Diallel analysis of the number of grains per ear in spring barley

SASHAYDIALL: A SAS Program for Hayman's Diallel Analysis

Different methods of diallel crossing are commonly used in plant breeding. The diallel cross analysis method proposed by Hayman is particularly useful because it provides information, among others, on additive and dominance effects of genes, average degree of dominance, proportion of dominance, direction of dominance, distribution of genes, maternal and reciprocal effects, number of groups of genes that control a trait and exhibit dominance, ratio of dominant to recessive alleles in all the parents, and broad-sense and narrow-sense heritability. In this paper, we fully describe a SAS-based software SASHAYDIALL for performing a complete diallel cross analysis based on Hayman's model with or without reciprocals. We demonstrate the use of SASHAYDIALL with two data sets; one is a published diallel cross data set with reciprocals in cabbage (Brassica oleracea L.), and the second is a data set from a multilocation diallel cross trial in maize (Zea mays L.) without reciprocals. With SASHAYDIALL, diallel experiments conducted in single sites can be analyzed to estimate various genetic parameters, and this analysis is extended over locations or environments to assess genetic effect × environment interaction. SASHAYDIALL is user-friendly software that provides detailed genetic information from diallel crosses involving any number of parents and locations.

Cross prediction studies on spring barley : 2. Estimation of genetical and environmental control of yield and its component characters

The genetical and environmental control of yield and its components in spring barley, tillers per plant, grain number and grain weight has been investigated by triple test cross and linear modelfitting analyses.Additive and dominance effects were observed for both grain number and grain weight, but tiller number was almost totally controlled by environmental factors. Epistatic effects were usually absent, only grain number exhibited such effects. The heritabilities of the yield components varied from low (0.15) for tiller number to high (0.51) for grain weight. Yield itself, measured on a single plant basis was mainly under additive and dominance control, with little evidence for epistasis. The heritability for single plant yield was low (0.22).The possibilities for early generation selection for yield are discussed, and the relative contributions of each genetic and environmental component are described.

The genetic control of morphological and yield characters in Vicia faba L

Complete diallel crosses were made within each of three populations of Vicia faba to examine the genetic control of morphological and yield characters. The Afghanistan and USSR populations consisted of five and the European of four genotypes. The phenotypic range of the genotypes in each population was similar for the characters studied.In each character additive gene effects were partly responsible for genetic variation but non-additive effects varied greatly in importance depending on the population examined. Differences were found in: a) the presence or absence of dominance; b) the partitioning of the dominant effects; c) the degree and direction of dominance; d) the presence or absence of epistasis; and e) the size of narrow-sense heritability estimates.It appears that in V. faba there exists much greater genetic variability than is evident by the examination of plant phenotypes. As different breeding techniques can be used to exploit different components of genetic variability, it is recommended that the possibility of differences in genetic architecture between geographical populations be taken into account in the planning of plant breeding programs. Advantage could then be taken of interactions between breeding methods and populations that are phenotypically but not genetically similar.

The inheritance of diastatic power and alpha-amylase contents in spring barley

In a diallel cross of 13 spring barley varieties, non-allelic interactions interfered with the analysis of diastatic power. Regression of W r on V r was less than unity both in the full experiment and in the sub-set of two-row varieties. The simple additive-dominance model was adequate for the analysis of alpha-amylase. Regression of W r on V r indicated directional dominance, increasing alphaamylase. For both characters non-additive variance was detected and the effects of directional dominance, asymmetry of gene distribution and SCA were evident. Significant GCA effects were also present. No serious obstacles to the improvement of either character in adapted two-row varieties were apparent.

A study of the inheritance and inter-relationships of some agronomically important characters in spring barley

The results of genetical analyses of data for the characters ear number, grain number per ear, 1000 corn weight and straw length are presented. These data were obtained from the F1 and F2 generations of a half diallel cross between 13 barley varieties, 4 of which were six-row types. Separate analyses were also conducted on the sub-set comprising two-row genotypes only.Analyses of variance detected a high level of dominance in F1 for all the characters and in general the dominance effects were directional and positive. Apparent overdominance resulting from interaction was detected in the F1 of crosses between two-row and six-row parents for 1000 corn weight.Evidence suggested that selection had resulted in the accumulation of dominant genes having an increasing effect on the morphological components of yield. A high proportion of dominant genes acting to increase straw length was also detected and it was concluded that considerable further shortening of the straw might be possible by selection in a segregating population though possibly at the expense of yield.Genotypic correlation coefficients were computed and provided evidence that further genetic improvement for yield should be possible within the two-row genotypes.