Search Results (71)

The launch of a successful quality-oriented breeding program requires both mining the residual diversity in grain quality parameters contained in the elite, high-yielding breeding material with good agronomic performance and introgression of new germplasm, such as local landraces, with a high level of targeted quality parameters per se. This study analyzed the combining abilities of 31 maize landraces and two divergent inbred lines–testers (ZPL217 and ZPL-255/75-5) regarding the yield and protein, starch, and lipid content, assessed by Near Infrared Reflectance (NIR) spectroscopy as a fast, non-destructive, and cost-effective method. The general combining ability (GCA) defines the average behavior of genotype in hybrid combination, resulting from additive gene action, so positive GCA values of landraces AN13 and AN197 for protein, AN632 for lipids, and AN594 for starch content indicate that they can be valuable sources of the mentioned properties in quality-oriented maize breeding programs. The obtained correlation between starch content and protein and yield (−0.948 **; 0.587 **) pointed out that an increase in the protein content during breeding will be accompanied by a decrease in the starch content and yield. The specific combining ability (SCA) of the testers used, suggests their possible application in establishing and improving quality breeding programs’ initial material. Full article

The worldwide rise in soil salinization is among the most critical consequences of climate change, posing a significant threat to food security. Wheat (Triticum aestivum L.), a staple crop of paramount importance worldwide, encounters significant production limitations due to abiotic stressors, particularly salinity. Consequently, the development and cultivation of salt-tolerant wheat genotypes have emerged as an essential strategy to sustain agricultural productivity and safeguard global food security. The aim of the present study was to investigate the effect of salinity (150 mM) on the performance and combining ability of 10 hybrid combinations (F2) and their parents that were obtained through a line × tester mating design at the seedling stage. Morphological, physiological, and biochemical traits were assessed under both control and salt-stress conditions. Among the assessed traits, SFW emerged as the strongest predictor of salt tolerance, demonstrating the highest correlation with MFVS and the greatest contribution in the regression model. The results highlighted distinct responses among the studied genotypes. Hybrid H5 demonstrated particular promise, surpassing the performance of the superior parent for Na⁺, K⁺, K⁺/Na⁺ and proline (Pro). Furthermore, tester T1 emerged as a good combiner for proline (Pro), total soluble sugars content (Sug), chlorophyll content (Chl) and root length (RL) under saline conditions. In contrast, under control conditions, line L1 and testers T2, T3, and T5 exhibited superior performance, demonstrating significant general combining ability (GCA) effects for four traits simultaneously. Hybrid H4 emerged as outstanding under salt stress, exhibiting favorable specific combining ability (SCA) effects for Na⁺, K⁺/Na⁺ ratio, root length (RL), relative water content (RWC), and total soluble sugars content (Sug). Under normal conditions, hybrids H7 and H10 exhibited significantly superior performance across three traits simultaneously. Non-additive genetic effects predominantly influenced the studied traits under both conditions. The parental and hybrid combinations show promise for incorporation into breeding programs designed to improve salt tolerance under the specific conditions studied. Full article

Crossing between selected lines could combine the additive genetic variance accumulated within the lines and the non-additive genetic variance between the lines in the genetic improvement of aquatic animals, thus obtaining progeny with favorable traits. However, the value of this breeding strategy has not been investigated in the Fujian oyster Crassostrea angulata due to the lack of available sufficiently selected lines. In this study, a complete 3 × 3 diallel cross was established between the normal (N), golden (G), and black (B) shell lines of C. angulata. The growth (shell height and living weight) and survival of three purebred groups and six hybrid groups under three environments (Luoyu, Jiangkou, and Houhai) were comprehensively evaluated during the larval and grow-out stages. The general combining ability (GCA) of the parental lines and the specific combining ability (SCA) of the hybrid groups were also estimated. The shell heights of the hybrid groups were significantly lower than those of their parental groups on day 25, exhibiting negative heterosis (MPH: −13.01 to −1.45; HPH: −16.69 to −5.76). Meanwhile, the survival rates of the hybrids were significantly higher than those of the parental groups. A negative value of SCA was recorded for NG (N♀ × G♂) (−0.031), which was in line with its lower survival rate on day 25. Significant heterosis was observed in the growth and survival of each hybrid group during the grow-out stage. The shell height and living weight of the hybrid groups were significantly higher in Houhai than in Luoyu and Jiangkou, but the survival rate in Houhai was significantly lower than in the other two sites. BG (B♀ × G♂) and GB (G♀ × B♂) had higher SCA values than the other four groups, which was consistent with their superior traits. The heterosis of shell height, living weight, and survival rate of BG was significantly greater than in the other five hybrid groups, which could be used as potential parents for breeding high-quality diploid and triploid Fujian oysters. This study demonstrated that the traits of C. angulata could be significantly improved by crossing between different selected lines, providing a reference for evaluating the utilization value of non-additive genetic effects (heterosis) between selected lines in bivalves. Full article

