containing associations of the herbicide tebuthiuron (TBT), the insecticide thiamethoxam (TMX), vinasse (VIN), and millet (Pennisetum glaucum) cultivation. We conducted the experiment under greenhouse conditions using a completely randomized design with five replications. Treatments consisted in soil application of tebuthiuron (1000 g ha-1 a. i), thiamethoxam (330 g ha-1 a. i), vinasse (113 m3 ha-1) with or without P. glaucum cultivation. The monitoring extended to 50 days after sowing (DAS) and evaluated the ecotoxicological potential from Lactuca sativa seeds as test-organism. Seed germination and root development determined the germination index (GI) concerning the negative control, which was prepared with water. Thus, P. glaucum highlighted a beneficial influence on soil health, thereby mitigating the ecotoxicological effects of TBT and TMX. Results emphasized the importance of the timing in soil sample collection, where early collections after plant seeding result in higher germination rates and rapid soil health improvements. Furthermore, vinasse reduced the ecotoxicological impact of pesticides and TBT presence presented harmful effects to test-organism. The interaction between P. glaucum growth period and soil sampling had a profound impact on ecotoxicity bioassays, which highlighted the importance of early intervention. Therefore, P. glaucum and vinasse can be valuable components in effective phytoremediation strategies, pointing towards future research and enhancement of approaches for sustainable treatment strategies of agricultural soils with pesticides.

Effect of Regulated Deficit Irrigation on Cucumber Growth and Fruit Yield in Greenhouse Conditions

Effect of Regulated Deficit Irrigation on Cucumber Growth and Fruit Yield in Greenhouse Conditions

Evaporation and Transpiration Components of Crop Evapotranspiration and Growth Parameters of Lettuce Grown under Greenhouse Conditions

Evaporation and Transpiration Components of Crop Evapotranspiration and Growth Parameters of Lettuce Grown under Greenhouse Conditions

WITHDRAWN: Enhancing Maize Growth Under Drought and Lead Stress with Deashed Biochar and Growth-Promoting Rhizobacteria

The agricultural sector faces significant challenges due to water scarcity and increasing lead (Pb) contamination, adversely affecting crop productivity by generating reactive oxygen species (ROS) during Pb stress and drought. Biochar and plant growth-promoting rhizobacteria (PGPR) are emerging as effective tools to manage oxidative stress, yet the combined use of deashed biochar (BC) and PGPR remains underexplored. This study aimed to investigate the synergistic effects of BC and Agrobacterium fabrum on maize growth and biochemical attributes. Two levels of BC (control and 0.5%) were applied with and without A. fabrum under no Pb stress (0 mg Pb/kg soil) and 400 mg Pb/kg soil stress conditions. Additionally, seeds inoculated with A. fabrum were subjected to no drought stress (65% field capacity w/v) and drought stress (40% field capacity w/v). Conducted with three replicates in a randomized design within controlled greenhouse conditions, the study demonstrated that BC+A. fabrum treatment significantly improved maize germination (53.33%), shoot length (69.32%), root length (11.76%), and total soluble protein content (32.36%) under 400 mg Pb/kg soil stress compared to controls. Furthermore, BC+A. fabrum effectively mitigated drought stress, enhancing chlorophyll a (55.02%), chlorophyll b (50.61%), and total chlorophyll (53.37%) levels compared to controls. Analysis of key antioxidants (peroxidase, superoxide dismutase, catalase, and ascorbate peroxidase) revealed BC+A. fabrum ability to modulate antioxidant defenses in maize, underscoring its potential as a sustainable strategy to enhance maize growth resilience under combined Pb and drought stress conditions. Future studies should explore the long-term effects and field applicability of BC+A. fabrum treatments to optimize agricultural sustainability and productivity in Pb-contaminated and drought-prone environments.

