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Background: Sorghum downy mildew (SDM) of maize caused by the fungus Peronosclerospora sorghi (Weston and Uppal) C.G. Shaw is one of the most important diseases of maize and it remains vital constraint in maize production. Since maize is the highly cross pollinated crop, exploitation of heterosis is one of the breeding methods to increase the production. Negative values in the expression of heterosis indicate a contribution towards resistance which is highly needed in order to have reduced incid ence of sorghum downy mildew in maize hybrids. Methods: The materials selected as parents for the present study consisted of nine maize inbred lines which comprised of three resistant (UMI102, UMI936(w) and UMI285), three moderately resistant (UMI176, UMI13 and UMI57) and three susceptible (UMI79, UMI432 and UMI467) inbreds to SDM incidence. Nine inbred lines were crossed in all possible combinations including reciprocals in diallel fashion and the resultant seventy two hybrids along with their parents and the check (COH(M)5) were raised and evaluated for resistance against SDM under glass house condition. The extent of heterosis was estimated over mid parent, better parent and popular check hybrid. Result: Analysis of variance for sorghum downy mildew incidence revealed highly significant differences among parents and hybrids indicating greater diversity among the genotypes for sorghum downy mildew incidence under study. Out of seventy two hybrids, only three hybrids namely UMI 13 × UMI 936 (W), UMI 467 × UMI 936 (W) and UMI 432 × UMI 936 (W) exhibited three types heterosis significantly in negative direction. [ABSTRACT FROM AUTHOR]

The article evaluated the genetics of six cucumbers (Cucumis sativus L.) cultivars and 30 hybrids based on morpho-yield traits. The dominant and epistatic gene effects managed the fruit weight in three cucumber hybrids (C-25/1, A-6, and A-9), while additive gene effects in three other hybrids were supreme. For productivity per plant, dominant genes with epistatic effects controlled these in three accessions, while additive effects played a special role in manifesting the trait in three other hybrid (C-25/1, A-6, and A-9) genes. Likewise, dominant genes with epistatic effects controlled the yield per plant trait in three accessions, while additive effects influenced the attribute in three other hybrids (C-25/1, A-6, and A-9). According to these traits, the promising hybrids were С-25/1 х С25/2, С-26 х С-25/2, С-26 х С25/1, А-9 х С-26, and А-6 х С-25/1. The cucumber F1 hybrids C-26 x C29, A-9 x A-6, and A-9 x C-25/2 showed characteristics of large fruits weighing 108.2 to 113.1 g. In the accessions, C-25/1, A-6, and A-9, the additive gene effects dominated the studied trait (σ2ĝi > σ2si). The superior-in-yield hybrid combinations were C-26 x C-29, A-9 x A-6, and A-6 x A-9, with a total fruit yield of 691 to 769 g per plant. [ABSTRACT FROM AUTHOR]

In Ecuador, introduced coffee cultivars were selected, but there is no history of new cultivars having been developed through conventional genetic improvement. The objective of this research was to obtain improved coffee genotypes for the southern area of Manabí, for this the coffee germplasm bank of the State University of Manabí, located at the Andil Farm, was used in the 2021 campaign, where they were obtained F1 hybrid families using nine parental accessions (Acawa, Arara, Yellow Burbon, Catimor CIFC, Yellow Catuai, Catucai 25L, Catucai 78515, Red Caturra and Geisha), which were recombined in a Griffin diallelic design, obtaining 1477 genotypes. On the same Farm, in the nursery in the 2022 - 2023 campaigns, the materials were planted in a completely randomized experimental design. The general combinatorial aptitude (GCA) and the specific combinatorial aptitude (SCA) were determined for plant height (PH), stem diameter (SD), number of pairs of leaves (NPL), leaf area (LA), heterosis and heterobeltiosis of parents and progenies. The results showed that the Typica parent was salient and significant for PH. SD and LA. The 021-105 family was outstanding for PH, NPL and LA. The GCA for PH, SD, NPL and LA of the parents was good. There was heterosis for PH, SD and LA, in families 021-101 and 021-104; and, heterobeltiosis for PH in families 021-105, 021-106, 021-, 021-108 and 021-109; and, for LA in families 021-105 and 021-109. Genotypes with potential to be future cultivars were identified. [ABSTRACT FROM AUTHOR]

This present work aimed to evaluate the self-incompatibility and self-compatibility behaviour of the Brazilian Feijoa Active Germplasm Bank accessions. The presence or absence of the self-incompatibility of the accessions was accessed through hand self-pollination. Out of 210 accessions evaluated from 2001 to 2018, 53.3% were registered as self-incompatible, while 46.7% were self-compatible with different degrees of self-compatibility based on the number of formed fruits. Subsequently, the fruit set as a result of inter-crosses between five self-incompatible accessions were evaluated. Fifty per cent of the reciprocal crosses exhibited similar productive efficiency based on fruit set. Self-incompatible accessions, although compatible with each other, revealed differences in restoration, based on the number of fruit and seeds between reciprocal crosses. Using Spearman's correlation (rs), significant association between the number of seeds and fruit set in fruits from hand self-pollination were detected in two harvests (rs= 0.64, rs= 0.72, respectively). There was also a positive correlation between the number of seeds and yield of pulp (%) in hand self-pollination (rs= 0.30; rs= 0.39, P < 0.01), hand cross-pollination (rs= 0.35, rs= 0.64) and open pollination (rs= 0.58, rs= 0.72), respectively. These associations suggest that the number of seeds could be directly related to the pulp yield and the self-compatibility of feijoa. [ABSTRACT FROM AUTHOR]

