High-yielding Lines Research Articles

Root xylem plasticity to improve water use and yield in water-stressed soybean.

We tested the hypothesis that increasing the number of metaxylem vessels would enhance the efficiency of water uptake in soybean (Glycine max) and decrease the yield gap in water-limited environments. A panel of 41 soybean accessions was evaluated in greenhouse, rainout shelter, and rain-fed field environments. The metaxylem number influenced the internal capture of CO2 and improved stomatal conductance, enhancing water uptake/use in soybeans exposed to stress during the reproductive stage. We determined that other root anatomical features, such as cortex cell area and the percentage of stele that comprised cortical cells, also affected seed yield under similar growth parameters. Seed yield was also impacted by pod retention rates under drought stress (24-80 pods/plant). We surmise that effective biomass allocation, that is, the transport of available photosynthates to floral structures at late reproductive growth stages (R6-R7), enables yield protection under drought stress. A mesocosm study of contrasting lines for yield under drought stress and root anatomical features revealed that increases in metaxylem number as an adaptation to drought in the high-yielding lines improved root hydraulic conductivity, which reduced the metabolic cost of exploring water in deeper soil strata and enhanced water transport. This allowed the maintenance of shoot physiological processes under water-limited conditions.

General and Specific Combining Ability and Heterosis for Yield in Cucumber Fresh Market Lines

ABSTRACTCucumber (Cucumis sativus L.) yield quantity and quality can be improved. Estimates of combining ability are useful in determining breeding value of cucumber lines by suggesting the appropriate use in breeding to generate new hybrids with high yield and quality. The research was conducted to estimate general and specific combining ability and heterosis in seven inbred lines proposed for cucumber breeding according previous research. The highest early yield specific combining ability (SCA) and general combining ability (GCA) were related to lines B10 and B12 and crosses B12 × A0 and B10 × A4. Lines A11 and B12 had the highest positive and negative cull yield GCA and the crosses A0 × B10 and A0 × B12 had the highest negative cull yield SCA. Lines B10, A4, and B12 and crosses B12 × A0, B10 × A11, and B10 × A4 had the highest positive marketable yield GCA and SCA. Lines B10 and A4 and crosses B12 × A0, B10 × A11, and B10 × A4 had the highest positive total yield GCA and SCA. Lines B10, B12, and A11 and the B10 × A4 cross had the highest positive simple weight index (SWI) GCA and SCA. Lines B10 and A4 are proposed for high-yield hybrid production, and their hybrid next generation are suitable for selecting and releasing new high-yielding lines.

Genotype by environment interaction of “carioca” seeded common bean advanced lines in northeastern Brazil

The objectives of the present work were to identify common bean lines with high grain yield, adaptability and stability; stratify the environment; and detect the most important factors for the genotype by environment (G×E) interaction in northeastern Brazil. Nineteen experiments were conducted in a randomized block design with three replications during the rainy growing season at 11 locations in the States of Pernambuco, Alagoas, Sergipe, and Bahia in 2009 and 2010. In each experiment, 16 “carioca” seeded lines were evaluated, and the grain yield, assessed. Data were subjected to analyses of variance and adaptability and stability by the methodologies of Annicchiarico and Additive Main Effects and Multiplicative Interactions (AMMI), analysis of the factors for environmental stratification and joint analysis with decomposition of the G×E interaction in genotype by year and genotype by location. According to the AMMI method, BRS Estilo and CNFC 11951 were selected as stable high-yielding lines. CNFC 11954, IPR Juriti, CNFC 11948 and BRS Estilo were identified as stable high-yielding lines based on the methodology of Annicchiarico. BRS Estilo was identified as stable according to both methodologies and was therefore considered suitable for growth in the Northeast region for use as a parent line in regional breeding programs. The locations in this region used to test the common bean lines were informative, except Carira, which could be eliminated from the assay network. Interaction among genotypes, locations and years were observed, suggesting that assessments shoud be conducted at the largest number of locations and years, in this order of importance.

Elevated Genetic Diversity in an F2:6 Population of Quinoa (Chenopodium quinoa) Developed through an Inter-ecotype Cross.