Development of efficient and scalable regeneration tissue culture method for Cannabis sativa

Large scale production of uniform disease-free plants is crucial for Cannabis sativa biotechnology. Existing micropropagation protocols rely heavily on shoot multiplication from existing meristems via direct organogenesis. Such protocols do not allow multiplication of plant material through continuous sub-culturing. Protocols that use indirect regeneration are usually not efficient enough and have very low multiplication rates. In the present study, an efficient protocol that uses a combination of direct organogenesis and callogenesis to induce multiple shoot development cultures is developed. Callogenesis was induced from various explants cultured on the media having various combinations of thidiazuron (TDZ) and naphthaleneacetic acid (NAA); best callogenesis and shoot regeneration was achieved from hypocotyl explants cultured on TDZ 0.4mgl-1 NAA 0.2mgl-1. Hypocotyls with cotyledonary node and shoot apical meristem were significantly better for shoot regeneration than explants without it. Shoots obtained from multiple shoot cultures were successfully rooted and then acclimatized under greenhouse conditions to develop into adult cannabis plants.

Enhanced tomato (Solanum lycopersicum L.) yield and soil biological properties through integrated use of soil, compost, and foliar fertilization under greenhouse conditions

This study investigates the combined effects of standard soil fertilization, composted animal manure, and foliar fertilization on tomato yield, soil nutrient content, and soil biological properties under greenhouse conditions. The experiment was conducted from March to October 2023 using a completely randomized block design with four replications. The treatments included: 1) Control (no fertilization), 2) Standard soil fertilization (30 kg N/da, 8 kg P2O5/da, 40 kg K2O/da), 3) Standard soil fertilization + composted animal manure (2 t/da), 4) Standard soil fertilization + foliar fertilization (1 kg 17-17-17/100 liters of water every 20 days), and 5) Standard soil fertilization + compost + foliar fertilization. Tomato seedlings (Solanum lycopersicum L. cv. Roma) were transplanted into pots filled with clay soil. Throughout the experiment, soil moisture content was maintained at field capacity. Plants were harvested on October 30, 2023, and data on fruit yield, soil nutrient content (NPK), and soil biological properties (microbial biomass C, CO2 production, and dehydrogenase enzyme activity) were recorded. The highest yield (4.5 kg/plant) was observed in the treatment combining standard soil fertilization, composted animal manure, and foliar fertilization, representing a 275% increase compared to the control (1.2 kg/plant). The standard soil fertilization treatment alone yielded 2.8 kg/plant (133.3% increase), while the combination with composted animal manure yielded 3.5 kg/plant (191.7% increase), and with foliar fertilization, 3.9 kg/plant (225% increase). Soil analyses showed significant increases in available nitrogen, phosphorus, and potassium in the combined treatments. The highest biological properties were also recorded in the combined treatment.

Effect of zeolite application on soil enzyme activity of potted sandy soil cultivated with Swiss chard and cabbage

A zeolite pot experiment was conducted at the Agricultural Research Council Infruitec-Nietvoorbij in Stellenbosch, South Africa, under greenhouse conditions. The experiment aimed to investigate the impact of zeolite application on soil enzyme activities in sandy soils cultivated with Swiss chard (Beta vulgaris Var. cicla) and cabbage (Brassica oleracea Var. capitata L.) over two years (2018-2019). Different zeolite-to-soil ratios (0:1, 1:9, 2:8, and 3:7 w/w) were used, with each pot containing 12 kg of soil. The experiment involved 72 pots for each vegetable, arranged in a randomized complete block design (RCBD). Soil enzyme activities, including acid phosphatase, β-glucosidase, and urease, as well as soil chemical properties (pH, total plant-available nitrogen, organic carbon, and phosphorus), were analyzed. Key findings indicate that the effect of zeolite application on enzyme activities varied between the vegetable species. Zeolite application significantly increased (P

Effects of Different Doses of Biochar Applications on Yield and Nutrient Element Concentrations on Wheat Grown under Salt Stress

In the study, the effects of different doses of biochar applications on the yield and nutrient uptake of wheat grown under salt stress in greenhouse conditions were investigated. The study was conducted in 2 kg capacity plastic pots with three replications using a random plot design. In the study, salt doses were applied as 0 dS m-1, 6 dS m-1 and 12 dS m-1 (in the form of NaCl), and biochar doses (BC) were applied as 0%, 0.5%, 1% and 2% W/W. At the end of the study, the dry matter yield of wheat plant and sodium (Na), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), zinc (Zn), manganese (Mn), iron (Fe) and copper (Cu) concentrations were determined. Study results showed that BC applications increased the dry matter production of the plant, and the highest was obtained with 2% BC application at 6 6 dS m-1 salt dose, 1.85 g pot-1. However, due to increasing salt doses, BC applications had no effect on the phosphorus and potassium concentrations of the wheat plant, except for calcium, and decreases were determined in the average values. In the study, although all BC applications increased iron, zinc, manganese and copper concentrations compared to the control, when evaluated in terms of average values, decreases were detected in the microelement concentrations of the plant due to increasing salt doses

Role of eggplant trichome in whitefly oviposition and its relevance to biological control under greenhouse conditions.

