Hybrid Production Lines Research Articles

Selection of extra-early white quality protein maize (Zea mays L.) inbred lines for drought and low soil nitrogen resilient hybrid production

In West and Central Africa (WCA), drought and low soil nitrogen (low N) impede increased maize (Zea mays L.) productivity and production. Due to climate change, the two stresses usually occur together, leading to food, nutritional, and economic insecurity in the sub-region. There is, therefore, the need for the development and availability of high-yielding extra-early maturing white Quality Protein Maize (QPM) synthetics and hybrids with resilience to the prevailing stresses through the identification of superior climate smart (extra-early maturing) QPM inbreds under stress (drought and low soil N) conditions. The study was conducted to identify stress-resilient QPM inbred lines for hybrid production and assess the association between grain yield and other studied characters. During the 2012 minor and major rainy seasons, 96 extra-early white QPM inbreds and four (4) normal endosperm maize inbred checks were assessed in multi-location trials under stress and optimal conditions in Nigeria. The experiments were laid out in a 10 × 10 simple lattice design with two replications. Data were recorded on grain yield and other agronomic traits. Significant variations (p < 0.01) were detected among the inbred lines for measured characters, indicating adequate genetic variability among the inbreds to allow for selection and improvement of grain yield and other measured traits. Grain yield was interrelated with all the traits used in the selection index. Moderate to high estimates of heritability were observed for most of the measured traits under stress conditions, indicating that the traits could be easily transmitted to the progenies. Fifty-seven out of the 96 QPM inbreds evaluated exhibited varying degrees of resilience to drought and low N. The QPM inbreds with desired traits may be used as genetic resources for the incorporation of tolerance genes into QPM populations in the tropics, as well as for the development of drought and low N resilient synthetics and hybrids in WCA.

Oil yield prediction for sunflower hybrid selection using different machine learning algorithms

Due to the increased demand for sunflower production, its breeding assignment is the intensification of the development of highly productive oil seed hybrids to satisfy the edible oil industry. Sunflower Oil Yield Prediction (SOYP) can help breeders to identify desirable new hybrids with high oil yield and their characteristics using machine learning (ML) algorithms. In this study, we developed ML models to predict oil yield using two sets of features. Moreover, we evaluated the most relevant features for accurate SOYP. ML algorithms that were used and compared were Artificial Neural Network (ANN), Support Vector Regression, K-Nearest Neighbour, and Random Forest Regressor (RFR). The dataset consisted of samples for 1250 hybrids of which 70% were randomly selected and were used to train the model and 30% were used to test the model and assess its performance. Employing MAE, MSE, RMSE and R2 evaluation metrics, RFR consistently outperformed in all datasets, achieving a peak of 0.92 for R2 in 2019. In contrast, ANN recorded the lowest MAE, reaching 65 in 2018 The paper revealed that in addition to seed yield, the following characteristics of hybrids were important for SOYP: resistance to broomrape (Or) and downy mildew (Pl) and maturity. It was also disclosed that the locality feature could be used for the estimation of sunflower oil yield but it is highly dependable on weather conditions that affect the oil content and seed yield. Up to our knowledge, this is the first study in which ML was used for sunflower oil yield prediction. The obtained results indicate that ML has great potential for application in oil yield prediction, but also selection of parental lines for hybrid production, RFR algorithm was found to be the most effective and along with locality feature is going to be further evaluated as an alternative method for genotypic selection.

