Cucumber Genotypes Research Articles

Genetic Diversity Analysis in Cucumber (Cucumis sativus L.) Based on Morphological Traits

Evaluation of fifteen diverse genotypes of cucumber was carried out in a randomized complete block design for studying genetic divergence. Presence of wide genetic diversity, among the genotypes studied was confirmed by using Mahalanobis D2 statistics. Based on the interactions genetic distances of cucumber genotypes had grouped into five separate clusters inferring that the genetic divergence between them was quite high. The germplasm were so divergent, that only six genotypes were grouped in cluster V and three genotypes in each cluster I and III. The two genotypes SKY/AC-270-613481 and JB/11-091-613462 were grouped as cluster II and the genotype Tripura local was so divergent in all the characters that they were allotted as a separate group as cluster IV. Cluster mean analysis proclaimed that, genotypes in cluster I recorded maximum value for vine length (3.36 m), number of leaves per plant (43.85), number of branches per plant (12.98), leaf area (144.71 cm2), number of female flowers per plant (20.30), fruiting period (52.20 days), fruit set (89.10 %), average fruit weight (214.72 g), number of fruits per plant (19.00), fruit yield per plant (2.50 kg), fruit yield per ha (31.23 t/ha), rind thickness (2.79 mm) and flesh thickness (3.02 cm), whereas, same cluster I recorded minimum value for traits viz., internodal length (6.55 cm), days to appearance of first male flower (30.34 days), days to appearance of first female flower (31.81 days), node number at which first female flower appeared (4.00), days to first harvest (41.22 days) and number of seeds per fruit (211.69) which are negatively desirable characters in the crop production and crop improvement programme.

Photosynthetic contribution and characteristics of cucumber stems and petioles

BackgroundPhotosynthesis in the green leafless blade tissues or organs of plants has been studied in some plants, but the photosynthetic characteristics of stems and petioles are poorly understood. Cucurbitaceous plants are climbing plants that have substantial stem and petiole biomass. Understanding the photosynthetic contribution of cucumber stems and petioles to their growth and the underlying molecular mechanisms are important for the regulating of growth in cucumber production.ResultsIn this study, the photosynthetic capacity of cucumber stems and petioles were determined by 14CO2 uptake. The total carbon fixed by the stems and petioles was approximately 4% of that fixed by one leaf blade in the cucumber seedling stage, while the proportion of the carbon accumulated in the stems and petioles that redistributed to sink organs (roots and shoot apexes) obviously increased under leafless conditions. The photosynthetic properties of cucumber stems and petioles were studied using a combination of electron microscopy and isotope tracers to compare these properties of stems and petioles with those of leaf blade using two genotypes of cucumber (dark green and light green). Compared with those of the leaf blades, the chlorophyll contents of the cucumber stems and petioles were lower, and the stems and petioles had lower chloroplast numbers and lower stoma numbers but higher thylakoid grana lamella numbers and larger stoma sizes. The Chl a/b ratios were also decreased in the petioles and stems compared with those in the leaf blades. The total photosynthetic rates of the stems and petioles were equivalent to 6 ~ 8% of that of one leaf blade, but the respiration rates were similar in all the three organs, with an almost net 0 photosynthetic rate in the stems and petioles. Transcriptome analysis showed that compared with the leaf blades, the stems and petioles has significantly different gene expression levels in photosynthesis, porphyrin and chlorophyll metabolism; photosynthetic antenna proteins; and carbon fixation. PEPC enzyme activities were higher in the stems and petioles than in the leaf blades, suggesting that the photosynthetic and respiratory mechanisms in stems and petioles are different from those in leaf blade, and these results are consistent with the gene expression data.ConclusionsIn this study, we confirmed the photosynthetic contribution to the growth of cucumber stems and petioles, and showed their similar photosynthetic patterns in the terms of anatomy, molecular biology and physiology, which were different from those of cucumber leaf blades.

