Cross Combinations Research Articles

Research on optimal design of 6in offshore flange connector’s sealing structure

Taking the maximum contact pressure as the objective function for, the optimal design model of the offshore flange connector was established to analyze the impact of the flange cone's angle and the curvature radius of the lenticular gasket's contact surface on the sealing performance of the connector. An optimized three-dimensional model of the offshore flange connector was constructed using the MATLAB software's fmincon function to obtain the optimal size of the cone angle and curvature radius. The maximum contact pressure and maximum equivalent stress values of the non-optimized and optimized offshore flange connectors under the cross combination of two design pressures and six operating temperatures were analyzed by Workbench software, and the sealing performance of the non-optimized and optimized offshore flange connectors was compared according to the sealing judgment basis. The results show that compared with the previously studied offshore flange connector, the sealing structure of optimized offshore flange exhibits maximum increase in contact pressure increase but maximum decrease in equivalent stress. Under actual operating circumstances, the optimized offshore flange connection performs better in sealing and is less prone to breakage.

Variation of fruit morphology and genetic divergence of indigenous pointed gourd

Thirty one indigenous pointed gourd genotypes were studied in Terai region of West Bengal, India to observe variation of fruit morphology and genetic divergence using Mahalanobis D2 statistics and principal component analysis. The field experiment was designed in RBD with three replications at Uttar Banga Krishi Viswavidyalaya, West Bengal, India during the year 2018-19and 2019-20. All the genotypes were arranged into eight divergent clusters in which cluster I included maximum number followed by cluster II. The highest contribution towards genetic diversity was shown for node at the first female flower (37.85%) followed bychlorophyll a content of leaf (16.77%) and seeds per fruit (12.04%). Principal component-1 had maximum variability (43.83%) with positive loading for the characters like node at the first female flower (0.298), appearance of first female flower (0.265), days to fruit maturity (0.194) and internodal length (0.137). Based on the inter and intra cluster distance cross combinations in between lines PCP-17 and PCP-19, PCP-17 and PCP-9, PCP-17 and PCP-28, PCP-19 and PCP-11, PCP-14 and PCP-9 and PCP-23 and PCP-10 may be utilized in future improvement programme of pointed gourd. Bangladesh J. Bot. 53(1): 193-201, 2024 (March)

Exemplifying the breeding potential of ornamental banana hybrids through palynological studies

Ornamental bananas (OBs) are known for their bright colour, bract, and attractive foliage with significant ornamental value. The OBs are tolerant to abiotic (cold and drought) and biotic stresses (pests and diseases), having immense scope for studying their breeding potential and the development of two hybrids from the cross of Karpooravalli (ABB) × M. acuminata subsp. zebrina (ZB) has sparked curiosity to explore the Ornamental Banana Hybrids (OBHs). Therefore, the present study explored the breeding potential of OBHs and wild species (M. acuminata subsp. zebrina [ZB]). Among these, maximum pollen viability (PV), pollen germination (PG), pollen output/anther (PO/A) and pollen size (PS) were recorded in ‘ZB’ (99.60%), ‘OZ2’ (64.70%), ‘OR14’ (2859.80) and ‘OV1’ (115.50 μ), respectively. Boxplot was performed to study the distribution pattern of all three cross combinations, which provided a good result with larger variability in ‘OZ’ followed by ‘RZ’ for PV, PG and PS. In contrast, higher variability for PO/A was obtained in ‘OR’. A positive correlation was recorded between PV, PG and PS, whereas PO/A was negatively correlated with all the attributes studied. Hierarchical cluster analysis categorized the OBHs and wild species into three clusters, with clusters I, II and III exhibiting the highest PG (%), PV (%) and PO/A, respectively. No significant difference was observed in the case of PS. Hence, these OBHs can be utilized as a pollen source for breeding and developing a novel hybrids

Genetic Potential of Newly Developed Maize Hybrids under Different Water-Availability Conditions in an Arid Environment.

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.