Method of rescheduling for hybrid production lines with intermediate buffers

Method of rescheduling for hybrid production lines with intermediate buffers

Registration of Tx3440 through Tx3482 sorghum germplasm

AbstractThe sorghum [Sorghum bicolor (L.) Moench] germplasm lines Tx3440–Tx3482 (Reg. no. GP‐900–GP‐942, PI 695271–PI 695313) were developed and released by Texas A&M AgriLife Research, Lubbock, TX, in 2020. Breeding crosses from these lines were made in Lubbock, TX, with grow‐out and selection of subsequent generations completed in breeding nurseries throughout Texas over a period of years. Once selected, these lines were test for agronomic performance in replicated trials across multiple locations and years. Within the set, Tx3340–Tx3482 represent diverse pedigrees and an array of combinations of grain color, plant color, and other agronomic traits. The lines are individually resistant to selected abiotic (pre‐ and/or post‐flowering drought) stress and biotic stress (grain weathering caused by diverse genera that include Fusarium spp., Curvularia spp., and Alternaria spp.; and anthracnose caused by Colletotrichum sublineola). These lines provide the sorghum industry with sources of drought tolerance, grain weathering, and anthracnose resistance in a diverse array of elite genetic backgrounds for use as seed parent lines for hybrid production and for new line development.

Generation of Transgene-Free Maize Male Sterile Lines Using the CRISPR/Cas9 System.

Male sterility (MS) provides a useful breeding tool to harness hybrid vigor for hybrid seed production. It is necessary to generate new male sterile mutant lines for the development of hybrid seed production technology. The CRISPR/Cas9 technology is well suited for targeting genomes to generate male sterile mutants. In this study, we artificially synthesized Streptococcus pyogenes Cas9 gene with biased codons of maize. A CRISPR/Cas9 vector targeting the MS8 gene of maize was constructed and transformed into maize using an Agrobacterium-mediated method, and eight T0 independent transgenic lines were generated. Sequencing results showed that MS8 genes in these T0 transgenic lines were not mutated. However, we detected mutations in the MS8 gene in F1 and F2 progenies of the transgenic line H17. A potential off-target site sequence which had a single nucleotide that was different from the target was also mutated in the F2 progeny of the transgenic line H17. Mutation in the MS8 gene and the male sterile phenotype could be stably inherited by the next generation in a Mendelian fashion. Transgene-free ms8 male sterile plants were obtained by screening the F2 generation of male sterile plants, and the MS phenotype could be introduced into other elite inbred lines for hybrid production.

An optimisation support for the design of hybrid production lines including assembly and disassembly tasks

The optimisation problems related to the assignment of tasks to workstations in assembly and disassembly lines have been largely discussed in the literature. They are known, respectively, as Assembly Line Balancing and Disassembly Line Balancing Problems. In this study, both types of task performed on the identical product are integrated in a common hybrid production system. Therefore, the logistic process is simplified and disassembly tasks can supply easier the assembly tasks with the required components. The considered production system has the layout of two parallel lines with common workstations. The product flow is conventional in the assembly line and reverse in the disassembly line. The paper provides a new mathematical model for designing such a hybrid system and an approximate approach based on ant colony optimisation for solving large-scale instances. The solution method is tested in a case study. The obtained results are compared with the solution provided by the design of two independent lines. The analysis of the results highlights the potential benefits of the hybrid production system.

Towards development of new ornamental plants: status and progress in wide hybridization.

The present review provides insights into the key findings of the hybridization process, crucial factors affecting the adaptation of new technologies within wide hybridization of ornamental plants and presents perspectives of further development of this strategy. Wide hybridization is one of the oldest breeding techniques that contributed enormously to the development of modern plant cultivars. Within ornamental breeding, it represents the main source of genetic variation. During the long history of wide hybridization, a number of methods were implemented allowing the evolution from a conventional breeding tool into a modern methodology. Nowadays, the research on model plants and crop species increases our understanding of reproductive isolation among distant species and partly explains the background of the traditional approaches previously used for overcoming hybridization barriers. Characterization of parental plants and hybrids is performed using molecular and cytological techniques that strongly facilitate breeding processes. Molecular markers and sequencing technologies are used for the assessment of genetic relationships among plants, as the genetic distance is typically depicted as one of the most important factors influencing cross-compatibility in hybridization processes. Furthermore, molecular marker systems are frequently applied for verification of hybrid state of the progeny. The flow cytometry and genomic in situ hybridization are used in the assessment of hybridization partners and characterization of hybrid progeny in relation to genome stabilization as well as genome recombination and introgression. In the future, new research and technologies are likely to provide more detailed information about genes and pathways responsible for interspecific reproductive isolation. Ultimately, this knowledge will enable development of strategies for obtaining compatible lines for hybrid production. Recent development in sequencing technologies and availability of sequence data will also facilitate creation of new molecular markers that will advance marker-assisted selection in hybridization process.

