Relative Efficiency of Anther Culture and Chromosome Elimination Techniques for Haploid Induction in Triticale × Wheat and Triticale × Triticale Hybrids

Summary The study was undertaken to evaluate the relative efficiency of anther culture and chromosome elimination (by crosses with maize) techniques of haploid induction in intergenotypic triticale and triticale × wheat hybrids. For this, 15 triticale × wheat and 8 triticale × triticale F₁ hybrids were subjected to anther culture and were also simultaneously crossed with the `Madgran Local' genotype of maize (Zea mays L.) to induce haploids through the chromosome elimination technique. The haploid embryo formation frequency through the chromosome elimination technique was significantly higher in both, triticale × wheat (20.4%) and triticale × triticale (17.0%) F₁ genotypes, as compared to the calli induction frequencies through anther culture (1.6 and 1.4%, respectively). Further, four triticale × wheat and three triticale × triticale F₁ genotypes failed to respond to anther culture, whereas, all the F₁ genotypes formed sufficient number of haploid embryos through the chromosome elimination technique with no recovery of albino plantlets. The haploid plantlet regeneration frequencies were also significantly higher through the latter technique in both triticale × wheat (42.7%) and triticale × triticale (49.4%) F₁s as compared to anther culture (8.2 and 4.0%, respectively), where the efficiency was drastically reduced by several constraints like, high genotypic specificity, low regeneration frequency and albinism. The overall success rates of obtaining doubled haploids per 100 pollinated florets/anthers cultured were also significantly higher through the chromosome elimination technique (1.1% in triticale × wheat and 1.5% in triticale × triticale hybrids), proving it to be a highly efficient and economically more viable technique of haploid induction as compared to anther culture, where the success rates were only 0.2% and 0.1%, respectively.     

Genetic control of crossability of triticale with rye

Limited genetic knowledge is available regarding crossability between hexaploid triticale (2n= 6x= 42, 21″, AABBRR, amphiploid Triticum turgidum L.‐Secale cereale L.) and rye (2n= 14, 7″, RR). Our objectives were to determine (1) the crossability between triticales and rye and (2) the inheritance of crossability between F₂ progeny from intertriticale crosses and rye. First, ‘8F/Corgo’, a hexaploid triticale, was crossed as a female with two landrace ryes, ‘Gimonde’ and, ‘Vila Pouca’ and two derived north European cultivars, ‘Pluto’ and ‘Breno’. These crosses produced 21.7, 20.9, 5.9, and 5.6%, seed‐set or crossability, respectively, showing that the landrace ryes produced higher seed‐set than the cultivars. Second, ‘Gimonde’ rye was crossed as a male with four triticales for 3 years. The control cross, ‘Chinese Spring’ wheat × rye, produced 80‐90% seed‐set. Of the four triticales, ‘Beagle’ produced 35.7‐56.8% seed‐set. The other three triticales produced less than 20% seed‐set, showing that the triticales differ in crossability with ‘Gimonde’ rye. Third, six FiS from intertriticale crosses (‘8F/Corgo’בBeagle’, ‘Beagle’בCachirulo’, ‘Lasko’בBeagle’, ‘8F/Corgo’בCachirulo’, ‘Lasko’בCachirulo’, ‘Lasko’ב8F/Corgo’) were crossed to ‘Gimonde’ rye. Results indicated that lower crossability trait was partially dominant in the two F₁S from crosses involving ‘Beagle’(high crossability) with‘8F/Corgo’ and ‘Cachirulo’(low crossability) and completely dominant in the ‘Beagle’בLasko’ cross, as it happens in wheat. Fourth, segregants in four F₂ populations (‘Lasko’בBeagle’, ‘8F/Corgo’בBeagle’, ‘Lasko’ב8F/Corgo’, and‘8F/Corgo’בCachirulo’) were crossed with rye. Segregation for crossability was observed, although distinct segregation classes were blurred by environmental and perhaps other factors, such as self‐incompatibility alleles in rye. Segregation patterns showed that ‘Beagle’, with high crossability to rye, carries either Kr1 or Kr2. The three triticales with low crossability with rye were most likely homozygous for Kr1 and Kr2. Therefore, it is likely that the Kr loci from A and B genomes acting in wheat also play a role in triticale × rye crosses.     