Application of machine learning for identification of heterotic groups in sunflower through combined approach of phenotyping, genotyping and protein profiling

Application of machine learning in plant breeding is a recent concept, that has to be optimized for precise utilization in the breeding program of high yielding crop plants. Identification and efficient utilization of heterotic grouping pattern aided with machine learning approaches is of utmost importance in hybrid cultivar breeding as it can save time and resources required to breed a new plant hybrid/variety. In the present study, 109 genotypes of sunflower were investigated at morphological, biochemical (SDS-PAGE) and molecular levels (through micro-satellites (SSR) markers) for heterotic grouping. All the three datasets were combined, scaled, and subjected to unsupervised machine learning algorithms, i.e., Hierarchical clustering, K-means clustering and hybrid clustering algorithm (hierarchical + K-means) for assessment of efficiency and resolution power of these algorithms in practical plant breeding for heterotic grouping identification. Following the application of machine learning unsupervised clustering approach, two major groups were identified in the studied sunflower germplasm, and further classification revealed six smaller classes in each major group through hierarchical and hybrid clustering approach. Due to high resolution, obtained in hierarchical clustering, classification achieved through this algorithm was further used for selection of potential parents. One genotype from each smaller group was selected based on the maximum seed yield potential and hybridized in a line × tester mating design producing 36 F1 cross combinations. These F1s along with their parents were studied in open field conditions for validating the efficacy of identified heterotic groups in sunflowers genetic material under study. Data for 11 agronomic and qualitative traits were recorded. These 36 F1 combinations were tested for their combining ability (General/Specific), heterosis, genotypic and phenotypic correlation and path analysis. Results suggested that F1 hybrids performed better for all the traits under investigation than their respective parents. Findings of the study validated the use of machine learning approaches in practical plant breeding; however, more accurate and robust clustering algorithms need to be developed to handle the data noisiness of open field experiments.

Genetic Variability and Selection Parameters for Yield and Its Contributing Traits in Bread Wheat (Triticum aestivum L. em. Thell)

Ten bread wheat genotype and their all possible cross combinations excluding their reciprocals (10 parents+45 F1s+45 F2s) were evaluated in a randomized block design with three replications during Rabi2022-2023 at Student’s Instructional Farm, C. S. Azad University of Agriculture and Technology-208002, Kanpur, U.P to get the extent of variability and related parameters to select effectively for grain yield and quality character. It is the big challenge for researchers to get high grain yield with high protein. The data was recorded on fourteen characters viz., days to heading (50%), days to maturity, plant height (cm), number of productive tillers per plant, chlorophyll content, spike length (cm), number of spikelets per spike, number of grains per spike, weight of grain per spike (g), 1000 grain weight (g), biological yield (g), harvest index (%),protein content (%) and grain yield per plant (g). The variability among parents was highest for days to maturity it ranged from 117.33 to 137.67 with the mean value 126.60. The variation in F1 progenies was highest for plant height ranged from 85.97 to 120.53 with the mean value of 96.71.The variation in F2 progenies was highest for plant height ranged from 83.70 to 120.20 with the mean value of 94.99. The result showed higher estimated values for phenotypic coefficient of variability(PCV) of all the fourteen characters as compared to their corresponding genotypic coefficient of variability (GCV). Highest value of PCV and GCV were noted for grain yield per plantin both generation F1s and F2s except GCV were observed for none of the character F1s. high heritability estimates were recorded for all characters in both generation F1s and F2s.High genetic gain was observed for grain yield per plant followed by biological yield per plant in both generation F1s and F2s.

Exploitation of the Genetic Variability of Diverse Metric Traits of Durum Wheat (Triticum turgidum L. ssp. durum Desf.) Cultivars for Local Adaptation to Semi-Arid Regions of Algeria.