Performance analysis of non-homogeneous hybrid production lines based on decomposition method

For analysing performance of non-homogeneous hybrid lines, several new techniques are proposed to transform non-homogeneous production lines into homogeneous lines so that the traditional decomposition method can be utilised to analyse non-homogeneous hybrid lines. The techniques are complementary to the current transformation technique. The techniques are tested and discussed by numerical experiments based on the decomposition method. It is shown that the new transformation techniques have good estimations on the performance of the lines with weak non-homogeneousness in comparison with the traditional technique. Furthermore, the discussion of the techniques clears several questions about the traditional transformation technique, which were answered in former studies. The new techniques help promote the application of the homogenisation technique of non-homogeneous lines.

Cytoplasmic Male Sterility in Russian Dandelion

Russian dandelion (Taraxacum kok-saghyz) is a candidate species for introducing natural rubber production into North America, and its domestication is currently underway to create an economically viable crop. Development of hybrid cultivars is essential to maximize the yield potential of the species, and cytoplasmic male sterility (CMS) is an important breeding tool that can facilitate this process. Male sterility was discovered in two full-sib russian dandelion families, and additional crosses were performed to create F2, F3, and backcross generations to assess inheritance of the phenotype. A sterility-inducing cytoplasm (S) that could be restored to fertility by a dominant allele at a single nuclear restorer of fertility (Rf) gene and a fertility-inducing cytoplasm (F) were identified. Characteristics of the CMS system were 1) (S)rfrf × (F)rfrf crosses produced only sterile progeny, 2) crosses where the female parents were (F) produced only fertile progeny, and 3) segregation was observed only when the maternal parent had (S). Sterility was not stable in all plants; some with sterility-inducing cytoplasm produced small amounts of pollen or formed both sterile and fertile flowers simultaneously. On the basis of seasonal differences in the frequency of partially sterile plants, sterility was stable at low temperatures and unstable at high temperatures. This germplasm can be of central importance for development of stable CMS lines for hybrid production.

Performance Analysis of Non-Homogeneous Hybrid Production Lines

 Abstract—For analyzing performance of non-homogeneous hybrid lines, a new technique of dealing with nonhomogeneous lines is proposed to transform a non-homogeneous production line into a homogeneous line, which is based on decomposition method. The technique extends the applicability of decomposition method to nonhomogeneous lines. The technique is discussed by numerical experiments comparing with aggregation method, what's more, the advantages and disadvantages are specified. The technique complements and develops the system analysis techniques of hybrid production lines. Index Terms—Hybrid system, system performance, Non-homogeneousness, decomposition method.

An Extended System Aggregation Method for Hybrid Production Lines with Multiple Failure Rate and Unreliable Limited Buffers

In this study, a new system performance evaluation method is introduced to the two-machine line. After that, the extended system aggregation model is developed and corresponding aggregation formulations are deduced.Different from traditional production models, the production line features unreliable buffers and multiple stochastic failure modes of the machines. The method is applicable to analyzing the cases arising from two or more stochastic events or more complex production lines

An Extended System Aggregation Method for Hybrid Production Lines with Multiple Failure Rate and Unreliable Limited Buffers

An Extended System Aggregation Method for Hybrid Production Lines with Multiple Failure Rate and Unreliable Limited Buffers

Performance Evaluation of Hybrid Production Lines with Multiple Stochastic Failure Modes and Unreliable Limited Buffers

A hybrid manufacturing system which consists of two machines is examined. Unreliable buffers and multiple stochastic failure modes of the machines are introduced to the system. A new method of the system performance evaluation is presented. The states of the system are analyzed in detail based on a discrete model and a new solution technique is given to determine the state probabilities. The method can be used to analyze the cases arising from two or more stochastic events or longer (or more complex)production lines. Numerical results are also offered to testify the method and show some characteristics of the system.

