W. Gottschalk - Böcker
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2 produkter
2 produkter
1 059 kr
Skickas inom 10-15 vardagar
Mutation breeding has been introduced into modern plant breeding in the early 1940's. In spite of pessimistic predictions, the application of experimental mutagenesis has led to encouraging results demonstrating that mutation breeding is a well-functioning method in many crops. So far, more than 500 varieties, developed by means of induced mutations, have been officially released; others have been approved for registration. Many mutants with characters of agronomic interest cannot be utilized directly because of their unsatisfying yielding capacities, or of other negative traits which are partly due to the pleiotropic action of the mutant genes. Sometimes their negative selection value can be overcome by transferring them into the genomes of other varieties. According to experience available, the efficiency of mutant genes can conSiderably vary depending on the genotypic background in which they become effective. The interactions between mutant genes and genotypic back ground cannot be predicted. Therefore, mutants with valuable traits should be crossed with many varieties and strains in order to discern positive and negative interactions. In this way, genotypes can be selected in which the mutant gene is able to express its action without showing negative by-effects. This procedure has been used for about 10 years by combining the methods of mutation and crossbreeding. Mutation breeding is predominantly used in annual diploid and allo polyploid self-fertilizing crops, while it causes much more difficulties in cross-pollinating species.
533 kr
Skickas inom 10-15 vardagar
Investigations on seed proteins have been intensively carried out during the past two decades. This is valid with regard to both their chemical composition as well as their nutritive value. The development of new biochemical and physical methods has resulted in obtaining deep insights into the structures of seed proteins and their mutual interactions. Intensive exchange of information between the scientists participating in national and international research programmes has given strong impulses for intensifying the research in this field. For the quantitative and quali tative investigations of seed proteins, not only some model plants were used; on the contrary, they were carried out on a large number of different crops important for different regions of the earth. In this way, a level of knowledge has been reached which could not be expected in this diversity within such a short period. This holds not only true for biochemical but also for physiological characters of the species of the limiting amino acids studied. With regard to nutritional aspects, the problem was of special interest, but also seed proteins acting as antinutritional factors were analysed in detail. Based on the knowledge of seed protein structures, it was possible to perform investigations on the genetic basis of their synthesis. This was done under two different aspects: The basic knowledge on the genes involved should be widened; moreover, it should be tried to improve the seed proteins quantitatively and qualitatively under the influence of mutant genes.