Effect of Endogenous Hormone Levels and Ratios in Explants of Ten Genotypes of Cucumber on Their Regeneration in Vitro

Effect of Endogenous Hormone Levels and Ratios in Explants of Ten Genotypes of Cucumber on Their Regeneration in Vitro

Mean performance and genetic variability of parthenocarpic gynoecious cucumber inbreds under protected conditions of Eastern India

An experiment was conducted during Kharif, 2018 to evaluate the mean performance and to find out the nature and extent of genetic variability among eight inbreds of parthenocarpic gynoecious cucumber genotypes under naturally ventilated polyhouse situated at polyhouse complex of department of Horticulture (Vegetable and Floriculture), BAU, Sabour, Bhagalpur, Bihar of Eastern India. The experiment was laid out in randomized block design with three replications. Data were taken on six competitive plants for 13 growth and yield attributing traits, including total soluble solids (TSS) and per cent disease index for downy mildew (PDI). Among eight cucumber inbreds, BRPCU-1 showed earliness in respect of days to first female flower, node to first female flower and days to first fruit harvest, and disease tolerance to downy mildew. However, inbreds BRPCU-3, BRPCU-5 and BRPCU-7 were high yielders in fruits per plant and yield per plant. Non-additive gene effects were manifested for most of the earliness, while additive gene effect was observed for yield and fruits per plant.

The amino acid permease (AAP) genes CsAAP2A and SlAAP5A/B are required for oomycete susceptibility in cucumber and tomato.

Cucurbit downy mildew (DM), caused by the obligate biotroph Pseudoperonospora cubensis, is a destructive disease in cucumber. A valuable source of DM resistance is the Indian cucumber accession PI 197088, which harbours several quantitative trait loci (QTLs) contributing to quantitatively inherited DM resistance. With a combination of fine‐mapping and transcriptomics, we identified Amino Acid Permease 2A (CsAAP2A) as a candidate gene for QTL DM4.1.3. Whole‐genome and Sanger sequencing revealed the insertion of a Cucumis Mu‐like element (CUMULE) transposon in the allele of the resistant near‐isogenic line DM4.1.3. To confirm whether loss of CsAAP2A contributes to partial DM resistance, we performed targeting induced local lesions in genomes on a DM‐susceptible cucumber genotype to identify an additional csaap2a mutant, which indeed was partially DM resistant. In view of the loss of the putative function as amino acid transporter, we measured amino acids in leaves. We found that DM‐inoculated leaves of line DM4.1.3 (with the csaap2a mutation) contained significantly fewer amino acids than wild‐type cucumber. The decreased flow of amino acids towards infected leaves in csaap2a plants compared to the wild type might explain the resistant phenotype of the mutant, as this would limit the available nutrients for the pathogen and thereby its fitness. To examine whether AAP genes play a conserved role as susceptibility factors in plant–oomycete interactions, we made targeted mutations in two AAP genes from tomato and studied the effect on susceptibility to Phytophthora infestans. We conclude that not only CsAAP2A but also SlAAP5A/SlAAP5B are susceptibility genes for oomycete pathogens.

English

In the present study, fifteen cucumber genotypes were screened against Zucchini yellow mosaic virus (ZYMV) and root-knot nematode (Meloidogyne incognita) individually and in combinations. All the cucumber genotypes behaved differently regarding root and shoot lengths and weights, number of galls, eggmasses and ZYMV infection when inoculated with M. incognita and ZYMV alone and in combinations. None of the fifteen cucumber genotypes was found immune, highly or moderately resistant to M. incognita. Two genotypes viz., Alpha Prime and Patio were found resistant to the nematode. Contrarily, Max Pack and Beti-alpha were highly susceptible as evident by maximum galls on their roots and reductions in growth variables. Similarly, the genotypes Best PIC, Songrooh, Northern Pack, C-7 and C-5 appeared as moderately susceptible whereas Shaheen, Jakson, C-1, C-2, C-3 and C-9 genotypes showed susceptible reactions to the nematode alone. Similar trend was noticed when the genotypes were inoculated with both the nematode and the virus. Similarly, on the basis of disease rating scale, two genotypes viz., Alpha Prime and Patio were grouped as moderately resistant to ZYMV. On the other hand, eleven genotypes viz., Max Pack, Shaheen, Songrooh, Northern Pack, Jakson, Beti-alpha, C-1, C-2, C-3, C-5 and C-9 were catalogued as highly resistant while two genotypes Best PIC and C-7 were categorized as susceptible against ZYMV alone. Similarly, all the genotypes behaved in the same way when inoculated with M. incognita. Two genotypes Alpha Prime and Patio were found resistant against both the pathogens inoculated simultaneously and hence are recommended for cultivation. © 2021 Friends Science Publishers

