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Northeast China (NEC) is a major spring maize (Zea mays L.) growing belt, and the outputs substantially influence national grain production. However, the maize grain yield per unit area has little changes in recent years, partially due to the lack of elite germplasm resources and innovation. Therefore, this study aimed to determine the performance of diverse populations in NEC to propose appropriate strategies for the utilization of elite germplasm to broaden the genetic base of Chinese germplasm. Fifteen diverse maize populations from the International Maize and Wheat Improvement Center (CIMMYT) and the U.S. were crossed to two local tester lines, representing Chinese heterotic groups Reid and Lancaster, for evaluating the combining ability and heterosis in three locations (Gongzhuling, Jilin Province, and Harbin and Suihua, Heilongjiang Province) in NEC over two years. The U.S. (BS13(S)C7 and BS31) and Chinese (Ji Syn A) populations exhibited more favorable alleles for high yield potential in all locations tested. Furthermore, the PH6WC × BS31 and PH6WC × Ji Syn A crosses had higher grain yields, and an appropriate number of days to silking, ear height, and resistance to lodging at Gongzhuling and Harbin in NEC. The best strategies for utilizing these diverse germplasms may be to develop new inbred lines from the existing elite populations or improve the grain yield and resistance to lodging of the elite line PH4CV for broadening the genetic base of the Chinese group Lancaster in NEC. [ABSTRACT FROM AUTHOR]

To ensure food and feed security, modern maize hybrids must not only perform well under changing climate conditions but also consistently achieve higher and stable yields, exhibit maximum tolerance to stress factors, and produce high quality grains. In a study conducted in 2022 and 2023, 50 maize hybrids were developed from crosses of five elite (highly productive) inbred lines and ten lines possessing favorable genes for carotenoid content. These hybrids were tested under particularly unfavorable conditions for maize cultivation. The aim was to identify which lines effectively transmit the desired traits to the offspring (general combining ability—GCA), and to identify superior hybrids in terms of productivity, adaptability, and quality (specific combining ability—SCA). The study revealed that total carotenoids ranged from 2.30 to 40.20 μg/g for the inbred lines and from 7.45 to 25.08 μg/g for hybrids. A wider distribution of values was observed in the inbred lines compared to the hybrids for key carotenoids such as lutein, zeaxanthin, β-cryptoxanthin, and β-carotene. Among the hybrids, notable performers in yield, adaptability, and carotenoid content included E390×D302, A452×D302, and A447×D302. The paternal inbred line D302 exhibited a high general combining ability for yield (1446 kg ha−1) and, when crossed with several inbred lines, produced hybrids with enhanced yields and higher levels of zeaxanthin, lutein, and β-carotene, as well as improved unbroken plants percent. [ABSTRACT FROM AUTHOR]

Background: Orange maize genotypes are sources of provitamin A (PVA) carotenoids, which are precursors of vitamin A. PVA deficiency and drought constitute major challenges causing increasing food and nutritional insecurity in sub-Saharan Africa (SSA). Breeding of drought-tolerant provitamin A hybrid maize can mitigate these challenges. This study was undertaken to determine the combining ability of newly developed extra-early orange inbreds for grain yield and related traits under managed drought stress and rain-fed conditions, determine the mode of gene action conditioning the inheritance of the traits, and classify the inbreds into heterotic groups. Methodology: One hundred and ninety-six extra-early orange hybrids comprising 180 testcrosses, 10 single crosses, and 6 commercial checks were evaluated under managed drought and rain-fed conditions at Ikenne. In addition, 41 inbreds comprising 36 orange lines and 5 PVA testers involved in the hybrid development were assessed under drought and rain-fed conditions. Results: The means square for general combining ability (GCA) and specific combining ability (SCA) were significant for grain yield and most other traits under both growing conditions. The contributions of GCA to performance were larger than SCA in each growing condition. Broad-sense and narrow-sense heritability estimates for grain yield were 66% and 37% under managed drought and 88% and 32% under rain-fed conditions, respectively. Mid-parent heterosis and better-parent heterosis for grain yield were 338% and 247% under managed drought, while 173% and 137% under rain-fed conditions. Significant positive correlations existed among grain yield of hybrids, heterosis, and specific combining ability under managed drought. The 41 inbred lines were classified into three heterotic groups under both growing conditions. Sixteen testcross hybrids out-yielded the best commercial check under managed drought. Conclusion: The testcross hybrids have great potential for commercialization to address the problem of drought and PVA deficiency in SSA. Inbred TZEEIOR 510 showed desirable GCA effects for grain yield and 04 other traits under drought. [ABSTRACT FROM AUTHOR]

Drought is a major constraint on maize (Zea mays L.) production and productivity in Sub-Saharan Africa (SSA). The increase in frequency and severity of drought, driven by climate change, is expected to worsen in the future. These occurrences are likely to adversely affect maize production and productivity, threatening the economic and social stability of millions of smallholder farmers. Understanding the genetics of hybrid performance under drought stress is crucial for designing breeding strategies to develop high-yielding hybrids. This study aimed to (i) evaluate the performance of three-way cross hybrids developed from elite inbred lines, including several drought-tolerant lines, using a line-by-tester mating design, and (ii) estimate the general combining ability (GCA) and specific combining ability (SCA) effects of the tropical maize inbred lines under managed drought and optimum conditions. A total of 265 maize inbred lines from the CIMMYT global maize breeding program were used as parents and crossed to six single cross testers to generate 795 testcross hybrids. These hybrids, along with six commercial hybrids as a check, were evaluated under managed drought and optimum conditions. Significant (p < 0.001) variations were observed among genotypes and genotypes-by-environment interactions (GEIs) for grain yield and other traits. There was a preponderance of GCA variance (lines and tester) over SCA variance, indicating that additive effects were more important in determining grain yield and other key traits under both managed drought and optimum conditions. Ten inbred lines (S2_8, S10_1, S6_4, S10_14, S2_14, S10_15, S8_7, S2_3, S8_15, and S13_5) with desirable GCA effects for grain yield and other traits were identified. Fourteen testcross hybrids were identified with high grain yield and desirable agronomic traits under both drought and optimum conditions. The identified lines and hybrids are useful sources to be used in breeding and deploying as stress-tolerant hybrids. High correlations observed between observed and GCA-predicted hybrid performance suggest the possibility to evaluate more hybrids with fixed resources. The study demonstrates that it is feasible to obtain high-yielding and drought-tolerant lines and hybrids. These testcross hybrids should undergo rigorous on-farm trials to ensure consistent performance before commercialization and release. Deploying these hybrids could help in mitigating the effects of drought stress in SSA and contribute to improved maize productivity in the region. [ABSTRACT FROM AUTHOR]