Abiotic stresses pose significant challenges to wheat farming, yet exploiting the genetic variability within germplasm collections offers an opportunity to effectively address these challenges. In this study, we investigated the genetic diversity of key agronomic traits among twenty durum wheat cultivars, with the intention to pinpoint those better suited to semi-arid conditions. Field trials were conducted at the ITGC-FDPS Institute, Setif, Algeria, during the winter season of 2021/22. A completely randomized design was used with three replicates. Statistical analyses revealed significant variation among the genotypes for most of the studied traits, with some cultivars exhibiting a superior performance in a stressful environment. Notably, traits like the number of grains per spike (NGS) and the grain yield (GY) displayed high genotypic coefficients of variation (CVg). Except for membrane thermostability (MT) and biological yield (BY), the majority of the assessed traits exhibited moderate-to-high heritability estimates. Genotypic and phenotypic correlation studies have confirmed the importance of many yield-related traits in the expression of GY. The harvest index (HI) underscored the highest genotypic direct effect on GY, followed closely by spike number (SN), serving as consistent pathways through which most of the measured traits indirectly influenced GY. The cluster analysis categorized the durum wheat cultivars into seven distinct clusters. The largest inter-cluster distance was observed between clusters G3 and G4 (D2 = 6145.86), reflecting maximum dissimilarity between the individuals of these clusters. Hybridizing divergent clusters may benefit future breeding programs aiming to develop potential durum wheat varieties through cross combinations. This study's findings contribute to sustainable agriculture efforts by facilitating the selection of genotypes with enhanced resilience and productivity, particularly for cultivation in challenging semi-arid regions.

Correlation dependence of selective valuable traits of yellow lupine

As a result of the conducted study, it was found that the combinations of crosses 16-20, 22-20 and 24-20 with dominance in F1, transgression in F2 on biologically valuable traits in selective respect in F3 confirm their correlation relationship and differ in the type of utilization. The 16-202c hybrids are seed oriented due to high plant survival rate and high number of beans on the main raceme. The material of hybrids 16-204v, 22-202c, 24-202c is universal, characterized by high productivity, which is confirmed by the correlation with the number of seeds and their weight (by grain), with the height of the remaining plants to harvesting, the number of beans on them and lateral branching (by herbage). The analysis of pairing of economically useful traits on seed productivity revealed a positive relationship between the number and weight of seeds from the main inflorescence in combinations 5-202c (r = 0.74 and 0.82), 22-20 (r = 0.89 and 0.92), 24-20 (r = 0.80 and 0.71), 30-20 (r = 0.94 and 0.93) and others. High correlation was found between the grain yield and the number of surviving plants to harvest in hybrids 5-202c (r = 0.92), 30-202c (r = 0.83), 6-202d (r = 0.73), 22-20 (r = 0.79), 24-20 (r = 0.80). Regardless of the combination of crosses, the number and weight of seeds from the main inflorescence with the correlation coefficient from 0.71 to 0.93 have a strong positive effect on the seed productivity of most hybrids. A positive effect was obtained from the number of beans from the main raceme in combinations 17-202c (r = 0.90), 25-202c (r = 0.81), 24-20 (r = 0.77), and 5-202c (r = 0.90). The herbage yield of yellow lupine was influenced by the plant height (r = 0.61–0.93), the number of surviving plants to harvest (r = 0.51–0.95), the presence of lateral shoots with beans (r = 0.54–0.63) in hybrids 5-202c, 16-202c, 22-202c, 24-202c and others.

Assessing the Genetic Variation of Swarna rice (Oryza sativa L.) Cultivars using SSR marker

