Showing papers on "Diallel cross published in 1981"

Inheritance of salt tolerance in rice

Abstract: The genetic behavior of salt tolerance was studied in artificially salinized conditions at the International Rice Research Institute. Divergent selection, carried out at a salinity level where the ECe was 15.2 mmhos/cm at 25 C in F3 lines from two crosses confirmed the effects of salt tolerance on F4 progeny with realized heritability values of 0.39 and 0.62, respectively. In a cross between two tolerant cultivars there was clear over-dominance for tolerance, despite the high environmental fluctuation which resulted in a low genetic response as indicated by a low but significant repeatability of 0.20–0.25, and many progeny lines more tolerant than the parents were recovered. The superior tolerance of these progenies compared to the parents was confirmed subsequently at 3 different salt levels. In the same experiment a cross between tolerant and susceptible cultivars produced some progeny of comparable tolerance with tolerant sources. In a 6×6 diallel cross experiment with two tolerant, moderate, and susceptible varieties each, both general and specific combining ability were significant. The findings indicate the possibility of breeding rices more tolerant than existing tolerant cultivars through cumulative crosses of tolerant cultivars. Further improvement can be attained by crossing highly tolerant lines with donors of good agronomic traits and pest and disease resistance.

Heterosis and Combining Ability in Peas

Abstract: Ten diverse cultivars of peas (Pisum sativum L.) were crossed in diallel and the parents, F1s and F2s evaluated for five quantitative characters. All traits studied except plant height showed considerable heterosis and inbreeding depression. Yield heterosis based on the mid-parent averaged 47 per cent and on the high parent 22 per cent. Both general and specific combining ability were important for all the traits studied; however, additive gene effects were predominant in the inheritance of these quantitative characters.

Phenotypic and genetic relationships between yield components in maize

Abstract: Physiological components of kernel development — LAG period, effective filling period duration (EFPD) and grain filling rate (GFR) — ear moisture release (ΔU), ear size (row number and kernels per row), days from emergence to silking and number of leaves, were examinated on 45 F1 hybrids (10×10 diallel cross) in order to study their genetic relationships with yield. Combining ability analysis revealed that all trait variability derived mainly from g.c.a. effects. LAG period and EFPD were the traits most affected by genotype-environment interaction.

Combining ability analysis over environments in diallel crosses of linseed (Linum usitatissimum L.).

Abstract: This paper reports on combining ability studies for yield and its component traits in diallel crosses involving ten ecogeographically and genetically diverse linseed (Linum usitatissimum L.) cultivars in the F2 generation over three locations. The general combining ability (GCA) and specific combining ability (SCA) mean squares were significant at all three locations for all traits. Combined analysis over locations showed the same trend of significance. The ratio of GCA to SCA mean squares was significant for all the traits in individual location analysis as well as in combined analysis. This indicated the predominant role of additive gene effects in the inheritance of these characters. The GCA mean squares were several times larger than SCA mean squares for all the traits, indicating the presence of considerable magnitude of additive genetic variance and the additive x additive components of the epistatic variance. Consequently, effective selection should be possible within these F2 populations for all characters. Significant genotype-location and GCA-location interactions indicated that more than one test location is required to obtain reliable information. The inexpensive and reliable procedure used for making the choice of parents was the determination of breeding values of the parents on the relative performance of their F2 progeny bulks.

Genetic analysis of seed yield, oil content and their components in safflower (Carthamus tinctorius L.).

