Half Diallel Research Articles

Hayman’s diallel analysis for yield and attributing traits in sesame (Sesamum indicum L.)

Eight sesame (Sesamum indicum L.) genotypes were crossed in a half diallel mating fashion. The analysis of variance for combining ability revealed that the mean sum of squares are due to the general combining ability were highly significant for all the traits. The t2 test specified the fulfillment of assumptions required under diallel analysis for all the traits studied except the number of effective branches per plant, capsule length (cm) and harvest index (%). The component D measures the additive effects of genes. It was significant for all the traits except seed yield per plant and harvest index. The components H1 and H2 were significant for all the traits except days to maturity revealing the importance of fixable and non-fixable component. Greater values of H1 than H2 and the ratio of H2/4H1 (< 0.25) confirmed the unbalanced distribution of gene at the loci in the parents’ implying dominance for all the traits. It was also confirmed by greater than one value of KD/KR components for all the traits which suggested the higher frequency of dominant genes than recessive genes in the parents. The component F was significant for days to flowering, days to maturity, capsule length, oil content and leaf area per plant. The graphical analysis showed the regression line intercepted Wr axis below the origin indicating over dominance for plant height, the number of seed per capsule, oil content and leaf area per plant. The regression line intercepted the positive side of Wr axis for days to maturity which implies the presence of partial dominance.

Genetics of stem rust resistance in four popular durum wheat cultivars

A study was conducted to understand the mode of inheritance and extent of diversity of stem rust resistance in four popular durum wheat cultivars of central India viz., HI 8498 (Malav Shakti), HI 8663 (Poshan), HI 8713 (Pusa Mangal) and HI 8737 (Pusa Anmol) using Puccinia graminis tritici (Pgt) pathotypes 15-1 (123G15) and 40-3 (127G29). These cultivars were crossed with susceptible parents i.e., Motia and Malvi Local and were also crossed among themselves in half diallel fashion. The F2 and F3 segregation data revealed that a single dominant gene each controlled resistance to the pathotype 40-3 in HI 8713 and HI 8663, while two dominant genes each governed resistance to this pathotype in HI 8737 and HI 8498. A single dominant gene each conditioned resistance to the pathotype 15-1 in all the four cultivars. The F2 segregation data of the intercrosses among the resistant parents showed that three different resistance genes controlled resistance among four cultivars against each Pgt pathotype 40-3 and 15-1. These genes seem to be different from the most commonly postulated stem rust resistance genes in Indian durum wheat germplasm viz., Sr11, Sr12, Sr7b and Sr9e which are ineffective/less effective against the test pathotypes. Hence, the genes identified in the present study can be utilized in broadening the genetic base of stem rust resistance in Indian durum wheat.

USING BIPLOT ANALYSIS OF F1 FABA BEAN DIALLEL DATA TO PREDICT COMBINING ABILITY

This study was carried out under insect cages during 2017/18 and 2018/19 seasons at Giza Research Station, ARC, Egypt to investigate the combining ability possibility prediction and relationship between biplot graph and Griffing of half diallel data, and to identify promising genotypes. Six parental faba bean genotypes and their half diallel crosses (15 F1’s) were evaluated under a randomized complete block design in three replications. The results reflected significant differences for both GCA and SCA in most traits, indicating the important role of both additive and dominant components in the inheritance. Meanwhile, Baker’s ratio emphasized the preponderant role of additive gene action in controlling the most studied traits. Simple correlation results showed that seed yield may be raised through selecting most pods and seeds per plant, which recorded the highest heritability in broad and narrow sense (hb 2 and hn 2%) estimates coupled with highest genetic advance (GA %) in faba bean. Biplot graph (innovative) and Griffing (traditional) analysis exhibited equivalent results for gca and sca effects and are meaningful for identifying Giza 843 (P1), Misr 1 (P2) and Giza 40 (P6) as the best parents and Giza 843 x Misr 1 (C12), Giza 843 x Nubaria 1 (C15), Misr 1 x Giza 3 (C24), Giza 716 x Nubaria 1 (C35) and Nubaria 1 x Giza 40 (C56) as promising five crosses. Then, GT-biplot method is considered as the best alternative analysis for giving a complete picture about the interrelationships among genotypes and traits (for relative comparing genotypes based on multiple traits). Hence, number of pods and seeds per plant traits could be used for the improvement of seed yield. Besides, five faba bean crosses were distinguished which possess genetic factors for high yield and highly promising to be employed in the development of high yielding populations of faba bean breeding programs.