Swarna rice cultivars (Indian cultivar) are widely grown in the northern part of Bangladesh because of their higher yield, drought tolerance, higher quality of grain and good plant appearance. Therefore, a study was conducted to observe genetic diversity among eight Swarna cultivars grown in Bangladesh. The genetic diversity of the cultivars was assessed by one hundred SSR (simple sequence repeat) markers. Among these, forty-four primers were polymorphic. In total, 188 alleles from eight rice genotypes with an average of 4.27 alleles per locus were identified. Allele numbers varied from 2 to 11. The average polymorphism information content (PIC) was 0.533, with a range of 0.195 to 0.889. The most suitable markers found were RM149, RM232, and RM3421, which provided the highest PIC value of 0.889. Genetic dissimilarity coefficient values between pairs indicated that the Guti Swarna and Nepali Swarna cultivars along with the Guti Swarna and Deshi Guti Swarna cultivars were the most genetically distant (0.818) cultivars whereas the Nepali Swarna and Nironjon Swarna cultivars were the closest (0.091). A dendrogram constructed based on polymorphism indicated five major groups. It was observed that the Guti Swarna and Sumon Swarna cultivars formed two different solitary groups, I and II whereas the Nepali Swarna and Nironjon Swarna formed group III, the Lal Swarna and Swarna5 constructed group IV, and the Deshi Guti Swarna and Tiger Indian Swarna were in group V. Our findings may help in designing appropriate cross combinations for further improvement of Swarna cultivars.

Assessment of combining ability for targeted traits in periwinkle (Catharanthus roseus (L.) G. Don) through diallel analysis

Catharanthus roseus (L.) G. Don is a vital summer season perennial semi shrub and multipurpose drought resilient flower crop of the tropical region of the Indian subcontinent. This industrially dominant crop is primarily availed as border, bedding and pot culture in landscaping; and also cultivated for its anti-cancer alkaloid compounds enriched plant parts. Hence, the present study was focused to explore diversity. Six inbred lines of periwinkle were crossed in full-diallel fashion with an objective of identifying superior cross-combinations for high general, specific and reciprocal combining ability. The analysis of variance for combining ability was highly significant for growth and flowering traits indicated existence of both additive and non-additive gene actions. However some traits showed only additive effect due to non-significant general combining ability. The parental lines of Vi-13–2 and Vi-15–2 expressed superior general combining effects for flower yield and considered as good general combiners for crossing programmes. The cross combinations Vi-15–1 × Vi-14–3 and Vi-16 × Vi-15–2 exhibited significantly positive specific combining ability effects for flower yield and considered as good specific direct combiners. High specific direct cross combiners necessitate poor × good, good × good and poor × poor parental combinations and can be contribute additive × dominance, additive × additive, dominance × dominance and epistatic gene interactions. The specific reciprocal cross combiners identified as Vi-14–3 × Vi-29 and Vi-14–3 × Vi-13–2 with superior expression in the reciprocal magnitudes for various traits might be due to cytoplasmic effects. The current investigation is designed to identify the best performing inbred lines for ornamental utilization as well as lines that can be exploited as parents in subsequent crosses.

Line×Tester Analysis for Heterosis and Combining Ability for Seed Yield and its Component Traits in Indian Mustard

Twelve advanced lines/varieties of Indian mustard (Brassica juncea L.) were selected for building the experimental material. It consisted of 8 lines and 4 testers, mated in Line × Tester design during rabi season 2018-19. These parents alongside with their 32 F1s were evaluated in RBD in rabi season 2019-20 for 13 traits including seed yield per plant (g), glucosinolate content (µmole/g) and oil content (%). Analysis of variance for combining ability showed that significant differences were present amid treatments for all the characters, except for siliqua length and seeds per siliqua. Line PAB 17-1 was identified as a good combiner on the basis of their GCA effect for seed yield, test weight; PAB 17-15 for number of primary branches, number of secondary branches, PAB 17-21 for plant height, length of main raceme, siliquae on main raceme, glucosinolate content and PAB 17-23 for oil content. Highest significant SCA effect was shown by cross-combination PAB 17-2×PHR-2 for seed yield per plant, PAB 17-23×NRCHB-101 for glucosinolate content and PAB 17-1×PAB-9511 for oil content. Cross combination PAB 17-2×PHR-2 showed highest heterobeltiosis (BP) for seed yield per plant followed by PAB 17-1 × PHR-2. The magnitude of heterosis over BP in the desired direction was quite high ranging from -36.18 to 160.14. Cross PAB 17-23×PHR-1 for oil content showed highest heterosis over BP. Cross combination PAB 17-15×PAB-9511 showed highest relative heterosis for seed yield per plant and PAB 17-20×PAB-9511 for oil content. Similarly PAB 17-2×PHR-2 showed highest economic heterosis for seed yield per plant.

