Shade House Conditions Research Articles

Effect of Vermicompost and Phyto-regulator on Zucchini Fruits (Cucurbita pepo L.) Grown in Shade Houses

Objective: To assess the influence of vermicompost (LC) and phytoregulator (AMP) in the cultivation of zucchini, under shade house conditions. Design/methodology/approach: A randomized block experimental design with eight treatments and six repetitions was used. Results: The treatments did not affect fruit diameter and pH variables. The Jacobo+LC+AMP treatment induced fruit length, and all treatments where the phytoregulator was applied increased fruit weight and commercial yield. For fruit firmness and total soluble solids, the trend was not clear due to the effect of the treatments. Findings/conclusions: The application of the phytoregulator induced fruit weight and yield.

Pollination by multiple species of nectar foraging Hymenoptera in Prasophyllum innubum, a critically endangered orchid of the Australian Alps

Context Australia has numerous threatened species of terrestrial orchid, with a particularly high incidence of rarity in the genus Prasophyllum R.Br. Although there has been research on mycorrhizal associations and propagation, little is known about the reproductive ecology of threatened Prasophyllum. Understanding which animals are responsible for pollination and the impact of herbivores on reproduction may inform conservation actions. Aims For the nationally Critically Endangered Prasophyllum innubum, we aimed to determine the pollinator species, test for self-pollination, quantify levels of reproductive success and herbivory, and identify herbivores. Methods Pollinator observations were undertaken at wild populations of P. innubum, whereas an experiment testing for self-pollination was undertaken in shadehouse conditions. We quantified reproductive success and herbivory at two populations and attempted to identify herbivores using game cameras. Key results Pollination occurred via three species of bee and a sphecid wasp, all of which attempted feeding on floral nectar. Fruit set averaged 72–84% at wild sites, whereas only 6% of flowers set fruit via self-pollination when insects were excluded. Just 4% of inflorescences were completely consumed by herbivores, and no herbivory was captured on camera. Conclusions P. innubum has a generalist rewarding pollination system that confers high levels of reproductive success, with herbivory having little impact on reproduction. Implications Pollinator availability is unlikely to restrict conservation translocation site selection of P. innubum because of a generalist pollination system. If herbivores are a threat for this species, it is likely to be through alteration of habitat rather than direct grazing.

Efficacy of Different Concentrations of IBA and NAA on Growth of Hardwood Cuttings of Fig (Ficus carica L.) cv Dinkar

An investigation was conducted to know the influence of growth hormones on shoot growth in hardwood cuttings of fig (Ficus carica L.). The experiment was set up in RBD having thirty cuttings with three replications treated with different concentrations of growth hormones viz., T1 (IBA 1000 ppm), T2 (IBA 2000 ppm), T3 (NAA 1000 ppm), T4 (NAA 2000 ppm), T5 (IBA 1000 ppm + NAA 1000 ppm), T6 (IBA 2000 ppm + NAA 2000 ppm) along with control. Present study revealed earliest sprouting, maximum shoot diameter, shoot length and number of leaves, fresh and dry weights shoot with T6 (IBA 2000 ppm + NAA 2000 ppm). On the basis of findings of this study fig hardwood cuttings treated with IBA 2000 ppm + NAA 2000 ppm under the shade house conditions can be recommended to nursery growers and researchers to obtain desirable shoot growth under Bundelkhand region of Uttar Pradesh.

Growth regulators on shooting and adventitious rooting of Mimosa caesalpiniifolia adult stem cuttings

Mimosa caesalpiniifolia, crucial for fencing and firewood in Brazil's Caatinga dry forest, presents a promising avenue for commercial propagation. The challenges faced in seed propagation, such as the scarcity of inputs and the difficulties in overcoming dormancy, highlight the advantages of vegetative methods. These methods emerge as a viable alternative, enabling uniform and large-scale production of clonal plantlets. This technique ensures consistent plant quality, which is crucial given the wide variety of uses for this species. Additionally, the use of plant growth regulators is critical to enhance the success of vegetative propagation, promoting the formation of robust roots and overall development of plants from cuttings of adult trees. Recognizing the significance of creating clonal forests of M. caesalpiniifolia and the necessity for understanding methods to expedite this endeavor, this study was designed to assess the shooting and adventitious rooting of stem cuttings sourced from adult M. caesalpiniifolia trees, examining the effects of auxinic agents. M. caesalpiniifolia cuttings were harvested through vegetative rescue from six randomly selected adult trees, treated with indole-3-butyric acid (IBA) and indole-3-acetic acid (IAA) at concentrations of 0, 1,000, 2,000, and 4000 mg L−1, using a completely randomized design in a 2 × 4 factorial arrangement. The evaluations included assessing root presence, number of shoots, vigor of clonal plantlets and plant survival under greenhouse conditions, shade house conditions, and full sun exposure. The study did not reveal any significant interaction between growth regulators and their concentrations under these conditions. IBA at intermediate concentrations enhanced root growth, while cuttings without growth regulators exhibited superior aerial development. A decrease in survival percentages with increasing concentrations of regulators was observed, while cuttings without regulators demonstrated better morphological development. The study suggests for large-scale nurseries, natural rooting and shoot formation in M. caesalpiniifolia cuttings may suffice for successful propagation without IBA or IAA.