Low soil nitrogen (N) is a significant challenge to maize (Zea mays L.) production in Sub-Saharan Africa, particularly for small-scale farmers. Developing maize hybrids tolerant to low N is crucial for improving yields under such conditions. This study examined the genetic basis of agronomic traits in intermediate/late maturing maize inbred lines under contrasting N conditions, focusing on general combining ability (GCA) and specific combining ability (SCA) effects. Two hundred and thirty-seven F1 hybrids from 79 inbred lines crossed with three testers in a line x tester mating design, were evaluated across eight environments in Nigeria. Line x tester analysis revealed that GCA effects, primarily from lines, predominantly influenced grain yield and other traits across both N conditions, except for ear height and plant aspect under low N, where SCA effects also had significant impact. A significant (p ≤ 0.01) positive correlation was observed between GCA and SCA effects, suggesting a positive relationship between additive and non-additive genetic components. Lines SMLW146 and SMLW147 were identified as valuable resources for breeding low-N tolerant hybrids. Additionally, considering non-additive effects, hybrids SMLW22 × SAM50M and SMLW106 × SAM50M (under low-N) and SMLW3 × IITA1876, SMLW84 × IITA1876, and SMLW165 × IITA1876 (under optimum-N) were promising combinations for high grain yield. Morphological traits like plant height and ear height, phenological traits like days to anthesis and silking, and qualitative traits like ear aspect and plant aspect were identified as important for selecting genotypes with improved grain yield under low-N conditions. [ABSTRACT FROM AUTHOR]

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This study was conducted to evaluate the combining ability of newly acquired maize inbred lines over the environments. Twenty-eight crosses developed by crossing eight elite inbreds in a half-diallel mating design were evaluated during kharif, 2019 for 12 agro-morphological traits in RBD with two replications at two different environments reflecting diverse agro-climatic and ecological conditions of North-Western Himalayas (SAREC, Kangra and HAREC, Bajaura). Analysis of variance showed that there was sufficient amount of genetic variability in the material studied. In accordance to Bartlett’s test, error variance was homogeneous only for six traits. Estimates of σ2SCA were higher as compared to σ2GCA both within and across environments for all the traits, except days to 75 per cent brown husk at Kangra, representing prevalence of non-additive gene action for these traits. The inbred line B73 at Bajaura, and LM14 at Kangra were found to be good general combiner for most traits. The inbreds with good GCA can be used as potential parents for the development of high yielding single cross maize hybrids. The hybrid combinations namely, B73 × BAJIM1811 and BAJIM1522 × BAJIM1811 were identified as potentially superior ones at Kangra and Bajaura environments. The identified promising hybrids need further assessment for their superiority in performance across the locations and over years.

Combining ability analysis for yield and yield components in some important rice germplasm through line x tester analysis of 24 intervarietal crosses developed by crossing 4 testers with 6 lines. The 24 crosses were grown in a randomized block design with three replications and were evaluated for grain yield per plant and other yield components. The experiments were conducted at the Department of Plant breeding and genetics, Faculty of Agriculture, Annamalai University. Analysis of variance for line x tester revealed highly significant differences between the characters studied. The mean squares ratio of GCA and SCA were below one for all the characters studied. This might be due to the effect of non-additive gene action. The estimates of gca performance indicated that the lines viz., ADT - 37, ADT - 45, ADT - 43 and the testers viz., Kuzhi Adichan, Kalurundai Samba and Kalanmak are good general combiners for grain yield per plant. The best sca performance were observed in the crosses, ADT - 45 x Kalurundai Samba and ADT - 37 x Kalurundai Samba. [ABSTRACT FROM AUTHOR]

The most important step in plant breeding is the correct selection of parents, and it would be wise to use heterotic groups for this. The purpose of this study is to analyse yield and its components as well as genetic diversity in line × tester wheat populations. It also seeks to present a coherent framework for the isolation of early superior families and the development of heterotic groups in bread wheat. F1 and F2 generations of 51 genotypes, including 36 combinations between 12 lines and three testers and 15 parents, were evaluated for yield and its components in a three-replication experiment according to the randomized block design. Line × tester analysis of variance, general and specific combining abilities, heterosis, heterobeltiosis and inbreeding depression were calculated. Heterotic groups created based on general and specific combining abilities were compared with each other. The results showed that there was sufficient genetic variation in the population and that further genetic calculations could be made. The selections made based on general and specific combining abilities, heterosis values and average performance of genotypes without heterotic grouping indicated different genotypes for each feature. The creation of heterotic groups made it possible to select genotypes that were superior in terms of all the criteria listed. It was concluded that heterotic groups created based on specific combining abilities may be more useful for breeding studies. [ABSTRACT FROM AUTHOR]

BackgroundOrange maize genotypes are sources of provitamin A (PVA) carotenoids, which are precursors of vitamin A. PVA deficiency and drought constitute major challenges causing increasing food and nutritional insecurity in sub-Saharan Africa (SSA). Breeding of drought-tolerant provitamin A hybrid maize can mitigate these challenges. This study was undertaken to determine the combining ability of newly developed extra-early orange inbreds for grain yield and related traits under managed drought stress and rain-fed conditions, determine the mode of gene action conditioning the inheritance of the traits, and classify the inbreds into heterotic groups.MethodologyOne hundred and ninety-six extra-early orange hybrids comprising 180 testcrosses, 10 single crosses, and 6 commercial checks were evaluated under managed drought and rain-fed conditions at Ikenne. In addition, 41 inbreds comprising 36 orange lines and 5 PVA testers involved in the hybrid development were assessed under drought and rain-fed conditions.ResultsThe means square for general combining ability (GCA) and specific combining ability (SCA) were significant for grain yield and most other traits under both growing conditions. The contributions of GCA to performance were larger than SCA in each growing condition. Broad-sense and narrow-sense heritability estimates for grain yield were 66% and 37% under managed drought and 88% and 32% under rain-fed conditions, respectively. Mid-parent heterosis and better-parent heterosis for grain yield were 338% and 247% under managed drought, while 173% and 137% under rain-fed conditions. Significant positive correlations existed among grain yield of hybrids, heterosis, and specific combining ability under managed drought. The 41 inbred lines were classified into three heterotic groups under both growing conditions. Sixteen testcross hybrids out-yielded the best commercial check under managed drought.ConclusionThe testcross hybrids have great potential for commercialization to address the problem of drought and PVA deficiency in SSA. Inbred TZEEIOR 510 showed desirable GCA effects for grain yield and 04 other traits under drought.

