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Enhanced grain yield has been achieved in bread wheat ( Triticum aestivum L.) through development and cultivation of superior genotypes incorporating yield-related agronomic and physiological traits derived from genetically diverse and complementary genetic pool. Despite significant breeding progress, yield levels in wheat have remained relatively low and stagnant under marginal growing environments. There is a need for genetic improvement of wheat using yield-promoting morpho-physiological attributes and desired genotypes under the target production environments to meet the demand for food and feed. This review presents breeding progress in wheat for yield gains using agronomic and physiological traits. Further, the paper discusses globally available wheat genetic resources to identify and select promising genotypes possessing useful agronomic and physiological traits to enhance water, nutrient-, and radiation-use efficiency to improve grain yield potential and tolerance to abiotic stresses (i.e. elevated CO2, high temperature, and drought stresses). Finally, the paper highlights quantitative trait loci (QTL) linked to agronomic and physiological traits to aid breeding of high-performing wheat genotypes.

The study aimed to identify optimal ethyl methanesulphonate (EMS) dose and soaking duration to induce genetic variation in selected founder tef ( Eragrostis tef [Zucc.] Trotter) cultivars. Study conducted using a 3 × 5 × 4 factorial experiment with seeds from three founder cultivars (Emerson, Highveld and Ivory), five EMS doses (0.00%, 0.50%, 1.00%, 1.50% and 2.50%) and four soaking durations (1, 2, 4 and 8 h). Data were collected on M 1 to M 3 derivatives on the following parameters: germination percentage, days to 50% emergence, seedling survival, seedling height, root length and number of tillers. Ideal EMS dose of 2.11% and 4-hour soaking duration were discerned at M1 and used in large-scale mutagenesis, enabling the development of M 2 and M 3 generations. There were significant ( p  < 0.001) interactions of cultivar × dose, cultivar × soaking duration, and dose × soaking duration for germination percentage, days to 50% emergence, seedling survival percentage and shoot height. EMS dose had a highly significant ( p  < 0.001) effect on all assessed traits except root length. Study identified following EMS mutagenesis conditions as ideal for tested founder cultivars: 1.67% at 4-hours soaking duration Emerson, 2.97% at 4-hours soaking duration Highveld and 1.67% at 4-hours soaking duration Ivory.

In the face of climate changes and limited water availability for irrigated crop production, enhanced drought tolerance and adaptation is vital to improve wheat productivity. The objective of this study was to determine the responses of newly bred and advanced mutant lines of wheat based on agronomic traits and biomass allocation under drought-stressed and non-stressed environments for production and breeding. Fifty-three mutant lines, including the parental check and six check varieties, were evaluated under non-stressed (NS) and drought stressed (DS) conditions in the field and controlled environments using a 20 x 3 alpha lattice design with two replicates. The following agronomic data were collected: days to 50% heading (DTH), days to maturity (DTM), plant height (PH), number of productive tillers (PTN), shoot biomass (SB), root biomass (RB), total biomass (TB), root: shoot ratio (RSR), spike length (SL), thousand seeds weight (TSW) and grain yield (GY). Data were analyzed and summarized using various statistical procedures and drought tolerance indices were computed based on grain yield under NS and DS conditions. Significant (P < 0.05) differences were recorded among the mutant lines for most assessed traits under NS and DS conditions. Grain yield positively and significantly (p < 0.001) correlated with PTN (r = 0.85), RB (r = 0.75), SB (r = 0.80), SL (r =0.73), TB (r = 0.65), and TSW (r = 0.67) under DS condition. Principal component analysis revealed three components contributing to 78.55% and 77.21% of the total variability for the assessed agronomic traits under DS and NS conditions, respectively. The following traits: GY, RB, SB, and PTN explained most of the variation with high loading scores under DS condition. Geometric mean productivity (GMP), mean productivity (MP), harmonic mean (HM), and stress tolerance index (STI) were identified as the best drought tolerance indices for the identification of tolerant lines with positive correlations with GY under NS and DS conditions. Among the advanced lines tested, LMA16, LMA37, LMA47, LMA2, and LMA42 were selected as the superior lines with high performance and drought tolerance. The selected lines are recommended for multi-environment trails and release for production in water-limited environments in South Africa.