The combined release of the predatory mite Amblyseius swirskii (Athias-Henriot) and the mirid Nesidiocoris tenuis (Reuter) provides effective biological control of the tobacco whitefly (Bemisia tabaci (Gennadius)) in greenhouse eggplant. However, knowing how plants' trichomes affect pest-predator interactions could improve whitefly management. Here, the effect of two varieties with either the presence or absence of trichomes was assessed on naturally occurring whitefly populations and predator abundance in a first experiment under field conditions. Predator-prey models were developed to assess the effect of trichomes on pest and predator population dynamics under field conditions. In a second semi-field experiment, the occurrence and oviposition preferences of B. tabaci and A. swirskii in the same eggplant varieties were compared. Significantly higher numbers of whitefly and mite, adults and eggs, were found on the hairy variety in both experiments. However, no differences were found in N. tenuis abundance between varieties under field conditions. Predator-prey models showed that whitefly growth rate increased in the hairy variety. N. tenuis and A. swirskii showed different fitness parameters according to the variety, with the former displaying better performance in the hairless variety and the latter in the hairy variety. Both predators effectively controlled the increase in whitefly populations in both varieties. Overall, the findings suggest that the hairless variety is more effective in deterring whiteflies. Additionally, the higher population of A. swirskii on the hairy variety indicates that this predator benefited from both the presence of trichomes and the prey.

Editing of the MeSWEET10a promoter yields bacterial blight resistance in cassava cultivar SC8.

Cassava starch is a widely used raw material for industrial production and food source for people. However, cassava bacterial blight (CBB) caused by Xanthomonas axonopodis pv. manihotis (Xam) results in severe yield losses and is the most destructive bacterial disease in all worldwide cassava-growing regions. Xam11 is a highly pathogenic subspecies from China that infects the Chinese local cassava South China No. 8 (SC8) cultivar with marked symptoms. This study showed that the transcription activator-like effector TALE20Xam11 of Xam11 strain regulates the expression of disease-susceptibility gene MeSWEET10a by binding to the EBETALE20 region of the MeSWEET10a promoter in cassava cultivar SC8. CRISPR/Cas9-generated mutations of the EBETALE20 region resulted in a significant reduction in MeSWEET10a expression after infection by Xam11, correlating with reduced disease symptoms, smaller lesion sizes and decreased bacterial proliferation compared with the wild type. Importantly, the edited plants maintained normal growth, development and yield characteristics under greenhouse conditions. The results lay a research foundation for breeding resistant cassava cultivar SC8 to bacterial blight.

Effects of ethyl methanesulfonate on growth and yield parameters of wheat and tolerance to imazamox

In the present study objective bread wheat (Triticum aestivum L.) and durum wheat (Triticum durum Desf.) lines resistant to Imazamox herbicides and effective lethal ethyl methanesulfonate (EMS) doses for plants. During first year (2019/2020), 1000 seeds of bread wheat and durum wheat treated with 11 different EMS doses were sown under field and greenhouse conditions. During second year (2020/2021), M1 (first generation) cereal seeds were grown as M2 (second generation) in field experiments. Herbicide with Imazamox active ingredient at 125 ml da-1 was applied to the approximately 15 cm tall plants in the M2 generation. In bread and durum wheat lines, emergent plants were observed up to a dose of 60mM EMS. The effective EMS doses for the wheat species were determined as 80 mM for bread wheat and 50 mM for durum wheat. Bangladesh J. Bot. 53(3): 487-493, 2024 (September)

Impact of Pulse Electric Field Stimulation on Negative Air Ion Release Capacity of Snake Plants