Quinoa (Chenopodium quinoa) is a seed crop of the Andean highlands and Araucanian coastal regions of South America that has recently expanded in use and production beyond its native range. This is largely due to its superb nutritional value, consisting of protein that is rich in essential amino acids along with vitamins and minerals. Quinoa also presents a remarkable degree of tolerance to saline conditions, drought, and frost. The present study involved 72 F2:6 recombinant-inbred lines and parents developed through hybridization between highland (0654) and coastal (NL-6) germplasm groups. The purpose was to characterize the quinoa germplasm developed, to assess the discriminating potential of 21 agro-morpho-phenological traits, and to evaluate the extent of genetic variability recovered through selfing. A vast amount of genetic variation was detected among the 72 lines evaluated for quantitative and qualitative traits. Impressive transgressive segregation was measured for seed yield (22.42 g/plant), while plant height and maturity had higher heritabilities (73 and 89%, respectively). Other notable characters segregating in the population included panicle and stem color, panicle form, and resistance to downy mildew. In the Principal Component analysis, the first axis explained 74% of the total variation and was correlated to plant height, panicle size, stem diameter, biomass, mildew reaction, maturation, and seed yield; those traits are relevant discriminatory characters. Yield correlated positively with panicle length and biomass. Unweighted Pair Group Method with Arithmetic Mean-based cluster analysis identified three groups: one consisting of late, mildew-resistant, high-yielding lines; one having semi-late lines with intermediate yield and mildew susceptibility; and a third cluster consisting of early to semi-late accessions with low yield and mildew susceptibility. This study highlighted the extended diversity regenerated among the 72 accessions and helped to identify potentially adapted quinoa genotypes for production in the Moroccan coastal environment.

Analysis of yield-attributing traits for high-yielding wheat lines in southwestern Japan

Development of wheat cultivars that achieve high yields despite the short growing season is essential for increasing wheat production in southwestern Japan. The objectives of this study were to assess the genetic progress in grain yield and to clarify yield-attributing traits of high-yielding wheat lines in southwestern Japan. We conducted field experiments for two growing seasons (2012–2013 and 2013–2014) using three commercial wheat cultivars (Shiroganekomugi, Chikugoizumi, and Iwainodaichi) and four high-yielding wheat lines including Hakei W1380 developed in southwestern Japan. In an ancillary field experiment, we compared a commercial cultivar, Shiroganekomugi, and a high-yielding line, Hakei W1380, in the 2014–2015 season. Across the two seasons, grain yield of high-yielding lines was generally higher than commercial cultivars. Hakei W1380 achieved the highest grain yield across the two seasons, and successfully produced more than 900 g m−2 in the 2013–2014 season. Correlation analysis showed that recent yield progress of wheat lines in southwestern Japan was derived from enhanced biomass production and grain number m−2. Larger numbers of grains m−2 in high-yielding lines than in commercial cultivars were associated with higher crop growth rate at the pre-anthesis stage, and therefore higher spike dry weight m−2 at anthesis. Genotypic differences in crop growth rate from jointing to anthesis resulted mainly from differences in leaf area index. These results indicate that further improvements in grain yield in southwestern Japan could be achieved by increasing the amount of radiation intercepted at the pre-anthesis stage and grain number m−2.

Development and application of a novel genome-wide SNP array reveals domestication history in soybean.

Domestication of soybeans occurred under the intense human-directed selections aimed at developing high-yielding lines. Tracing the domestication history and identifying the genes underlying soybean domestication require further exploration. Here, we developed a high-throughput NJAU 355 K SoySNP array and used this array to study the genetic variation patterns in 367 soybean accessions, including 105 wild soybeans and 262 cultivated soybeans. The population genetic analysis suggests that cultivated soybeans have tended to originate from northern and central China, from where they spread to other regions, accompanied with a gradual increase in seed weight. Genome-wide scanning for evidence of artificial selection revealed signs of selective sweeps involving genes controlling domestication-related agronomic traits including seed weight. To further identify genomic regions related to seed weight, a genome-wide association study (GWAS) was conducted across multiple environments in wild and cultivated soybeans. As a result, a strong linkage disequilibrium region on chromosome 20 was found to be significantly correlated with seed weight in cultivated soybeans. Collectively, these findings should provide an important basis for genomic-enabled breeding and advance the study of functional genomics in soybean.