BREEDING FOR HIGHER FIBRE QUALITY TRAITS IN UPLAND COTTON THROUGH LINE × TESTER ANALYSIS

The experiment was conducted using a randomized complete block design with three replications at Shah Abdul Latif Experimental Farm, Sindh Agriculture University, Tandojam. Employing a line × tester mating design in upland cotton (Gossypium hirutum L.), twenty-one cross combinations were obtained from seven females and three males. F1 and F2 generations, along with their parents, were sown in a randomized complete block design with three replications during 2012-13 and 2013-14. Studied traits included lint yield (g) per plant, G.O.T (%), staple length (mm), fiber fineness (mic.value), and fiber strength (g/tex). Throughout the growing period, recommended cultural practices were followed. Analysis of variance revealed high significance for genotypes, parents, crosses, and their interactions (P×C) for all traits. In the F1 generation, lint yield and staple length under line × tester (L×T) were highly significant. For the F2 generation, genotypes, parents, crosses, and P×C were highly significant for all traits except G.O.T%, where lines, testers, and L×T were highly significant for all traits except G.O.T%. Cross VH-292 × VH-291 excelled in lint yield per plant, while CRIS-342 × IR-3701 demonstrated superior fiber fineness and strength. VH-292 × VH-291 also displayed higher lint yield per plant, while CRIS-342 × FH-113 exhibited longer staple length with increased fiber fineness. Significant mean squares for genotypes (parents, crosses, and parents × crosses) indicate the data's utility for assessing parental performance, hybrid evaluation, heterotic effects, and inbreeding depression.

Identification of Potential Tropical Maize Inbred Lines with Early Maturity for Drought-Prone Environments

The present study was undertaken during October, 2020–January, 2021 at Maize Research Centre, Professor Jayashankar Telangana State Agricultural University, Rajendranagar, Hyderabad, Telangana state, India to identify potential inbred lines and hybrids with early maturity and high yield through combining ability analysis and heterosis. Six lines and four testers were crossed in L×T design to obtain 24 crosses. Evaluation of these crosses and their parents for combining ability revealed significant differences due to lines, testers and their crosses indicating the existence of wider variability among the material used in the study. Maize line MGC 434 (91 days), two testers GP-170 and PFSR-56 (91 days), and one hybrid MGC-445×PFSR-132 (83 days) were identified as early duration genotypes. Four lines MGC-444 (-3.13), MGC-440 (-2.71), MGC-439 (-1.96) and MGC-445 (-0.46) with significant negative GCA effects were identified as best general combiners for early maturity. Eight hybrids, MGC-439×BML-14 (-4.99), MGC-445×PFSR-56 (-4.65), MGC-461×PFSR-56 (-3.65), MGC-445×PFSR-132 (-3.60), MGC-434×BML-14 (-2.32), MGC-439×GP-170 (-2.10), MGC-440×PFSR-56 (-2.07) and MGC-440×GP-170 (-1.01) with significant negative SCA effects were considered as best cross combinations with early maturity. The inbred parents and cross combinations with early maturity identified in the study can be utilized for development of hybrids suitable to drought prone environments.

Heterosis and Diallel Analysis for Grain Yield, Yield Attributes and Physiological Traits in Barley (Hordeum vulgare L.)