Genetic improvements for yield-component traits in bread wheat (Triticum aestivum L.) have resulted in substantial contributions to wheat yield increases globally. Conversely, yield gains have tended to reduce genetic gains for grain quality traits, requiring a strategic breeding approach for simultaneous improvement of grain yield and grain quality. The objective of this review is to highlight breeding progress on genetic improvement of agronomic, physiological, and biochemical traits, grain quality, and bread-making attributes in bread wheat. Genetic gains for agronomic, physiological, and biochemical yield-component traits and their influence on yield response and genetic potential are discussed. Genetic changes in grain quality traits and bread-making attributes and how they are influenced by gains for yield and yield-component traits are also presented. Also, the paper presents wheat genetic resources to enhance genetic gains for yield-component and quality traits. Perspectives on future breeding efforts to improve genetic gains for yield, yield-related traits, and grain quality traits are discussed. Genetic gain in grain yield of 15.3 ha−1 year−1 (0.7%) were reported for Siberia, 15.3–57.5 kg ha−1 year−1 for Canada, 15.3–103.5 kg ha−1 year−1 for China, 15.3–31.0 kg ha−1 year−1 for Iran, 33.9–34.8 kg ha−1 year−1 for Brazil, 33.1–40 kg ha−1 year−1 for Mexico, 14.6–30.4 kg ha−1 year−1 for the USA, 18 kg ha−1 year−1 for Australia, and 58.0 kg ha−1 year−1 for Turkey. The most important agronomic traits that contributed to significant improvements in yield gains include short plant height, high biomass production, higher harvest index, increased number of kernels per spike, and greater thousand kernel weight.

An overview of phytochemical compounds, phytohormones and flesh textural properties influencing fruit quality of watermelon fruit, and developed genomic and genetic resources for fruit quality breeding. Fruit quality traits of sweet watermelon ( Citrullus lanatus var. lanatus ) are crucial for new product development and commercialization. Sweet watermelon fruit quality traits are affected by the compositions of phytochemical compounds, phytohormones, and fruit flesh firmness which are affected by genes, the growing environment and their interaction. These compositions determine fruit ripening, eating quality, and postharvest shelf-life. Knowledge of the genetic profile and analyses of quality traits in watermelon is vital to develop improved cultivars with enhanced nutritional compositions, consumer-preferred traits, and extended storage life. This review aims to present the opportunities and progress made on the genetic analysis of fruit quality traits in watermelon as a guide for quality breeding based on economic and end-user attributes. The first section of the review highlights the genetic mechanisms involved in the biosynthesis of phytochemical compounds (i.e., sugars, carotenoids, amino acids, organic acids, and volatile compounds), phytohormones (i.e., ethylene and abscisic acid) and fruit flesh structural components (i.e., cellulose, hemicellulose, and pectin) elicited during watermelon fruit development and ripening. The second section pinpoints the progress on the development of molecular markers and quantitative trait loci (QTL) analysis for phytochemical compounds, phytohormones and fruit quality attributes. The review presents gene-editing technology and innovations associated with fruit quality traits for selection and accelerated cultivar development. Finally, the paper discussed gene actions conditioning fruit ripening in citron watermelon ( C. lanatus var. citroides [L. H. Bailey] Mansf. ex Greb.) as reference genetic resources to guide current and future breeding. Information presented in this review is useful for watermelon variety design, product profiling and development to serve the diverse value chains of the crop.

Genetic resources of tepary bean ( Phaseolus acutifolius A. Gray) germplasm collections are not well characterized due to a lack of dedicated genomic resources. There is a need to assemble genomic resources specific to tepary bean for germplasm characterization, heterotic grouping, and breeding. Therefore, the objectives of this study were to deduce the genetic groups in tepary bean germplasm collection using high-density Diversity Array Technology (DArT) based single nucleotide polymorphism (SNP) markers and select contrasting genotypes for breeding. Seventy-eight tepary bean accessions were genotyped using 10527 SNPs markers, and genetic parameters were estimated. Population structure was delineated using principal component and admixture analyses. A mean polymorphic information content (PIC) of 0.27 was recorded, indicating a relatively low genetic resolution of the developed SNPs markers. Low genetic variation (with a genetic distance [GD] = 0.32) existed in the assessed tepary bean germplasm collection. Population structure analysis identified five sub-populations through sparse non-negative matrix factorization (snmf) with high admixtures. Analysis of molecular variance indicated high genetic differentiation within populations (61.88%) and low between populations (38.12%), indicating high gene exchange. The five sub-populations exhibited variable fixation index (F ST ). The following genetically distant accessions were selected: Cluster 1:Tars-Tep 112, Tars-Tep 10, Tars-Tep 23, Tars-Tep-86, Tars-Tep-83, and Tars-Tep 85; Cluster 3: G40022, Tars-Tep-93, and Tars-Tep-100; Cluster 5: Zimbabwe landrace, G40017, G40143, and G40150. The distantly related and contrasting accessions are useful to initiate crosses to enhance genetic variation and for the selection of economic traits in tepary bean.