Influence of winter and spring wheat genetic backgrounds on haploid induction parameters and trait correlations in the wheat × maize system

The interactive influence of winter and/or spring wheat genetic background on haploid induction parameters and trait correlation was studied by hybridizing five elite and diverse genotypes each of winter and spring wheat and their F₁s (winter × winter, spring × spring, and winter × spring, generated in a diallel design excluding reciprocals) with a single genotype of maize. Data were recorded with respect to per cent seed formation, embryo formation, and regeneration. High genetic variability was present among the wheat genotypes (parents + F₁s) for the three haploid induction parameters. Significant differences were obtained within and between different groups viz., spring wheats, winter wheats, spring × spring wheats, winter × winter wheats, and winter × spring wheats with respect to the three haploid induction parameters based on ANOVA. The winter genotypes (winter parents and winter × winter wheat hybrids) responded better than the spring groups (spring wheat parents, spring × spring and winter × spring wheat hybrids) with respect to embryo formation and winter × spring wheat hybrids yielded significantly the highest numbers of regenerants. Correlation studies amongst the haploid induction parameters indicated that the genes controlling seed formation and haploid plantlet regeneration are negatively correlated when the genetic backgrounds of both ecotypes are combined in winter × spring hybrids. Haploid embryo formation had no association with seed formation and regeneration in all genetic backgrounds, suggesting independent inheritance.     

Analysis of anther culture response in hexaploid triticale

The androgenic response of five varieties and 10 F₁ intervarietal hybrids of 6 × triticale was analysed. The overall response involved three independent phenomena: the production of embryoids, the capability of embryoids to regenerate plants, and the production of green plants. Each of these factors appeared to be controlled by independent genetic systems. From a practical point of view, the product of these three factors, the number of green haploid plants per anther (GPA), is the most reliable variable for the evaluation of genotypes. Positive heterotic effects on GPA were observed in the hybrids, which may indicate that GPA is controlled predominantly by additive genes. No correlation was found between the number of green haploid plants produced by hybrids and that yielded by the best parental line. Therefore, it is difficult to predict the yield of green haploid plants that can be produced by a hybrid simply from the number produced by its parents.     

Heterosis for yield and other agronomic traits of winter triticale F1 and F2 hybrids

Triticale is generally treated as a self‐pollinating crop and line breeding is practised. Hybrid breeding has been discussed for some time, but there is little information for winter triticale. This study investigated heterosis for eight agronomic traits in F₁ and F₂ hybrids grown together with their parents as drilled plots in three environments. On average, grain yield heterosis was 12.5 dt/ha (a relative 10.5%) compared with the mid‐parent value for F₁ hybrids, and 6.2 dt/ha (5.0%) for F₂ hybrids and withawide range of 4.4–17.1 dt/ha for F₁ hybrids. A positive contribution to the heterosis of yield was made by kernels/spike and 1000‐kernel weight, whereas spikes/m² showed negative heterosis. Hybrid plants in F₁ and F₂ were taller than mid‐parents (8.3 cm and 5.3 cm, respectively), with a tendency to earlier heading. The negative heterosis for falling number in F₁ and F₂ hybrids could be a problem for commercial production of triticale hybrids. By selecting parents for combining ability and the identification of heterotic patterns, grain yield heterosis of 20% appears feasible.     