Effect of Fungicides and Application Intervals for the Control of Black Spot of Roses

The efficacy of the fungicide pydiflumetofen + difenoconazole (Postiva) was evaluated at varying application rates and intervals to control black spot disease (Diplocarpon rosae) in rose (Rosa spp. ‘Coral Drift’). Container-grown roses were arranged in a completely randomized design with five single-plant replications. Experiments were conducted under greenhouse and shade-house conditions (56% shade) in 2021/2022 and 2023. Black spot disease in roses was developed naturally. Pydiflumetofen + difenoconazole at 1.1 , 1.6, and 2.2 mL⋅L–1, and standard fungicide azoxystrobin + benzovindiflupyr (Mural) at 0.5⋅g L–1 were sprayed on foliage to runoff on a 2- or 4-week interval. Plants that were not treated with fungicide served as the controls. Plants were evaluated weekly for disease severity (0%–100% foliage affected) and defoliation (0%–100% defoliation). The season-long area under the disease progress curve (AUDPC) and area under the defoliation progress curve (AUDFC) were calculated for the evaluation period. Pydiflumetofen + difenoconazole reduced significantly black spot disease severity, AUDPC, defoliation, and AUDFC both in greenhouse and shade-house conditions compared with control plants, and was as effective as azoxystrobin + benzovindiflupyr. All the application rates and intervals of pydiflumetofen + difenoconazole were equally effective in reducing black spot severity and AUDPC. Our findings suggest that pydiflumetofen + difenoconazole at the lowest rate with the longest application interval is the most cost-effective, and has similar efficacy as treatments with higher rates and more frequent intervals.

Improving Salinity Tolerance of Cucumber Plants Grown under Shadehouse Conditions by Grafting onto Some Genotypes and F1 Hybrids of Cucurbit Rootstocks

Improving Salinity Tolerance of Cucumber Plants Grown under Shadehouse Conditions by Grafting onto Some Genotypes and F1 Hybrids of Cucurbit Rootstocks

Chemical Control of Powdery Mildew of Bigleaf Hydrangea

The efficacy of the fungicide pydiflumetofen + difenoconazole (Postiva) was evaluated at varying application rates and intervals for the control of powdery mildew (Golovinomyces orontii, formerly Erysiphe polygoni) in bigleaf hydrangea (Hydrangea macrophylla ‘Nikko Blue’). Container-grown hydrangeas were arranged in a completely randomized design with six single-plant replications. Experiments were done in 2022 and 2023 under both greenhouse and shade house conditions (56% shade). Powdery mildew in hydrangea was developed naturally. Pydiflumetofen + difenoconazole at 1.1, 1.6, and 2.2 ml·L−1 and a standard fungicide azoxystrobin + benzovindiflupyr (Mural) at 0.5 g·L−1 were sprayed to runoff on 2-, 4-, and 6-week intervals. Plants that were not treated with fungicide served as the control. Plants were evaluated weekly for disease severity (0% to 100% foliage affected) and defoliation (0% to 100% defoliation). The season-long area under the disease progress curve (AUDPC) and defoliation progress curve (AUDFC) were calculated for the evaluation period. The initial and final plant height and width were recorded, and height and width increase were determined. Pydiflumetofen + difenoconazole and azoxystrobin + benzovindiflupyr significantly reduced final disease severity, AUDPC, and defoliation both in the greenhouse and shade house compared with control plants. In both greenhouse trials and the 2022 shade house trial, AUDFC was reduced in all treatments compared with the control plants. However, AUDFC was not reduced by all treatments in the 2023 shade house trial. Pooled over application intervals, the low rate of pydiflumetofen + difenoconazole was as effective as the medium and high rates of pydiflumetofen + difenoconazole and azoxystrobin + benzovindiflupyr in reducing final powdery mildew severity and AUDPC both in the greenhouse and shade house in both 2022 and 2023. No significant differences between application intervals were noted in final disease severity and progress. Control of powdery mildew with fungicides failed to increase plant dimensions (i.e., plant height and width) compared with the no fungicide control. Because all application rates and intervals of pydiflumetofen + difenoconazole provided comparable powdery mildew disease control, it is suggested that using a low rate of pydiflumetofen + difenoconazole with the longest application interval (6 weeks) is the most cost-effective approach for managing powdery mildew in bigleaf hydrangeas.