Identification of Resistant Sources of Vigna spp. against Yellow Mosaic Disease

The cultivation of green gram (Vigna radiata (L.) and black gram (Vigna mungo (L.) Hepper) in Jharkhand, India, is adversely affected by most destructive yellow mosaic disease (YMD), but the etiological agent in this region is not identified so far. Disease incidence and severity as high as 100 per cent in farmers' fields is common, often resulting in considerable yield losses in both the crops. Therefore, an attempt was made during crop seasons 2009 and 2010 at three locations viz., Ranchi, Dumka and Chianki of Jharkhand state with aim to confirm the identity of etiological agent of YMD as well as to identify the resistant sources of green gram and black gram against YMD. The identity of the etiological agent causing YMD in Vigna spp. in Jharkhand, India was confirmed as Munbean yellow mosaic India virus (MYMIV) in polymerase chain reaction using species specific primers. Out of twelve genotypes of green gram, only two genotypes, Meha and ML 1477 and two of eight genotypes of black gram, KU 323 and BS 23-13 were recorded either as resistant or highly resistant at all the three locations of Jharkhand which could be used as resistant donors against MYMIV in crop improvement programmes to develop high-yielding lines/ varieties and increased acreage of green gram and black gram crops.

Appraisal of wheat germplasm for adult plant resistance against stripe rust

Abstract The resurgence of wheat stripe rust is of great concern for world food security. Owing to resistance breakdown and the appearance of new virulent high-temperature adapted races of Puccinia striiformis f. sp. tritici (Pst), many high yielding commercial varieties in the country lost their yield potential. Searching for new sources of resistance is the best approach to mitigate the problem. Quantitative resistance (partial or adult plant) or durable resistance is reported to be more stable than race specific resistance. In the current perusal, a repertoire of 57 promising wheat lines along with the KLcheck line Morocco, developed through hybridisation and selection of local and international lines with International Maize and Wheat Improvement Center (CIMMYT) origin, were evaluated under natural field conditions at Nuclear Institute for Agriculture and Biology (NIAB) during the 2012−2013 and 2013−2014 time periods. Final rust severity (FRS), the area under the rust progress curve (AURPC), the relative area under the rust progress curve (rAURPC), and the coefficient of infection (CI) were unraveled to infer the level of quantitative resistance. Final rust severity was recorded when the susceptible check exhibited 100% severity. There were 21 lines which were immune (no disease), 16 which were resistant, five moderately resistant, two resistant-to-moderately resistant, one moderately resistant-to-moderately susceptible, 5 moderately susceptible-to-susceptible, one moderately susceptible, and six exhibited a susceptible response. Nevertheless, 51 lines exhibited a high level of partial resistance while the three lines, NW-5-1212-1, NW-7-30-1, and NW-7-5 all showed a moderate level of partial resistance based on FRS, while 54 lines, on the basis of AURPC and rAURPC, were identified as conferring a high level of partial resistance. Moreover, adult plant resistance was conferred by 47 wheat lines, based on CI value. It was striking that, 13 immune lines among 21 were derived from parents of CIMMYT origin. Cluster analysis was executed to determine the diversity among the wheat genotypes based on stripe rust resistance and yield parameters. All genotypes were grouped into nine clusters exhibiting a high level of diversity at a 25% linkage distance. There were 29 wheat lines resistant to stripe rust that were grouped into the first three clusters, while 4 high-yielding lines were in Cluster VIII. The susceptible check, Morocco, was separated from rest of lines and fell in the last cluster i.e. Cluster IX. Based on the results, inter-crossing immune/ resistant lines is recommended, and with high yielding lines − it is also recommended that cultivars with improved disease resistance and yield potential be developed.

High-density genetic linkage map construction and QTL mapping of grain shape and size in the wheat population Yanda1817 × Beinong6.