THE GENETIC SYSTEM CONTROLLING AGRONOMIC TRAITS IN CANOLA

To determine the types of combining abilities, heterosis and genetic behavior of agronomic traits, six divergent canola genotypes were crossed using a half diallel mating design (excluding reciprocal crosses). The parents and their crosses were evaluated using a randomized complete block design with three replicates at Kafr-El-Hamam/Sharkia and Etay-El-Baroud/Behaira Agricultural Research Stations, Agricultural Research Center, Egypt. The preponderance of dominance gene action was observed for most studied traits as verified by the average degree of dominance and narrow-sense heritability. The GGE biplot revealed that N.A.36 and N.A.39 at Kafr-El-Hamam and N.A.39 and N.A.14 at Etay-El-Baroud were the best general combiners for seed weight plant-1 and N.A.36, N.A.38 and N.A.39 at Kafr-El-Hamam and N.A.36, N.A.39 and N.A.14 at Etay-El-Baroud for seed oil content, which associated with proportion of desirable genes either dominant or recessive. Superior crosses than better parents for seed weight plant-1 were observed in four crosses [N.A.36 and N.A. 37] x [N.A.38 and N.A.14] at Kafr-El-Hamam and two crosses [N.A.37] x [N.A.38 and N.A.14] at Etay-ElBaroud as well as for seed oil content in four crosses [N.A.39 and N.A.14] x [N.A.37 and N.A.38] at Kafr-El-Hamam and two crosses in [N.A.18] x [N.A.37 and N.A.38] at EtayEl-Baroud.

Determination of genetic parameters for inheritance of grain protein content in durum wheat

The aim of the study is to determine the genetic architecture and heritability of a basic quantitative trait related to grain quality of durum wheat. For this purpose, a half diallel cross was made in the period 2014–2016. Five modern durum wheat varieties were crossed to produce hybrid combinations. The testing period allowed for the cultivation of three F1 and two F2 generations. Parents and hybrids were grown under field conditions in three replications using a randomized block method. Protein content in the grain was measured by the standard method for its determination. The mean values of the trait have been statistically processed, and this has provided useful information for improving the quality of durum wheat grain. The heritability of the trait is influenced by additive variance and the dominant parameters. The larger dominant parameters determine that dominance plays a major role in the trait expression. This is also evidenced by manifestations of dominance and overdominance. In our cases, the selected parents contain more dominant genes in their genotype. The values of the trait increase with the accumulation of recessive genes. The varieties Victoria and Predel have more recessive genes in most cases than other tested parents. The heritability of the trait is mainly influenced by simple additive-dominant genetic system, but under certain conditions the presence of complementary epistasis is possible. Heritability coefficients indicate that effective selection of a genotype by phenotype is possible, but it should start in later segregated generations.

Estimation of combining ability and heterosis by using diallel mating design in Kabuli genotypes of chickpea

An experiment consisting of six parents and 15 hybrids (developed by using 6 x 6 half diallel mating design) in kabuli chickpea was laid out in RBD design with three replications to estimate combining ability and heterosis. The ANOVA (Analysis of Variance) for different characters revealed highly significant differences among genotypes for all traits under study.The estimates of SCA variance were found to be higher than the GCA variance for all the characters under consideration, indicating good prospects for exploitation of non-additive gene action for grain yield and its components under study. Estimates of the ratio of gca variances to the sca variances for all the characters is less than one indicating the preponderance of non-additive gene effects (dominance and epistasis) in controlling the expression of all the characters under study. Line KAK2 was identified as good general combiner for plant height, canopy width, number of secondary branches per plant, number of pods per plant, pod length, grain yield per plant, biological yield per plant, 100 seed weight and harvest index. High estimates of heterosis over better parent, mid parent and standard check was exhibited by three crosses viz., PKC1 × HK4, KAK2 × HK4 and JGK1 × HK4.