Indigenously produced biochar retains fertility in sandy soil through unique microbial diversity sustenance: a step toward the circular economy.

Agricultural productivity in the arid hot desert climate of UAE is limited by the unavailability of water, high temperature, and salt stresses. Growing enough food under abiotic stresses and decreasing reliance on imports in an era of global warming are a challenge. Biochar with high water and nutrient retention capacity and acid neutralization activity is an attractive soil conditioner. This study investigates the microbial community in the arid soil of Dubai under shade house conditions irrigated with saline water and the shift in the microbial community, following 1 year of amendment with indigenously prepared biochar from date palm waste. Amplicon sequencing was used to elucidate changes in bacterial, archaeal, and fungal community structures in response to long-term biochar amendment. Samples were collected from quinoa fields receiving standard NPK doses and from fields receiving 20 and 30 tons ha-1 of biochar, in addition to NPK for 1 year. Water holding capacity, pH, electrical conductivity, calcium, magnesium, chloride, potassium, sodium, phosphorus, total carbon, organic matter, and total nitrogen in the soil from biochar-treated and untreated controls were determined. The results show that soil amendment with biochar helps retain archaeal and bacterial diversity. Analysis of differentially abundant bacterial and fungal genera indicates enrichment of plant growth-promoting microorganisms. Interestingly, many of the abundant genera are known to tolerate salt stress, and some observed genera were of marine origin. Biochar application improved the mineral status and organic matter content of the soil. Various physicochemical properties of soil receiving 30 tons ha-1 of biochar improved significantly over the control soil. This study strongly suggests that biochar helps retain soil fertility through the enrichment of plant growth-promoting microorganisms.

Mapping of QTLs Associated with Biological Nitrogen Fixation Traits in Peanuts (Arachis hypogaea L.) Using an Interspecific Population Derived from the Cross between the Cultivated Species and Its Wild Ancestors.

Peanuts (Arachis hypogaea L.) are an allotetraploid grain legume mainly cultivated by poor farmers in Africa, in degraded soil and with low input systems. Further understanding nodulation genetic mechanisms could be a relevant option to facilitate the improvement of yield and lift up soil without synthetic fertilizers. We used a subset of 83 chromosome segment substitution lines (CSSLs) derived from the cross between a wild synthetic tetraploid AiAd (Arachis ipaensis × Arachis duranensis)4× and the cultivated variety Fleur11, and evaluated them for traits related to BNF under shade-house conditions. Three treatments were tested: without nitrogen; with nitrogen; and without nitrogen, but with added0 Bradyrhizobium vignae strain ISRA400. The leaf chlorophyll content and total biomass were used as surrogate traits for BNF. We found significant variations for both traits specially linked to BNF, and four QTLs (quantitative trait loci) were consistently mapped. At all QTLs, the wild alleles decreased the value of the trait, indicating a negative effect on BNF. A detailed characterization of the lines carrying those QTLs in controlled conditions showed that the QTLs affected the nitrogen fixation efficiency, nodule colonization, and development. Our results provide new insights into peanut nodulation mechanisms and could be used to target BNF traits in peanut breeding programs.

Physiological and biochemical changes in desiccation and rehydration cycles of Selaginella convoluta (Selaginellaceae)

Abstract Vegetative desiccation tolerance (VDT) is a biological process that allows resurrection plants to complete desiccation-rehydration cycles and survive without permanent damage. Physiological and biochemical changes related to the VDT were evaluated in the lycophyte Selaginella convoluta from the Caatinga biome, a seasonally dry tropical forest of northeastern Brazil. As representative of the oldest division of extant vascular plants, the investigation of VDT mechanisms in this species serves as an opportunity to provide information for research communities interested in functional traits related to water-limited conditions. The experiments were performed with plants in their natural habitat, in dry and rainy seasons, and in pots under shade house conditions. Relative water content, chlorophyll a fluorescence, gas exchange, activity of antioxidant enzymes, concentration of chlorophylls, proteins, total amino acids, proline, and soluble carbohydrates in leaf tissues were evaluated throughout the process of complete dehydration and subsequent re-watering of intact plants. The overall results reveal the capacity of S. convoluta to tolerate extreme dehydration and rapidly recover upon rehydration. This species minimizes potential damages during the desiccation-rehydration cycle due to the presence of inductive mechanisms (photochemical preventing, sucrose accumulation) and constitutive mechanisms (antioxidant activity of catalase and ascorbate peroxidase), which share similarities with the VDT of both angiosperms and bryophytes.

