In different crop plants, combining ability and heterosis are used as important diagnostic tools for assessing the performance of parental genotypes and their hybrids. This research aimed to evaluate heterotic and combining ability effects in the diallel crosses of melon (Cucumis melo L.) for yieldand quality-related traits. Seven melon (C. melo L.) genotypes were grown and crossed in a complete diallel fashion to produce F1 hybrids. During the 2019 crop season, 49 melon genotypes (7 parents + 42 F1 hybrids) were grown in a randomized complete block design with three replications. Observations were made for seven characters. Analysis of variance revealed significant (P ≤ 0.01) differences among the melon genotypes for harvest age, fruit flesh thickness, fruit total soluble solids, fruit length, and fruit diameter and merely significant differences (P ≤ 0.05) for fruit weight. Combining ability analysis revealed that mean squares due to general combining ability (GCA) were significant for fruit diameter but were nonsignificant for all other traits. However, mean squares due to specific combining ability (SCA) were significant for all traits. The parental genotypes PK-165, PK-464, and PK-669 exhibited the highest and desirable GCA effects for yield and quality traits. Hence, these genotypes could be used to generate high-yielding hybrid/open-pollinated cultivars. GCA:SCA ratios further revealed that the traits of harvest age, fruit flesh thickness, fruit total soluble solids, fruit length, and fruit weight were controlled by dominant gene action, whereas fruit diameter was managed by additive and dominant genes. The majority of the traits were controlled by nonadditive gene action, verifying that the said breeding material could be efficiently used for the production of hybrid cultivars on the basis of heterotic effects.

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COMBINING ABILITY AND HETEROTIC STUDIES ON HYBRID MELON (Cucumis melo L.) POPULATIONS FOR FRUIT YIELD AND QUALITY TRAITS

/pdf/effect-of-soil-irrigation-with-two-types-of-seaplant-extract-22cp3r05pg.pdf

EFFECT OF SOIL IRRIGATION WITH TWO TYPES OF SEAPLANT EXTRACT AND HUMIC ACID ON GROWTH, QUANTITY AND QUALITY OF YIELD IN LETTUCE (Lactuca sativa L.)

Fruit shape index (round shape) and seed size have important effects on pumpkin yield. To investigate these traits and to create the most desirable state, a cross was made between two pumpkin cultivars. This study aimed to estimate the main gene effects (additive, dominant and di-genic epistasis) and to determine the mode of inheritance for fruit shape and seed size by generation mean analysis. Six generations, namely P1, P2, F1, F2, BC1, and BC2 from a cross between Zucchini and hull-less seed Pumpkin, S10 × P25, were constructed and evaluated for fruit length, fruit width, fruit shape index, and some seed-related traits (seed length, seed width, and seed thickness). The experiment was conducted in the research field of the Faculty of Agricultural Science, University of Guilan, Rasht, Iran in 2019. Results showed a significant difference between generations in terms of fruit and seed traits. Scale and joint scale tests showed the presence of epistasis for some traits. According to the results of the average traits of different generations, standard heterosis and hetrobeltiosis were observed. Concerning the fruit shape index and seed width, there was a dominance effect. The broad-sense heritability of the traits was relatively high for all traits and between 52 and 94%. Narrow sense heritability was between 26 and 90% and relatively low for the fruit shape index and seed width. Therefore, selection of elite lines and production of their hybrids are recommended as two methods suitable for breeding to achieve a round shape index and a larger seed size.

/pdf/investigation-of-gene-effects-on-fruit-shape-index-and-seed-bjyjumm1ix.pdf

Investigation of gene effects on fruit shape index and seed size in generations resulting from the crossing of Zucchini and hull-less seed Pumpkin

Summer squash (Cucurbita pepo L.) is a self-pollinated crop belonging to Cucurbitaceae. It is an annual crop that is grownup in tropical and subtropical areas. It is one of the most vital and economical vegetables in cultivation. Globally, squash is used as food and medicine for the presence of vitamins and antioxidants. C. pepo plants vary in shape, color and size, with several varieties and landraces. There are many types of Cucurbita species with diverse genomes and chromosome numbers. The number of summer squash chromosomes (2n) ranges from 40 to 48. Squash harbors a great diversity dependent on ploidy, regional and morphological characteristics. The introduction of new alleles through the crossing of different genetic resources for the C. pepo, for example, crossing common genotypes with locally developed genotypes with those developed locally increases genetic diversity and the preselection of characteristics of interest. A fair natural variability in the degree of phenotypes must be ensured. The main targets of squash breeders and geneticists are to enhance various desirable morphological characteristics, including tolerance to biotic and abiotic stress and crop characteristics. Achieving these targets can be comforted by using modern genomics methods to enhance the traditional breeding program. This chapter provides an outline of the shortcomings of the summer squash origin and historical background, botanical description, economic and health importance, photochemistry, cultivation requirements, biodiversity and conservation of germplasm, cytogenetics, aims and stages of squash breeding programs and traditional approaches of breeding. Additionally, it discusses new plant breeding methods involving marker-assisted breeding and genetic engineering. 

Advances in Summer Squash (Cucurbita pepo L.) Molecular Breeding Strategies

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ESTIMATING OF HETEROSIS AND GENETIC VARIABILITY IN SUMMER SQUASH( Cucurbita pepo L.)

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COMBINING ABILITY FOR YIELD AND ITS COMBONENTS IN MELON (Cucumis melo L.) DEPENDING ON FULL - DIALLEL CROSS

This experiment was conducted in an unheated plastic house in Horticulture and Landscape design Department, college of Agriculture and Forestry, Mosul University during the winter season of the year 2013-2014 to investigate the possibility of lettuce crop production under protected condition during the winter season, which cannot be grown in the field at this time in Mosul City. Two lettuce cultivars were used Binco and Paris Island, the seeds were planted in 5/9 and transplanted inside the unheated plastic house in 5/11 at two agricultural distances: 30 and 40 cm and plants were fertilized with two organic fertilizers: Pow hums and Humistar which were applied to the soil as a solution at a rate of 3 gm.l for the two organic fertilizers, the control treatment was fertilized with a chemical fertilizer at the recommended rates. An RCBD factorial experiment with 12 treatments (2 x 2 x 3) were used. Results showed that there were no significant differences between the two varieties in most vegetative growth and yield traits while there were a significant superiority of the 40 cm distance on the 30 cm distance in head circumference, leaf area, stem weight and mean marketable head weight while there were a significant superiority of the treatment of 30 cm planting distance in terms of marketable and total yield. It is worth to note that there were no significant differences between the organic fertilization treatments with the normal chemical fertilized plants in terms of vegetative and yield in all vegetative traits mentioned traits expect the mean stem weight.

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Effect of chemical and organic fertilizer and agricultural distances on growth and yield of two lettuce (lactuca sativa l.) varieties grown under unheated plastic house

Shamil Y.Hassan AL-Hamdany

Papers

ESTIMATING OF HETEROSIS AND GENETIC VARIABILITY IN SUMMER SQUASH( Cucurbita pepo L.)

COMBINING ABILITY FOR YIELD AND ITS COMBONENTS IN MELON (Cucumis melo L.) DEPENDING ON FULL - DIALLEL CROSS

Effect of chemical and organic fertilizer and agricultural distances on growth and yield of two lettuce (lactuca sativa l.) varieties grown under unheated plastic house