Genetic Evalution of some Economical Traits in Summer Squash

This study aimed to estimate significance of heterosis, combining ability, genetic parameters and heritability for vegetative, flowering, yield and fruit quality traits using15 F1hybrids obtained from 6×6 half diallel mating system without reciprocals. The results indicated that analysis of variance exhibited highly significant for the mean squares of the genotypes for all traits, except for, parents which was significant for fruit diameter and parents vs. hybrids was insignificant for average fruit weight and fruit diameter, but it gave significant for fruit length. None of the F1 hybrids had the highest values for all traits.The maximum significant desirable heterosis values over mid-parent were -17.19, 61.36, 44.14, -5.46, 17.26, 308.83, 296.41, -23.58 and -12.79% for stem length, number of branches/plant, leaves/plant, days to opening the first female flower, average fruit weight, number of fruits/plant, yield/plant, fruit length and fruit diameter, respectively. Also, the heterosis over better parent were recorded the following values;-18.18, 32.47, 37.66, -6.97, 14.77, 205.54, 204.98, -20.43 and -14.48% for same traits listed before. The analysis of variance for both GCA and SCA revealed highly significant estimates for all traits. The GCA was higher than SCA for all the traits. The inbred lines P1, P3, P4, P5 and P6 were the good combiner for number of branches/plant , days to opening the first female flower and fruits/plant, average fruit weight, fruit length, number of leaves/plant and stem length, respectively.. The estimates of heritability in broad sense (h2b.s.%) were higher than their corresponding in narrow sense(h2n.s.%) for all traits.

HALF DIALLEL ANALYSIS OF SEVEN PEA CULTIVARS FOR SEED YIELD AND ITS COMPONENTS FOR F4 GENERATION UNDER SULAIMANI CONDITION

The present study was carried out at Qlyasan locations, in Kurdistan Region-Iraq, Agricultural Research Station, College of Agricultural Engineering Sciences-University of Sulaimani, according to half diallel mating system using seven pea cultivars (1-Avolla, 2-Americana, 3-Jeza, 4-Joneor, 5-Pack land, 6-Arvena and 7-Samara) with 21 F4 crosses. The genotypes were planted in a completely randomized block design with three replications. Highly significant mean squares due to genotypes were recorded indicating the presence of sufficient variability among genotypes for all traits. The mean squares due to gca and sca were significant for all the studied traits. The highest positive heterosis values estimated as the F4s deviation from mid parental values recorded by the cross 2×6 and 4×5 for almost all traits. Maximum positive gca effect values for seed weight plant-1, biological yield plant-1 and pods number plant-1 were recorded by parent 4, while parent 2 showed the best value for some components. The cross 4×5 was the best sca combiner for seed weight plant-1 and some its components including pods number plant-1, pod weight plant-1 and seed number pod-1. The type of gene action as controlled the inheritance of all characters was over dominance except 100-seed weight. Heritability in broad sense was found to be high for all treats except seed number pod-1 which was moderate, while at narrow sense it was high for average pod weight, pod length, seed weight pod-1 and 100-seed weight.