High-density genetic linkage maps are necessary for precisely mapping quantitative trait loci (QTLs) controlling grain shape and size in wheat. By applying the Infinium iSelect 9K SNP assay, we have constructed a high-density genetic linkage map with 269 F 8 recombinant inbred lines (RILs) developed between a Chinese cornerstone wheat breeding parental line Yanda1817 and a high-yielding line Beinong6. The map contains 2431 SNPs and 128 SSR & EST-SSR markers in a total coverage of 3213.2 cM with an average interval of 1.26 cM per marker. Eighty-eight QTLs for thousand-grain weight (TGW), grain length (GL), grain width (GW) and grain thickness (GT) were detected in nine ecological environments (Beijing, Shijiazhuang and Kaifeng) during five years between 2010–2014 by inclusive composite interval mapping (ICIM) (LOD≥2.5). Among which, 17 QTLs for TGW were mapped on chromosomes 1A, 1B, 2A, 2B, 3A, 3B, 3D, 4A, 4D, 5A, 5B and 6B with phenotypic variations ranging from 2.62% to 12.08%. Four stable QTLs for TGW could be detected in five and seven environments, respectively. Thirty-two QTLs for GL were mapped on chromosomes 1B, 1D, 2A, 2B, 2D, 3B, 3D, 4A, 4B, 4D, 5A, 5B, 6B, 7A and 7B, with phenotypic variations ranging from 2.62% to 44.39%. QGl.cau-2A.2 can be detected in all the environments with the largest phenotypic variations, indicating that it is a major and stable QTL. For GW, 12 QTLs were identified with phenotypic variations range from 3.69% to 12.30%. We found 27 QTLs for GT with phenotypic variations ranged from 2.55% to 36.42%. In particular, QTL QGt.cau-5A.1 with phenotypic variations of 6.82–23.59% was detected in all the nine environments. Moreover, pleiotropic effects were detected for several QTL loci responsible for grain shape and size that could serve as target regions for fine mapping and marker assisted selection in wheat breeding programs.

Ecological stability of spring barley varieties on productivity and the creation of a valuable source of material

In the 2004-2013 studies on adaptive capacity and plasticity of spring barley varieties (2004-2006) and dependence on the efficiency of selection valuable lines of hybrids (2007-2013) from these varieties are carry out.Results. According to the environmental estimation for the lower ranks of genotypic effect (in fact the overall adaptive capacity), the regression coefficient (degree of plasticity) and environmental sustainability for the lesser amount of their rank level relative the practical value of spring barley 26 varieties in separate grounds was defined. According to the estimation on stages of the selection process are high-yielding lines received from crosses between these varieties are pick out. Valuable lines are created with using mainly varieties with environmental relevance, stability of the individual characteristics of the elements of the structure of productivity. 08-73 Line transferred to the State variety testing in 2013, as a varieties of Malyovnychyi.Conclusions. The efficiency of selection of line hybrids depends on the level of environmental values at rank of genotypic effect and regression coefficient for the individual structural elements of productivity of plants.

Use of wheat genetic resources to develop biofortified wheat with enhanced grain zinc and iron concentrations and desirable processing quality

As a major cereal crop worldwide, wheat contributes on average one-fifth of the calories in the human diet and is the main source of protein and nutrients for much of the world's population. Wheat varieties with improved nutritional quality, high grain yield and desirable processing quality attributes in adapted genetic backgrounds can help alleviate nutrient deficiencies among resource poor people. This paper reports advances in targeted crosses of landraces and ancestors of common wheat (Triticum aestivum L.), such as Aegilops tauschii, Triticum turgidum ssp. diccocoides, T. turgidum ssp. dicoccum and T. aestivum ssp. spelta species, which feature significant genetic variation for grain zinc and iron, with high-yielding bread wheat lines from the CIMMYT breeding program that have desirable processing and end-use quality. High-yielding lines that resulted from these crosses possessed preferred processing quality traits and 10–90% higher grain micronutrient concentrations than popular commercial varieties.