Drought is a major constraint on maize (Zea mays L.) production and productivity in Sub-Saharan Africa (SSA). The increase in frequency and severity of drought, driven by climate change, is expected to worsen in the future. These occurrences are likely to adversely affect maize production and productivity, threatening the economic and social stability of millions of smallholder farmers. Understanding the genetics of hybrid performance under drought stress is crucial for designing breeding strategies to develop high-yielding hybrids. This study aimed to (i) evaluate the performance of three-way cross hybrids developed from elite inbred lines, including several drought-tolerant lines, using a line-by-tester mating design, and (ii) estimate the general combining ability (GCA) and specific combining ability (SCA) effects of the tropical maize inbred lines under managed drought and optimum conditions. A total of 265 maize inbred lines from the CIMMYT global maize breeding program were used as parents and crossed to six single cross testers to generate 795 testcross hybrids. These hybrids, along with six commercial hybrids as a check, were evaluated under managed drought and optimum conditions. Significant (p < 0.001) variations were observed among genotypes and genotypes-by-environment interactions (GEIs) for grain yield and other traits. There was a preponderance of GCA variance (lines and tester) over SCA variance, indicating that additive effects were more important in determining grain yield and other key traits under both managed drought and optimum conditions. Ten inbred lines (S2_8, S10_1, S6_4, S10_14, S2_14, S10_15, S8_7, S2_3, S8_15, and S13_5) with desirable GCA effects for grain yield and other traits were identified. Fourteen testcross hybrids were identified with high grain yield and desirable agronomic traits under both drought and optimum conditions. The identified lines and hybrids are useful sources to be used in breeding and deploying as stress-tolerant hybrids. High correlations observed between observed and GCA-predicted hybrid performance suggest the possibility to evaluate more hybrids with fixed resources. The study demonstrates that it is feasible to obtain high-yielding and drought-tolerant lines and hybrids. These testcross hybrids should undergo rigorous on-farm trials to ensure consistent performance before commercialization and release. Deploying these hybrids could help in mitigating the effects of drought stress in SSA and contribute to improved maize productivity in the region.

The current breeding effort aims to develop new wheat genotypes with higher genetic potential, thereby contributing to food security. Ten wheat genotypes were crossed in a half-diallel mating design. The F1 progeny from the 45 crosses, along with their ten parents, were evaluated in a randomized block design to estimate combining ability and the nature of gene action. Analysis of variance for combining ability revealed significant mean squares for both general and specific combining abilities across all studied traits. This indicates the importance of both additive and non-additive gene effects in the inheritance of these traits. The GCA/SCA ratio suggested the predominance of non-additive genetic action for all studied traits. Only five parents (HD3086, UP 2748, WH 1105, UP 2565, and HD 2967) exhibited good general combining ability for yield and associated traits. However, but none of them were found good combiners for all traits. Twenty-one crosses exhibited significant specific combining ability for yield and associated traits. The crosses UP 2748 x HD 3059, UP2565 x HD3086, WH 1105 x UP 2526, WH 1105 x WH 1021, and HD 2967 x WH 1021 were identified as good specific combiners for higher grain yield and associated traits. Utilizing these crosses in breeding programs that exploit heterosis can lead to the creation of new wheat genotypes with a broader genetic base. This approach, which involves crossing high-performing parents for some traits with low-performing parents for others, has the potential to produce offspring with superior characteristics in the next generation due to interactions between dominant genes.

Geraniums (Pelargonium spp.) are ornamental plants that are widely popular because of their abundant flowering, color variability, different flower patterns, and ease of cultivation. Genetic breeding of this species aims to reduce the plant size and flower color. The objective of this study was to carry out morphoagronomic characterization of parents and F1 hybrids and to estimate the combined capacity and hybrid performance in the circulating diallel in F2 geranium (Pelargonium sp.). We obtained 18 and 275 plants from the F1 and F2 generations, respectively. Characterization of the parental genotypes and F1 and F2 hybrids was performed based on the descriptors for Pelargonium. Parents and F1 hybrids were grouped using the Tocher and UPGMA methods and diallel analyses in the F2 generation. The F1 hybrids G8, G11, and G17 exhibited color combinations suitable for commercialization and are promising for inclusion in breeding programs. The effects of general combining ability (GCA) and specific combining ability (SCA) were significant for these traits were also significant. The results showed the presence of both additive and non-additive genes. However, non-additive and dominant genes were predominant in most characteristics studied. Diallel analysis of the F2 hybrids revealed that the best hybrid combinations for reducing plant height were 14 × 11, 14 × 13, and 15 × 12. Therefore, the implementation and use of diallel analysis were efficient in selecting superior parental genotypes and producing hybrids with high yields. [ABSTRACT FROM AUTHOR]

Combining ability assessment helps select parents and hybrids with high performance, which can lead to increased yield and effective crop improvement. The present study aimed to evaluate 24 diverse crosses for ten different quantitative traits using line x tester mating in the kharif season. The experiment involved the assessment of crosses, which included 4 females, 6 males, and 1 commercial cultivar (Nishant). The evaluation employed a randomized block design (RBD) with three replications. Major discrepancies were observed in the genotypes of both parents and hybrids for all traits, indicating a significant amount of variation in fruit yield and other characteristics that contribute to yield. JBR-20-05 was found the best general combiner for days to 50% flowering, fruit length and plant height. JBR-20-04 was found to be the best general combiner for average fruit weight, fruit girth and total fruit yield per plant. The genotype identified in the JBR-20-07 study, resistant to fruit and shoot borer infestation, held significant potential for use in breeding and selection programs to enhance the resistance of brinjal varieties. Estimation of Specific combining ability effect revealed that among the hybrids, the hybrids JBR-20-04 x JBR-20-05 recorded highly significant specific combining ability (SCA) effects for total fruit yield per plant. The cross JBR-20-03 x JBR-20-05 showed high desirable significance to SCA for fruit and shoot borer infestation. Variance due to general combining ability was less than the variance due to SCA, and the ratio of GCA to SCA variance was less than unity. When choosing hybrids to enhance yield in brinjal (Solanum melongena L.) through breeding, it is crucial to prioritize specific traits that directly contribute to increased production. [ABSTRACT FROM AUTHOR]

The most important step in plant breeding is the correct selection of parents, and it would be wise to use heterotic groups for this. The purpose of this study is to analyse yield and its components as well as genetic diversity in line × tester wheat populations. It also seeks to present a coherent framework for the isolation of early superior families and the development of heterotic groups in bread wheat. F1 and F2 generations of 51 genotypes, including 36 combinations between 12 lines and three testers and 15 parents, were evaluated for yield and its components in a three-replication experiment according to the randomized block design. Line × tester analysis of variance, general and specific combining abilities, heterosis, heterobeltiosis and inbreeding depression were calculated. Heterotic groups created based on general and specific combining abilities were compared with each other. The results showed that there was sufficient genetic variation in the population and that further genetic calculations could be made. The selections made based on general and specific combining abilities, heterosis values and average performance of genotypes without heterotic grouping indicated different genotypes for each feature. The creation of heterotic groups made it possible to select genotypes that were superior in terms of all the criteria listed. It was concluded that heterotic groups created based on specific combining abilities may be more useful for breeding studies.