Nature of Inheritance to Heat Stress and Selection of Inherent Genotypes in Tropical Maize

Maize is an important cereal in sub-Saharan Africa. Its production is however hampered by both biotic and abiotic factors. Among the abiotic factors, heat stress has been reported to cause yield losses. The objective of this study was therefore to identify tolerant genotypes to heat stress and determine the type of gene action conditioning heat tolerance in tropical maize. To achieve these objectives, five maize inbred lines (L2 [P1]; DTS 6,36 [P2]; L5527 [P3]; DTS 6,6 [P4] and DTS 6,92 [P5]) were mated in a 5 x 5 half diallel. Their progeny were evaluated at a heat prone site (Lusitu) and at the University of Zambia (UNZA), a control site. The experiment was laid as a randomised complete block design with two replications in each site. Highly significant differences (P ≤ 0.01) were obtained among genotypes in Lusitu with regards to all measured parameters. The crosses[P2 (DTS 6,36) x P4 (DTS 6,6)] and [P4 (DTS 6,6) x P5 (DTS 6,92)]were identified as tolerant genotypes to heat stress. Further analysis showed that the general combining ability (GCA) effects for parent P4 (DTS 6, 6) and P3 (L5527) were positively and negatively significantly different (P ≤ 0.01) from zero respectively with regards to all measured parameters. On the other hand, crosses [P1 (L2) x P3 (L5527)] &amp; [P4 (DTS 6,6) x P5 (DTS 6,92)]were found to possess desirable significant (P ≤ 0.05) specific combining ability (SCA)effects from zero. The results of baker’s ratio obtained for responseto heat stress for all secondary traits measured were found to be greater than 0.88. This implied that additive gene action was more important in conditioning the response of these traits to heat tolerance.

Hybrid Breeding for MLN Resistance: Heterosis, Combining Ability, and Hybrid Prediction.

Prior knowledge on heterosis and quantitative genetic parameters on maize lethal necrosis (MLN) can help the breeders to develop numerous resistant or tolerant hybrids with optimum resources. Our objectives were to (1) estimate the quantitative genetic parameters for MLN disease severity, (2) investigate the efficiency of the prediction of hybrid performance based on parental per se and general combining ability (GCA) effects, and (3) examine the potential of hybrid prediction for MLN resistance or tolerance based on markers. Fifty elite maize inbred lines were selected based on their response to MLN under artificial inoculation. Crosses were made in a half diallel mating design to produce 307 F1 hybrids. All hybrids were evaluated in MLN quarantine facility in Naivasha, Kenya for two seasons under artificial inoculation. All 50 inbreds were genotyped with genotyping-by-sequencing (GBS) SNPs. The phenotypic variation was significant for all traits and the heritability was moderate to high. We observed that hybrids were superior to the mean performance of the parents for disease severity (−14.57%) and area under disease progress curve (AUDPC) (14.9%). Correlations were significant and moderate between line per se and GCA; and mean of parental value with hybrid performance for both disease severity and AUDPC value. Very low and negative correlation was observed between parental lines marker based genetic distance and heterosis. Nevertheless, the correlation of GCA effects was very high with hybrid performance which can suggests as a good predictor of MLN resistance. Genomic prediction of hybrid performance for MLN is high for both traits. We therefore conclude that there is potential for prediction of hybrid performance for MLN. Overall, the estimated quantitative genetic parameters suggest that through targeted approach, it is possible to develop outstanding lines and hybrids for MLN resistance.

Combining Ability Analysis of Dry Matter Content, Reducing Sugars and Yield of Potato (Solanum tuberosum L.) Genotypes in Uganda

Potato (Solanum tuberosum L.) in Uganda is a major food and cash crop mainly grown in the highland regions by small-scale farmers. The increasing importance of potato as a processed product requires new varieties possessing quality processing attributes with acceptable yield. The objectives of this study were to estimate the combining ability effects for dry matter content, reducing sugars, and yield related traits in potato. Nineteen F1 families generated from eight parents using a half diallel mating design were evaluated for dry matter content, reducing sugars, average weight per tuber and total tuber yield at Kachwekano research station. Additive genetic effects were predominant for dry matter content while non-additive effects for the other traits. The GCA/SCA ratios were 0.58, 0.28, 0.17 and 0.44 for dry matter content, reducing sugars, average weight per tuber and total tuber yield respectively. Broad sense heritability estimates were 50.6% for dry matter content, 77.8% for reducing sugars, 90.3% for average weight per tuber and 29.5% for total tuber yield. Parents NAROPOT 3 and 395096.2 had desirable GCA effects for both dry matter content and reducing sugars. Families of nkrk19.17 x Rutuku had desirable SCA effects for dry matter content while Rutuku x 393077.54 and nkrk19.17 x 392657.8 had desirable SCA effects for reducing sugars. Additive genetic effects for dry matter content imply that, genetic gains can be achieved through different selection methods and trait transferred to the respective progenies. The selected parents and families will be subjected to further clonal evaluation and selection.