Linking root traits and grain yield for rainfed rice in sub-Saharan Africa: Response of Oryza sativa × Oryza glaberrima introgression lines under drought

Rainfed rice ecosystems account for more than 80% of the total rice area in sub-Saharan Africa, and large parts of this region frequently experience drought stress. One potential approach to improve the drought resistance and local adaptation of high-yielding rice varieties in rainfed regions of sub-Saharan Africa is to cross them with the African rice species Oryza glaberrima. In this study, 200 introgression lines (ILs) from crosses of O. sativa (IR64) and O. glaberrima (RAM90 and RAM54) were evaluated in three field experiments under different rainfed drought scenarios in Tanzania and the Philippines. The objectives of the study were to select ILs for yield and traits associated with drought resistance, and to analyze the genetic variation in water uptake, root growth, and drought response that were observed among the ILs in a previous greenhouse lysimeter study. Several ILs showed improved yield under drought stress and well-watered conditions compared with the recurrent parent IR64. One cluster of ILs that showed the highest yield across all environments included genotypes with the lowest canopy temperature under drought. In 10 selected ILs, root length density was negatively correlated with canopy temperature and soil moisture, and positively related to shoot biomass, but not significantly correlated with grain yield under drought. Although root growth in the field correlated well with root growth in the previous lysimeter study, only some of the highest-yielding lines under drought in the field were those that showed more water uptake in lysimeters. These results confirm the complex relationship among grain yield, root growth, and additional physiological mechanisms underlying crop growth and productivity in the field. The high-yielding ILs under both drought and well-watered conditions in this study can be used as donors to improve drought resistance in target rainfed rice environments in sub-Saharan Africa.

Phenotypic Traits and Photosynthetic Characteristics of Jerusalem Artichoke ( Helianthus tuberosus L.) in the Semi-arid Area

To speed up breeding process for Jerusalem artichoke in semi-arid area, it is necessary to investigate traits related to yield and photosynthetic characteristics. Four stable lines including two high-yield lines and two low-yield lines were screened as materials, agronomic traits and photosynthesis parameters were determined. The results showed that the tuber yield, shoot biomass and root biomass of Jerusalem artichoke high-yield lines were significantly higher than those of low-yield lines, and the plant height, stem diameter, leaf area, leaf number of high-yield lines were also significantly higher than those of low-yield lines, then compared with low-yield lines, the high-yield lines showed a stronger growth vigor. LCP and Rd of high-yield lines were significantly lower than those of low-yield lines, but the difference of other parameters were not significant. Correlation analysis indicated that tuber yield had significantly positive correlation with plant height, stem diameter, leaf area, leaf number, shoot biomass and root biomass, while significantly negative correlation with LCP and Rd. Hence, in semi-arid area more leaf number, larger leaf area and well-developed root system are very important and reliable indicators and lower LCP and Rd are important reference value for breeding high-yield lines in Jerusalem artichoke.

Construction of Molecular Genetic Linkage Map of Sugarbeet

Molecular genetic map is a fundamental tool for genomic research. In this study, a molecular genetic map was constructed using an F2 population consisting of 200 individuals from a cross between sugarbeet JV34-2(the high beet yield and low sugar content line) and sugarbeet 2B023(the low beet yield and high sugar content line) and a total of 561 SRAP primers and 114 SSR primers. Approximately 56 out of 561 and 20 out of 114 primers, respectively, showed polymorphisms. Each of these polymorphic primers produced at least one scorable polymorphic DNA band which was visible enough for detection and scoring. The map consisted of nine linkage groups which included 141(123 SRAP and 18 SSR) markers, and covered 1399.88 cM with an average distance of 9.92 cM. Three markers were still unlinked. All nine linkage groups consisting of 3–26 markers were 15.69–237.21 cM in length. Twenty point five six percent partially segregated markers distributed in the map, were mainly located on Chr.3 linkage groups, and the others were mapped on Chr.1, Chr.2, Chr.8, and Chr.9. This is the first gene map of sugarbeet, constructed by SRAP and SSR markers in China. It will provide the basis for gene mapping of important characters and cloning of excellent gene in sugarbeet.