Mean performance of gynoecious cucumber hybrids in sub-tropical climate of eastern India

A field study was conducted in zaid season of 2019 to investigate the mean performance of 27 diverse genotypes (5 parents, 20 F1 crosses and 2 standard checks) of cucumber for earliness, growth and yield attributing traits following full diallel mating design by utilizing two gynoecious lines, two monoecious lines and one parthenocarpic gynoecious line. Analysis of variance in randomized block design suggested that there were significant differences among the genotypes for 10 quantitative traits out of 13 traits used in the study. Results showed that gynoecious hybrids (involving both gynoecious parents) expressed earliness for flowering and fruiting, i.e., took minimum days to first female flower anthesis, node to first female flower, and days to first fruit harvest. The result of the present study showed that hybrid BRPCU-8 × BRGCU-4 was found to be better for earliness related traits viz., days to first flowering, first fruit harvest, and node to first female flower. Hybrid BRCU-10 × BRCU-1 was the better performer for fruit morphological traits viz., fruit length, fruits per plant, average fruit weight and yield-related traits; hybrid BRCU-1 × BRPCU-8 was superior for vegetative growth traits, namely crop duration and vine length. Monoecious cucumber hybrids involving both monoecious parents such as Punjab Naveen × BRCU-1 outperformed gynoecious hybrids involving gynoecious parents for growth characteristics such as vine length and crop duration. Overall, hybrid BRGCU-10 × BRCU-1 was observed as the best genotype.

Optimizing a Seedling Screening Method for Anthracnose Resistance in Watermelon

Among three races of Colletotrichum orbiculare, which cause anthracnose of cucurbits, screening for race 2 resistance was studied under greenhouse conditions at various inoculum concentrations, and plants were rated on different days postinoculation (DPI). The objectives of this study were optimizing inoculum concentration and phenotyping DPI for seedling resistance. Five inoculum concentrations were compared (2.5 × 104, 5 × 104, 1 × 105, 2.5 × 105, and 5 × 105conidial spores/ml). Four watermelon genotypes (‘Black Diamond’, ‘Charleston Gray 133’, PI 543210, and PI 189225) and two cucumber genotypes (‘Marketer’ and ‘H19 Little Leaf’) were evaluated. Disease was recorded on the percentage of cotyledon area lesion, severity of hypocotyl lesion (SHL), severity of petiole lesion (SPL), and percentage of leaf area lesion (PLL), as well as a disease index (INDX) from 5 to 14 DPI. There was a significant difference among genotypes and inoculum concentrations. The resistant PI 189225 was significantly different (P < 0.05) from the highly susceptible PI 543210. Inoculum 1 × 105spores/ml was at par with 5 × 105and 2.5 × 105but significantly different from 5 × 104and 2.5 × 104for AUDPS PLL, AUDPS INDX, AUDPS SPL, and AUDPS SHL. Inoculum at 1 × 105spores/ml was optimal to differentiate germplasm. A genotype plus genotype-by-environment biplot showed that PLL was a representative rating. A single PLL rating on 9 DPI would optimize resources for screening a large set of germplasm for anthracnose resistance in a watermelon breeding program.