Biological and Molecular Characterization of Watermelon mosaic virus Affecting Squash Plants Yield and Quality in Egypt

Survey of vegetable crops in different regions Ismailia Governorate in Egypt conducted detection of Watermelon mosaic virus. The virus detected using DAS-ELISA form naturally infected watermelon and squash plants, exhibiting severe yellow mosaic, vein clearing, blistering and distortion of leaves. Isolation and identification of WMV was carried out by studying host range, symptomatology, modes of transmission, serological reaction and electron microscopic examination. The molecular detection of WMV done using RT-PCR with specific primers designed for coat protein gene. RT-PCR products 825bp of coat protein gene of WMV cloned and then sequenced. The coat protein gene of the Egyptian isolate of WMV showed nucleotide sequences similarity ranged from 95%-99% with different isolates available in Gene Bank. The experiments carried out under greenhouse condition, (HRI) - (VRD) from2014 to 2017. Five squash inbred lines used making half diallel to produce 10 hybrids to determine performance some variables under WMV infection condition. A complete block design was used. The evaluation process performed through two experiments. First experience, cultivation the genotypes with a commercial hybrid after infection to evaluate the performance of genotypes for yield and some characteristics. Therefore the percentage of reduction in yield estimated. The second experiment without infection and evaluate the performance for the same variable. The study found that, there were significant differences between all the genotypes that were inoculated and noninoculated. The reducing in yield ranged 14.6: 30%. Therefore, the study recommended attention to the hybrid that achieved a decrease of 14.6% by continuing to work on it.

English

Maize (Zea mays L.) is one of the cereals that provide calorie requirements in the majority of Ethiopians diet. The national average maize yield in Ethiopia is low and thus knowledge of combining ability and heterosis is a prerequisite to develop high yielding maize varieties. The objective of the present study is to estimate combining abilities of double haploid (DH) maize inbred lines for grain yield and related agronomic traits, and to identify crosses with higher standard heterosis. A total of 36 diallel crosses generated by crossing nine maize DH lines using half diallel mating scheme and four standard checks were studied for different desirable agronomic traits during 2017 cropping season at Ambo and Kulumsa Agricultural Research Centers. The genotypes were evaluated in alpha lattice design replicated twice in both locations. Analyses of variances showed significant mean squares due to crosses for most traits studied. The highest grain yields were obtained from crosses L1 x L3, L3 x L8, L4 x L8 and L8 x L9. GCA mean squares were significant for all studied traits, while SCA mean squares were significant only for grain yield, days to anthesis, ear per plant and ear diameter. Relatively larger GCA over SCA variances were observed in the current study for most studied traits revealing the predominance of additive gene action in controlling these traits. Of the DH inbred lines, L3 and L8 were the best general combiners for grain yield, and hence are promising parents for hybrid development. Inbred lines &nbsp;L2, L4, L6, L7 and L8 were good combiners for earliness whereas, L1, L2 and L6 showed negative and significant GCA effects for plant and ear height. In this study, none of the crosses showed positive and significant standard heterosis for grain yield. &nbsp; Key words: Combining ability, general combining ability, highland maize, standard heterosis, specific combining ability.