A New Method to Produce 4× Triticales and their Application in Studying the Development of a New Polyploid Plant

F₁ hybrids of triticale × rye derived from commercial varieties were backcrossed to the respective triticale parent. Selfing of the backcross generation yielded a large number of 4× triticales containing a genetically balanced wheat genome. This indicates that the 28-chromosome F₁ plants with the genomic constitution of ABRR produced functional 14-chromosome gametes in high frequency each with a complete wheat and rye genome. The cytological mechanism leading to the formation of tetraploid triticales is described. The chromosomal constitution of the wheat genome in the progenies of 30 back cross plants was analysed by the C-banding technique. One offspring possessed a complete B genome of wheat. The production of tetraploid triticale through backcrossing in comparison to selfing the ABRR hybrid is largely independent of the genotype; it leads to new tetraploids in just three generations and it reduces the chance of translocations between the homoeologous wheat chromosomes. The possibility of studying the effect of different mixtures of chromosomes of the A and B genomes of wheat on the phenotype of the tetraploid triticale is discussed.     

Relationship between hybrid performance and AFLP based genetic distance in highland maize inbred lines

The objectives of this study were to determine the crossing performance of highland maize inbred lines for grain yield, days to silk and plant height; estimate genetic distance (GD) among the inbred lines and in association with tester parents, and to investigate the relationship of GD with hybrid performance and midparent heterosis (MPH). A total of 26 inbred lines were crossed with six (population and line) testers in a factorial-mating scheme. The F_1’s and the parents were evaluated at five locations in Ethiopia. Nine amplified fragment length polymorphism (AFLP) primer pairs were used to genotype all the parents. The F_1’s were found to vary widely for grain yield and other traits measured. Yield superiority of more than 30% over the best hybrid check was obtained for some testcross hybrids. Midparent heterosis on average was moderate for grain yield and, plant height. And for days to silking, MPH values were mostly negative. Mean GD values determined from the inbred lines by population tester (0.680) and line tester (0.661) combinations were not significantly different. Cluster analysis separated the tester parents from the corresponding inbred lines. AFLP grouping of the inbred lines was in agreement with their pedigree records. Genetic distances derived from the inbred lines × all testers and from the population testers’ sub-group were not positively correlated with hybrid performance and MPH for most traits. In contrast, correlations of GDs involving the line testers’ sub-group with F_1’s and MPH were significantly positive but with low magnitude to be of predictive value.     

Heterosis and combining ability vis-à-vis association for green fruit yield and component traits involving male sterile lines in chilli (Capsicum annuum) under wet temperate zone of North Western Himalayas

Fourteen genetically diverse inbred lines comprising of four genic male sterile lines and 10 often pollinated lines as testers were crossed following ‘line × tester’ mating design to generate 40 F₁s. These F₁s, parents and check ‘CH-27’ were evaluated in α-lattice square design, replicated thrice during summer seasons of 2020 and 2021. The male sterile line DPChMS 9-2 was good general combiner for marketable fruit yield and eight other component traits while testers namely, DPCh 10, PBC 535, VVG, Him Palam Mirch-2 and DPCh 40 showed significant GCA for majority of yield related traits. The hybrids DPChMS 9-2 × HPM-2, DPChMS 9-2 × DPCh 40, DPChMS 9-2 × DPCh 101, DPChMS 9-2× VVG and DPChMS 26-1× HPM-1 were the most desirable based on specific combining ability (SCA) and economic heterosis for fruit yield and other important traits. Heterosis was positively correlated with SCA indicating prediction of potential hybrids can be made based on both these parameters simultaneously. Present study provides an opportunity to exploit top hybrids for stability and commercial cultivation.     

Inheritance and allelic relationship among gene(s) for blast resistance in pearl millet [Pennisetum glaucum (L.) R. Br.]

Six blast‐resistant pearl millet genotypes, ICMB 93333, ICMB 97222, ICMR 06444, ICMR 06222, ICMR 11003 and IP 21187‐P1, were crossed with two susceptible genotypes, ICMB 95444 and ICMB 89111 to generate F₁s, F₂s and backcrosses, BC₁P₁ (susceptible parent × F₁) and BC₁P₂ (resistant parent × F₁) for inheritance study. The resistant genotypes were crossed among themselves in half diallel to generate F₁s and F₂s for test of allelism. The F₁, F₂ and backcross generations, and their parents were screened in a glasshouse against Magnaporthe grisea isolates Pg 45 and Pg 53. The reaction of the F₁s, segregation pattern of F₂s and BC₁P₁ derived from crosses involving two susceptible parents and six resistant parents revealed the presence of single dominant gene governing resistance in the resistant genotypes. No segregation for blast reaction was observed in the F₂s derived from the crosses of resistant × resistant parents. The resistance reaction of these F₂s indicated that single dominant gene conferring resistance in the six genotypes is allelic, that is same gene imparts blast resistance in these genotypes to M. grisea isolates.     