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. Full article

Lodging is a key factor affecting maize yield and harvestability. This study utilized Reid population baselines and their improved lines as female parents and No-Reid population baselines and their improved lines as male parents to form 48 incomplete diallel crosses. The genetic improvement effects, combining ability, and heterosis of three lodging resistance-related traits (stem tension, puncture strength, and crushing strength at the third internode) were analyzed. Regarding genetic improvement, the results indicated that all three traits were significantly improved in the improved lines compared to the baselines, with improvements increasing in each round. Combining ability analysis showed positive general combining ability (GCA) effects for the improved lines J133A, JM25, JM115, and JM1895 in all three traits, with higher GCA values than the baselines and first-round improved lines. Heterosis analysis revealed the highest advantages for the combinations J133A × JM115 (stem tension), JM25 × JM115 (crushing strength), and J133A × J1865 (puncture strength). These findings suggest that the improved female lines J133A and JM25, along with male lines JM115 and JM1895, not only possess strong lodging resistance but also exhibit high yield potential in the cross J133A × JM115, offering new materials and varieties for maize mechanization. Full article

Maize (Zea mays L.) is one of the most widely cultivated grain crops globally. In sub-Saharan Africa (SSA), it plays an important role in ensuring both food and income security for smallholder farmers. This study was conducted to (i) assess the performances of testcross hybrids constituted from maize lethal necrosis (MLN) tolerant doubled haploid (DH) lines under various management conditions; (ii) estimate the combining ability effects and determine the nature of gene action in the DH lines; and (iii) identify DH lines and testcross hybrids for resistance to MLN, high grain yield, and other important traits. Eleven DH lines were crossed with 11 single-cross testers using the line-by-tester mating design, and 115 successful testcross hybrids were generated. These hybrids, along with five commercial check hybrids, were evaluated across four optimum management conditions, two MLN artificial inoculations, and one managed drought environment in Kenya. Under each management condition, the effects of genotypes, environments, and genotype-by-environment interactions were significant for grain yield (GY) and most other traits. Hybrids T1/L3, T10/L3, and T11/L3 exhibited higher grain yields under at least two management conditions. A combining ability analysis revealed that additive gene effects were more important than non-additive effects for GY and most other traits, except for leaf senescence (SEN) and MLN disease severity score. DH line L3 exhibited a desirable general combining ability (GCA) effect for GY, while L5 was the best general combiner for anthesis date (AD) and plant height (PH) across all management conditions. DH lines L2, L6, and L7 showed negative GCA effects for MLN disease severity. Single-cross testers T11 and T10 were good general combiners for GY under all management conditions. Hybrids T2/L11, T9/L10, and T2/L10 demonstrated high specific combining ability (SCA) effects for GY under all conditions. This study identified DH lines and testers with favorable GCA effects for grain yield, MLN resistance, and other agronomic traits that can be used in breeding programs to develop high-yielding and MLN-resistant maize varieties. Better-performing testcross hybrids identified in the current study could be verified through on-farm testing and released for commercial production to replace MLN-susceptible, low-yield hybrids grown in the target ecologies. Full article