The present investigation was conducted to study the combining ability and heterosis of F1’s crosses and their parents for yield and its components in seven pea genotypes Via Line X Tester analysis during two growing seasons. Three varieties of pea as lines (Javor, NS minima, Oregon sugar pod) and four varieties as testers (Giant sugar pod, Green sage, Lancet, and Provence) have been crossed to produce 12 F1 crosses, during the first growing season at Qliasan Research Station. Emasculation and crossing were done by hand and sufficient seeds for crosses were produced. During the growing season of 2015-2016, the F1 seeds with their parents were implemented in the field experiment using RCBD with three replicates in Girdjan Research Station, to determine parental combinations through studying the general and specific combining abilities and their variances to improve pea crosses. The results showed that line parent 3 recorded a maximum pod length, and pod yield plant-1, while tester parent 4 produced the maximum values for seed weight pod-1, 100 seeds weight, number of pods plant-1, and seeds yield plant-1. The results indicated that the cross 2×5 produced the maximum values for a number of pods plant-1, pod yield plant-1, and seeds yield plant-1. Parent line 3 showed a maximum negative GCA effect value of -8.92, while tester 7 exhibited a maximum positive GCA effect value of 7.447. Hybrid 2 × 7 had the highest positive heterosis values for two traits number of pods plant-1, and seed yield plant-1.

To ensure food and feed security, modern maize hybrids must not only perform well under changing climate conditions but also consistently achieve higher and stable yields, exhibit maximum tolerance to stress factors, and produce high quality grains. In a study conducted in 2022 and 2023, 50 maize hybrids were developed from crosses of five elite (highly productive) inbred lines and ten lines possessing favorable genes for carotenoid content. These hybrids were tested under particularly unfavorable conditions for maize cultivation. The aim was to identify which lines effectively transmit the desired traits to the offspring (general combining ability—GCA), and to identify superior hybrids in terms of productivity, adaptability, and quality (specific combining ability—SCA). The study revealed that total carotenoids ranged from 2.30 to 40.20 μg/g for the inbred lines and from 7.45 to 25.08 μg/g for hybrids. A wider distribution of values was observed in the inbred lines compared to the hybrids for key carotenoids such as lutein, zeaxanthin, β-cryptoxanthin, and β-carotene. Among the hybrids, notable performers in yield, adaptability, and carotenoid content included E390×D302, A452×D302, and A447×D302. The paternal inbred line D302 exhibited a high general combining ability for yield (1446 kg ha−1) and, when crossed with several inbred lines, produced hybrids with enhanced yields and higher levels of zeaxanthin, lutein, and β-carotene, as well as improved unbroken plants percent.

We selected ten Ajowan parents (Carum copticum L.) from a genetically diverse population to evaluate gene effects, heritability, and correlations among their morphological traits. We poly-crossed the parents to produce half-sib genotypes. The evaluations comprised the number of days to flowering, plant height, number of fertile branches, number of umbrellas per plant, number of seeds per umbel, seed yield per plant, harvest index, essential oil percentage, and essential oil yield. Parents and polycross progeny seeds grew in a randomized complete block design with three replications at the University of Tehran, 2015-2017. The results showed broad-sense heritability ranged from 0.64 to 0.96 in parents and their progenies. Narrow-sense heritability appeared through the regression of progenies on the parents (h²po) and via progeny analysis (h²n), suggesting that additive genes control these traits. The correlation of seed yield with plant height, number of fertile branches, number of umbrellas per plant, and number of seeds per umbel were positive and significant. The results indicated a significant negative correlation between thymol and γ-terpinene in parents and half-sib families. We reported wide variations and high heritability for most of the evaluated traits in the ajowan populations that can improve seed and essential oil yields. [ABSTRACT FROM AUTHOR]

In the present study twenty-eight hybrid combinations resulting from the half-diallel mating of eight quality protein maize (QPM) inbred lines were chosen in order to examine the potential to combine and gene activity for ten yield and component attributes. As part of the All India Coordinated Research Project (AICRP) on maize during the kharif-2020 season, the experiment was done at the research farm of college of Agriculture, Odisha University of Agriculture & Technology (OUAT) Bhubaneswar, using a randomized complete block design replicated thrice. Every observation recorded was subjected to statistical evaluation and it was revealed that the mean squares derived from the general combining ability (gca) and specific combining ability (sca) were highly significant (p ≥0.01). Estimates of sca effects were greater than that of gca effects for all of the variables used in the study, suggesting to the predominance of dominant gene action. The inbred lines Q4-DQL 2221-1-1(833.792), Q2-DQL 2099 (517.658) and Q3- DQL 2159 (350.325) shows high gca effects for yield and its attributing traits due to more additive gene action thus identified as good general combiners for yield. Twelve of the twenty-eight crosses showed significant (p ≥0.01 and 0.05) positive sca effect on grain yield. The best experimental crosses for grain yield based on per se performance and sca effects were Q2 x Q8 (2106.748), Q1 x Q6 (2053.048), Q3 x Q7 (2027.082), and Q3 x Q6 (1719.884).

In this article we compared two approaches: one is Griffing approach for numerical components and other is Hyman's approach for graphical representation of the components through the mating design of Complete Diallel Cross design for p=5 parental lines. Griffing (1956) approach was a numerical approach based on the estimates of combining ability effects. Here use his fourth method. Hayman (1954) approach also have four components namely (i) complete, (ii) partial, (iii) over-dominance and (iv) no dominance. Hayman's approach based on the estimation of parts of variation. We use three mutually orthogonal Latin squares design of order 5 for the construction of mating designs. ANOVA and estimates of combining ability derived and analyzed. We demonstrate the numerical accuracy of the proposed design Griffing method I and Hayman's method by using Turnip data of 5x5 crosses of plant height. [ABSTRACT FROM AUTHOR]

Introduction Low diversity and poor genetic basis of germplasm in temperate regions is a significant challenge in maize breeding. Maize germplasms from tropical and subtropical regions often contain a broader genetic base and show larger diversity than germplasms from temperate regions. Therefore, it seems that foreign germplasms, especially germplasms from tropical and subtropical regions, can be used as a potential solution to strengthen the genetic base of germplasm in temperate regions. However, the efficiency of screening methods to identify superior and suitable sources of foreign germplasm remains a major challenge. The objective of this study was to determine the optimum number of testers and select suitable testers for screening maize lines derived from tropical and subtropical CIMMYT germplasm. Materials and methods In this experiment, three testers of temperate regions (MO17, B73, K1264/5-1) were crossed with 25 lines originated from the CIMMYT maize germplasm based on line×tester mating system. A total of 75 crosses along with the control hybrid (SC704) were evaluated in alpha-lattice experimental design in two replications each with four incomplete blocks in two regions (Moghan and Jiroft). Analysis of variance was done based on line×tester method, as well as separation of the effect of crosses into its components using the method suggested by Kemptorn (1957). GGE-biplot graphical analysis based on the methodology proposed by Fan et al. (2010) was also used to estimate the effects of general combining ability (GCA) and specific combining ability (SCA). Research findings The results showed that out of the 75 crosses, 32 crosses had higher and significant grain yield compared to the control hybrid SC704. The superiority of the superior cross compared to the control hybrid ranged from 1.46 to 3.77 tons per hectare. These findings highlighted the potential of utilizing tropical and subtropical CIMMYT germplasm to enhance maize yield in temperate regions of Iran. Based on the results, the lines No. 22, 9, 19, 12, 20, 5, 17, 21, 24, 14, 15, 23, and 11 had the highest positive GCA for grain yield, respectively. In general, in terms of grain yield, GCA, and SCA, it is possible to directly use lines No. 4, 5, 9, 11, 12, 19, 22, and 24 extracted from tropical and subtropical CIMMYT germplasm to improve grain yield in temperate regions. Evaluating the efficiency of the temperate maize testers also showed that two testers B73 and MO17 were highly efficient in selecting superior line derived from tropical and subtropical CIMMYT germplasm. Conclusion The results of the current study showed that it is possible to use maize germplasms from tropical and subtropical regions of CYMMIT to improve grain yield in temperate regions. Also, one temperate maize tester has the ability to distinguish superior sources (not all of them), although the use of two testers greatly reduces the risk of not choosing (deleion) a superior source. [ABSTRACT FROM AUTHOR]