To investigate the effects of pulse electric field stimulation on the photosynthetic electron transport chain and negative air ion (NAI) release capacity of snake plants, the chlorophyll content, fluorescence induction kinetics curve (OJIP curve), chlorophyll fluorescence parameters, and NAI release concentration of snake plants kept under identical greenhouse conditions under different pulse electric field stimulations were compared and analyzed. The experimental results show that (1) after pulse electric field stimulation, the chlorophyll content in treatment group T1 (5 kv) and T2 (7 kv) of snake plants increased by 6.30% and 6.70%, respectively, with significant differences observed between the two treatment groups and the control group (CK). (2) In both treatment groups, the OJIP curve exhibited higher values for the inflection point (I) and peak (P) compared to the origin (O) and inflection point (J) values, with the rising trend in the I–P segment being more gentle than that of the O–J segment. Additionally, the J band was above 0, with the peak value in the T2 group being higher than that in the T1 group. (3) The chlorophyll fluorescence parameters showed fluctuating variations. Specifically, Fm, TRo/CSo, ETo/CSo, and DIo/CSo showed ascending trends in the treatment groups. Fv/Fo, Sm, and ABS/RC exhibited descending trends; Fv/Fm, Vj, ETo/RC, and φEo showed relatively minor changes. The PIabs displayed a decreasing trend. The PItotal in the CK was greater than that in the T1 and T2 groups. (4) After 4 h of pulse electric field stimulation, the NAI concentration increased by 87.60% in the T1 group and by 62.09% in the T2 group, compared to the same measurement taken at 3 h. Pulse electric field impacts the photosynthetic electron transport chain of snake plants, thereby influencing their NAI release capacity. This study aims to elucidate the physiological responses of the chloroplasts in snake plants to pulsed electric field stimulation and to lay the foundation for enhancing the plant’s release of negative air ion concentrations through physical and technological means.

Side effects of semi-synthetic insecticide spinetoram on the whitefly parasitoid Encarsia formosa.

Insecticide risk assessment for biological control agents is essential for implementing integrated pest management (IPM) programs. Spinetoram is a naturally derived insecticide used to control a variety of agricultural sap-sucking insect pests, and Encarsia formosa Gahan (Hymenoptera: Aphelinidae) plays a key role in the biocontrol of greenhouse whiteflies. Despite its presumed safe ecotoxicological profile, the side effects of spinetoram on E. formosa are partially unknown, especially at sublethal doses. In the laboratory, we estimated the lethal concentrations (LC) of spinetoram on E. formosa by topical exposure of pupae and 48 h residual contact exposure of emerged adults. Afterwards, we assessed the impact of spinetoram LCs on the life history traits (juvenile development, adult longevity, parasitism, adult emergence) and population growth parameter (the instantaneous rate of increase, ri) of the parasitoid. Probit analysis allowed the estimation of LC10 = 0.10 mg/L, LC50 = 0.56 mg/L, and LC90 = 3.28 mg/L. Spinetoram at LC10 had no impact on the observed parameters of E. formosa. Conversely, spinetoram at LC50 and LC90 significantly reduced adult longevity by 19.2% and 40.6%, total parasitism by 33.4% and 38.7%, and total adult emergence by 29.6% and 39.1%, respectively. Also, the ri of E. formosa was significantly affected by spinetoram LC50 and LC90 with a reduction of 8.17 and 29.83%, respectively. Our results suggested that spinetoram significantly threatens the effectiveness of E. formosa when applied at the field recommended rate. However, further validation of spinetoram under greenhouse conditions is required for a comprehensive risk assessment for E. formosa in IPM programs. © 2024 Society of Chemical Industry.

Effects of Microbial Biostimulants on Maize and Its Pest, the Western Corn Rootworm, Diabrotica virgifera virgifera

The western corn rootworm, Diabrotica virgifera virgifera, (Coleoptera: Chrysomelidae) is a serious pest of maize in the USA and Europe. Microbial plant biostimulants such as bacteria, fungi, and algae are designed to stimulate plant nutrition and growth, with some hypothesized to also possess insecticidal properties. We tested 10 biostimulants (four bacteria, five fungi, and one alga) under laboratory and greenhouse conditions. Most biostimulants did not affect the eggs, larvae, or adults of D.v. virgifera. However, in the laboratory, 10% of biostimulants improved egg hatching, and 40% killed some larvae, including the fungi Beauveria bassiana, Rhizophagus irregularis, and Trichoderma asperellum, and the bacterium Ensifer meliloti. Under potted-plant conditions in the greenhouse, these insecticidal effects were not detectable. However, several biostimulants slightly increased height and shoot length of uninfested maize plants, but reduced volume and length of their roots as well as above-ground biomass. Interestingly, 30% of the biostimulants enhanced the plant’s defence against larvae, for example, Bacillus amyloliquefaciens, B. subtilis, and E. meliloti. These may warrant further research into their modes of action as well as field trials to better understand and optimize their potential use in sustainable and integrated pest management.