Abstract: The genetic architecture of seed yield, oil content and their components was studied in a diallel cross of F1 and F2: eleven parents, representing an adequate diversity for all considered characters in safflower were used. Combining ability analysis revealed the predominance of gca variance for plant height, total capitula, seed weight, seed number and seed yield in F1 and F2 generations and for days to flowering and oil content in F1. The analysis of components of variance indicated that the non-additive factor was the major influence on total capitula and seed yield in F1s, and F2s, and on plant height, seed weight and seed number in the F2 alone. The heterogeneity of the dominance component over generations has been attributed to coupling phase linkage. All four Indian parents, namely S 144, A1, MS 49 and 6 spl, together with G 1157 and US 104 in the exotic group, were the best combiners for seed yield and/or for one of its components while the remainder of the exotic parents were characterized by high gca effects for oil content. VFstp 1 and Frio were the only parents approximating both properties of oil content and seed yield. Breeding methods, such as biparental mating followed by reciprocal recurrent selection, were suggested for the simultaneous improvement of seed yield and oil content.

Genetics of escape-avoidance conditioning in laboratory and wild populations of rats: a biometrical approach.

Abstract: The interest of biometrical geneticists in the genetic architecture of behavior is explained with reference to the additive, dominance, and epistatic components of variation and their relation to evolutionary pressures. For one phenotype, escape-avoidance conditioning inRattus norvegicus, a fairly complete description of its genetic architecture has been gradually built and the major conclusions from four studies of this phenotype are reported: a selection study initially demonstrated the presence of large amounts of additive genetic variation and produced phenotypically extreme lines needed for later work; a diallel cross provided the opportunity for detailed examination of the dominance effects; a triple test cross permitted a similar examination of epistatic effects; and finally, another triple test cross using wild rats provided a confirmatory first attempt to test the assumption that a wild population's genetic architecture did not differ markedly from that found in laboratory populations. In relating the genetic findings to the evolutionary significance of behaviors in the escape-avoidance paradigm, it is argued that interspecific comparisons might play a major role.

Genetic Variation for Acetylene Reduction Rate and Other Characters in Alfalfa

Abstract: The objective of this study was to determine the general (GCA) and specific (SCA) combining abilities of alfalfa (Medicago sativa L.) for rate of acetylene reduction, plant dry weight, N content (%), total plant N and nodule score. The parental clones were selected from the commercial cultivars ‘Beaver,’ ‘Roamer,’ ‘Saranac,’ and ‘Rambler.’ Five strains of Rhizobium meliloti Dang., including four single strains and one commercial inoculant ‘Balsac’ were used. The most effective strain of Rhizobium was NRG61, while RM110 was the poorest. Diallel analysis of the six-parent half diallel cross revealed that mean squares of both GCA and SCA were highly significant for all characters except the SCA mean square for nodule score. The highly significant interactions of GCA and SCA with Rhizobium strains suggested differential expressions of gene effects for alfalfa genotypes with different strains of Rhizobium. The GCA variance components were higher than SCA for total plant dry weight, total plant N and nodule score. This suggested that the major portion of the total genetic variation was additive. Recurrent selection for these characters should be possible. However, the additive and non-additive gene effects were equally important for acetylene reduction rate with Rhizobium strains NRG43, NRG61, and NRG118. Reciprocal recurrent selection method might be necessary to improve this character with these single Rhizobium strains. Combining ability analysis for each of the parental clones indicated that Clone 4 had consistently high and positive GCA effects over all Rhizobium treatments. Clone 2 was on the other extreme with negative GCA effects in all cases. None of the other parental clones produced consistently positive GCA effects across all the Rhizobium strains

General and specific combining ability for yield in a diallel cross among 18 maize populations (Zea mays L.)

Abstract: A study was carried out on diallcl crosses among 18 maize populations. An analysis was conducted on ear weight data using Griffing's Method 2, Model I to determine general and specific combining ability effects. General combining ability (GCA) was found to be significant but specific combining ability (SCA) was not. Both location x GCA and location x SCA interactions were found to bc significant. Thc rcsults showed that populations CMS 06 and CMS 05 have the highest GCA effects. The cross (CMS 07 x CMS 10) gave the highest SCA cffect.

Analysis of two-way escape-avoidance conditioning measures from a diallel cross of eight strains of rats.