Combining ability estimates for yield and fibre quality traits in 4 × 13 line × tester crosses of Gossypium hirsutum

The aim of this study was to estimate the general combining ability of the parents and specific combining ability of hybrids considered for the development of high yielding and better quality cultivars. Seventeen genotypes and 52 F₁ hybrids obtained by crossing 4 lines and 13 testers in line × tester mating system during 2003 were sown in randomized complete block design in 2004. Line × Tester analysis revealed significant GCA and SCA effects for all the traits except fibre elongation. Preponderance of non-additive gene action was obtained for seed cotton yield per␣plant and majority of its component traits including fibre traits. Among the parents: PIL-8 for days to 50% flowering, CCH-526612 for boll weight, CITH-77 for number of open bolls per plant and CNH-36 for seed cotton yield per plant were detected with higher general combining ability. Parent, CCH-526612 for 2.5% span length, fibre strength and fibre elongation and AKH-9618 for micronaire value, fibre strength and fibre elongation were good combiners for fibre quality traits. The F₁s achieved high seed cotton yield by producing more number of open bolls. The high yielding hybrids with acceptable fibre quality traits were: CISV-24 × LH-1995, H-1242 × PIL-8 and RS-2283 × SGNR-2 deducted with significant SCA effects for seed cotton yield and fibre characteristics; 2.5% span length and fibre strength. These cross combinations involved at least one parent with high or average GCA effect for a particular trait.     

Studies on Low Crossabilities Encountered with the Hordeum bulbosum Method for Haploid Production of Barley, Hordeum vulgare L.

Crosses were made between four spring barley (Hordeum vulgare L.) cultivars and five F₁, hybrids with one genotype of Hordeum bulbosum L. in two locations to investigate further previous low crossabilities which had been found in the barley cultivar ‘Apex’ with H. bulbosum. Data at all the main steps of the H. bulbosum technique were recorded and statistically analyzed. Significant differences between barley genotypes were demonstrated for all characters. It was confirmed that ‘Apex’ has poor crossability with H. bulbosum. Out of the three F₁ hybrids having ‘Apex’ as one parent, two exhibited low crossability similarly to ‘Apex’ but one showed significantly higher seed setting than ‘Apex’. The effect of the location was only significant on seed setting, while genotype X location interactions were significant on seed setting, seed quality and rate of haploid plants in relation 10 florets pollinated. Another problem which has influenced the success rate of the H. bulbosum method was found in the cultivar ‘Havilla’. Although seed setting and seed quality were high for this cultivar, embryo differentiation was low. However, this latter problem was found to influence less the overall success rate than poor crossability. Mahalanobis's distances were calculated and the dendrite of the shortest distances between barley genotypes was plotted.     

Relative efficiency of different Gramineae genera for haploid induction in triticale and triticale x wheat hybrids through the chromosome elimination technique