The aim was to study the genetic control of the agronomic efficiency at low N availability in maize. Experiments were conducted in seven environments in a square lattice design with 49 hybrids, consisting of 48 crosses and one commercial hybrid, evaluated with and without application of N in top dressing. Grain yields with (GYHN) and without (GYLN) application of nitrogen in top dressing were assessed, and these traits were used to calculate the agronomic efficiency at low N availability (AELN) and the harmonic mean of the relative performance (HMRP). According to the joint analysis of variance of the diallel crosses and the estimates of the general and specific combining abilities, these traits were highly significant. Note that in general AELN was controlled by non-additive genetic effects and the hybrids H7, H3, H47 and H10 and the lines IG3-2, IG3-1, IG4-5, IG4-1 and IG4-6 show higher grain yield without top dressing. [ABSTRACT FROM AUTHOR]

This study estimated the general and specific combining abilities and mean heterosis of tobacco lines of the varietal groups Flue-Cured Virginia (FCV) and Air-Cured Burley (BY). In addition, possible advantages and an improved strategy of using hybrids in tobacco breeding in the tropics were discussed. Ten BY and 13 FCV lines were crossed in a diallel mating design. The hybrids and parental lines were evaluated at two locations in Southern Brazil. The mean heterosis was 5.37% for FCV and zero for BY lines, although higher than 15% in some combinations. The occurrence of heterosis indicates dominance in the control of tobacco yield. Tobacco breeding programs must focus primarily on improving the performance of lines per se and then on the identification of the best hybrid by testing combinations. [ABSTRACT FROM AUTHOR]

Our objectives were to evaluate general and specific combining ability (SCA) and genetic divergence among tropical maize inbred lines using single sequence repeat (SSR) markers. Thirteen inbred lines were crossed based on a complete diallel scheme. Hybrids and three checks were evaluated in a lattice experimental design. Silk and anthesis flowering, average plant height, average ear height, white spot (Pantoea ananatis) and gray leaf spot (Cercospora zeae-maydis) severity, and grain yield were evaluated. Significant differences (p < 0.05) for general and specific combining abilities were observed for all traits. Based on additive effects, inbred lines 1 (Flash) and 12 (SG 6015) were selected to reduce the flowering period and plant and ear height. Inbred lines 2 (CD 303) and 3 (AG 8080) were selected to reduce disease severity. For the simultaneous increase in grain yield and reduced severity of diseases, line 11 (AG 9090) as a parent or tester in topcross schemes is recommended. According to non-additive effects, crosses 2 (CD 303) x 13 (DKB 747) and 11 (AG 9090) x 12 (SG 6015) were selected for grain yield and future breeding programs. Six groups were identified using SSR markers; a major group contained six inbred lines. Because of the minor relationship between genetic divergence and SCA effects on grain yield limits, the use of the groups for future divergent crosses is recommended. [ABSTRACT FROM AUTHOR]

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 yield- and 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. [ABSTRACT FROM AUTHOR]

Background and aims: Although the races of maize native to the Northeast of Argentina (Misiones) have been described and a work on phenetic relations has been published, nevertheless little is known about genetic relationships, this being the main objective of this work. M&M: A group of 6 races of maize and the "F," offspring of crosses derived from a diallel scheme have been evaluated on the basis of 21 morphological vegetative, reproductive and phenological quantitative traits using ANOVA and multivariate statistical methods (discriminant canonic analysis and cluster analysis). Results: The ANOVA showed highly significant differences among parental races and progeny for almost all the variables. The first two canonical variables (CV) explain almost 67% of overall variation. The most important discriminating characters associated with the first CV correspond to dimensions of ears and grains, while the traits contributing to the second CV are related mainly to vegetative and reproductive morphology. Racial groups defined by cluster analysis were described. Conclusions: Cluster analysis allowed distinguishing related racial groups. The genetic relationships observed from diallel crosses are different according to the parameter considered for regrouping. The results obtained are important from the taxonomic and evolutionary point of view and facilitate the choice of material to be used in breeding programs. [ABSTRACT FROM AUTHOR]