Bacterial wilt is a disease caused by Ralstonia solanacearum, which affects over 450 plant species and causes significant reduction in crop yields including of tomato (Solanum lycopersicum) worldwide. Developing and identifying tomato genotypes with Ralstonia solanacearum tolerance and high yield potential, presents an opportunity for improvement of crop productivity. The objective of this study was to explore the heritability of tomato resistance against bacterial wilt and the genetic variation within the population for breeding purposes. A breeding population was created by crossing two bacterial wilt-resistant (MT56 and BL333) and three commercially desirable susceptible (Assila, Rambo and Heinz) tomato varieties, using North Carolina Design II, in a screen house at the Makerere University Agricultural Research Institute, Kabanyolo (MUARIK). Results showed that the Area Under Disease Progress Curve was significant (P<0.001), indicating that cumulative disease progress was less in resistant genotypes of segregating generations. Disease severity increased with days after inoculation (DAI), with Heinz showing the highest level of susceptibility. The General Combining Ability for male parent (GCAm) was significant (P< 0.01), and Specific Combining Ability (SCAfxm) and GCAf were significant (P<0.01) for the F2 generation. Broad-sense heritability was higher than the narrow-sense heritability in both F1 and F2 generations, suggesting that non-additive gene action predominately controlled tomato resistance to bacterial wilt infestation. The genetic diversity ranged from 0.5 to 0.6759, with a mean value of 0.5787. Polymorphism Information Content (PIC) varied from 0.375 to 0.6357, with a mean of 0.4888, indicating a high degree of variation. SLM 12-2 was the most polymorphic marker, with a PIC of 0.6357. The Unweighted Pair-Group Method with Arithmetic Average (UPGMA) classified all tomato genotypes into six clusters, namely Clusters 1 and 2 (Susceptible parents), Cluster 3 (Resistant parents), Clusters 4 and 5 (New source of resistance), and Cluster 6 (F1P1xP5). [ABSTRACT FROM AUTHOR]

In the present study twenty-eight hybrid combinations resulting from the halfdiallel mating of eight quality protein maize (QPM) inbred lines were chosen in order to examine the potential to combine and gene activity for ten yield and component attributes. As part of the All India Coordinated Research Project (AICRP) on maize during the kharif-2020 season, the experiment was done at the research farm of college of Agriculture, Odisha University of Agriculture & Technology (OUAT) Bhubaneswar, using a randomized complete block design replicated thrice. Every observation recorded was subjected to statistical evaluation and it was revealed that the mean squares derived from the general combining ability (gca) and specific combining ability (sca) were highly significant (p ≥0.01). Estimates of sca effects were greater than that of gca effects for all of the variables used in the study, suggesting to the predominance of dominant gene action. The inbred lines Q4-DQL 2221-1-1(833.792), Q2-DQL 2099 (517.658) and Q3- DQL 2159 (350.325) shows high gca effects for yield and its attributing traits due to more additive gene action thus identified as good general combiners for yield. Twelve of the twenty-eight crosses showed significant (p ≥0.01 and 0.05) positive sca effect on grain yield. The best experimental crosses for grain yield based on per se performance and sca effects were Q2 x Q8 (2106.748), Q1 x Q6 (2053.048), Q3 x Q7 (2027.082), and Q3 x Q6 (1719.884). [ABSTRACT FROM AUTHOR]

Two experiments were conducted. One in the open field during the spring season 2021, in which crosses- and Reciprocal-Crosses (full diallel crossing) were conducted between five selected okra varieties and the other was a comparative experiment in the heated plastic green-house of the Department of Horticulture and Gardening Engineering, College of Agriculture, University of Tikrit, Iraq for the winter season 2022. The results showed that the differences between the parental genotypes and their reciprocal and Reciprocal-Crosses led to the emergence of hybrid vigour and in the desired direction in the results of a number of crosses, where the special values for the hybrid’s strength were calculated based on the average of the best (shortest) father H (BP), as the hybrid’s strength was characterised as in the plastic greenhouse, the hybrid (P5xP4) had a significant negative value, while 19 hybrids had undesirable positive values. In the open field, 11 hybrids had negative and significant hybrid strength, 2 had non-significant negative values and 7 had undesirable positive values. The results also showed that the effects of the general ability of compatibility for the first generation in the plastic green-house were high for the genotype P4, where the effects of GCA were significant and negative, as well as the parental styles recorded high and negative values, respectively, P3 and P2, while the effects of the P5 models and P1 were highly significant and positive, and the effects of the genera were positive. The results also showed that the effects of the specific combining ability varied in terms of genetic values of hybrids between the plastic green-house and the open field. The hybrids P3xP1, P4xP5, P4xP2, P1xP2, P3xP2 and P5xP3 had the highest negatively significant values for the effects of the special ability of compatibility in the greenhouse, while the hybrids P1xP2, P5xP3, P4xP3 and P1xP5 had the highest negative significant values in the open field. Percentage exceeded the average vigour of the hybrids for the characteristic of the number of okra branches in the open field compared to the plastic green-house, where 9 hybrids recorded negative and significant hybrid strength, with (P1xP5) having the highest value -40.994 and (P3x P2) the lowest. It had 12 leaf models. A negative and significant hybrid, where (P2xP5) had the highest value and (P5xP4) the lowest, 3 hybrids had non-significant negative values and 5 had undesirable positive values. In the plastic greenhouse, 10 hybrids had high and negative significant values, including P2xP45. [ABSTRACT FROM AUTHOR]

Diallel crossing system is widely employed to enumerate quantitative inheritance for homozygous parental lines. Such experiments are considered for highly inbred lines. Parents may be individuals, plants, animals etc. In this paper, Partial Diallel Crosses (PDC) are constructed using Latin square design for v parental lines, where v 5. The method is illustrated with suitable examples and variance of the constructed PDC plans are tabulated for v 50. [ABSTRACT FROM AUTHOR]