The study was undertaken to evaluate the relative efficiency of different Gramineae genera for haploid induction in triticale (x Triticosecale) and triticale × wheat (Triticum aestivum) hybrids through the chromosome elimination (wheat × maize, Zea mays) system. Eight intergenotypic triticale and 15 triticale x wheat crosses were subjected to hybridization with nine different Gramineae genera viz., Z. mays, Sorghum bicolor, Pennisetum americanum, Setaria italica, Festuca arundinacea, Imperata cylindrica, Cynodon dactylon, Lolium temulentum and Phalaris minor in two separate experiments. This was followed by in vivo auxin treatment of the crossed spikes and subsequent rescue of the haploid embryos to regenerate green haploid plantlets. All the triticale and triticale x wheat crosses resulted in seed set in variable frequencies when hybridized with maize, I. cylindrica, pearl millet and sorghum. Seed set was also obtained with S. italica, F. arundinacea and P. minor in a few crosses in both groups. In general, all the triticale x wheat crosses, except for one in each case, resulted in embryo formation and green haploid plantlet regeneration when hybridizations were carried out with maize and I. cylindrica. However, the latter outperformed the former in embryo formation (25.48% vs. 20.0%) and regeneration (34.17% vs. 15.10%) frequencies, the differences being significant for regeneration frequencies. In the case of triticale hybrids, no significant differences between maize and I. cylindrica were observed for the three parameters of haploid induction. Embryo formation and regeneration were also observed in some of the triticale as well as triticale × wheat F₁ hybrids when hybridized with sorghum and pearl millet.     

Inheritance and allelism of wheat streak mosaic virus resistance in two Iranian wheat lines

Wheat streak mosaic (WSM) caused by wheat streak mosaic virus (WSMV) is a serious disease of wheat and many plants in the grass family. In previous studies genotypes collected from different parts of Iran, were screened for WSM resistance. Two resistant genotypes, “Adl Cross” and “4004” were crossed to one susceptible genotype “Marvdasht.” Reciprocal crosses were also made. Seedlings of parents, F₁, F₂, backcrosses to susceptible (BCS) and resistant (BCR) were evaluated for WSMV reaction based on scales 0–7, by artificial infection under greenhouse conditions. Allelism was studied by evaluating the F₁ and F₂ seedlings of the resistant × resistant cross. Inheritance of resistance to WSMV in Adl Cross and 4004 was controlled by one dominant gene. No allelism was observed between resistance genes. Among the F₂ seedlings of the resistant × resistant cross relatively more resistant genotypes with a zero score were observed. These two genes, therefore, can be incorporated into an adapted wheat cultivar to produce a more durable resistance.     

Heterosis and combining ability analysis in Chinese semi-winter × exotic accessions of rapeseed (<Emphasis Type="Italic">Brassica napus</Emphasis> L.)

Fourteen accessions (spring and winter types) and four testers (semi-winter type) of rapeseed (Brassica napus L.) were crossed in line?×?tester mating design to estimate general and specific combining ability for seed yield, yield components, and oil content. The F₁ hybrids and their parents were evaluated in four environments in northern China. Highly significant differences were detected among the parents and hybrids for all the traits across environments. Plant height, setting position of first primary branch and length of terminal raceme were controlled by additive genes, whereas primary branches per plant, siliques on terminal raceme, siliques per plant, seeds per silique, seed yield per plant, 1000-seed weight, oil content, and seed yield were controlled by non-additive gene action. The accessions SP-Armada, 9E49, and CZ25 and the tester Zhong9 were good general combiners for seed yield. Among the 56 F₁ hybrids, four hybrids: Zhong9?×?CZ25, GZ1R?×?9E38, Zhong7?×?9E38, and Zhong7?×?CZ49 showed higher yield than the control and were the outstanding combinations for seed yield. These hybrids were recommended to be included in future breeding programs for development of new high yielding varieties with more desirable traits. Both winter and spring germplasm have potential in Chinese semi-winter rapeseed breeding program, for seed oil content improvement, more attention may be paid to spring germplasm.     

Identification of Rye Chromosomes Involved in Tolerance to Barley Yellow Dwarf Virus Disease in Wheat × Triticale Hybrids

Common wheat × hexaploid triticale hybrids were produced and evaluated for tolerance to barley yellow dwarf virus disease (BYD). The BYD tolerance expression varied with wheat × triticale combination. The selection for BYD tolerance increased the recovery of tolerant genotypes in the next generations. Homozygous tolerant and susceptible lines were obtained in advanced generations. The rye chromosomes 1R, 2R, and 4R with 7R were transmitted as disomic or monosomic, disomic, and double disomic substitution to the late generations of ‘Musala’ (common wheat) בMuskox 658’ (triticale), ‘Encruzilhada’ (common wheat) בNord Kivu’ (triticale) and ‘Encruzilhada’× 12th. International Triticale Screening Nursery 267 (12ITSN267) (triticale), respectively. A clear association was established between the 1R chromosome of the ‘Muskox 658’ triticale line and the tolerance to BYDV. Results suggest that the 2R chromosome may be involved in BYD tolerance of ‘Nord Kivu’ triticale line.     

