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F1 cultivars are currently used in vegetable production because of their many superior agronomic advantages (high yield and quality, resistance/tolerance to biotic and/or abiotic stress factors, wide adaptability, etc.). It is not possible to produce hybrid vegetables without homozygous pure parental lines with defined traits and high combining ability. However, the production of homozygous pure parents needs a long time, great efforts, and high production cost. Moreover obtaining an F1 hybrid variety takes 8-10 years with traditional breeding methods, especially in a highly open-pollinated species such as Cucurbita spp. Doubled haploid (DH) technologies (parthenogenesis, androgenesis, and gynogenesis), called biotechnological breeding methods, have become an alternative to classical breeding methods and provide to obtain pure lines within 1-2 years by adapting to these technologies in F1 hybrid breeding programs. Although the DH technologies considered a meaningful approach to enhance the production of valuable double haploid plants, the implementation of these techniques needs labor-intensive efforts, high experiences, and advanced technologies. The main objective of this review to provide a summary of DH techniques applied in the Cucurbita species in the current progress.

This study was carried out to determine some morphological characteristics of 94 tomato genotypes at the S4 level and to reveal the relationships between these materials. In the study, leaf attitude, leaf length, leaf width, number of flowers, fruit color, fruit weight, fruit width, fruit length, the thickness of pericarp, fruit shape, fruit diameter, number of locules, and total soluble solid content (TTSC) were measured and observed in these genotypes. As a result of the phenotypic assessment, the maximum fruit weight values of the genotypes were observed as in G9 (317.59 g), G54 (310 g), G92 (292.85 g), G70 (287.01 g), and G110 (276.66 g); and the lowest fruit weight values were observed in G26 (18.302 g) and G8 (14.48 g). Average fruit length, fruit width, pericarp thickness, and the number of carpels were recorded (69.09 mm, 56.90 mm, 6.37 mm, and 4 carpels respectively). Tomato genotypes were also investigated using Cluster and Principal Component Analysis (PCA) method based on these measurements and observations. As a result of this analysis, five independent principal component axes were obtained. While these axes represent 69.28% of the total variation, the eigen values were ranged between 1.06 and 4.02. According to the PCA analysis results, genotypes G7, G81, G93, and G103 were prominent in terms of leaf length, fruit width, fruit weight, and carpel number parameters. Based on TSSC results, the G65 genotype was found to be the most prominent one, and the genotypes G12 and G114 exhibit promising results for fruit color. A high degree of morphological variation was detected among tomato genotypes.