Silicon Nutrition in Young Olive Plants: Effect of Dose, Application Method, and Cultivar

Silicon (Si) is a nonessential element for plant growth, but it influences the tolerance to biotic and abiotic stresses in many plant species. Most research about the uptake and beneficial effects of Si in plants has been carried out on monocotyledonous species, Si-accumulating plants. Little attention has been paid to woody crops, characterized as low-Si-accumulating plants. In this sense, available information about Si nutrition in olive trees is scarce. Therefore, this work aimed to study the effect of Si application on the uptake, accumulation, and organ distribution of Si in young olive plants by analyzing the influence of the dose, the method of application, and the cultivar. Three experiments were conducted under shade-house conditions with mist-rooted ‘Arbequina’ and ‘Picual’. The treatments consisted of different Si doses, ranging from 0 to 20 mg·L−1, depending on the experiment, applied by foliar sprays or through the irrigation water. Choline-stabilized orthosilicic acid (H4O4Si) was used as the source of Si. Results indicated that after 120 days of Si treatments, this element was accumulated in major proportion in the roots, followed by the leaves and the shoot of the plants. Si organ concentration increased according to the doses applied, independently of the olive cultivar and the method of Si application. Differences in leaf Si accumulation between treated and control plants were evident 60 days after its application. The dose of 20 mg·L−1 was the most effective to increase Si level in leaves under the trial conditions. Si is recommended to be applied periodically to ensure its accumulation in growing leaves.

Optimizing environmental conditions and irrigation regimes can improve grafting success in Persian walnut

The propagation of Persian walnut (Juglans regia) using grafting or budding is often difficult due to envi­ronmental factors. Temperature fluctuation and plant water status affect root pressure (xylem sap exudation “bleeding”) during budding or grafting. An experiment was conducted to find the optimum irrigation regime for patch budding (in July) and tongue grafting (in March) of Persian walnut on Juglans regia rootstock un­der three environmental conditions (greenhouse, shade-house and outdoor). The grafted/budded plants were subjected to three irrigation regimes including 1-day, 3-day and 7-day for 4 weeks after grafting/budding. Callus formation and quality, and graft/bud-take were recorded after four weeks. The survival rate and growth of the scions were measured after three months. Based on the results, grafting success under greenhouse, shade-house and outdoor conditions were 66.7%, 42.6% and 17.6%, respectively. The highest graft/bud take (94.4%) was obtained under greenhouse conditions with patch budding. The lowest grafting success (0%) was observed under outdoor conditions with patch budding. Under the greenhouse conditions, irrigation of the grafted plants with 7-day interval resulted in the highest graft success and plant growth. Irrigation with 3-day intervals was the best regime under shade-house conditions, while daily irrigation regime was required to obtain the highest grafting success for the outdoor grown plants. In general, the present experiment re­vealed that modifying outdoor conditions by applying a shade-house equipped by a mist system in warmer area can improve bud-take and success especially in patch budding by 40.76 and 33.1%, respectively.

Inibidor da biossíntese de giberelinas em pimenteiras ornamentais

ABSTRACT The objective of this study was to evaluate whether the inhibition of gibberellin biosynthesis affects the morphophysiological traits of potted ornamental Capsicum baccatum and Capsicum annuum growing under shade house conditions. Plants maintained in 2.7 L pots were arranged in a completely randomized design in a 2x4 factorial consisting of two pepper cultivars Chapéu-de-frade (C. baccatum) and Vulcão (C. annuum) and four paclobutrazol (PBZ) concentrations (0, 25, 50, and 75 mg L-1) with four replicates. At 30, 45, and 60 days after treatment, the plants were analyzed, and data were submitted to the analysis of general and regression variance. Gibberellin biosynthesis inhibition affected the morphophysiological and biochemical evaluations. For most evaluated traits, no interaction between factors was observed, suggesting that both pepper cultivars had a similar response to the growth regulator. PBZ-induced inhibition of gibberellin biosynthesis improved plant water status, which enhanced the vigor of potted pepper plants. The dramatic reduction of upper leaves promoted by plant growth regulators compared to basal ones negatively impacted the visual ornamental aspect of Chapéu-de-frade peppers.