Genome-Wide Characterization of Cucumber (Cucumis sativus L.) GRAS Genes and Their Response to Various Abiotic Stresses

The GRAS (gibberellic acid insensitive, repressor of GAI, and scarecrow) proteins are a family of plant-specific transcription factors that regulate plant growth, development, and stress response. Currently, the role of GRAS transcription factors in various abiotic stress responses has not been systematically studied in cucumber (Cucumis sativus L.), a popular vegetable crop. Here, we provide a comprehensive bioinformatics analysis of the 35 GRAS genes identified in the cucumber genome. In this study, cucumber genotypes, i.e., “CG104”, which is stress-tolerant, and genotype “CG37”, which is stress-sensitive, were examined to provide insight on potential differences in the GRAS-regulated abiotic stress pathways. Transcriptional analysis by RNA-seq or qRT-PCR of these two genotypes revealed common and divergent functions of CsGRAS genes regulated by low and high temperatures, salinity, and by exposure to the phytohormones gibberellin (GA) and abscisic acid (ABA). Notably, CsGRAS2 (DELLA) and CsGRAS26 (LISCL) were regulated by all abiotic stresses and hormone treatments, suggesting that they may function in the biological cross-talk between multiple signaling pathways. This study provides candidate genes for improving cucumber tolerance to various environmental stresses.

BREEDING AND PRODUCING NEW INBRED LINES AND F1 HYBRIDS OF PICKLING CUCUMBERS

Pickling cucumber is considered one of the important types of vegetables in Egypt, but there is less interest in it; this due to the lack of hybrids charactercterized with high productivity and good commercial traits. Production can be increased through increasing genetic diversity and thus productivity via plant breeding. The present experiment was conducted at Kaha Vegetable Research Farm, Wady El- Natroon and Ismailia during 2016-2020. Six cucumber genotypes from Netherland and Sweden Gene Banks (18-CGN, 8-CGN, 16-CGN, 11-NGB, 15-CGN and 21-NGB) were selfed pollinated for 6 generations to have pure inbred lines. They crossed by half diallel method to produce 15 F1 hybrids. Evaluation of the 6 parents, 15 produced hybrids and two commercially hybrids (Livina F1 and Magdalina) was carried out for fruit length, fruit diameter, fruit weight, number of female flowers per node, node of the first female flower, number of fruits/plant and total yield/plant was done. Heterosis, heritability, inbreeding depression and number of genes controlling studied traits were estimated. The results in the cross P1 x P5 showed the highest mid-parent heterosis values for studied characters that were positive by contrast. Most high-parent heterosis values for studied characters were negative. High inbreeding depression was observed. The inbreeding depression was positively and negatively lower significant indicating the presence of vigor in F2. High estimates of narrow and broad sense heritability were observed in the cross P1 x P5, but were moderate for number of female flowers per node and node of the first female flower. Concerning number of effective genes controlling most characters were found to be 1-2 pairs of genes (or group of genes); only fruit weight and node of the first female flower traits controlled by (4) and (9) additive genes respectively.

Morphological characterization and clustering of cucumber (Cucumis sativus) genotypes

Morphological characterization and clustering of cucumber (Cucumis sativus) genotypes

Redox Status, JA and ET Signaling Pathway Regulating Responses to Botrytis cinerea Infection Between the Resistant Cucumber Genotype and Its Susceptible Mutant.

Botrytis cinerea is an important necrotrophic fungal pathogen with a broad host range and the ability to causing great economic losses in cucumber. However, the resistance mechanism against this pathogen in cucumber was not well understood. In this study, the microscopic observation of the spore growth, redox status measurements and transcriptome analysis were carried out after Botrytis cinerea infection in the resistant genotype No.26 and its susceptible mutant 26M. Results revealed shorter hypha, lower rate of spore germination, less acceleration of H2O2, O2 -, and lower total glutathione content (GSH+GSSG) in No.26 than that in 26M, which were identified by the staining result of DAB and NBT. Transcriptome data showed that after pathogen infection, a total of 3901 and 789 different expression genes (DEGs) were identified in No.26 and 26M respectively. These DEGs were highly enriched in redox regulation pathway, hormone signaling pathway and plant-pathogen interaction pathway. The glutathione S-transferase genes, putative peroxidase gene, and NADPH oxidase were up-regulated in No.26 whereas these genes changed little in 26M after Botrytis cinerea infection. Jasmonic acid and ethylene biosynthesis and signaling pathways were distinctively activated in No.26 comparing with 26M upon infection. Much more plant defense related genes including mitogen-activated protein kinases, calmodulin, calmodulin-like protein, calcium-dependent protein kinase, and WRKY transcription factor were induced in No.26 than 26M after pathogen infection. Finally, a model was established which elucidated the resistance difference between resistant cucumber genotype and susceptible mutant after B. cinerea infection.