Chili (Capsicum annuum) consumption is often suggested, and using functional food cultivars is the most effective strategy post COVID-19 pandemic. Controlling chili breeding activity is one of the most effective methods to produce new hybrid varieties. However, the general combining ability (GCA), specific combining ability (SCA), and heterotic effect of functional biochemicals (polyphenol content, antioxidant activities, and α-glucosidase inhibitory compounds) remain poorly known in C. annuum. This study aimed to estimate these parameters in C. annuum by using five different genotypes and their hybrid combinations based on growth characteristics, yield, yield components, and fruit functional biochemicals. The F1 and F1R progenies were obtained from crosses in a greenhouse with a full diallel mating design. Each parent used in this study had a GCA advantage for each characteristic. The hybrid combination of IPB074 × IPB005 and IPB435 × IPB367 displayed the best yield results. However, the results indicated the opposite regarding α-glucosidase inhibitory compounds. The heterotic effect of functional biochemicals was observed for traits related to genotypes, polyphenol content, antioxidant activity, α-glucosidase inhibitory compounds, and similar properties related to yield and yield components, indicating their use in hybrid chili production. Full article

Cassava brown streak disease (CBSD) threatens cassava production in sub-Saharan Africa despite the availability of resistant varieties. Extreme environmental factors weaken plant defenses, reducing CBSD resistance. This study examined CBSD inheritance in cassava populations, assessed genetic variability, and identified superior sources of resistance using F1, S1, and half-sib offspring populations derived from resistant sources. The offspring underwent field evaluation at two distinct sites from 2019 to 2021, and the symptom-free genotypes were analyzed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Resistance to CBSD was categorized as most resistant, resistant, most tolerant, or tolerant based on symptoms and virus titers. The findings indicated that the resistance to CBSD is highly influenced by genotypes, F1/S1 types, and environmental conditions. An analysis of combining abilities revealed significant general combining abilities (GCAs) for CBSD, cassava mosaic disease (CMD), and traits associated with yield. The heritability estimates for resistance to CBSD varied between 43.4% and 63.2% for foliar symptoms and 14.6% and 57.9% for root necrosis across locations. The inheritance pattern involved a combination of additive and recessive genes with selfed (S1) populations displaying stronger and more effective resistance to the disease. The cassava brown streak virus (CBSV) was highly prevalent, and the Ugandan cassava brown streak virus (UCBSV) was not prevalent. Four genotypes were highly resistant to CBSD and could be key sources of resistance to this disease. Full article

A half-diallel cross study of seven melon inbred lines was carried out. The seven parents and their 21 F₁ hybrids were evaluated for precocity of maturity, average weight per fruit, and fruit quality (fruit size, rind thickness, and soluble solids). The Diallel analysis was investigated for breeding values of these melon genotypes via general and specific combining ability, relationships between general and specific combining ability, and heterosis for the evaluated traits. The analysis of variance of the traits evaluated indicated highly significant differences among genotypes, suggesting the presence of adequate genetic variation for breeding. Additive genetic effects were most important with respect to fruit weight, while genetic dominance and epistasis effects mainly controlled fruit quality traits (fruit size, rind thickness, and TSS). Parent 1 (P1) and parent 3 (P3) had significant positive general combining ability effects for fruit weight. Also, P3 had positive general combining ability effects for fruit length and diameter, and cavity diameter. P3 was found to show maximum significant GCA in the desirable direction for all the traits except for TSS. Evaluation of heterosis (%) revealed that hybrid P1 × P3 can be considered as the best-performing hybrid for average fruit weight, TSS, and precocity, which also exhibited the highest positive and significant SCA effect for these traits. These results suggested that, among the melon genotypes studied, there is the potential to generate superior new varieties in hybrid production. Full article