The present study was carried out during November–April, 2019–2020 and 2020–21 with eight diverse barley genotypes and their developed 28F1s (half diallel, excluding reciprocals) to ascertain gene effects, hetrosis and correlations for grain yield, yield attributes and physiological traits under water limited conditions of Bundelkhand region. Days to heading and days to maturity exhibited general mean values of 86 days and 127 days, respectively. The parental genotypes, DWRB180, RD2794 and RD2899 showed early spike emergence and maturity. The cross combinations, namely DWRB160 /DWRB180, DWRB180/RD2907 and BH946/RD2552 were promising for flag leaf length and width. The GCA effects were significant and prevalent for all the characters, except days to heading, plant height and tillers count. The parents, DWRB160 (5.29**) and BH902 (1.59**) depicted high GCA effects for 1000 grain weight. The parents, DWRB180, RD2552, and BH946 exhibited significant positive GCA effects for leaf area index and chlorophyll fluorescence, whereas the genotypes, RD2907, BH946 and RD2899 showed higher GCA effects for chlorophyll content. Grain yield exhibited significant positive correlations with flag leaf width (0.60**), tillers per meter (0.35*), grains per spike (0.39*), harvest index (0.53**), chlorophyll content (0.69**), leaf area index (0.49**) and chlorophyll fluorescence (0.68**). The parents, BH946, DWRB180 and RD2907 and the hybrids, RD2552/DWRB180, BH902/RD2794, DWRB160/DWRB180 and BH946/RD2907 were found promising for yield and yield attributes in the dry agro-ecology of Bundelkhand region. The crosses, DWRB160/BH902 and DWRB160/BH946 can be explored for developing superior segregants for malt barley breeding.

DCLGM: Fusion Recommendation Model Based on LightGBM and Deep Learning

The recommendation system can mine valuable information according to user preferences, so it is widely used in various industries. However, the performance of recommendation systems is generally affected by the problem of data sparsity, and LightGBM can alleviate the impact caused by data sparsity to a certain extent. To this end, this paper proposes a fusion recommendation model based on the LightGBM and deep learning—CLGM model. The model is composed of LighGBM, cross network and deep neural network. First, the features in the dataset are fused and extracted through LightGBM, and the feature with the highest classification accuracy is selected as the input of the neural network layer; Then, using the cross network and the deep neural network, the linear cross combination feature relationship and nonlinear correlation relationship between high-order features are respectively obtained; finally, the results obtained by the pre-order network are linearly weighted and combined to obtain the final recommendation result. In this paper, AUC and Logloss are used as evaluation indicators to verify the model on the public dataset Criteo and dataset Avazu. The simulation experiment results show that, compared with the four typical recommendation models, the recommendation effect of this model is better.

Evaluation of Superior Cross Combinations and Identification of Better Parental Stocks from Early Clonal Trials in Sugarcane

Sugarcane is a clonally propagated crop and genetic improvement involves crossing of diverse species of Saccharum clones. Identification of desirable cross combination is one of the essential steps in the development of superior varieties. This study was conducted with an objective of identification of best cross combination based on their ability to produce superior clones by contributing desirable traits and suitability of a parental stock as “FEMALES” or “MALES” based on their ability to transmit positive genes to progeny. Sixteen biparental crosses with minimum of 20 progenies were screened for NMC (≥10) and HR Brix (≥20 units) in first clonal selection. The significance of parental stocks performance in cross combination was tested using “t‟ test assuming unequal variance. Progenies obtained from Co 06015, Co 0241 and Co 8347 recorded 20.99%, 20.82% and 20.81% of HR Brix, while Co 0209, Co 06015 and Co 94008 recorded 14.23, 12.76 and 11.88 of mean NMC when they used as male in crossing. Clones derived from Co 99006, Co 0403 and Co 06002 showed 20.93%, 20.82% and 20.81% of HR Brix, whereas Co 07010, Co 99006 and 2007-285 recorded 13.68, 12.21 and 11.40 mean NMC when they were used as female in crossing. Crosses viz., Co 99006 x Co 06015, Co 0403 x Co 0241, 2007-285 x Co 0209 and Co 94005 x Co 86011 has contributed 63%, 32%, 30% and 28% desirable selections respectively. The clones Co 06015 and Co 99006 are proven male and female can be used abundantly in crossing for the development of superior clones. The clones Co 8347, Co 0241, Co 0209 and Co 94008 are best males, whereas Co 0403, Co 06002, Co 07010 and 2007-285 are best females need to be crossed extensively for the development of superior varieties combining quality and cane yield traits.