Response of some olive cultivars to different salinity levels under shade house conditions

Response of some olive cultivars to different salinity levels under shade house conditions

Observations on the Potential of an Endophytic Fungus Associated with Cacao Leaves against Phytophthora palmivora

A study was conducted to test the pathogenicity of an endophytic fungus associated with asymptomatic cacao leaves, to determine its identity through cultural, morphological and molecular characterization, and to evaluate itsantagonistic ability vs. Phytophthora palmivora causing cacao black pod rot disease. Experiments were carried out under laboratory and shade house conditions. Homogeneity of variances and normal data distribution were determined using Bartlett’s and Shapiro–Wilk tests, respectively. Inoculation of the endophyte in healthy cacao seedlings and pods at 5 × 105 to 1 × 106 conidia per mL by spraying resulted in asymptomatic infections. The endophyte was recovered from artificially inoculated tissues 14 and 26 days after inoculation (DAI) (UF18 seedlings), and at 10 (K9 seedlings) and 14 DAI from cacao pods. The endophyte was identified as Colletotrichum siamense based on its cultural, morphological and molecular characteristics. In vitroanti-pathogen assays showed that C. siamense had the potential to limit pathogen growth by antibiosis. At 3, 5 and 7 days after incubation period (DAIP), growth of the pathogen in co-cultivation with the endophyte measured 60.0, 70.0 and 71.0 mm, respectively, which wasconsiderably lower than the growth of the pathogen alone.

In vitro germination, initial development and acclimatization of Cattleya nobilior Rchb. f. (Orchidaceae): an approach to curb the eventual endangerment of this exuberant, near-threatened Cerrado species

ABSTRACT: The objective of the present study was to evaluate the effects of different culture media on the in vitro germination and initial development of Cattleya nobilior, and to acclimatize this species using soybean straw as a substrate component, aiming the production of plants at large scale to reintroduce it in natural environments. Anatomical characteristics associated with development during acclimatization are also depicted. The influence of Murashige and Skoog, Knudson, and Vacin and Went culture media on the in vitro germination and protocorm development were assessed. Acclimatization was accomplished using different proportions of soybean straw (SS) and Bioplant (BP) as substrates. Anatomical studies were conducted on the leaves of plants during acclimatization. KC was the most suitable culture medium for both germination and initial development of C. nobilior. Regarding acclimatization, it is recommended that a substrate composed of 60% SR and 40% BP be initially used. Upon transfer to shade-house conditions, plants should be grown in a mix of 40% SR: and 60% BP. The leaf anatomical characteristics observed are typical of epiphytic orchids adapted to water-poor environments, which indicates that SR did not negatively affect the development of the species. The in vitro propagation of C. nobilior as described herein is efficient for its multiplication for commercial and conservation purposes and SS can be used as an alternative component of the substrate for its acclimatization.
 KEYWORDS: Foliar anatomy, culture media, soybean straw.

Selección de un consorcio microbiano promotor del crecimiento de plántulas de cebolla en condiciones de umbráculo

The practice of producing more vigorous seedlings represents a competitive advantage at the time of transplanting a crop, and the use of combined biofertilizers are a sustainable ecological alternative. The objective of this research was to select a microbial consortium for the production of F1 2000 hybrid onion seedbeds under shade-house conditions. Five rhizobacterial strains of the genera Rhizobium (ME01 strain), Bradyrhizobium (Leu2A and YE1 strains), Ochrobactrum (ES1 strain) and Pseudomonas (Alf strain), which have shown favorable effects on pepper and lettuce seedlings. These rhizobacteria were inoculated in a mixed manner (microbial consortium) in onion as follows: Alf+ES1, ME01+ES1, ES1+Leu2A, Alf+Leu2A, YE1+ES1, ME01+Alf, YE1+Alf, ME01+YE1, YE1+Leu2A, ME01+Leu2A, using a soil from San Juan de Lagunillas-Mérida, Venezuela under shade-house conditions for 60 days. The following variables were determined: number of leaves, pseudostem base diameter, aerial and root length, aerial and root fresh and dry weight. Additionally, a CO2 assimilation curve under different light levels was carried out on the seedlings of the selected consortium to observe their photosynthetic response. The consortium ME01 + Leu2A (Rhizobium tropici + Bradyrhizobium japonicum) increased all studied variables, especially the pseudostem base diameter, essential for onion cultivation, and yielded higher seedlings CO2 assimilation rates. The use of this microbial consortium is recommended as an option for agricultural production under seedbed conditions.