Heterotic Potential, Potence Ratio, Combining Ability and Genetic Control of Quality and Yield Traits in Bell Pepper Under Net-House Conditions of NW Himalayas

The present experiment was carried out with the aim of identifying outstanding specific combiners and best parental lines along with the understanding of genetic control of fruit quality and yield traits of bell pepper under net-house conditions in northwestern Himalayas of India. Eight inbred lines were crossed in half diallel manner, and the resulted twenty-eight F1 hybrids along with a standard check variety were evaluated under net-house conditions. California Wonder and Solan Bharpur parental lines were found to be the best combiner for earliness, whereas Yolo Wonder, California Wonder, Nishath-1 and UHFBP-3 reported as best parental line for fruit quality, yield and yield contributing traits based on their general combining effects. Solan Bharpur × Yolo Wonder, Yolo Wonder × Nishath-1, California Wonder × Solan Bharpur, California Wonder × UHFBP-3 and UHFBP-3 × KC-12 cross-combinations found outstanding based on heterosis and specific combining ability for most of the traits under net-house condition. The present studied hybrids illustrated the presence of over-dominance effect for yield and yield contributing traits under study. Predominance of nonadditive gene action for all the characters suggested the usefulness of exploitation of hybrid vigor.

Assessment of combining ability with elite genotypes in sesame (Sesamum indicum L.) by half diallel mating design

The present investigation was undertaken with the objective of studying the extent of heterosis and to estimategeneral and specific combining ability effects in 28 hybrids of sesamum obtained by crossing 8 x 8 genotypes in half diallel fashion. The analysis of variance revealed that significant differences among treatments, parents, hybrids and parents v/s hybrids for all characters except days to maturity and capsule width. Among parents, LOCAL and G-1 was good general combiners for seed yield/plant. Considering both per se and GCA effect, the parents LOCAL and AKT306 were the best. The highest SCA effect for seed yield/plant was exhibited by cross G-1 x IC-204025 along with superior SCA effect for plant height, number capsule/plant and seed/capsule. The crosses AKT-306 x YLM-17 and LOCAL x AKT-101 with significant SCA effects indicated the predominace of additive gene action for seed yield hence progeny selection in the segregating generation is more useful.

Combining Ability Analysis for Yield and Processing Qualities in White Onion (Allium cepa L.)

Eight diverse white onions parents were selected and crossed in half diallel fashion in order to determine the combining ability to identify promising hybrids for nine traits including yield and processing quality. Analysis of variance for general and specific combining ability revealed that GCA and SCA variances were significant (p&lt;0.05) for all characters. Among the parents exotics JV16 and JV12 was proved to be a good general combiner for yield and processing quality characters. Among the crosses AF x JV12, was best specific combination for bulb weight, bulb diameter, total soluble solids, per cent bolting, per cent doubles, pungency and yield. It is evident from present investigation that the hybrids combinations AF x JV12, PW x JV12, J16 x JV12 and PS x JV12 exhibited the high per se performance and SCA effect for bulb yield and processing quality characters could be advanced by selecting desirable segregants and recombinants in each generation for funneling the new genotype or using further advanced breeding programme.

Diallel Analysis of some Quantitative Traits in Eight Inbred Lines of Maize and Gge Biplot Analysis for Elite Hybrids

An 8x8 half diallel analysis were performed at two planting dates to study the importance of types of combining ability (GCA and SCA) and its interaction with environment in F1 of maize. Planting dates (D), crosses (Cr), GCA, SCA, CrxD, GCAxD, SCAxD were significant for all traits. GCA/SCA exceeded the unity for most traits. Non-additive seemed to be more prevalent for plant, ear heights and grain yield plant-1. P8 gave significant positive () effects for all studied traits. High SCA effects were exhibited by the crosses P1xP7, P1xP8, P2xP5, P3xP4, P3xP8, P4xP7, P4xP8 and P5xP6 for grain yield plant-1 across planting dates. Superiority of P2xP5 and P3xP8 over SC Hytech 2031 reached 13.84 and 6.16%, respectively. However, useful heterotic effects relative to SC 128 mean value were 21.14 and 10.22%, for the aforementioned crosses, respectively. P1xP8, P4xP8 and P5xP6 gave positive insignificant out-yielded than check hybrids. The five superior hybrids P2xP5 (G1), P3xP8 (G2), P5xP6 (G3), P1xP8 (G4) and P4xP8 (G5) along with SC10 (G6), SC 128 (G7) and SC Hytech 2031(G8) were evaluated in 2019 season at various environments using RCBD with 3 replicates to identify environments and suitable adapted maize hybrids. Stable genotypes are ranked descending for means of grain yield as follows: G1 > G8> G2> G7. G1, G8, and G2 were above average stability while genotypes G7 showed below average stability. Thus, G1 (P2xP5) and G2 (P3xP8) are promising crosses, and it's recommended to register as new varieties with high productivity and stability across environments.