Rapid Incorporation of D-genome Chromosomes into A and/or B Genomes of Hexaploid Triticale

Two series of progenies were developed from hybrids between octoploid (AABBDDRR) and tetraploid triticale ((AB)(AB)RR). One arose from the successive selfing of the F₁s, while the second was established after one backcross of the F₁ hybrids with the respective 8 × triticale parent. Altogether, 250 F₃ and BC₁F₂ lines were developed, of which 112 were karyotyped in the F₄/F₅ or in BC₁F₃/BC₁F₄ generations using C-banding and SDS-PAGE. The 112 lines represented 61 different karyotypes, of which 39 appeared to be stabilized, having pairs of homologous wheat chromosomes only, while 22 karyotypes exhibited 1—3 heterologous pairs. The frequency of karyotypically stabilized lines originating from the series with one backcrossing was much higher (79.5 %) than those derived from the successive selfing of the F₁ hybrids (51.7%). Six lines had the pure hexaploid triticale chromosome constitution. The frequency of disomic substitutions of D genome chromosomes for their homoeologous A and/or B genome chromosomes ranged from one to six per line with an average of 1.7. Except for 3B and 6B all possible D(A/B) substitutions were obtained. Chromosomes ID and 3D substituted for their homoeologues with the highest frequency, while the substitution of chromosome 4D for 4A or for 4B was the least frequent. D(R) substitutions were found in eight lines only. A complete set of 6x triticale lines was established in which chromosome ID was present in all possible combinations, i.e. single 1D(1A/1B/1R) disomic substitutions as well as disomic ID addition.     

Performance of pearl millet isonuclear hybrids involving different cytoplasmic male-sterility systems

The performance of pearl millet hybrids involving four sources of cytoplasmic male sterility (CMS), including the most-exploited A₁ source, was compared to evaluate the effects of cytoplasm on grain yield. The mean grain yield of hybrids possessing A₂, A₃ and A₄ cytoplasms was either similar to or significantly higher than that of their counterpart hybrids with A₁ cytoplasm. Hybrids based on A₃ and A₄ cytoplasms produced, on average, 8% more grain compared with those based on A₁ cytoplasm. This suggested that these CMS sources could be used as alternatives to A₁ cytoplasm to widen the cytoplasmic base of hybrids. The results indicated that most of the variation in hybrids was accounted for by pollinator and cytoplasm × pollinator interactions, suggesting the use of genetically diverse pollinators in pearl millet hybrid breeding.     

Heterosis,combining ability and genetic effect,and relationship with genetic distance based on a diallel of hybrids from five diverse <Emphasis Type="Italic">Gossypium barbadense</Emphasis> cotton genotypes