Common bean parents and populations resistant to white mold (WM, caused by Sclerotinia sclerotiorum) were selected based on estimates of general combining ability (GCA) and specific combining ability (SCA) for WM severity in three field nurseries in Brazil. Twenty-seven populations were obtained by partial diallel crosses between parents from two groups: GI) three sources of partial resistance identified abroad and GII) nine Brazilian cultivars and elite lines. Populations were advanced in bulk up to the F6 generation. The overall mean of WM severity from combined analysis ranged from 2.83 to 5.03 (scale of 1 to 9 scores) in the F6 population. The score of the susceptible control BRS Requinte was 7.21. The GI parents K-59, in Oratórios, MG, and Viçosa, MG, and K-407 and PI204717, in Goianira, GO, contributed to increase resistance to WM. The most promising populations for obtaining elite lines resistant to WM were K-59/BRS Executivo, PI204717/BRS Campeiro, PI204717/Jalo Precoce, K-59/BRS Radiante, and K-407/BRS Cometa. [ABSTRACT FROM AUTHOR]

Twenty one wheat hybrids and their seven parental genotypes were evaluated in the research farm of the Faculty of Agriculture ,Ain shams University, Shoubra El-khema, Cairo, Egypt, in 2016/2017 growing season. The genetic analysis was conducted using Griffing( 1956 ,)Method 2, model 1). Significant differences among parent genotypes and their 21 crosses for all the studied traits (days to 50% heading, days to maturity, flag leaf area, plant height, number of spikes/ plant, spike length, number of spikelets/ spike, number of kernels/ spike, 1000-kernel weight and grain yield/ plant) were detected. This indicated that, variability exists among these populations may increase the chance appearance of good new combination that can be isolated in the succeeding generations. Parents versus crosses mean squares as an indication for average heterosis over all crosses were significant for all studied traits. Mean squares of general (GCA) and specific (SCA) combining abilities were significant for all studied traits except spike length trait for SCA which was insignificant. GCA/SCA ratios were more than unity for all studied traits, which indicating that the additive type of gene action is of great importance in the inheritance of these traits. Heterosis over the better parents showed that, the best hybrids were Gemmiza 9xGiza 168, Sakha 93x Giza, 168, Sakha 94x Jawahir-14, Sakha 94x Bob white, Giza 168xAcsad 925 and Jawahir-14x Bob white for grain yield/ plant trait and some of the other studied traits. The best general combiner parents were Sakha 94, Jawahir-14 and Bob white for grain yield/ plant trait and some of the other studied traits. The best SCA hybrids were Gemmiza 9x Sakha 93, Gemmiza 9x Giza 168, Sakha 93x Jawahir-14, Sakha 94xJawahir-14, Sakha 94x Acsad 925, Sakha 94xBob white, Giza 168x Jawahir- 14, Giza 168x Acsad 925, Jawahir-14x Bob white and Acsad 925x Bob white for grain yield/ plant trait and some of the other studied traits. These result could be used in wheat breeding programs. Wheat (Triticum aestivum L.) is one of the leading cereals and staple food in many countries of the world including Egypt. It plays a remarkable role in meeting the food requirements of the country [Barutcular et al 2017; Ljubičić et al 2017; Singh, S.P. and V. Sharma, 2017; Thomas et al 2017 and Tiwari et al 2017]. In Egypt, wheat is the main winter cereal crop used as a staple food for urban and rural societies and the major source of straw for animal feeding [Ismail 2015, Hamda and Ibrahim 2016 and Kandil et al 2016]. However, total wheat consumption has increased drastically due to over population growth by about 2.5 % per year. Egypt imports about 45 % of its wheat requirements. This reflects the size of the problem and the efforts needed to increase wheat production. Thus, increasing production per unit area appears to be one of the important factors for narrowing the gap between wheat production and consumption. Information regarding general and specific combining ability of wheat genotypes is a prerequisite to launch a successful wheat-breeding programs. Diallel mating design has been extensively used to analyze the combining ability effects of wheat genotypes and also to provide information regarding genetic mechanisms controlling grain yield and other traits. Knowledge of general and specific combining ability. influencing yield and its components has become increasingly important for plant breeders in the choice of suitable parents for developing potential possessing varieties in wheat. Many researchers gave reviews, which revealed that both general and specific combining ability were involved in the improvement of yield and its contributing traits in wheat such as [Tiwari et al 2017; Patel, 2017; Ljubičić et al 2017; Kumar et al 2017 and Ahmad et al 2017]. [ABSTRACT FROM AUTHOR]

Half F2 diallel crosses of eight spring cultivars of rapeseed were used in partial circulant diallel analyses to estimate biometric genetic parameters for phenological traits, yield components and seed yield. The greatest variation in the GCA-to-SCA mean square ratio was related to days to flowering, and its lowest variation to days to maturity. A high coefficient of variation of the narrow-sense heritability estimate was obtained for days to maturity, followed by plant height and seed yield. For diallel analysis with a low number of parents, the differences of the heritability estimates of the traits were small; therefore, for precise estimation of heritability, a high number of diallel crosses will be preferred. [ABSTRACT FROM AUTHOR]