Combining Ability Analysis , Estimation of Heterosis and Some Genetic Parameters Using Half Diallel Cross in Bread wheat (Triticum aestivum L.)

Combining Ability Analysis , Estimation of Heterosis and Some Genetic Parameters Using Half Diallel Cross in Bread wheat (Triticum aestivum L.)

Exploring Heterosis in Melon (Cucumis melo L.).

Heterosis is the superiority of an F1 hybrid over its parents. Since this phenomenon is still unclear in melon, a half diallel experiment based on eight genetically distant breeding lines was conducted in six environments of Central Italy, assessing commercially important traits: yield, total soluble solids (TSS), and days to ripening (DTR). To estimate the additive (general combining ability; GCA) and the non-additive gene effects (specific combining ability; SCA), yield was analyzed by Griffing’s methods two and four, and the results were compared to the GGE (Genotype plus Genotype by Environment interaction) biplot methodology; TSS and earliness were evaluated only by Griffing’s method four. Overall, GCAs were significantly more relevant than SCAs for all examined traits. Least square means (LsM), mid-parent heterosis (MPH), best-parent heterosis (BPH), as well as Euclidean and Mahalanobis’ distances were calculated and compared with the genetic distance (GD). As a few correlations were found statistically significant (only for TSS), it was difficult to predict the value of a hybrid combination only by knowing the genetic distance of its parents. Despite this, heterosis was observed, indicating either the presence of epistatic effects (additive × additive interactions) and/or an underestimate of SCAs embedded within Griffing’s method. The significant Env × Entries source of variation suggests development of hybrids in specific environments. The results are discussed with a breeding perspective.

Production of New F1 Hybrids Cucumber (Cucumis sativus, L.) in Open Field

This investigation was carried out at Kaha Vegetable Research Farm, Kalubia Governorate, Egypt 2015 and 2016 to study heterosis percentage over mid and better parents, potence ratio and correlation coefficient between traits for some important economical characters in cucumber. Five different parental lines of cucumber obtained from Cornell University which included parental line1380-1(P1); parental line87- 674-1(P2); parental line99-340(P3); parental line99-357(P4) and parental line99-347(P5) were carried out by 5 x 5 half diallel mating design, the experimental design was randomized complete block with three replicates. The obtained results generally that the utilized parental lines appeared to have wide ranges of diversity in the different studied traits and their indicated differences were found significant in the most situations. The results exhibited that the highest significant heterosis (47.30%) was reported for early yield per feddan(ton) followed by total yield per feddan (45.81%) and fruit shape index (40.78%), while the largest significant heterosis over better parent (33.97 and 32.86%) was recorded for early yield per feddan followed by (31.53 and 31.50% ) for total yieldThe results illustrated that plant length(cm) and number of leaves per plant exhibited significant and positive genotypic and phenotypic correlation with fruit length(cm), fruit shape index(cm), early yield per feddan(ton), average fruit weight(g), number of fruits per plant and total yield per feddan (ton). These positive correlations indicated that a selection programme based on any of these traits will be resulted in increasing yield. Negative and significant association was estimated with days to anthesis first female flower and fruit diameter(cm).