Evaluation of Habanero Pepper (Capsicum chinense Jacq.) Varieties under Shade House Conditions in Yucatan, Mexico

Habanero pepper (HP) is the main emblematic horticultural species of the Yucatan Peninsula in Mexico and it is highly valuable for commercial purposes. Since the Yucatan Peninsula has been qualified by official instances with the Denomination of Origin, a very promising horizon is opened for new varieties to be demanded by the local and abroad commercial markets. Nowadays all varieties are being produced under open field conditions but its agronomic and qualified behaviour has never been evaluated under shade house production systems. Keeping in mind the foregoing, the Jaguar (Ja), Mayapan (Ma) and Calakmul (Ca) varieties were evaluated and compared with a control, the Rey Pakal (RP) hybrid during the Fall-Winter season. A 1200 m2 shade house was used, covered with a white mesh with a density of 52 × 25 threads/square inch. RP and Ma reached the highest height (68.29 and 63.14 cm) and stem diameter (4.48 and 4.46 cm), compared to the rest of the evaluated varieties (Ca and Ja). A greater precocity is projected in Ca and RP to set flower buds, flowers and fruits than in Ja and Ma. In general, flower buds setting was recorded between 23.4 and 25.6 days after transplanting (DAT), flowering was from 30.3 to 40.5 DAT and the fruit set from 42.2 to 45.3 DAT. The four genetic materials had a similar behavior in terms of phenology. RP (hybrid) and Ma (Variety) showed the higher yields.

Azospirillum brasilense and Solarized Manure on the Production and Phytochemical Quality of Tomato Fruits (Solanum lycopersicum L.)

Tomato is a vegetable crop with probiotic interest. Currently subject to a global biosecurity emergency due to the epidemic caused by COVID-19, humanity is seeking to maintain its health and become stronger by eating vegetables that have probiotic properties. Considering the request of tomato farmers in the Comarca Lagunera (CL) region, the objective of this work consisted of determining the impact of bioinoculation with Azospirillum brasilense (Ab) and solarized manure (M) on the yield and phytochemical quality of tomato fruits produced in shade mesh. Seeds of the saladette variety TOP 2299 were inoculated with Ab at 1 × 108 CFU.mL. Before 46 days after being sowed, seedlings were transplanted in soil enriched with manure solarized at a rate of 0, 40, 80, 120 and 160 t ha−1; a chemical fertilization (CHF) treatment was also adopted (366-95-635). Emergence, growth, root length, bromatological studies (protein and lipids in plant), yield and organoleptic (Vit C, phenols, flavonoids and lycopene) variables were considered. The results show that biofertilization based on Ab + M40 can be an alternative to produce tomato in shade-house conditions in the CL compared with non-inoculated and CHF treatments.

Genome-Wide Association Mapping Identifies Novel Loci for Quantitative Resistance to Blackleg Disease in Canola.

Blackleg disease, caused by the fungal pathogen Leptosphaeria maculans, continues to be a major concern for sustainable production of canola (Brassica napus L.) in many parts of the world. The deployment of effective quantitative resistance (QR) is recognized as a durable strategy in providing natural defense to pathogens. Herein, we uncover loci for resistance to blackleg in a genetically diverse panel of canola accessions by exploiting historic recombination events which occurred during domestication and selective breeding by genome-wide association analysis (GWAS). We found extensive variation in resistance to blackleg at the adult plant stage, including for upper canopy infection. Using the linkage disequilibrium and genetic relationship estimates from 12,414 high quality SNPs, GWAS identified 59 statistically significant and “suggestive” SNPs on 17 chromosomes of B. napus genome that underlie variation in resistance to blackleg, evaluated under field and shade-house conditions. Each of the SNP association accounted for up to 25.1% of additive genetic variance in resistance among diverse panel of accessions. To understand the homology of QR genomic regions with Arabidopsis thaliana genome, we searched the synteny between QR regions with 22 ancestral blocks of Brassicaceae. Comparative analyses revealed that 25 SNP associations for QR were localized in nine ancestral blocks, as a result of genomic rearrangements. We further showed that phenological traits such as flowering time, plant height, and maturity confound the genetic variation in resistance. Altogether, these findings provided new insights on the complex genetic control of the blackleg resistance and further expanded our understanding of its genetic architecture.