To date, no studies on the inheritance of Fusarium spp. ear rot resistance in popcorn are available. The purpose of this paper was to investigate the additive-dominance model to estimate the genetic components of variance, heritability and the inheritance pattern in a diallel for popcorn, by Hayman's approach. The experiment was carried out in two environments, using eight parent lines. The following traits were measured: grain yield (GY), popping expansion (PE), incidence of ears infected by Fusarium (FusIE), total number of kernels infected by fungi (FunIK) and total number of kernels infected by Fusarium spp. (FusIK). The results indicated that the incidence of FusIK (Fusarium-infected kernels), FunIK (fungus-infected kernels), and FusIE (Fusarium-infected ears) is controlled by dominant genes. Parent L77 had a high number of favorable alleles for all resistance-related traits, as well as for PE. The strategy recommended for reduction of FunIK, FusIK, and FusIE consists of exploiting hetorosis using inbred lines with favorable alleles. [ABSTRACT FROM AUTHOR]

Fusarium oxysporum f. sp. phaseoli ( Fop) is a soil pathogen that causes wilt in common bean ( Phaseolus vulgaris L.) and is one of the most important diseases of this crop. The use of resistant cultivars is the most effective method of controlling losses from this pathogen, and studying the inheritance of Fop resistance could provide useful insights for developing cultivars with resistance. Thus, the aim of this study was to determine the inheritance of resistance to fusarium wilt in common bean. The parents, F and F plants from seven crosses between resistant and susceptible parents of a partial diallel scheme 3 × 5 were inoculated with the isolate FOP UFV 01. During each generation, the plants were individually evaluated to determine disease severity. Among the eight parents, five were resistant, and three were susceptible to fusarium wilt. Only two phenotypic classes were observed in the parents (resistant and susceptible). Based on the performance of the F generation, all the individuals were resistant, indicating that resistance is dominant over susceptibility. Different results were obtained for the segregation of plants from the F generation based on the methods applied to determine the inheritance of resistance. However, the maximum likelihood estimator method, which was the most suitable methodology, showed that Fop resistance in common bean is a dominant trait governed by few major genes plus polygenes. These findings can support breeding programs in obtaining Fop-resistant cultivars. [ABSTRACT FROM AUTHOR]

The aim of this work was to estimate the combinatory aptitude, genetic variance and heterosis of eight creole corn varieties. The research work was carried in Irapuato, Guanajuato, México, during 2008 and 2009. A randomized complete block design with three replications was used to evaluate the twenty-eight crosses under method 4 Griffing (1956). Each experimental plot included four rows five meters long with a separation of 0,75 m. The general combing ability and specific (ACG and ACE) were highly significant (P<0.01) for all traits except flowering days. The dominance variance (s2D) was larger and more important than additive variance (s2A) for most of the traits, indicating that non-additive genetic genes were important on the expression of those traits on crosses. It was observed that varieties P6 (creole #5), P7 (creole #2) and P8 (creole San Antonio) had larger variance effects (s2ACE) for long cob, number of rows per cob, total cob number, and grain yield. Some outstanding crosses were identified for their high grain yield as well as heterosis, mainly those that included germoplasm of creole #5, #2 and San Antonio. According to the aforementioned we recommend to draw lines from the above populations and cross them to produce hybrids. [ABSTRACT FROM AUTHOR]

Combining ability was determined in an 8 × 8 diallel intra specific F1 crosses in rapeseed (Brassica napus L.) during 2011-2013 to scrutinized potential lines, hybrids, and nature of gene action involved in the inheritance of maturity and plant architecture traits. Analyzed data revealed highly significant differences among the genotypes for days to flowering, maturity, plant height, primary branches plant-1 and main raceme length. Analysis of combining ability revealed highly significant GCA (general combining ability), SCA (specific combining ability) and RCA (reciprocal combining ability) effects for the studied traits. Based on GCA, best general combiners were AUP-7 for earlier flowering and maturity, AUP-2 for plant height, AUP- 14 for primary branches plant-1 and AUP-9 for main raceme length. Based on SCA effects, best F1 hybrids were AUP-7 × AUP-14 (days to flowering), AUP-8 × AUP-9 (days to maturity), AUP-17 × AUP-18 (plant height), AUP-14 × AUP-20 (primary branches plant-1) and AUP-14 × AUP-20 (main raceme length) and could be utilize in future rapeseed breeding programs. The estimates of variances of combining ability (σ2GCA, σ2SCA) and predictability ratio (σ2GCA/σ2SCA>1.00) indicated that gene action was predominantly additive for days to flowering while, for the rest of the traits non additive gene action was responsible as the predictability ratio was less than unity which was further confirmed by higher values of variances of SCA than GCA. In present study for all the traits except days to flowering, non-additive gene action was prominent therefore selection should be delayed to late segregation generation. [ABSTRACT FROM AUTHOR]

Vitamin A deficiency (VAD) is of public health significance in the developing world. In spite of extensive promotion of orange-fleshed sweetpotato(Ipomoea batatas)varieties (OFSPs), they are poorly utilized in Ghana because of their low dry matter and high sugar content. The objective of this study was to develop farmer- and consumer-preferred beta-carotene-rich varieties to increase OFSP utilization in Ghana and beyond. One released variety in Ghana (Apomuden) and four other varieties which are introductions (Beauregard, Resisto, CIP 442850, and CIP 443035) were used as parents. They were crossed using the full diallel mating design. There was significant genetic variation for the traits and among the F1hybrids. Significant positive and negative heterosis was found, but the levels were not adequate for the development of non-sweet, high dry matter, and high beta-carotene-rich varieties. Twenty-one F1hybrids that had comparable beta-carotene content and storage root yield but lower sugar content than the only released high-beta-carotene variety in Ghana were identified for further testing for potential release. [ABSTRACT FROM PUBLISHER]