Metabolome and transcriptome analyses reveal chlorophyll and anthocyanin metabolism pathway associated with cucumber fruit skin color

BackgroundFruit skin color play important role in commercial value of cucumber, which is mainly determined by the content and composition of chlorophyll and anthocyanins. Therefore, understanding the related genes and metabolomics involved in composition of fruit skin color is essential for cucumber quality and commodity value.ResultsThe results showed that chlorophyll a, chlorophyll b and carotenoid content in fruit skin were higher in Lv (dark green skin) than Bai (light green skin) on fruit skin. Cytological observation showed more chloroplast existed in fruit skin cells of Lv. A total of 162 significantly different metabolites were found between the fruit skin of the two genotypes by metabolome analysis, including 40 flavones, 9 flavanones, 8 flavonols, 6 anthocyanins, and other compounds. Crucial anthocyanins and flavonols for fruit skin color, were detected significantly decreased in fruit skin of Bai compared with Lv. By RNA-seq assay, 4516 differentially expressed genes (DEGs) were identified between two cultivars. Further analyses suggested that low expression level of chlorophyll biosynthetic genes, such as chlM, por and NOL caused less chlorophylls or chloroplast in fruit skin of Bai. Meanwhile, a predicted regulatory network of anthocyanin biosynthesis was established to illustrate involving many DEGs, especially 4CL, CHS and UFGT.ConclusionsThis study uncovered significant differences between two cucumber genotypes with different fruit color using metabolome and RNA-seq analysis. We lay a foundation to understand molecular regulation mechanism on formation of cucumber skin color, by exploring valuable genes, which is helpful for cucumber breeding and improvement on fruit skin color.

Physiological and growth responses of cucumber (Cucumis sativus L.) genotypes to Egyptian broomrape (Phelipanche aegyptiaca (Pers.) Pomel) parasitism

Lack of consensus on effective approaches for Egyptian broomrape (Phelipanche aegyptiaca) management in host plants has focused attention on the identification of resistant or tolerant genotypes by evaluating plant physiological responses to parasitism. In the current study, the response of 35 cucumber (Cucumis sativus L) genotypes to Egyptian broomrape parasitism was investigated in a completely randomized design with 4 replications. Parasitism by Egyptian broomrape led to a significant decrease in shoot and root dry weight of C. sativus compared to the control treatment which varied across different genotypes. Parasitism resulted in significant but variable increases in hydrogen peroxide, malondialdehyde, protein and phenolic compound content across all genotypes. Catalase-specific activity, ascorbate peroxidase and peroxidase in Egyptian broomrape-infected treatments also differed to that in control treatments. In addition, underground attachments number plant−1 (UAN), emerged spikes number plant−1 (ESN), total attachment number plant−1 (TAN), attachment dry weight (g)/plant−1 (ADW) were significantly different among various cucumber genotypes. As a result of our analysis, genotypes were classified into four clusters. The Khassib greenhouse genotype was different to other genotypes with increases in total phenolic compound content and catalase activity being higher compared to the other three clusters. At the same time, shoot dry weight losses, malondialdehyde enhancement and UAN traits in Khassib had the lowest values compared to the other genotypes when parasitized by broomrape.

Direct regeneration of haploid or doubled haploid plantlets in cucumber (Cucumis sativus L.) through ovary culture

This paper reports a simple and effective method of directly producing cucumber plants through unfertilized ovary culture. The paper involves an experiment investigating factorial interactions between TDZ treatment, cold pretreatment, genotypes of cucumber, to improve plant induction. Cold pretreatment was effective in stimulating the ovary. The results showed that cold pretreatment for 4 days, TDZ for 0.06 mg·L−1, the interaction with genotype can be used as an effective strategy to improve the efficiency of gynogenesis. The plant regeneration induction rate was highest (79.3%). In addition, we observed the process of cucumber megasporogenesis and plant regeneration. The plants obtained from ovary culture of cucumber were identified as diploid or haploid by flow cytometry, consistent with the results of chromosome counting. The diploid plants were further identified as pure doubled haploid using simple sequence repeats (SSR). The doubling treatment we used was one of the simplest and most effective methods, completed in a short time (1 h) with a doubling rate of 75%. The acclimation rate for the surviving was 70%. This work provides a basis for promoting haploid breeding in cucumber.

