| Possibilities for increasing the content of lysine
in the wheat grains K. DJELEPOV and Tsv. RACHINSKA Inst. for Wheat & Sunflower. Tolbuhin, Bulgaria The increase of protein content in the grain of the cereals, wheat inclusive, is an important problem in all breeding work. Breeders are searching for ways and methods to increase its quantity and to change its amino acid composition. Protein in the present wheat varieties contains smaller quantities of the irreplaceable aminoacids lysine, methionine, tryptophan, due to which its biological of full value reduces. Breeding for higher protein content is, however hampered by the polygenic character of its inheritance and by the significant protain phenotypic variation, dependent on the conditions of growing. A number of studies (ZAFGREN et al. 1968; LELATA et al. 1972) have proved the existence of negative correlation between productivity and protein content and between protein and amino acid composition of the grain. Some results obtained by crossing mutants of high-protein content and different varieties show some advantages of the latter, when used as donors of high protein content and of certain protein components (SHOLZ 1976, ROBSON 1976) Our task was, through the usage of mutagene factors, to develop wheat forms of higher lysine content and to transfer it to other varieties and lines. On 1967 such a mutant of high lysine content M 1155 was developed by gamma irradiation of dry seeds of variety Skorospelka 35. On 1969 the some mutant in M2 was selected, as a short-stemmed form. In 1972 the analysis of the biochemical qualities of a series of consolidated mutant lines in M5 established the high lysine content of M 1155. Irrespective of the variation of lysine in the separate years, it remains always over 3.2% of the protein, at 2.7% for the initial variety and 2.6% for the standard-Sadovo I. The newly developed high-lysine mutant line was however of some substantial defects, therefore it could not be used directly as a variety. So the same year it was included in hybridization together with other mutant lines of better economic qualities. A considerable number of progenis was selected in F2, two of which at the preliminary analysis, manifested a more favourable combination of the desired characters. That selection materials therefore got the numbers 61-779 and 64-779. Those number due to their morphological non-uniformity were divided into lines. Results for two successive years concerning the productivity and the protein and lysine content both in the initial forms and the lines studied are given in Table 1. |
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