Six white maize (Zea mays L.) inbred lines were crossed in a half diallel mating scheme at Gemmeiza Agric. Res. Stn. in 2009 season. In 2010 season, the resulting lS crosses along with three check hybrids.; SC 10, SC 128 and SC 129 were evaluated at Gemmeiza and Mallawy Agric. Res. Stations. General combining ability (GCA) and specific combining ability (SCA) effects were estimated according to Griffing (19S6) model 1, method 4. Location mean squares were highly significant for ear diameter and 100-Kernel weight, while crosses and cross x location interaction mean squares were highly significant for all traits. Mean squares due to GCA and SCA were significant revealing that both additive and non-additive types of gene effect were involved in the inheritance of the studied traits. GCA/SCA mean square exceeded the unity for no. of rows ear-1 at Mallawy and combined data, no. of kernels row-1 at Gemmeiza and grain yield at Gemmeiza and combined data, indicated the predominance of additive (a) and (aa) gene effects in the genetic variance of these cases, while the same ratio mean squares were less than unity for the rest of the cases indicating that non-additive genes played an important role in the inheritance of these traits. 'P3' was considered as a good general combiner for 100-kernel weight at Gemmeiza. The cross; P2 x PS had significant inter-and intra-allelic interactions for no. of kernels row-1, 100-kernel weight and grain yield at both locations. The crosses; P2 x PS, P3 x P4 and P3 x P6 were superior to the three check hybridS'for 100-kernel weight and grain yield. [ABSTRACT FROM AUTHOR]

The aim of the present research was to study the combining ability and heterosis effect for seed yield and its components in sesame under Shandaweel (Upper Egypt) conditions, usirlg half diallel ,crosses during the summer seasons of 2012 and 2013. Eight genotypes were crossed to produce 28 hybrids However, results indicated that genotype variance was significant for all the studied traits. The general (GCA) and specific combining ability (SCA) effects were highly significant for all the studied traits, indicating that additive and non-additive gene actions were involved in the inheritance of all traits. Both additive and dominance components were important for all traits. Among genotypes, Giza 32 proved itself as a good combiner for all the studied traits. 820 proved to be a good combiner for all the studied traits except for oil percentage. Shandaweel 3 also proved itself as a good combiner for the studied traits except for plant height and fruiting zone. Hence, these three local pare nts could be used as donor parents in hybridization programs for transferring desirable traits. With respect to SCA, the crosses (Giza32xline107-2) had significant SCA for all the studied traits; (Giza32xline102f7) had significant SCA for the studied traits except for 1000-seed weight, while (Line102f7xB20) had significant SCA for all studied traits except for oil perce?tage. Meanwhile, the crosses (Shandaweel3xLine87) and (Line107-2xline109f7) had significant SCA for the studied traits except for oil percentage and 1000-seed weight. However, cross (Shandaweel3xlinelllfll) had significant SCA for the studied traits except for seed yield plot-1 and seed weightplant-1, while cross (Line102f7xline87) for all the studied traits except for 1000-seed weight and capsule number. Some crosses showed the maximum desirable heterotic effects over mid and better parents as cross (Line102f7xB20) for seed yield plot-1, seed weight plant-1 and number of capsules plant-1, and cross (Line87xlinelllfll) for oil percentage, cross (Shandaweel3xGiza32) for 1000-seed weight, cross (Shandaweel3xline87) for plant height and fruiting zone. Heritability estimates in broad sense ranged from 77.4 for 1000-seed weight to 97.9 for number of capsulesplant-1. The general and specific combining abilities were highly significant for all traits, indicating that additive and non-additiye gene action were involved in the inheritance of those traits. [ABSTRACT FROM AUTHOR]

Investigations were made with ten varieties of tobacco types : Prilep (P- 23, P- 76, P- 66-9/7, P-84), Yaka (YK 10-7/1), Djebel (Xanthe, XDj-M), Basmak (MB-3), Samsun (SM-1), Sirdili (SM-LL) and Virginia (MV-1) and their 45 diallel crosses for resistance to diseases, with an emphasis on black shank - Phytophthora parasitica var. nicotianae. The trial with parental genotypes and their hybrids was set up in 2011, 2012 and 2013 at the Experimental field of the Scientific Tobacco Institute - Prilep in randomized block design with three replications. Traditional agricultural practices were applied during the growing season. The resistance/susceptibility degree was estimated according to a scale recommended by FAO. The aim of this paper is the detection of resistance to black shank and creation of resistant lines, using diallel analysis to obtain a knowledge on the genetics of this disease. The highest resistance to the disease was recorded in YK 10-7/1 and SM-LL, while the varieties MV-1 and P-76 showed to be the most susceptible. The highest resistance in the diallel was recorded in the crosses where one of the parents was YK 10-7/1, which indicates a possession of dominant gene of resistance. In the process of breeding, the method of Back-cross hybridization was used in order to increase the varieties resistance to the black shank disease. [ABSTRACT FROM AUTHOR]