Yield gains in crop plants, such as citron watermelon can be realised through combining ability tests and hybrid breeding. The objective of the study was to determine the combining ability and hybrid performance of citron watermelon genotypes for agronomic traits. Five contrasting and relatively high-yielding citron watermelon genotypes were crossed in a 5 × 5 half-diallel mating design and 10 F1 hybrids were developed. The 15 families (five parents and 10 F1 hybrids) were evaluated across two environments using a randomized complete block design with three replications. Data was collected on various agronomic traits and subjected to analysis of variance (ANOVA) and combining ability analysis. Significant (P < 0.001) genotype × environment interaction effects were observed for most assessed traits. General combining ability (GCA) and specific combining ability (SCA) effects were significant (P < 0.001) for most traits. Environment × GCA was non-significant, whereas Environment × SCA effects were significant (P < 0.001) for most traits. The ratios of GCA/SCA variances were less than unity for most traits, indicating non-additive gene action of the traits. Broad-sense heritability varied from low to moderate, implying variable selection response of the assessed traits among the F1 hybrids. The parental genotypes WWM16 with positive GCA effects for fruit and seed yields and WWM66, with positive GCA effects for the number of seeds per fruit and seed yield, were identified for hybrid breeding. The following F1 hybrids: WWM04 × WWM16, WWWM03 × WWM66 and WWM16 × WWM50 with positive SCA effects on total fruit yield per plant and marketable fruit yield per plant, and WWM04 × WWM50, WWM03 × WWM16 and WWM03 × WWM66 with positive SCA effects for number of seeds per fruit and total seed yield were identified. The study identified novel and best-performing F1 hybrids of citron watermelon for economic traits and are recommended for multi-environmental evaluations, variety registration and commercialization. [ABSTRACT FROM AUTHOR]

Fall armyworm (FAW, Spodoptera frugiperda) emerged as a major lepidopteran pest destroying maize in sub‐Saharan Africa. A diallel mating design was used to generate 210 experimental hybrids from 21 lines. Experimental hybrids and four checks were evaluated in two locations. Commercial checks suffered higher foliar and ear damage compared to the top 15 hybrids. Mean squares associated with the genotypic variation were higher than genotype‐by‐environment interactions for foliar and ear damage traits. Heritabilities were moderate to high. Significant correlations were observed between grain yield (GY) with ear rot (−0.54) and ear damage (−0.45). Positive and significant GCA effects were observed for GY in seven parental lines, which were developed from multiple insect resistance breeding programmes. CKSBL10153 has the highest GCA value for GY and shows significant GCA effects for foliar and ear damage traits. These lines were identified as the ideal combiners for GY and FAW resistance and are therefore recommended for utilization as testers in the development of FAW‐resistant three‐way cross‐hybrid maize with correlated response for increased GY. GCA and marker‐based prediction correlations of GY were 0.79 and 0.96, respectively. Both GCA effects and marker‐based models were effective in predicting hybrid performance for FAW resistance. [ABSTRACT FROM AUTHOR]

Copyright of Ecosistemas y Recursos Agropecuarios is the property of Universidad Juarez Autonoma de Tabasco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Globally, cotton yield and lint quality improvement especially through selection of promising genotypes continue to remain a pressing task for the sustainability of lint supplies to the textile industry. To achieve these goals, the use of diallel analysis is of prime pertinence in plant breeding to identify and screen out the elite genetic combinations and stable fidelity in subsequent generations. An experiment was carried out to study combining ability of the parental genotypes and their half-diallel hybrids for yield component, seed yield and fiber quality traits. The results showed highly significant differences among tested genotypes, indicating remarkably high genetic variability for all the studied traits. The ratio of δ²GCA/δ²SCA > 1 for all traits under study exhibited the preponderance of additive gene action for inheritance of all traits under investigation. The results indicated that selection could be significantly responsive and performed in early segregating generation. Additionally, parents, Coker 139, Aleppo 90 and NIAB 414 were superior general combiner for yield and fiber quality traits. Likewise, hybrids especially Millinium x Aleppo 124, Aleppo 124 x NIAB Kiran and Aleppo 118 x NIAB Kiran showed unmatched response variables. Thus based on these recorded findings, these hybrids can be exploited in future's breeding programs for boosting cotton yield and fiber quality through development of new promising varieties of cotton. [ABSTRACT FROM AUTHOR]

Testcross factorials in newly established hybrid breeding programs are often highly unbalanced, incomplete, and characterized by predominance of special combining ability (SCA) over general combining ability (GCA). This results in a low efficiency of GCA-based selection. Machine learning algorithms might improve prediction of hybrid performance in such testcross factorials, as they have been successfully applied to find complex underlying patterns in sparse data. Our objective was to compare the prediction accuracy of machine learning algorithms to that of GCA-based prediction and genomic best linear unbiased prediction (GBLUP) in six unbalanced incomplete factorials from hybrid breeding programs of rapeseed, wheat, and corn. We investigated a range of machine learning algorithms with three different types of predictor variables: (a) information on parentage of hybrids, (b) in addition hybrid performance of crosses of the parental lines with other crossing partners, and (c) genotypic marker data. In two highly incomplete and unbalanced factorials from rapeseed, in which the SCA variance contributed considerably to the genetic variance, stacked ensembles of gradient boosting machines based on parentage information outperformed GCA prediction. The stacked ensembles increased prediction accuracy from 0.39 to 0.45, and from 0.48 to 0.54 compared to GCA prediction. The prediction accuracy reached by stacked ensembles without marker data reached values comparable to those of GBLUP that requires marker data. We conclude that hybrid prediction with stacked ensembles of gradient boosting machines based on parentage information is a promising approach that is worth further investigations with other data sets in which SCA variance is high. [ABSTRACT FROM AUTHOR]

Bottle gourd [Lagenaria siceraria (Molina) Standl.] is cultivated for multiple utilities, including as a leafy vegetable, for fresh and dried fruits and seeds. It is an under-researched and -utilized crop, and modern varieties are yet to be developed and deployed in sub-Saharan Africa (SSA). There is a dire need for pre-breeding and breeding of bottle gourds for commercialization in SSA. Therefore, this study aimed to determine the combining ability and heterosis among selected genotypes of bottle gourd for fruit yield and related traits under drought-stressed and non-stressed conditions to select the best parents and hybrids. Eight preliminarily selected and contrasting parents with drought tolerance were crossed using a half-diallel mating design. The 8 parents and 28 crosses were evaluated under non-stressed (NS) and drought-stressed (DS) conditions across two growing seasons (2020/21 and 2021/22) using a 6 × 6 alpha lattice design with three replicates. Data were collected on fruit yield and related traits and subjected to analysis of variance, combining ability and heterosis analyses. Significant (p < 0.05) specific combining ability (SCA) and general combining ability (GCA) effects were computed for fruit yield per plant (FYPP). The SCA × environment and GCA × environment interaction effects were highly significant (p < 0.001) for FYPP and SYPP. The results suggest that genetic effects were affected by the test environment. Parental genotypes BG-58 and GC recorded positive and significant GCA effects for FYPP under the DS condition, whereas GC recorded positive and significant GCA effects for FYPP under the NS condition. The two genotypes are ideal breeding parents for population development to select genotypes with high fruit and seed yields. Crosses BG-27 × BG-79, BG-79 × BG-52, BG-79 × BG-70, BG-80 × BG-70, BG-80 × GC, and BG-70 × GC recorded high and positive SCA effects for FYPP and SYPP under DS condition. Crosses BG-81 × BG-52, BG-81 × GC, BG-27 × BG-79, BG-27 × GC, BG-79 × GC, BG-80 × BG-70, BG-81 × BG-58, BG-27 × BG-80, BG-27 × BG-58, BG-79 × BG-52, BG-52 × BG-58, BG-80 × BG-58, and BG-58 × BG-70 recorded high and positive SCA effects for FYPP and SYPP under NS condition. Crosses BG-80 × BG-58, BG-27 × BG-79, BG-79 × BG-52, BG-27 × BG-52, and BG-52 × BG-80 showed high and positive mid- and better-parent heterosis under DS condition for FYPP and SYPP. Crosses BG-27 × GC, BG-79 × GC, BG-27 × BG-58, and BG-27 × BG-79 showed high and positive mid- and better parent heterosis under NS condition for FYPP and SYPP. The newly selected families are recommended for multi-environment evaluation forrelease and commercialization in South Africa or similar agroecologies. [ABSTRACT FROM AUTHOR]