Biocontrol Potential of Bacillus strains against soybean cyst nematode (Heterodera glycines) and for promotion of soybean growth

The soybean cyst nematode (SCN, Heterodera glycines) is the most yield-limiting pathogen in soybeans worldwide. Using chemical pesticides to control this disease is harmful to human and environment. It is urgent to develop environment-friendly nematicides. The aim of this study was to discover novel biocontrol agents on H. glycines control and soybean growth under greenhouse and field conditions Eight Bacillus strains were isolated from soil rhizosphere soils and the stability and efficiency of H. glycines was assessed in greenhouse and field experiments in 2021 and 2022. In particular, the Ba2-6 strain had the highest potential, because it was a biocontrol agent against H. glycines shown to cause 93.85% juvenile mortality. Furthermore, strains Ba 1–7, Ba2-4, and Ba2-6 effectively reduced the number of females and improved the soybean seed number per plant. Based on their morphological, physiological, biochemical and molecular (16 S rRNA) characteristics, the three strains were identified as B. aryabhattai (Ba1-7), B. megatherium (Ba2-4), and B. halotolerans (Ba2-6). The ability of Ba2-6 to induce systemic resistance to H. glycines in soybeans was investigated by the split-root system and real-time quantitative PCR experiments. The results indicated that the Ba2-6 strain induced systemic resistance to suppress the penetration of H. glycines, and enhanced gene expression of PR1, PR3a, PR5, and NPR1-2, involved in the salicylic acid and jasmonic acid pathways. The study suggests that the strains of B. aryabhattai Ba1-7, B. megatherium Ba2-4, and B. halotolerans Ba2-6 can be considered as effective biocontrol agents to control H. glycines. Further, B. halotolerans Ba2-6 not only promotes soybean growth but also enhances resistance to H. glycines by regulating defense-related gene expression and inducing systemic resistance in soybean.

Deciphering the genetic basis of salinity tolerance in a diverse panel of cultivated and wild soybean accessions by genome-wide association mapping

Key messageIn a genome-wide association study involving 269 cultivated and wild soybean accessions, potential salt tolerance donors were identified along with significant markers and candidate genes, such as GmKUP6 and GmWRKY33.Salt stress remains a significant challenge in agricultural systems, notably impacting soybean productivity worldwide. A comprehensive genome-wide association study (GWAS) was conducted to elucidate the genetic underpinnings of salt tolerance and identify novel source of salt tolerance among soybean genotypes. A diverse panel comprising 269 wild and cultivated soybean accessions was subjected to saline stress under controlled greenhouse conditions. Phenotypic data revealed that salt tolerance of soybean germplasm accessions was heavily compromised by the accumulation of sodium and chloride, as indicated by highly significant positive correlations of leaf scorching score with leaf sodium/chloride content. The GWAS analysis, leveraging a dataset of 32,832 SNPs, unveiled 32 significant marker-trait associations (MTAs) across seven traits associated with salt tolerance. These markers explained a substantial portion of the phenotypic variation, ranging from 14 to 52%. Notably, 11 markers surpassed Bonferroni’s correction threshold, exhibiting highly significant associations with the respective traits. Gene Ontology enrichment analysis conducted within a 100 Kb range of the identified MTAs highlighted candidate genes such as potassium transporter 6 (GmKUP6), cation hydrogen exchanger (GmCHX15), and GmWRKY33. Expression levels of GmKUP6 and GmWRKY33 significantly varied between salt-tolerant and salt-susceptible soybean accessions under salt stress. The genetic markers and candidate genes identified in this study hold promise for developing soybean varieties resilient to salinity stress, thereby mitigating its adverse effects.