Investigations were made with six oriental varieties of tobacco types Prilep, Djebel and Yaka (P-23, P-84, P10- 3/2, P-76, Xanthi Djebel 1 and YV 125/3) and fifteen F1 hybrids for the characters flowering time and length of growing season from tobacco transplanting in field to the end of harvest. The field trial was set up in 2010 and 2011 in Tobacco Institute - Prilep in a randomized block design with four replications. All appropriate cultural practices were applied during the growing season. Statistical processing of data was performed by using the analysis of variance (ANOVA) The aim of this work was to study the mode of inheritance and to detect possible heterotic effects for the above biological characters, which will allow a selection of lines with longer growing season, higher productivity and some other positive characters inherited from the early-maturing parent. They would be promising genotypes intended for arid regions with poorer soils and longer growing season. The period from tobacco transplanting to 50% flowering in parental varieties ranged from 45 to 95 days in Xanthi Djebel-1 (XDj-1) and in P-76, respectively, while the period from transplanting to the end of leaf harvesting in these two genotypes ranged from 70 to 145 days. There were differences in inheritance of the two stages among hybrids. The most common types of inheritance were partial dominance and dominance. The early-maturing parent dominated in the first period, while the late-maturing parent dominated in the second period and there was also an appearance of heterosis. [ABSTRACT FROM AUTHOR]

The paper concerns the mode of inheritance and assessment of heterotic effect in si× diallel F1 crosses of four parental genotipes (large - leaf variety Burley B - 2/93 and the oriental Suchum S1 with pink flowers, Suchum S2 with white flowers and Prilep P - 84), for the following characters: stalk without inflorescence, leaf number per stalk, middle belt leaf area, green mass yield and dry mass yield per stalk. The trial was set up in the field of Scientific tobacco institute - Prilep, in randomized blocks with four replications during 2007, 2008 and 2009 and traditional cultural practices were applied in tobacco growing. The analysis of variance was used to determine statistically significant differences between parents and their hybrids for the characters investigated during the three - years period. Positive heterosis with poor heterotic effect was recorded in S1 × S2 hybrid for stalk height without inflorescence and for green/dry mass yields per stalk, while in S2 × P-84 only for height of the stalk without inflorescence. Negative heterosis with poor heterotic effect was recorded in hybrids S1 × P-84 for leaf number and for green/dry mass yields and S2 × P-84 for leaf number and green massyield per stalk. The low heterotic effect indicates that utilization of heterosis in investigated tobacco genotypes is without economical justification, but in the same time it points out to the eventual breeding activities for creation of new more superior varieties. [ABSTRACT FROM AUTHOR]

Six corn populations drawn from outstanding forage quality germplasm, and 15 of their direct crosses were assessed in four sites located between 1,117 and 1,932 m asl. The purpose of the present study was to determine general and specific combining ability and mid parent heterosis for whole plant dry matter (TDM), ear dry matter (EDM), stover dry matter (SDM), in vitro dry matter digestibility (IVDMD), neutral detergent fiber content (NDF) and crude protein (CP). Populations showed significant differences for all dry matter yield characteristics, but not for forage quality, while crosses showed differences for EDM and IVDMD. General combining ability effects (GCA) were high and significant only for TDM, while specific combining ability effects (SCA) were significant for IVDMD. Population P3 had the highest GCA for TDM (0.66 t ha-1) and P5F for EDM (0.49 t ha-1). Early cross P1*P2 had the highest heterosis for TDM (17.6 %) and highly significant SCA effects for both TDM and IVDMD (1.48 t ha-1 and 22.6 g kg-1, respectively), while crosses P2*P5F, P1*P4 and P1*P6F had high mid parent heterosis for EDM, with values ranging from 18.6 % to 26.2 %. None of the crosses showed mid parent heterosis for forage traits of importance. [ABSTRACT FROM AUTHOR]

Breeding for drought tolerance requires the knowledge of gene action governing different physiological and yield traits. Six wheat genotypes were crossed in 6 x 6 half diallel fashion during 2009. The parents and their 15 F1 hybrids were evaluated in a randomized complete block (RCB) design with four replications under two irrigation treatments during 2010 at Sindh Agriculture University, Tandojam-Pakistan. All the physiological and yield traits were significantly affected by the water stress treatments. Physiological and yields traits like productive tillers plant-1, grains spike-1, grain yield plant-1, relative water content, stomatal conductance and leaf area were good indicators to distinguish drought tolerance of wheat genotypes. The wheat cultivars such as TD-1, Sarsabz and SKD-1 performed well under stress conditions. The mean squares for general and specific combining ability were significant for all the parameters suggesting that both genetic variances were substantial. Generally, in stress conditions, the GCA was predominant as compared to SCA variances. The GCA effects of the parents in non-stress and in water stress conditions revealed that TD-1, Sarsabz and Kiran were good general combiners, hence are potential parents to be used in hybridization and selection programmes for the development of drought tolerant breeding material. It was interesting to note that hybrid performance per se was largely reflected in their SCA effects. Among the fifteen F1 hybrids evaluated, the crosses TD-1 x TJ-83, Kiran x Sarsabz and Sarsabz x Moomal were good specific combiners for majority of the traits, thus these hybrids may be considered as prospective hybrids under drought conditions. [ABSTRACT FROM AUTHOR]