The cultivated tetraploid Gossypium barbadense L. cotton produces superior natural fibers for the textile industry in the world. However, the possibility in utilization of heterosis to further increase its lint yield has not been extensively explored. In this study, two commercial US Pima cotton cultivars and three exotic G. barbadense lines, together with all of their possible hybrids in F₁ and F₂ progeny without reciprocals, were tested for lint yield, yield components, and fiber quality traits in four environments in 2005–2007. With a few exceptions, genotype (G), environment (E), and G × E were all significant or highly significant for all the traits studied. General combining ability (GCA) variances for all the traits in both F₁ and F₂ were also significant, while specific combining ability (SCA) variances were detected only for lint yield, fiber length, and micronaire in both generations and boll weight in F₁. GCA × E was also detected for lint percent, seed index, and fiber length in both F₁ and F₂, and boll weight in F₁, but none of the traits had significant SCA × E. As a group, F₁ and F₂ out-yielded the parent group by 20–40% and 6–10%, respectively. Mid-parent heterosis (MPH) for lint yield in F₁ was generally positive, ranging from ?4.7 to 116.4% with an average of 21.2–48.7%, while lint yield MPH in F₂ ranged from ?23.3 to 69.4% with an average of 6.4–12.4%. However, useful heterosis in lint yield was only detected in the hybrid between the two US commercial cultivars Pima S-7 and DP 340. MPH for other traits was low or not detected. MPH in F₂ was lower than that in F₁ but they were generally positively correlated. The genetic distances (GD) of the parents (based on 467 polymorphic RAPD and AFLP markers) between the five parents was not consistently correlated with MPH and SCA of their hybrids and dominant effects for lint yield and other traits. However, significant and positive correlations between GD of parents and the performance of their hybrids were detected for lint yield, lint percentage, and lint index in both F₁ and F₂ in most of the tests. GD of parents was also correlated with their GCA and additive effects in lint yield, lint percent, lint index, micronaire, plant height, and elongation. The results suggest that the close correlation between GD and hybrid performance per se was mainly due to the existence of GCA and additive effects from parents.     

Cytoplasmic male sterile and doubled haploid lines with desirable combining ability enhances the concentration of important antioxidant attributes in <Emphasis Type="Italic">Brassica oleracea</Emphasis>

The Brassica vegetable crops are rich source of important antioxidant compounds having anticancer and health promoting properties. Development of F₁ hybrids with better nutritional traits is one of the main breeding objectives in different vegetable crops. Our study is the first report of determining heterotic combinations utilizing cytoplasmic male sterile (CMS) and doubled haploid (DH) inbred lines for antioxidant compounds in snowball cauliflower. Twenty genetically diverse Ogura CMS lines of cauliflower and six DH male fertile inbred lines were crossed to develop 120 F₁ hybrids in line?×?tester mating design. The resulting 120 test cross progenies along with 26 parents and 4 standard checks were evaluated in 10?×?15 alpha lattice design with three replications during next cropping season. The CMS lines Ogu33-1A, Ogu122-5A and Ogu119-1A were good general combiner and CMS line Ogu118-6A was poor general combiner for majority of traits. Most of the heterotic hybrids were associated with high positive SCA effects. The proportions of σ²A/D and \(\upsigma^{2}_{\text{gca}} /\upsigma^{2}_{\text{sca}}\) ratios were less than unity in all the cases indicating preponderance of non-additive gene action in the genetic control of all the traits. Highest number of heterotic hybrids with SCA effects in desired positive direction was recorded for ascorbic acid content and phenolic content followed by total carotenoid content. The F₁ hybrids with better combining ability and better per se performance could be useful in accumulation of favourable allele for higher concentration of important anti-oxidant compounds.     

Fertility of Brachiaria ruziziensis in interspecific crosses with Brachiaria decumbens and Brachiaria brizantha: meiotic behaviour,pollen viability and seed set

Summary Colchicine induced tetraploid (2n=4x=36) Brachiaria ruziziensis were used as female parent in crosses with apomictic tetraploid species (2n=4x=36) Brachiaria decumbens and Brachiaria brizantha. Tetraploid B. ruziziensis pollinated with B. decumbens set significantly more seed than selfed or crossed with B. brizantha. The crossability between B. ruziziensis and B. decumbens is also better than between B. ruziziensis and B. brizantha. In addition, hybrid seedlings obtained in crosses involving B. brizantha are more frequently lethal. All the viable F₁ hybrids are tetraploid with 36 chromosomes. Meiotic chromosome behaviour suggest that the three species belong to the same genomic group and therefore the same agamic complex. Chromosome associations at metaphase I do not allow to identify fertile and sterile hybrids. The interspecific hybrids averaged a lower fertility than their female parent, but some hybrids were more fertile than their apomictic male parent.