Combining ability study for yield and quality traits in cucumber (Cucumis sativus L.)

Seven cucumber (Cucumissativus L.) genotypes (3 lines and 4 testers) were crossed in a line × tester mating design. The resultant 12 hybrids and their parents were evaluated using Randomised Block Design with two replications during Kharif 2018. Sufficient genetic variability was observed for all the characters under study. In this study, the parents L2 (Koradacherry local), T2 (Orathanadu local) and T3 (Aipatti local) exhibited high positive GCA (General Combining Ability) effects for yield related traits and high negative GCA effects for earliness characters. The parent T2 identified in this study may be used in multiple crossing programme to isolate high yielding varieties. Among the hybrid combinations, L2xT3, L1xT2 and L3xT4 expressed the maximum positive significant SCA (Specific Combining Ability) effects for yield and yield associated characters. In the above cross combinations one parent was a good combiner and the other was an average/poor combiner; hence the hybrids can be exploited for transgressive selection.

Characterization and potential mechanisms of resistance of cucumber genotypes to Bemisia tabaci (Hemiptera: Aleyrodidae)

Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae) is a major pest of several agricultural crops, being vector of an extreme number of viruses. The broad variety of host plants, high adaptability and evolution of resistance to insecticides evidence the difficult in the management of B. tabaci in the agriculture system. Host plant resistance is a valuable and sustainable method of insect management. To date, few studies have characterized the resistance of cucumber (Cucumis sativus L.) genotypes to B. tabaci, although this plant is one of the most preferred host of this hemipteran. The objective of this study was to assess the resistance of 60 cucumber genotypes against B. tabaci in greenhouse and laboratory conditions and to characterize the mechanisms of resistance involved based on morphological and physical plant parameters. Initially, 12 genotypes were selected in a screening bioassay. In general, ‘IAC-1214’ expressed high levels of antixenosis to the insect, causing low attractiveness to adults and non-preference for oviposition and colonization. 'Wellington' prolonged the development of the insect and provoked low levels of adult emergence, expressing levels of antibiosis. Antibiosis and/or antixenosis were detected in ‘IAC-1201’, ‘Campeiro’, ‘Japones’, and ‘IAC-1311’, while antixenosis was detected in ‘Kyria’ and ‘IAC-1175’. The density of the trichomes and the color of the leaves are described and discussed here. The selected genotypes present potential application in integrated programs that focus on reducing populations of B. tabaci in the agricultural system and in breeding programs aiming to explore resistant genotypes against the insect.

Expression analysis of defense-related genes in cucumber (Cucumis sativus L.) against Phytophthora melonis.

Phytophthora melonis is one of the most destructive cucumber disease, causing severe economic losses in the globe. Despite intense research efforts made in the past years, no permanent cure currently exists for this disease. With the aim to understand the molecular mechanisms of defense against P. melonis, root collars and leaves of four cucumber genotypes consisting of resistant Ramezz; moderately resistant Baby, and very susceptible Mini 6-23 and Extrem, were monitored for quantitative gene expression analysis of the five antifungal and/or anti-oomycete genes (CsWRKY20, CsLecRK6.1, PR3, PR1-1a and LOX1), at three points after inoculation with P. melonis. The gene expression analysis indicated, P. melonis strongly enhanced the expression of these genes after inoculation, in both the leaves and root collars. Further, not only the transcript levels of these genes were significantly higher in resistant and moderately resistance genotypes, but also the time point of the highest relative expression ratio for the five genes was different in the four cucumber genotypes. CsWRKY20 and PR3 showed the maximum expression in Ramezz at 48h post inoculation (hpi) while CsLecRK6.1, and LOX1 showed the highest expression at 72 hpi. In addition, PR1-1a showed the maximum expression in the Baby at 72 hpi. Root collars responded faster than leaves, and some responses were more strongly up-regulated in root collars than in leaves. The genes found to be involved in disease resistance in two different organs of cucumber after pathogen infection. The results suggest that increased expression of these genes led to activation of defense pathways, and could be responsible for a reduced P. melonis colonization capacity in Ramezz and Baby. Overall, this work represents a valuable resource for future functional genomics studies to unravel molecular mechanisms of Cucumis sativus-P. melonis interaction.