There is an ongoing endeavor within the potato breeding sector to rapidly adapt potato from a clonal polyploid crop to a diploid hybrid potato crop. While hybrid breeding allows for the efficient generation and selection of parental lines, it also increases breeding program complexity and results in longer breeding cycles. Over the past two decades, genomic prediction has revolutionized hybrid crop breeding through shorter breeding cycles, lower phenotyping costs, and better population improvement, resulting in increased genetic gains for genetically complex traits. In order to accelerate the genetic gains in hybrid potato, the proper implementation of genomic prediction is a crucial milestone in the rapid improvement of this crop. The authors of this paper set out to test genomic prediction in hybrid potato using current genotyped material with two alternative models: one model that predicts the general combining ability effects (GCA) and another which predicts both the general and specific combining ability effects (GCA+SCA). Using a training set comprising 769 hybrids and 456 genotyped parental lines, we found that reasonable a prediction accuracy could be achieved for most phenotypes with both zero common parents ( ρ = 0.36 − 0.61 ) and one ( ρ = 0.50 − 0.68 ) common parent between the training and test sets. There was no benefit with the inclusion of non-additive genetic effects in the GCA+SCA model despite SCA variance contributing between 9% and 19% of the total genetic variance. Genotype-by-environment interactions, while present, did not appear to affect the prediction accuracy, though prediction errors did vary across the trial's targets. These results suggest that genomically estimated breeding values on parental lines are sufficient for hybrid yield prediction. [ABSTRACT FROM AUTHOR]

Three field experiments were carried out during 2022 summer season at three diverse locations of Gemmeiza, Sakha and Mallawy Experimental Stations of Agricultural Research Center (ARC), Egypt. Thirty crosses (ten inbred lines crossed with three testers inbred line Sd. 7, Sk. 5 and SC 130) and four standard checks SC 10, SC 2031, TWC 321 and TWC 324 were evaluated for yield and yield related traits to evaluate using line × tester mating design. Analysis of variance revealed significant differences among genotypes for most traits indicating existence of variability among genotypes. Results showed that maternal parents play the most important role. The general combining ability effect showed that Gm. 1031, Gm.62 and Sk.5 are good combiners for earliest, shortened and lower ear placement. Four inbred lines (Gm. 267, Gm. 50, Gm.66 and Gm. 64) and testers Sk.5 were good general combiner for grain yield. The crosses (Gm. 62×Sc. 130), (Gm. 66× Sk.5) and (Gm. 64×sd. 7) had significant values of SCA for plant and ear height and the cross (Gm. 52 × SC. 130) had significant values of SCA for grain yield. Most of all crosses had better performance than check varieties for earliness, short plant and lower ear placement. The two crosses (Gm. 64×Sk.5) and (Gm. 64×SC. 130) were better than all check varieties for grain yield. For grain yield, the cross (Gm. 66×Sd. 7) had a significant superiority percentage over check (SC 2031) while the two crosses (Gm. 52×SC. 130) and (Gm. 64 × SC.130) had significant superiority percentages over checks (TWC321 and TWC324). Therefore, Identify superior crosses to improve the yielding ability in maize breeding programs. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agronomica Sinica is the property of Crop Science Society of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Rice (Oryza sativa L.) is a staple food that feeds over half of the world's population, and the contents of metallic elements in rice grain play important roles in human nutrition. In this study, the contents of important metallic elements were determined by ICP-OES, and included cadmium (Cd), zinc (Zn), manganese (Mn), copper (Cu), iron (Fe), nickel (Ni), calcium (Ca), and magnesium (Mg) in brown rice, in the first node from the top (Node 1), in the second node from the top (Node 2), and in roots of 55 hybrids and their parental lines. The heritability of metallic element contents (MECs), the general combining ability (GCA) for MEC, and the correlation between MECs in different organs/tissues of hybrids were also analyzed. The results indicated that: (1) there was a positive correlation between the contents of Cd and Zn in nodes and roots, but a negative correlation between the contents of Cd and Zn in brown rice of the hybrids(2) the GCA for MECs can be used to evaluate the ability of the parental lines to improve the metal contents in brown rice of the hybrids(3) the contents of Cd, Zn, Ca, and Mg in brown rice were mainly affected by additive genetic effects(4) the restorer lines R2292 and R2265 can be used to cultivate hybrids with high Zn and low Cd contents in the brown rice.

Abstract To generate high-yielding cultivars with favorable fiber quality traits, cotton breeders can use information about combining ability and gene activity within a population to locate elite parents and potential F1 crosses. To this end, in the current study, twelve cotton parents (eight genotypes as female parents and four testers) and their F1 crosses obtained utilizing the linex tester mating design were evaluated for their general and specialized combining abilities (GCA and SCA, respectively) of yield traits. The findings showed that for all the investigated variables, variances owing to genotypes, parents, crosses, and parent vs cross showed extremely significant (P ≤ 0.01) differences. Additionally, throughout the course of two growing seasons, the mean squares for genotypes (parents and crosses) showed strong significance for all the variables under study. The greatest and most desired means for all the examined qualities were in the parent G.94, Pima S6, and tester G.86. The best crossings for the qualities examined were G.86 (G.89 × G.86), G.93 × Suvin, and G.86 × Suvin. The parents' Suvin, G89x G86 and TNB were shown to have the most desired general combining ability effects for seed cotton yield/plant, lint yield/plant, boll weight, number of bolls/plants, and lint index, while Suvin, G.96 and pima S6 were preferred for favored lint percentage. For seed cotton yield, lint percentage, boll weight, and number of bolls per plant per year, the cross-G.86 x (G.89 × G.86) displayed highly significant specific combining ability impacts. The crosses G.86 × Suvin, Kar x TNB, G.93 × Suvin, and G.93 × TNB for all the studied traits for each year and their combined were found to have highly significant positive heterotic effects relative to better parent, and they could be used in future cotton breeding programs for improving the studied traits.