Reproductive relationships between taxa morphologically close to Elymus caninus (Poaceae: Triticeae).

A hybridological study of biotypes of species close to Elymus caninus: E. prokudinii, E. viridiglumis, E. goloskokovii, as well as a number of morphologically deviant biotypes in Russia and Kazakhstan, was carried out. The objectives were to study the levels of reproductive relationships and the degree of integration of the species E. goloskokovii, E. prokudinii, and E. viridiglumis into the E. caninus complex. Our estimates of the seed fertility of natural parental biotypes were within 60-90 %. Among the combinations of crossing in F1, the highest seed setting was found in the hybrids formed by parental pairs from close habitats, regardless of the taxonomic rank of biotypes. The highest fertility values (55.6 and 46.1 %) were found in combinations involving E. caninus, E. viridiglumis and E. goloskokovii. It has been concluded that the biotypes of these species included in sexual hybridization form a single recombination gene pool, within which slight differences in reproductive compatibility are observed. The nature of the inheritance of the diagnostic features of lemmas "presence of trichomes" and "length of awns", according to the digenic and monogenic type, respectively, is shown. The high seed fertility of the created hybrids and the presence of intermediate forms in the F2 generation according to distinctive features indicate the possibility of interspecific introgression when species grow together in natural populations. Thus, the assessment of the inheritance of diagnostic characters makes it possible to classify E. goloskokovii, E. prokudinii, and E. viridiglumis as intraspecific taxa of E. caninus s. l. Data were obtained on the morphological and reproductive properties of interspecific hybrids with the participation of the species E. mutabilis as a possible donor in the speciation of taxa close to E. caninus. In cross combinations of E. caninus × E. mutabilis and E. mutabilis × E. caninus, lower values of seed fertility of hybrids in the F1 and F2 generations were noted compared to hybrids between the species E. caninus, E. goloskokovii, E. prokudinii and E. viridiglumis. Nevertheless, on the basis of chorological and morphological criteria, we concluded that E. caninus and E. mutabilis are independent species.

Persistence of autozygosity in crossbreds between autochthonous and cosmopolitan breeds of swine: a simulation study

Crossbreeding might be a valid strategy to valorize local pig breeds. Crossbreeding should reduce homozygosity and, as a consequence, yield hybrid vigor for fitness and production traits. This study aimed to quantify the persistence of autozygosity in terminal crossbred pigs compared with purebreds and, in turn, identify genomic regions where autozygosity’s persistence would not be found. The study was based on genotyping data from 20 European local pig breeds and three cosmopolitan pig breeds used to simulate crossbred offspring. This study consisted of two steps. First, one hundred matings were simulated for each pairwise combination of the 23 considered breeds (for a total of 276 combinations), ignoring the sex of the parent individuals in order to generate purebred and crossbred matings leveraging all the germplasm available. Second, a few preselected terminal-maternal breed pairs were used to mimic a realistic terminal crossbreeding system: (i) Mora Romagnola (boars) or Cinta Senese (boars) crossed with Large White (sows) or Landrace (sows); (ii) Duroc (boars) crossed with Mora Romagnola (sows) or Cinta Senese (sows). Runs of homozygosity was used to estimate genome-wide autozygosity (FROH). Observed FROH was higher in purebreds than in crossbreds, although some crossbred combinations showed higher FROH than other purebred combinations. Among the purebreds, the highest FROH values were observed in Mora Romagnola and Turopolje (0.50 and 0.46, respectively). FROH ranged from 0.04 to 0.16 in the crossbreds Alentejana × Large White and Alentejana × Iberian, respectively. Persistence of autozygosity was found in several genomic segments harboring regions where quantitative trait loci (QTLs) were found in the literature. The regions were enriched in QTLs involved in fatty acid metabolism and associated with performance traits. This simulation shows that autozygosity persists in most breed combinations of terminal crosses. Results suggest that a strategy for crossbreeding is implemented when leveraging autochthonous and cosmopolitan breeds to obtain most of the hybrid vigor.