Abstract: In a study designed to investigate genotype-environment interaction, eight strains of laboratory rats were crossbred in a replicated diallel cross employing infantile stimulation and its absence as environment treatments. This paper reports on measures of the acquisition of two-way escape-avoidance conditioning, comprising number of avoidances, avoidance and escape latencies, and intertrial and presessional crossings, which were subjected to biometrical genetical analysis, all but the last successfully. Additive variation was prominent throughout and some measures showed directional dominance. Effects of stimulation were seen in avoidance number and crossings. The analysis of avoidances by successive blocks of trials using covariance:variance graphs revealed differences in the way the strains varied with respect to the changing relationships of proportions of dominant and recessive alleles governing this behavior. The results are discussed in the light of previous data and of their evolutionary implications.

Inheritance of shoot fly resistance in sorghum

Abstract: F1 and F2 diallel analyses were used in field-plot studies at Parbhani, India, in 1979 on the inheritance of resistance to Atherigona soccata Rond. and related characters in sorghum lines. Data were obtained for 3 characters, namely the percentage of dead hearts, the number of eggs per plant and percentage plant recovery. The first character was controlled by additive gene action, while the other 2 were controlled mainly by additive gene action but also by a certain degree of non-additive action. The heritability for resistance appeared to be about 23-25%

Heterosis and combining ability in sesamum

Abstract: A diallel cross involving ten varieties of sesamum was studied for heterosis and combining ability during 1975 at the J. N. Agricultural University, Jabalpur. In general, the magnitude of negative heterosis was higher than positive heterosis. Number of branches and number of capsules per plant were found to be the main contributing attributes for seed yield. ‘N66–173’ and ‘T.C. 66’ arc the best general combiners and ‘T.C. 66 × MS-l’ and ‘N66–173 × S.I. 1551’ showed high S.C.A. effects for yield.

Genetic aspects of resistance to cocoa swollen‐shoot virus in Ghana

Abstract: SUMMARY The inheritance of resistance in cocoa to infection with cocoa swollen-shoot virus was studied in seed inoculation experiments with progenies of Upper Amazon, Trinitario and West African Amelonado parents. In an eight parent diallel cross grown in two seasons and in six male × female factorial experiments, general combining abilities were much more important than specific combining abilities. The diallel cross revealed significant maternal effects but there was little evidence of specific reciprocal differences. Estimates of general combining abilities corresponded with expectation and were positively correlated with maternal effects, the latter indicating that tester parents should be used as males. The results from scaling tests with hybrids between selections from the River Nanay (a Peruvian tributary of the River Amazon) and Amelonado fitted a model with additive resistance; there was no evidence of dominance. Attempts to obtain stronger sources of resistance by hybridisation and selection were unsuccessful. In three crosses the resistance of individual seedlings was compared with that of the parents using test crosses but no evidence of transgressive segregation was obtained. In further experiments seedings of two hybrids between contrasting parents were heavily inoculated with virus so that few healthy survivors remained. Test crosses showed that these survivors and randomly selected seedlings of the same parentage did not differ as resistance sources.

Heritability and combining ability of vegetative and phenological characters of winged beans ( Psophocarpus tetragonolobus (L.) D.C.)

Abstract: The variability generated in a diallel cross between seven genotypes for vegetative and phenological characters was studied in the F 1 and F 2 generations in lowland Papua New Guinea. The mean narrow-sense heritability values of mean leaf size and leaf area index at flowering were 88·0 and 78·5%. The parental values of these characters gave good predictability of the performance of the parents in hybrid combination. For mean number of leaves per plant at flowering, environmental effects were of major importance, and consequently selection between crosses for number of leaves is considered futile. There was a large genotype ˣ environment interaction for time to first flower. The role of various environmental factors in causing the interaction for flowering is discussed.

