II. 35. Genetical control of pair selection for crosses in barley breeding for high protein content in grain.
C.F. Nikitenko, Scientific Research Institute of Agriculture of Central Regions of the Non-Chernozem Zone (1430I3 Moscow, Nemchinovka); M.A. Polukhin and V.A. Gorshkova, Dokuchayev Scientific Research Institute of Agriculture of the Central Chernozem Belt (397463 Voronezh region, Talovsky district).
For successful breeding of new high-yielding spring barley varieties with a high protein content in kernel it is essential to know regularities in inheritance not only of productive traits, but the protein content and correlation pattern of those traits (characters) both in parental forms and in hybrid generations. The latter is important even more because due to the great progress in plant breeding the quantity of high-valuable forms which may be used as components in crossing, significantly increased, and it complicates the problem of selecting the best component.
However, statistical methods of analysis of a splitting pattern in hybrids, developed for alternative characters, are useless in selection for quantitative characters. Therefore, it is necessary to apply some methods to evaluate initial stock for quantitative characters. In this case, even if without specific data about each of polygens, determining either quantitative character, a breeder may have a clear view of the polygen system on the whole, particularly on the availability and the ratio of additive, dominant and epistatic effects.
Earlier the authors (G.F. Nikitenko, M.A. Polukhin, V.A. Gorshkova, 1977) carried out diallelic analysis of hybrid combinations and showed genetical value of individual varieties as components of crosses in barley breeding for yield products quality (Table 1).
Table 1. Genetical parameters of F1, F2 and trait indices
In the course of 1973-1977 years further breeding work with hybrids received in diallelic crosses was still in progress.
The characteristics of selection lines F5 - F6 were in good agreement with selection value estimation of individual varieties made on the basis of genetical parameters calculated in diallelic analysis.
Many lines, selected from the combinations studied, in 1975 were superior to Donetsky 4 variety (standard) by protein content in kernel (Table 2). In 1976 those lines were significantly higher than the standard by productivity (by 10-20%) and superior by the ear length, number of spikelets and kernels in the ear (Table 3).
Table 2. Yield and quality of the best lines of spring barley.
Table 3. Characteristics of hybrids F6 according to the elements of yield structure (1976)
According to the data of 1976 the strains isolated from hybrid combinations (Spartan II x Europeum 353/133), (Spartan II x Nutans 187), (Spartan II x Moskovsky 121) turned out to be the most perspective ones.
Hybrid Spartan II x Europeum 353/133 is one from all twenty studied combinations of crosses that inherited the height of the plant, the number of spikelets and kernels in the ear from Europeum 353/133 variety. By those traits it showed high total combinative capacity (TCC). It inherited large grain from Spartan II variety, and according to the results of diallelic analysis this variety had the highest TCC by the given trait. On the account of such combination this hybrid proved highly productive; weight of kernels in one plant was 2.04 g.
Hybrid Spartan II x Nutans 187 inherited high productive tillering from Nutans 187 variety. Hybrid Evropeum 355/133 x Nutans 187 inherited high number of spikelets and kernels in the ear from Evropeum 353/133.
Thus, the study of genetical characters in a number of spring barley varieties on the basis of the data taken from the analysis of diallelic crosses has revealed the role of certain genetical interactions controlling development of characters and determining both productivity and yield quality, particularly protein content in the kernel. The analysis of variance and covariance regression gives a clear idea about genotype of each variety, and combinative capacity effects are characteristic of its breeding value as a feasible cross component.
On the basis of the results of the analysis of diallelic crosses it can be concluded that in genetical control of such characters as "height of plants", "productive tillering", "length of ear", "weight of kernels in ear and plant" effects of superdominance play the principal role and of characters "number of spikelets", "number of kernels in ear" effects of dominance do it. Meanwhile, in inheritance of characters "weight of 1000 kernels" and "protein" - additive gene effects are of great importance.
In the same analysis for characters "number of spikelets in ear", "number of kernels in ear" and "protein" relation between the number of recessive genes in parents and mean character expression in them was established. It was found out that the variety which possessed greater number of recessive genes would have higher meaning of the studied character and vice versa. For other studied characters such correlation was not discovered.
Jinks (1955) suggested that the detectable superdominance was in fact a reflection of non-allelic interactions, which played an important role. Nonallelic interaction of complementation type may be fixed in a homozygote and under favorable direction of the complmentation action may lead to the character reinforcement. Therefore, regularities established by us may be used for development of the most efficient breeding programs in the work with a certain group of varieties.
Moreover, some peculiarities of the work with the hybrids should be kept in mind. Particularly, isolation in early generations may be noneffective for those characters in genetical control of which superdominance effects prevail. However, for characters which are under the control of the additive gene systems, isolation may be initiated from early generations. In the latter case, beginning from F2, it is necessary to conduct a rigid discard of strains with a low protein content to isolate for productivity already in F4 - F5 only within the group of high-protein strains.
References:
Jinks, J.L. 1955. A survey of the genetical basis of heterosis in a variety of diallel crosses. Heredity 9:222-238.
Nikitenko, G.F., M.A. Polukhin, and V.A. Gorshkova. 1977. Genetical analysis of diallel crosses for the trait of protein in spring barley. BGN 7:53-55