The experiment was conducted to develop tomato hybrids by identifying parental lines with estimation of good combining ability effects and their variances through line x tester analysis of 44 genotypes including 32 F1 cross combinations using 12 parents after selfing (8 lines and 4 testers). The genotypes were evaluated for the yield and contributing traits. The analysis of variance (ANOVA) showed highly significant difference for all the characters suggesting the presence of genetic variability among the studied materials. The variance values of general combining ability (GCA) were lower than the specific combining ability (SCA) for all the traits except plant height. This indicates that these traits were under the control of non-additive (non-fixable) gene effects and could be exploited by heterosis breeding. The lines L1, L2, L3, L5, and testers T2, and T4 showed a desirable significant negative GCA effect for days to first flowering and days to maturity. The line L5 showed a positive significant GCA effect for most of the traits except fruit per cluster and L4 for plant height, cluster per plant, fruit per cluster, fruit per plant, fruit diameter, and yield per plant. Based on GCA effects across ten traits L4 and L5 were identified as the most promising parental lines for inclusion in hybridization programs. Outstanding crosses based on SCA effects across ten traits were L6XT1, L2XT3, L7XT2, and L4XT4. These crosses could be considered the most promising specific combiner for most traits which can be used to develop elite tomato varieties.

Testcross factorials in newly established hybrid breeding programs are often highly unbalanced, incomplete, and characterized by predominance of special combining ability (SCA) over general combining ability (GCA). This results in a low efficiency of GCA-based selection. Machine learning algorithms might improve prediction of hybrid performance in such testcross factorials, as they have been successfully applied to find complex underlying patterns in sparse data. Our objective was to compare the prediction accuracy of machine learning algorithms to that of GCA-based prediction and genomic best linear unbiased prediction (GBLUP) in six unbalanced incomplete factorials from hybrid breeding programs of rapeseed, wheat, and corn. We investigated a range of machine learning algorithms with three different types of predictor variables: (a) information on parentage of hybrids, (b) in addition hybrid performance of crosses of the parental lines with other crossing partners, and (c) genotypic marker data. In two highly incomplete and unbalanced factorials from rapeseed, in which the SCA variance contributed considerably to the genetic variance, stacked ensembles of gradient boosting machines based on parentage information outperformed GCA prediction. The stacked ensembles increased prediction accuracy from 0.39 to 0.45, and from 0.48 to 0.54 compared to GCA prediction. The prediction accuracy reached by stacked ensembles without marker data reached values comparable to those of GBLUP that requires marker data. We conclude that hybrid prediction with stacked ensembles of gradient boosting machines based on parentage information is a promising approach that is worth further investigations with other data sets in which SCA variance is high.

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]

Ranunculus is a well-known flower having a great economic value for its bright colors and vibrant patterns. Given the importance of the ranunculus cut flower, conducting this study elucidated the genetic behavior and variability of various morphological attributes in ranunculus genotypes. Assessment of six ranunculus genotypes measured germination percentage (%), days to emergence, days to maturity, stem length, stem thickness, flowers per plant, flower size, and flower duration on the plant. Analysis of variance depicted significant variation in all the studied traits except days to emergence, number of stems, and germination percentage. Clustering ranunculus genotype with the Euclidean distances-based hierarchical clustering resulted in two clusters of the genotype. One genotype (red) did not join any group, indicating an early separation of this genotype during the evolution of Ranunculus species. Correlation analysis showed that most studied traits negatively correlated, with only a few positively correlating traits. The number of flowers per plant and stem length showed a d positive correlation (0.7437 and 0.8064, respectively). Overall, the results showed that the red, yellow, and rose genotypes are the best performers for cultivation to produce betterquality flowers. Genetic analysis using line × tester analysis revealed higher values for the SCA component than GCA, suggesting non-additive gene action for most traits under study. Moreover, the hybrids developed in the current study developed new color combinations/shades. These hybrids could further benefit ranunculus stable variant improvement. [ABSTRACT FROM AUTHOR]

Early maturity and genotype by environment interaction (GEI) have always been challenging concerns for breeders in selecting appropriate parents for breeding programs. The presented study aimed to investigate early maturity and the dimension of gene action, as well as, assess the performance of half-diallel populations using eight advanced sweet corn inbred lines and their 28 F1 hybrids with two commercial checks for maturity and yield-related traits in the spring of 2018 at the Nowshera (plain) and Swat (hilly) areas, Khyber Pakhtunkhwa, Pakistan. Analysis revealed significant differences among the genotypes for the studied traits over both locations. General combining ability (GCA) effects were significant for all the traits at both the agro-climatic conditions, except 100-kernel weight, with the specific combining ability (SCA) effects relevant for grain yield at both locations. The GCA-SCA ratio for studied traits indicated dominance gene action, which also gained support by higher values of SCA than GCA variances. Based on the results, the identified inbred lines SWTS-1-8 and SODS-1 serve as good general combiners for traits like earliness and grain yield attributes, making them better parents to improve the stated characteristics in sweet corn. However, the F1 hybrids, i.e., NARCCCRI-19 × CCRI-34 at Nowshera and CCRI-34 × SODS-1 at Swat, showed the best specific combiners for maturity. Likewise, F1 hybrids, i.e., SWTS-1-4 × SWTS-1-8 and SWTS-1-8 × CCRIS-34, emerged as desirable for grain yield at Nowshera and Swat, respectively. The inbred lines for the mentioned hybrids can be a source of germplasm improvement, breaking through undesirable linkages in future sweet corn breeding programs. [ABSTRACT FROM AUTHOR]

Selfing and crossing methods were used to develop the cytoplasmic male sterility (CMS) lines from 2 elite F1 hybrids of CMS hot chilies. The pungency of the CMS lines was improved by backcrossing with the B cultivar. The first and second backcrossed progenies of the CMS lines showed significantly higher capsaicin contents than the F1 hybrids. One good female line K16 × BBC2 (K16), was selected and backcrossed with 3 good maintainer cultivars, C5, C9 and C0. Some incomplete male sterility of pollens was demonstrated in the F1 hybrids and the 1st backcrossed progenies while the partial sterility disappeared by the stage of the second and third generations of backcrossing. When K16 and P32 were crossed with restorers, fruit yields and yield components of certain F1 hybrids, parental lines and commercial varieties were significantly different. Heterosis of yield and yield components of the F1 hybrid chilies was significant. When K16 was used as a female parent, positive and significant heterosis of the F1 hybrids was the same as P32. Moreover, significant GCA of the restorer lines, C7, C8 and C9, was observed in some horticultural characteristics. Furthermore, significant differences of the specific combining ability of some characteristics were observed in a few F1 hybrids. [ABSTRACT FROM AUTHOR]