Phenometric studies on stalk juice and sugar contents of silo sorghum types

Bioenergies (among them e.g. bioalcohol) can be solutions for the replacement of fossil fuels. For its production, plants with high sugar or starch content can be used. Juice pressed from the stalk of sugar sorghum has high sugar content (14-17%) that makes it suitable for bioethanol production. During our experiment, we examined 53 restorer male lines; among them 22 were silo type sugar sorghum. We studied the following traits: plant height, breeding time, level of foliation, stalk diameter, characteristics of stalk medulla, juice content of stalk, sugar content of stalk juice. According to examined characteristics, we selected six restorer male lines for studies in the forthcoming years: RL 1, RL 2, RL 3, RL 4, RL 5, RL 9, RL 12, RL 15, RL 18. Their stalk medullas were wet, stalk diameters were medium-thick, sugar contents of juices varied between 17 and 24% at the end of milk mature. Harvest was made in September, they can be classified into early maturation group. Male sterile female lines were the following: SL 1, SL 2, SL 3, SL 4, SL 5. The maintainer male lines were: CL 1, CL 2, CL 3, CL 4, CL 5. In Hungary, there are only a few male sterile femalelines, so we will use these lines for hybrid production during the next years.

Genetic relationships among melon breeding lines revealed by RAPD markers and agronomic traits

RAPD markers and agronomic traits were used to determine the genetic relationships among 32 breeding lines of melon belonging to seven varietal types. Most of the breeding lines were Galia and Piel de Sapo genotypes, which are currently being used in breeding programmes to develop new hybrid combinations. A total of 115 polymorphic reliable bands from 43 primers and 24 agronomic traits were scored for genetic distance calculations and cluster analysis. A high concordance between RAPDs and agronomic traits was observed when genetic relationships among lines were assessed. In addition, RAPD data were highly correlated with the pedigree information already known for the lines and revealed the existence of two clusters for each varietal type that comprised the lines sharing similar agronomic features. These groupings were consistent with the development of breeding programmes trying to generate two separate sets of parental lines for hybrid production. Nevertheless, the performance of certain hybrids indicated that RAPDs were more suitable markers than agronomic traits in predicting genetic distance among the breeding lines analysed. The employment of RAPDs as molecular markers both in germplasm management and improvement, as well as in the selection of parental lines for the development of new hybrid combinations, is discussed.

Agronomic Traits and Chromosome Behavior of Autotetraploid Sorghums

AbstractThe agronomic performance and chromosome behavior of autotetraploid sorghum [Sorghum bicolor (L.) Moench] inbreds and F1 hybrids were investigated. Autotetraploids have possible commercial use and can serve as bridging species in crosses to natural tetraploids. Autotetraploid sorghum inbreds (2n = 40) had higher kernel weight, seed yield, and protein and amino acid content than their diploid counterparts. Stalk height and panicle length of the autotet‐raploids, however, were not different from those of the diploids, and seed set of autotetraploids was lower in early generations. Seed set of autotetraploid Ft hybrids was related to and higher than that of the autotetraploid parental inbred lines. Frequency of quadrivalents, anaphase I and II laggards, and quartet micronuclei varied among autotetraploids. Frequency of quadrivalents did not appear to be an important factor in seed set nor was it significantly associated with frequency of laggards. Aneuploids (2n = 39, 41) had higher percentages of laggards and micronuclei than did euploids (2n = 40). Methods of pollination significantly affected seed set in autotetraploid S4 lines. Differences in seed set among autotetraploid lines indicated the feasibility of selecting for lines with high seed set and utilizing those lines for hybrid production.