Seed weight in lucerne (Medicago sativa) may affect subsequent seedling vigour and stand establishment. A landrace of lucerne (Oman 2) from Oman has a 100-seed weight over 60% larger than the largest seeded parent used in previous studies. Crosses were made between Oman 2 and the smaller-seeded cultivar Titan 9, and segregating families were produced for genetic analysis and measurement of response to selection for seed size. There were significant differences in 100-seed weights between the parents (Oman 2 and Titan 9) and subsequent families. Regression of 100-seed weights of F2 families versus F1 parents was highly significant (p < 0.001), as well as 100-seed weights of the F3 families versus F1 parents. Analysis of diallel crossing among large and small-seeded F1 plants revealed highly significant general (GCAs) and specific (SCAs) combining abilities, as well as highly significant reciprocals. The GCA effect was much greater than the SCA effect with a GCA/SCA ratio of 15.9. This large ratio agrees with the significant regression coefficients and indicates that 100-seed weight in lucerne has high heritability. The significance of reciprocals was due to a large maternal effect in which large-seeded maternal parents produced progenies with significantly larger seeds relative to small-seeded parents. These results indicate that large-seeded plants should be used as the maternal parents in crosses and for recurrent selection to increase the seed size of progenies. Full article

Hybridization is an important evolutionary force, and heterosis describes the phenomenon where hybrids exhibit superior traits compared to their parents. This study aimed to evaluate the one-hundred-seed weight and fatty acid content in F₁ generations, investigating the effects of different parental crosses using a 9 × 3 incomplete diallel design (NCII). One of the challenges faced in this study was the complexity of accurately determining the influence of both genetic and environmental factors on trait inheritance. A total of 36 F₁ crosses were analyzed for general combining ability (GCA), specific combining ability (SCA), and heritability. The results showed that the level of each index in F₁ is closely related to its parents. Significant differences in GCA and SCA were observed among parental traits in most crosses. The ratio of GCA to SCA ranged from 0 to 3, indicating the pivotal role of SCA over GCA in castor breeding efforts. High narrow-sense heritability was recorded in palmitic acid (30.98%), oleic acid (28.68%), and arachidonic acid (21.34%), suggesting that these traits are predominantly under the control of additive gene action, and hence these characters can be improved by selection. Additionally, heterosis exhibited diverse patterns across traits. Based on the evaluated combining ability, heritability, and heterosis, the inbred lines CSR181 and 20111149 were recommended for castor crossbreeding due to their potential to yield progeny with optimal oil-related traits. This research contributes valuable knowledge to the field of castor breeding, providing a foundation for developing superior castor cultivars. Full article

Carrots (Daucus carota L.), a globally significant vegetable, lack extensive research on heterotic groups and diallel analysis to generate hybrid combinations. Thus, the objective of this study was to assess combining abilities and identify optimal carrot parents for producing hybrids suitable for tropical climates with elevated metabolite levels. Twenty carrot hybrids, ten parent plants, and three commercial cultivars were evaluated during the summers of 2020/2021 and 2021/2022. Agronomic evaluations were carried out and chlorophyll and carotenoid levels were determined, followed by a diallel analysis using Griffing’s Method III and GGE biplot analysis. There were significant general combining ability (GCA) effects for various agronomic traits, suggesting additive genetic effects. Based on GCA, cultivars 5, 4, and 2 were the most promising parents. Specific combining ability (SCA) revealed that hybrids 1 × 2 and 3 × 5 stood out in environment 1, whereas hybrids 1 × 5 and 5 × 3 performed well in environment 2. The GGE biplot analysis showed that hybrids 1 × 2 and 3 × 2 displayed larger average root diameters, belonged to the group with the best bolting percentages, and exhibited stability across environments. Moreover, hybrids 2 × 4, 3 × 1, 4 × 1, and 4 × 2 exhibited higher metabolite levels. These findings suggest the feasibility of obtaining superior hybrids tailored for the tropical carrot market. Full article

Breeding resistant wheat cultivars to Fusarium head blight (FHB), caused by Fusarium spp., is the best method for controlling the disease. The aim of this study was to estimate general combining ability (GCA) and specific combining ability (SCA) for FHB resistance in a set of eight genetically diverse winter wheat cultivars to identify potential donors of FHB resistance for crossing. FHB resistance of parents and F1 crosses produced by the half diallel scheme was evaluated under the conditions of artificial inoculation with F. graminearum and natural infection. Four FHB related traits were assessed: visual rating index (VRI), Fusarium damaged kernels (FDK), and deoxynivalenol and zearalenone content in the harvested grain samples. Significant GCA effects for FHB resistance were observed for the parental cultivars with high FHB resistance for all studied FHB resistance related traits. The significant SCA and mid-parent heterosis effects for FHB resistance were rare under both artificial inoculation and natural infection conditions and involved crosses between parents with low FHB resistance. A significant negative correlation between grain yield under natural conditions and VRI (r = −0.43) and FDK (r = −0.47) under conditions of artificial inoculation was observed in the set of the studied F1 crosses. Some crosses showed high yield and high FHB resistance, indicating that breeding of FHB resistant genotypes could be performed without yield penalty. These crosses involved resistant cultivars with significant GCA effects for FHB resistance indicating that that they could be used as good donors of FHB resistance. Full article