For in vivo production of doubled haploid (DH) lines in maize, the rate of haploid induction is of crucial importance. Maternal haploid induction depends primarily on the inducer used as a pollinator. However, the source germplasm used as a maternal parent and the environmental conditions for induction may also influence haploid induction and these aspects have not been examined in tropical maize so far. The objectives of our study were to (i) monitor the variation for haploid induction rate (HIR) among diverse source germplasm in tropical maize, (ii) determine the relative importance of general (GCA) and specific (SCA) combining abilities for HIR, and (iii) investigate the influence of summer and winter seasons and genotype × season interactions on this trait. Ten inbreds were mated in a half diallel design. The resulting 45 F single crosses were pollinated with the haploid inducer hybrid RWS × UH400 during the summer 2008 and winter 2009 seasons in a lowland tropical environment in Mexico. HIR of the single crosses averaged over seasons ranged from 2.90 to 9.66% with an overall mean of 6.74%. Mean HIR was significantly ( P < 0.01) higher during the winter (7.37%) than summer season (6.11%). Significant ( P < 0.01) variation was observed due to GCA effects of parental inbreds of single crosses but not for SCA, GCA × season and SCA × season interactions. Our study underpins that a higher HIR in tropical maize can be obtained by selecting appropriate source germplasm and undertaking pollination under favorable environmental conditions. [ABSTRACT FROM AUTHOR]

We examined the heterotic parameterizations of diallel crosses among 10 popcorn inbred lines in two different environments (municipalities of Campos dos Goytacazes and Itaocara, Rio de Janeiro State) and originating from tropical, temperate and subtropical germoplasm. Traits, including grain yield (GY), plant height (PH), ear height (EH), days to silking (FL) and popping expansion (PE), were measured. The inbred lines and the hybrids were evaluated in a randomized complete block design with three replications. The sources of genotypic variation, inbred lines and heterosis had significant effects on all traits. When the sources of heterotic variation were compared separately, estimated mean heterosis was found to be significant for all traits. When inbred lines and specific heterosis was investigated, only popping expansion was not significantly different, demonstrating that heterotic effects are favorable for developing superior hybrids. A direct relation between gi and Vi was made clear, especially for traits that were slightly influenced by the effects of dominance. Additivity was determined to have the best effect for improving popping expansion. The hybrid combinations had positive estimates of heterosis for the GY but not for PE. The hybrids P1 x P3 and P2 x P4 had the best responses for the GY and PE. The superiority of the combination P1 x P3 shows that the addition of genomes with different edaphoclimatic adaptations is an important factor in obtaining superior hybrids. [ABSTRACT FROM AUTHOR]

A 6 x 6 complete diallel mating design was used to study the inheritance of different plant traits in upland cotton (Gossypium hirsutum L.). Six genotypes viz., BJA-592, ACALA-SJ-4, 4-F, CP-15/2, CIM-497 and PB-899 were included in diallel crosses. Results revealed that over-dominance type of gene action was controlling the inheritance of monopodial and sympodial branches plant height number of bolls and boll weight. The line CP-15/2 possessed maximum dominant genes for monopodial branches, plant height and boll weight, BJA-592 for sympodial branches and ACALA-SJ-4 has maximum dominant genes for bolls per plant. However the cultivar CIM-497 carried maximum recessive genes for monopodial branches and plant height, PB-899 for bolls per plant and sympodial branches while ACALA-SJ-4 has maximum recessive genes for boll weight. [ABSTRACT FROM AUTHOR]

To measure genetic relatedness between populations, for breeding purposes, we analyzed 170 birds from six crossbred populations of three pure lines of White Leghorn chickens, using 14 microsatellite markers. All the microsatellites were polymorphic, with 2–6 alleles. The mean number of alleles per locus was 3.21. The effective number of alleles varied from 1.14 to 3.94. The observed heterozygosity varied from 0.133 to 1.00, with a mean of 0.748. The F values were mostly negative, with an average of −0.345. The mean F value was 0.056. The Nm values ranged from 1.91 to 42.17. The highest genetic identity was observed between IWI × IWK and IWK × IWI. The relation between any two groups of crosses was more than 85%. The results suggest that the crossbred populations were very closely related. [ABSTRACT FROM AUTHOR]

