IntroductionSince winter barleys generally produce higher grain yields than spring barleys, under conditions of little or no winterkill, plant breeders have been in search of winter hardy varieties that would permit a northern expansion of the crop. This search has not uncovered varietal material appreciably superior to winterhardy varieties already in commercial use. Attention of plant breeders has, therefore, been directed toward hybridization and concomitant genetic problems with the view of combining characteristics of several varieties into new types of higher winterhardiness.Pulham (1954) and Rohde and Pulham (1960) made diallel crosses between eighteen varieties of winter barley and studied winter-survival behavior of all F1 and F., progenies and of the original eighteen varieties. In revie~t~ing this work, the present authors noted that the full diallel techniques had not been followed in analysing the data. Rhode and Pulham (1960) consolidated the data of all experinients and calculated total variance, treatment variance, error variance etc.; but they did not separate the different components of variation, such as Ileritable-fixable, Ileritable-nonfixable and nonheritable variation, nor did they study how these interact in the expression of the character. It was felt, therefore, that it might be profitable to re-analyse the data using thc diallel techniques of Hayman (1 951). Accordingly, the original ra\v data were obtained from Dr. ~o h d e for inspection. T h e results of the re-analysis of these data are reported and discussed in the present paper.
Materials and Methods
SUMMARYHeritability of four quantitative characters in two crosses of Brassica campestris L. was found to be high. Dominance was detected only for plant height at heading time in both the crosses, and for sowing-to-heading period in Toria-TP × Toria-7. Transgressive segregation was expected in the segregating progenies for all the characters. Epistasis was complementary in all characters except in plant height at ripening time, where it was of the duplicate type. Additive × dominance type of epistasis was most significant and was present in most of the characters. Genes for most of the characters were linked with a major gene for seed colour (Rr). Yield was genetically correlated with the four quantitative characters studied.
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