High-yielding lines of wheat carrying Gpc-B1 adapted to Mediterranean-type environments of the south and west of Australia

The Gpc-B1 gene from wild emmer has been proposed as a potential mechanism for improving grain protein in bread wheat without reducing grain yield. Near-isolines with and without the Gpc-B1 gene in three Australian-adapted genetic backgrounds, Gladius, Wyalkatchem and VR1128, were compared in 14 experiments across the south and west of Australia for grain yield, grain protein content and grain weight. The donor parents of Gpc-B1 were the Canadian cultivars Burnside and Somerset. One of the 14 experiments was discarded because of inadequate rust control and confounding effects of Yr36, a gene closely linked to Gpc-B1. Heading date and test weight were measured in five experiments. Across all comparisons, Gpc-B1 increased grain protein content and reduced grain weight, with a negligible effect on grain yield. Selected lines containing Gpc-B1 in a Wyalkatchem background had comparable grain yields to the elite cultivar Mace, but with significantly higher grain protein contents, slightly higher grain weights, similar heading dates and acceptable test weights. The development of agronomically acceptable lines containing Gpc-B1 was partially attributed to the removal of undesirable genes from wild emmer during the breeding of the Canadian donor parents and the use of Australian recurrent parents with high test weights.

Genetic basis of soybean adaptation to North American vs. Asian mega-environments in two independent populations from Canadian × Chinese crosses

One of the goals of plant breeding is to increase yield with improved quality characters. Plant introductions (PI) are a rich source of favorable alleles that could improve different characters in modern soybean [Glycine max (L.) Merril] including yield. The objectives of this study were to identify yield QTL underlying the genetic basis for differential adaptation of soybeans to the Canadian, United States or Chinese mega-environments (ME) and to evaluate the relationship and colocalization between yield and agronomic traits QTL. Two crosses between high-yielding Canadian cultivars and elite Chinese cultivars, OAC Millennium×Heinong 38 and Pioneer 9071×#8902, were used to develop two recombinant inbred line (RIL) populations. Both populations were evaluated at different locations in Ontario, Canada; Minnesota, United States (US), Heilongjiang and Jilin, China, in 2009 and 2010. Significant variation for yield was observed among the RILs of both populations across the three hypothetical ME. Two yield QTL (linked to the interval Satt364-Satt591 and Satt277) and one yield QTL (linked to marker Sat_341) were identified by single-factor ANOVA and interval mapping across all ME in populations 1 and 2, respectively. The most frequent top ten high-yielding lines across all ME carried most of the high-yielding alleles of the QTL that were identified in two and three ME. Both parents contributed favorable alleles, which suggests that not only the adapted parent but also the PI parents are potential sources of beneficial alleles in reciprocal environments. Other QTL were detected also at two and one ME. Most of the yield QTL were co-localized with a QTL associated with an agronomic trait in one, two, or three ME in just one or in both populations. Results suggested that most of the variation observed in seed yield can be explained by the variation of different agronomic traits such a maturity, lodging and height. Novel alleles coming from PI can favorably contribute, directly or indirectly, to seed yield and the utilization of QTL detected across one, two or three ME would facilitate the new allele introgression into breeding populations in both North America and China.

Pseudomonas fluorescens N21.4 Metabolites Enhance Secondary Metabolism Isoflavones in Soybean (Glycine max) Calli Cultures

Phytopharmaceuticals are plant secondary metabolites that are strongly inducible and especially sensitive to biotic changes. Plant cell cultures are a good alternative to obtain secondary metabolites, in case effective stimulation can be achieved. In this study, metabolic elicitors from two rhizobacteria able to enhance isoflavone content in soybean seedlings were tested on three different soybean calli cell lines. Results show that metabolic elicitors from Chryseobacterium balustinum Aur9 were not effective. However, there are at least two different metabolic elicitors from Pseudomonas fluorescens N21.4, one under 10 kDa and another over 10 kDa, that trigger isoflavone metabolism in the three cell lines with different isoflavone content. Elicitors from N21.4 achieved total isoflavone increases up to 29.7% (0.205 mg/g), 64.5% (0.487 mg/g), and 23.4% (0.726 mg/g) in the low-, intermediate-, and high-yield lines, respectively. Therefore, these elicitors have a great potential to enhance isoflavone production in cell cultures for development of functional ingredients.