Evaluation of castor pistillate lines and analysis of mode of inheritance for resistance to Fusarium wilt disease in castor (Ricinus communis L.)

Castor is an industrially economic and valuable oilseed crop cultivated worldwide. There is a constant upsurge in demand for its oil. But wilt caused by Fusarium spp. is a devastating disease that severely affects the productivity depending upon the crop stage. Stable high yielding pistillate lines serve as donors in heterosis breeding programme and for further biotechnological advancements. Genetic characterization of wilt resistance indicated the role of duplicate dominant epistasis in YTP 1 × TMV 5, complementary epistasis in DPC 9 × JP 65 and JP 65 × SKI 215, duplicate recessive epistasis in YRCP 1 × DPC 9. Monogenic recessive nature of wilt resistance was reported in other four cross combinations viz., YRCP 2 × JP 65, SKP 84 × JP 65, YRCP 2 × DPC 9 and YRCP 2 × SKP 84. Magnified images taken using LED phase contrast microscope portrayed the presence of microconidia and macroconidia and Scanning Electron Microscope (SEM) image analysis showed the presence of intact internal cell structures in resistant check (48−1) while the cell structures were disturbed with mycelial growth in the susceptible check (JI 35). Among 21 pistillate lines screened, seven viz., DPC 9, DPC 16, SKP 84, JP 96, GEETA, M 574 and M 619–1 were resistant. By screening P1, P2, F1, F2, BC1F1 (P1) and BC1F1 (P2) generations of eight crosses under field and pot test method, the stable pistillate line DPC 9 was found to be wilt resistant. F1 generation plants expressed 100% susceptibility indicating the recessive nature of wilt resistance. JP 65 × SKI 215 and YRCP 1 × DPC 9 showed the minimum incidence comparing other F2 populations. The backcross (YRCP 1 × DPC 9) × DPC 9 was found to possess the lowest wilt incidence compared to other populations under field and green house condition. Hence the identified lines could be better used to develop wilt resistant high yielding hybrid and for further identifying and introgressing genomic regions conferring wilt resistance to high yielding popular variety through linkage/QTL mapping technique.

Estimation of Hetrosis in F1 Hybrids of Bread Wheat Genotypes

The experiment was conducted for estimation of the heterosis in F1 hybrids in wheat genotypes. The research was conducted at the experimental field of Seed Production Development Centre, Sindh Agriculture University Tandojam during Rabi growing season 2019-20. The experiment was laid-out in randomized complete block design (RCBD) using three replications. The performance of parents and their hybrids, and heterotic effects were measured in various aspects like earliness characters (days taken to 75% heading, days taken to 75% maturity), morphological and yield traits like plant height, tillers plant-1, yield plant-1, and a physiology related trait; relative water content. The study consisted of six varieties and their six F1 hybrids. The parents used were TD-1, Benazir-2013, TJ-83, Hamal, Imdad-2005, Kiran-95 and their crosses were as TD-1 × Hamal, TD-1 × Benazir-2013, Benazir-2013 × TD-1, TJ-83 × Benazir-2013, TJ-83 × Imdad, Kiran-95 ×Benazir-2013. Results revealed that all the parents and hybrids were highly significant for all the parameters studied at P<0.01 level. The F1 hybrids Benazir-2013 × TD-1, TD-1 × Benazir-2013, TD-1 × Hamal and Kiran -95 × Benazir-2013 had showed better response in mid parent heterosis and heterobeltiosis for most of the traits except plant height. On the basis of current findings, it could be concluded that these cross combinations may be used in bread wheat for yield improvement