Stem borer resistance in sorghum

Abstract: The nature of gene action for stem borer resistance was studied in F2 and F3 of a six variety diallel cross. Significant general and specific combining ability variances in F2 and F3, indicated that both additive and nonadditive components influence stem borer resistance. However, the higher magnitude of GCA in F3 indicated that stem borer resistance is predominantly governed by additive and additive × additive components of genetic variance. ‘IS 4664’, ‘CSV-3’ and ‘SR-18’ were good combiners. The GCA effects indicated that atleast one parent should be a good combiner in breeding for stem borer resistance.

Inheritance of tillering and flowering-time in early maturing maize

Abstract: A diallel cross and F2 populations derived from eight early maturing maize inbreds were used to investigate the inheritance of tillering and flowering-time (anthesis), and the possible relationship between tillering and flowering-time. Incomplete dominance for increased tillering was observed; potence ratios, representing the overall degree of dominance, ranged from 0.26 to 0.52. Dominance for early flowering ranged from incomplete with a potence ratio of 0.55 to overdominance with a potence ratio of 1.40. Broad-sense heritabilities were low for both characters. The genetic component of variation for tillering was due to general combining ability effects; specific combining ability effects were not significant. A significant negative linear relationship between tillering and flowering-time was found. Lack of independent assortment of tillering and flowering-time in F2 populations indicated that the two characters are genetically related.

Diallel analysis of yield and maturity components in maize

Abstract: The results indicated the predominance of additive gene action for days to anthesis, days to silk and days to husk drying and non-additive gene action for grain yield per plant.

Genetic diversity between diverse height categories of bread wheat

Abstract: Sixty four F1’s and F2 of wheat from a 8 × 8 diallel and 55 F2’s from a 10 × 10 diallel (where eight parents were common) were subjected to D2-analysis to measure the genetic diversity and components of genetic variation involving different height group parents and their F2, populations.

Research on the inheritance of seed dormancy in lettuce (Lactuca sativa L.) and selection for non-dormancy

Abstract: Inheritance of dormancy and the results of selection of non-dormant genotypes in segregating populations of lettuce were investigated. Diallel crosses were therefore carried out between two dormant (DOR) and two non-dormant (NDOR) cultivars. F1, F2 and F3 populations were analysed.

Studies on combining ability in strawberry (fragaria × ananassa): i. number of inflorescences, number of flowers, days to maturity and number of fruits

Abstract: A 10 × 10 complete diallel cross was carried out in the strawberry (Fragaria × ananassa Duch) Significant general (gca) and specific combining ability (sea) effects were recorded The variances d

Diallel analysis of forage yield and its components in sorghum

Abstract: The genetic anslysis was carried out for green fodder yield and other eight quantitive characters in forage sorghum...

Combining Ability for Developmental Traits in Soybean

Abstract: In a 10-variety diallel cross in soybean, both gca and sca variances were found to be highly significant for six developmental characters. Parental performance as judged by gca effects indicated that ‘EG 7034’, ‘EG 27500’, ‘Hernon-49’, ‘EG 39822’ and ‘EG 39821’ were good general combiners for different characters. In general, the superior combinations involved at least one high general combining parent.

Shoot Fly Resistance in Sorghum

Abstract: The present diallel analysis were undertaken to study combining ability for shoot fly (Atherigona soccata Rondani) resistance and other related characters in sorghum. General combining ability variances were higher than sea variances for dead heart (%), eggs/plant, plant recovery and yield/plant. These results indicated predominance of additive gene action for these traits. The nature of gene action for seedling height, tillers/100 plants, effective tillers and yield/productive plant was predominantly non-additive. All resistant parents recorded desirable gca effects for dead heart (%), eggs/plant and plant recovery. IS 5490 and IS 5604 were observed to be desirable general combiners for most of the characters. The parent 168 is also promising within the group of dwarf parents. Significant positive association between per se performance of parents and gca effects indicated that lines for breeding can be selected on the basis of parental performance. Predominance of additive genetic variance for shoot fly resistance indicated that exploitation of IS 5490, IS 5604 and 168 through biparental approach may be rewarding.