Background/Objectives: Induced mutagenesis is vital in genetic enhancement and trait discovery, for genetic analysis and breeding of novel crop varieties with desirable product profiles. Understanding the genetic relationships among newly developed mutant genotypes enables targeted selection and genetic recombination. Therefore, the objective of the current study was to assess the genetic diversity among mutant bread wheat genotypes developed through ethyl methanesulfonate (EMS) mutagenesis using phenotypic traits and diagnostic simple sequence repeat (SSR) markers to identify novel mutants and traits for breeding. Methods: Sixteen advanced (M6) mutant lines, one parental genotype, and three check varieties were genetically profiled using ten diagnostic SSR markers. The genotypes were evaluated for agronomic traits under drought-stressed (DS) and non-stressed (NS) conditions using a 10 × 2 alpha lattice design with two replications. Results: The SSR markers revealed a total of 21 alleles, with an average of 2.10 alleles per locus. An average polymorphic information content (PIC) of 0.51 was computed, revealing moderate informativeness of the genetic markers. Significant (p < 0.05) differences were observed among the test genotypes for key agronomic traits under NS and DS conditions. Grain yield positively and significantly (p < 0.001) correlated with plant height (r = 0.79), number of productive tillers (r = 0.82), root biomass (r = 0.77), shoot biomass (r = 0.74), spike length (r = 0.74), total biomass (r = 0.74), and thousand-seed weight (r = 0.64), under DS conditions. Principal component analysis explained 78.03 and 87.14% genotype variation for assessed agronomic traits under DS and NS conditions, with total biomass, shoot biomass, root biomass, productive tiller, plant height and grain yield as key traits contributing the most variation in the test genotypes. Conclusions: Wheat mutants LMA16, LMA44, and LMA53 were identified as genetically distinct and high yielders under drought stress conditions and recommended for production in rain-fed environments. The selected mutants are a valuable source of genes for wheat improvement programs.

Citron watermelon [ Citrullus lanatus var. citroides (L.H. Bailey) Mansf. ex Greb.] is an important genetic resource serving for food, feed, and breeding dessert watermelon ( C. lanatus var. lanatus ) and other cross-compatible species. Wide phenotypic variation exists among South African citron watermelon landraces which are yet to be systematicaly assessed for diverse uses and cultivar design. The objective of this study was to assess phenotypic diversity of citron watermelon landrace accessions of South Africa and to select desirable genotypes with suitable agronomic and horticultual traits for direct production, breeding and conservation. Thirty six citron watermelon landrace accessions were evaluated under field conditions in two seasons using a 6 × 6 alpha lattice design with three replicates. Data on key qualitative and quantitative traits were collected and subjected to non-parametric and parametric statistical analyses. The accessions showed wide phenotypic variation and unique traits for genetic improvement. Positive and significant correlations ( p  < 0.001) were recorded between total fruit yield per plant with plant height ( r  = 0.64), number of harvestable fruits ( r  = 0.70), number of marketable fruits ( r  = 0.73) and marketable fruit yield ( r  = 0.96). Seed yield per plant positively and significantly ( p  < 0.001) correlated with number of male flowers ( r  = 0.68), plant height ( r  = 0.61) and total fruit yield ( r  = 0.79). Prinicipal component analysis identified nine components which accounted for 86.38% of total variation amongst accessions for assessed phenotypic traits. Citron watermelon accessions WWM16, WWM67 and WWM79 were high-yielding suitable for fruit production for food or livestock feed. Accessions namely WWM03, WWM09, WWM16, WWM39, WM64 and WWM76 produced high fruit number and marketable fruit yield per plant which are recommended as parental genotypes for breeding. Furthermore, accessions WWM04, WWM15, WWM24, WWM28, WWM46, WWM66, WWM68, WWM76 and WWM79 were selected with higher seed production for the food or feed industry. The study recommends citron watermelon accessions such as WWM14, WWM16, WWM39, WWM41, WWM67 and WWM79 for use as leafy vegetables owing to their profuse branching ability and longer vine production. Whereas accessions including WWM03, WWM17, WWM35, WWM40, WWM50, WWM67, WWM79 and WWM85 are selected with larger fruit size. Accessions WWM05 and WWM09 are sour-flesh types which are suitable genetic stocks for breeding sweet-and-sour dessert watermelons. Orange-fleshed accessions such as WWM03, WWM04, WWM46, WWM64, WWM66 and WWM67 are recommended for fresh consumption, cooking, processing or variety design. Accessions WWM02, WWM03, WWM08, WWM14, WWM16, WWM23, WWM38, WWM40, WWM41 and WWM67 have red and white seed coat colour which are superior selections to prepare roasted citron watermelon seed snack.

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.

This study determined genotype-by-environment effect on grain quality among heat and drought tolerant bread wheat genotypes to select ideal genotypes for grain quality improvement. Gliadin (Gli), gluten (Glu), glutenin (Glut), gliadin: glutenin ratio (Gli: Glut ratio) and total protein content (TPC) were determined among 28 elite bread wheat genotypes under non-stressed and drought-stressed conditions. Additive main effect and multiplicative interaction and genotype and genotype-by-environment biplot were used for data analyses. Large genotypic effects were observed for Gli (55.42%), TPC (67.78%) and Gli: Glu ratio (49.77%), suggesting genotypic variation for these traits. High environmental influence of 89.65 and 89.06% were observed for Glu and Glut. Wheat genotypes LM03, LM22, LM23, LM41, LM44, LM60, LM62, LM71, LM73, LM71, LM85, LM90 and LM95 with high protein and protein-fractions and high levels of abiotic stress tolerance (i.e. heat and drought) were selected for breeding for high grain quality.