Cucumber Fusarium wilt resistance induced by intercropping with celery differs from that induced by the cucumber genotype and is related to sulfur-containing allelochemicals

Fusarium wilt is a serious soil-borne disease for cucumber production; however, intercropping with celery and using resistant cultivars could alleviate this problem. The aims of the study were to verify whether cucumber Fusarium wilt resistance induced by intercropping with celery differs from that induced by the cucumber genotype and whether celery synthesizes organosulfur allelochemicals to inhibit the growth of Fusarium oxysporum f. sp. cucumerinum (Foc). First, biochemical and transcriptome analyses were performed for the roots of two cucumber cultivars during the response to Foc infection in a monoculture system and cucumber/celery intercropping system, and the results indicated that the Fusarium wilt-resistant cucumber cultivar and cucumber intercropped with celery resulted in different immune responses against Foc inoculation. Then, the possible allelochemicals in the fresh root and rhizosphere soil of celery were extracted with acetone, separated and purified by chromatography four times and cocultured with Foc in vitro. Three organosulfur compounds, namely, thioglycolic acid, propanethiol and isopropyl isothiocyanate, were identified from the chromatography fractions, with the highest inhibition on Foc in the fourth chromatography by gas chromatography/mass spectrometry. All these compounds exhibited inhibitory effects on Foc, but thioglycolic acid showed stronger inhibition than the other two compounds and completely inhibited the growth of Foc colonies at concentrations of 50–100 μmol L−1. The information obtained will permit new management practices that prevent and control cucumber Fusarium wilt.

Producción de siete genotipos de pepino (Cucumis sativus L.) cultivados en ambiente protegido

El objetivo del estudio fue evaluar el rendimiento y la calidad de siete genotipos de pepino partenocárpico de tipo mediano (Corinto, Katrina, Macario, Modan, Paraíso, Primavera y 22-20-782), cultivados en condiciones de invernadero en la Estación Experimental Agrícola “Fabio Baudrit Moreno”, en Alajuela, Costa Rica. El cultivo se manejó con fertirrigación en sustrato de fibra de coco, y con poda a un tallo por planta. Los datos muestran una amplia variabilidad entre los genotipos en cuanto a edad al inicio de la floración (17 - 20 días después del trasplante -d.d.t.-), edad al inicio de la cosecha (28 - 30 d.d.t.), longitud del fruto (16,56 - 21,30 cm), diámetro del fruto (42,94 - 54,09 mm), número total de frutos por planta (26,31 - 49,41), peso del fruto (215,41 - 269,89 g), rendimiento comercial (13,66 - 22,66 kg/m2), rendimiento total (18,11 - 28,41 kg/m2) y porcentaje de sólidos solubles totales (2,89 - 3,22 °Brix). En términos generales, los frutos de pepino de primera calidad mostraron mayor longitud, diámetro y porcentaje de sólidos solubles totales que los de segunda calidad y de rechazo. Los genotipos 22-20-782 y Katrina obtuvieron el mayor rendimiento comercial (20,89 y 22,66 kg/m2, respectivamente) y primera calidad (12,48 y 12,49 kg/m2, respectivamente), por lo que se consideran los mejor adaptados a las condiciones en que se desarrolló la investigación; sin embargo, sus frutos son más pequeños (menor longitud, diámetro y peso) en comparación con los de otros genotipos, lo que podría afectar su potencial de comercialización en Costa Rica.