Marker-assisted introgression of qHSR1 to improve maize resistance to head smut

Head smut, one of the most devastating diseases in maize, causes severe yield losses worldwide. Resistance to head smut has been proven to be a quantitative inherited trait. In our previous study, a major resistance quantitative trait locus (named qHSR1) was detected on maize chromosome 2 (bin 2.09), and a number of molecular markers have been developed in the qHSR1 region. Here, we report the marker-assisted introgression of qHSR1 to improve maize resistance to head smut. The 10 maize inbred lines, namely Ji853, 444, 98107, 99094, Chang7-2, V022, V4, 982, 8903, and 8902, which have high yield potential but are susceptible to head smut, were selected for resistance improvement. Each of the 10 high-yielding lines was crossed with a donor parent Ji1037 that is completely resistant to head smut, followed by five generations of backcrossing to the respective recurrent parent. Marker-assisted foreground selection was conducted to identify qHSR1. Recombinant selection was carried out in the fourth backcross (BC4) generation by using the flanking markers to reduce the size of the Ji1037 donor segment carrying qHSR1. Background selection was performed in the BC5 generation with genome-wide SSR markers to select the line with the highest recovery rate of the recurrent parent genome. Self-pollination was conducted twice for the BC5 plant with both the shortest qHSR1 region and the highest recovery rate to obtain converted inbred lines harboring qHSR1. The 10 converted inbred lines all showed substantial improvement in resistance to head smut. Furthermore, the hybrids prepared from the converted lines also showed significant increase in resistance to head smut, while remaining mostly unchanged for other agronomic traits.

Biplot Approach for Identification of Heterotic Crosses in Linseed (Linum usitatissimumL.)

In India, among nonedible oilseed crops, linseed is a commercial crop having tremendous economic and industrial importance. The seed production is low due to limited resources, so the development of high-yielding lines with desirable characters is urgently needed. In the present study seven parents' half diallel data was subjected to biplot analysis to identify the heterotic crosses, genetically similar parents, and to study their interrelationship. Parent Sln-Ys with A-79 and A-03 with A-79 for capsules per plant and seed yield, parent Mukta with Sln-Ys and Mukta with BAU-45 for seeds per capsule, and parents Mukta, A-103, A-79 and A-94 for test weight had lowest correlation. Parent B [Mukta] and F [A-79] were good general combiner for all the traits. The crosses F [A-79] × A [Sln-Ys] and D [A-03] × F [A-79] for capsules per plant, test weight and seed yield per plant, cross D [A-03] × A [Sln-Ys] for capsules per plant and test weight and cross D [A-03] × F [A-79] for test weight and seed yield per plant were heterotic. None of the crosses were heterotic for seeds per capsule.

The Heterosis and Combining Ability of Diallel Crosses of Rapeseed Inbred Lines

The heterosis and combining ability of four rapeseed (Brassica napus L.) genotypes were estimated using diallel crosses. An experiment was conducted at Uludag University, Bursa, Turkey, during the 2005-2006 and 2006-2007 growing seasons using 4x4 full diallel crosses. All of the 12 F1 hybrids and their parents were planted in a randomized complete block design with three replications. The data obtained from the experiment were subjected to an analysis of variance. The analysis of variance indicated significant differences among parents and their hybrids in the F1 generation for all the characters studied except for 1000-seed weight, which was non-significant. Positive better-parent heterosis for seed yield per plant were found in all 12 hybrids tested. An analysis of the components of combining ability showed that general combining ability (GCA) and reciprocal combining ability (RCA) were highly significant (p ≤ 0.01) for plant height and number of pods per main raceme, whereas specific combining ability (SCA) was highly significant for all traits but 1000-seed weight. The parent genotypes PR1, PR3 and PR4 with the hybrids PR1 x PR3 and PR1 x PR4 showed higher GCA and SCA effects, respectively, and therefore could be used to develop high-yielding lines.