Drought is a crucial environmental stress that tremendously impacts maize production, particularly under abrupt climate changes. Consequently, breeding drought-tolerant and high-yielding maize hybrids has become decisive in sustaining its production and ensuring global food security under the global fast-growing population. The present study aimed to explore drought tolerance and agronomic performance of newly developed maize inbred lines and their hybrids. Ten newly developed maize inbred lines were crossed with two high-yielding testers using a line × tester mating design. The developed twenty hybrids alongside two high-yielding commercial hybrids were evaluated under water-deficit (5411 m³/ha) and well-watered (7990 m³/ha) conditions in dry summer climate conditions. Highly significant variations were detected among the evaluated hybrids for all studied agronomic traits under well-watered and water-deficit conditions. The inbred lines L10 and L6 were particularly notable, demonstrating the most significant negative general combining ability (GCA) effects for earliness, which is crucial for stress avoidance in both environmental settings. Inbred lines L11, L7, L6, and L1 also showed the highest positive and most significant GCA effects for key yield traits, indicating their potential as parents in breeding programs. The crosses L-10×T-1 and L-6×T-2 were outstanding for their heterotic effects on earliness in days to tasseling and silking. Similarly, the crosses L-4×T-2 and L-1×T-1 excelled in plant and ear heights under both irrigation regimes. The hybrids L-1×T-2 and L-7×T-1 demonstrated superior heterosis for chlorophyll content, number of rows per ear, and overall grain yield. Additionally, hybrids L-11×T-1 and L-11×T-2 exhibited remarkable heterotic effects for the number of grains per row, number of rows per ear, 100-kernel weight, and grain yield, highlighting their potential in breeding for productivity. Based on drought tolerance indices and cluster analysis, the cross combinations L-11×T-1, L-11×T-2, L-7×T-1, and L-1×T-2 were classified as the most drought-tolerant crosses. The principal component analysis highlighted traits such as days to tasseling, days to silking, chlorophyll content, plant height, ear height, number of grains per row, number of rows per ear, and 100-kernel weight can be taken as selection criteria for improving grain yield in maize breeding programs under limited water conditions. Based on the summarized results, the identified genetic materials could be considered promising under both conditions and hold potential for future breeding programs. Full article

Maize breeding is greatly affected by hybrid vigor, a phenomenon that hybrids exhibit superior performance than parental lines. The immortalized F₂ population (IMF₂) is ideal for the genetic dissection and prediction of hybrid performance. Here, in this study, we conducted the QTL mapping and genomic prediction of six traits related to plant architecture using an IMF₂ population. Broad-sense heritability of these traits ranged from 0.85 to 0.94. Analysis of genetic effects showed that additive variance was the main contributor to phenotypic variations. The mapping of quantitative trait loci (QTLs) revealed 10 to 16 QTLs (including pleiotropic loci and epistatic QTLs) for the six traits. Additionally, we identified 15 fine-tuning QTLs for plant height (PH). For genomic prediction (GP), the model of additive and dominance (AD) exhibited higher prediction accuracy than those fitting general combining ability (GCA) and its combination with special combining ability (SCA) effects for all tested traits. And adding the epistasis (E) effect into the AD model did not significantly increase its prediction accuracy. Moreover, the identified 15 fine-tuning QTLs of PH, which exerted large genomic prediction effects, were verified by the marker effect of GP. Our results not only provide an approach for the fine-mapping of fine-tuning QTLs but also serve as references for GP breeding in crops. Full article