In the genetic breeding of plants and animals, it is common to make the evaluation of treatments in diverse environmental conditions, emerging the necessity to project researches in a series of similar experiments, such as in the Griffing's designs. In such case, in most of the occasions, the combined analysis of the series of experiments, including the diallel crosses, has been done on the basis of a fixed effects lineal model, in spite of the random nature of the general and specific combining abilities in the diallel crosses experiments. Therefore, in the present work for Griffing's designs one and three, established in complete blocks of randomized designs, the combined empirical best linear unbiased predictors are derived from the general combining ability effects, based on the estimation methodology of random effects in a mixed effects model. Additionally, a computational algorithm is presented, in SAS/IML, for the combined analysis of experiments. [ABSTRACT FROM AUTHOR]

The inheritance of resistance to root-lesion nematode was investigated in five synthetic hexaploid wheat lines and two bread wheat lines using a half-diallel design of F1 and F2 crosses. The combining ability of resistance genes in the synthetic hexaploid wheat lines was compared with the performance of the bread wheat line ‘GS50a’, the source of resistance to Pratylenchus thornei used in Australian wheat breeding programmes. Replicated glasshouse trials identified P. thornei resistance as polygenic and additive in gene action. General combining ability (GCA) of the parents was more important than specific combining ability (SCA) effects in the inheritance of P. thornei resistance in both F1 and F2 populations. The synthetic hexaploid wheat line ‘CPI133872’ was identified as the best general combiner, however, all five synthetic hexaploid wheat lines possessed better GCA than ‘GS50a’. The synthetic hexaploid wheat lines contain novel sources of P. thornei resistance that will provide alternative and more effective sources of resistance to be utilized in wheat breeding programmes. [ABSTRACT FROM AUTHOR]

Although largely ignored until recently, parental effects on the phenotypes of their offspring are both ubiquitous in nature and of a potentially great importance to evolution. Our study examines the presence of extra-nuclear (maternal and paternal) effects in growth traits, development time and adult size in the sand cricket Gryllus firmus using a diallel cross of inbred lines. Sex linkage was shown to be nonsignificant for development time but the other traits could not be tested. We assume that they are nonsignificant but use the term ‘reciprocal’ effects to include this effect. We show that reciprocal effects are present in the growth traits and development time, where they account for 10–30% of the phenotypic variance. They are not present in adult size as indexed by head width. We demonstrate that reciprocal effects are due, at least in part, to maternal effects by an analysis of the positive correlation between egg size, a maternal trait, and the growth traits. The growth rate traits show no significant decline with age either with respect to extra-nuclear contributions to variance or difference between phenotypic means of reciprocal pairs. This study demonstrates that extra-nuclear effects are important contributors to the phenotypic variation in life history traits of G. firmus. [ABSTRACT FROM AUTHOR]

Four resistance components, i.e. incubation period, latent period, maturation period and pycnidial coverage, were studied in a diallel cross of four wheat cultivars differing in susceptibility to Septoria tritici. Inoculations and evaluations were carried out at the fourth leaf stage for two years. A combined ANOVA for both years exhibited a significant interaction between crosses and years for maturation period. A separate ANOVA for each year was done for this trait. The combined ANOVA showed that crosses were significantly different for incubation, latent period and pycnidial coverage. Cross effects were also significant for maturation period in each year for the separate ANOVA. Year effects were significant for latent period and maturation period. General combining ability (GCA) was significant and preponderant for incubation period, latent period and pycnidial coverage. For maturation period, the separated ANOVA showed the significance of the GCA for both years. Specific combining ability (SCA) was significant for incubation and pycnidial coverage and for maturation in one year. The preponderance of the additive genetic variance for all traits indicates the possibility of selecting for them in order to obtain improved cultivars. Incubation period was inherited independently of maturation period and pycnidial coverage, indicating that combinations of some of those characters may lead to more effective and durable resistance. [ABSTRACT FROM AUTHOR]

Compared with annual cultivated rice, perennial rice had great advantages of soil erosion control, labor saving, water and fertilizer management, etc. As the key organ for perenniality, rhizome can help grasses to achieve rapid expansion to occupy more environmental resources, and withstand the harsh environmental conditions. Oryza longistaminata, a perennial wild relative of rice with vigorous rhizomes, is an ideal donor for transferring perenniality to Asian cultivated rice (Oryza sativa). However, some hybrid F1 between O. longistaminata and cultivated rice didn't have rhizomes. Obtaining rhizomatous hybrid progeny becomes a prerequisite for the rhizomes study. In this work, four varieties of O. sativa and three accessions of O. longistaminata were used to carry out an incomplete diallel cross experiment. It was found that most F1 hybrids had rhizomes with varying length and numbers. Data analysis showed that the general combining ability (GCA) of the female parents had significant effect on rhizome-related trait of the F1s. Nevertheless, the GCA of the male parents and special combining ability of the hybrid combination played minor effect. And we speculated that the appropriate choice for female parents is more crucial to obtain rhizomatous hybrid. As the first incomplete diallel cross between O. longistaminata and O. sativa, this work would be benefit to appropriate parent selection for genetic research and breeding of perennial rice. [ABSTRACT FROM AUTHOR]