Abstract only

Height of plants is a quite complex genetic trait, which are inherited quantitativly characteristics. Yield of durum wheat was comparatively low due tostature its talln. Only after introduction of the lodging resistant varieties it was possible to increase yield ofits cultivars. In orderto receive short-stature and lodging resistant germplasm the Georgian tall variety Cerulescens 19/28 with the height varying within 135-140 cm has been chosen as a parent and crossed with foreign short-stature varieties Rolette, Cocorit 71, 454, Agathe, 623-3 with the height varying within 68-88 cm. Height of plants in first generation produced through crossing of the above mentioned fonns varied within 72-99 cm. In the second generation transgression with regard of the plant height was observed. Medium height and short-stem genotypes along with the extra tall plants were segregated in the second generation. Height of the plants segregated in the second generation population varied within 48.0-151.0 cm with the variation coefficient equal toI5.3-22.9, Whereas in inverse combinations height of the plants varied within 49-155 cm, and variation coefficient was within the limits of 13.3-21.1 %. Within each combination the parental types of both increased and reduced height have been also segregated out. In the short plants the length of inter-nodes was significantly reduced, while the number of inter- nodes coincided with that of paternal forms. The frequency ratio of tall and short plants in the second generation corresponded to the theoretical expectations. In the second generation, the ratio of tall and short plants was 13:3 respectively. Detail analysis of plants ofthe second generation clearly demonstrates the fact that short-stem genotypes (Rolette, Cocorit 71, 454, Agathe, 621-3) of foreign durum wheat carry inhibitors and genes determining short stem, while the genotype of Georgian durum wheat is a carrier of the recessive genes. Plants of the hybrid population produced from crosses of Georgian and foreign genotypes of durum wheat are divided into four height groups: I. plants that are higher than both parents; 2. plants that average height of both parents; 3. extra tall plants, produced from the short parents; 4. short plants. These results are interesting due to the fact that the crosses with of the above varieties generate plants of different height and productive tillering, and that should be explained by inequivalent activity of major genes determining short stature. Studies of inheritance of plant height in the first and second generations proved that: -intermediate heredity of height (hypothetic heterosis) takes place in the first generation of hybrid plants; lodging resistance in the first generation plants dominates in cases when maternal form is resistant to lodging; analyses of the second generation plants proved that Georgian variety of durum wheat is genetically different from the short-stature varieties. Hybrids produced from these varieties demonstrate the following segregation ratio for height in F 2 population: 13 (tall): 3 (short). it was proved that the genotype of durum, wheat species Cerulescens 19/28 carries two recessive genes (bb) and the inhibitor (II) of the recessive gene, determining shortening oftwo upper stem inter-nodes, while the short-stature varieties of foreign durum wheat (Rolette, Cocorit 71, 454, Agathe, 621-3) carrythe dominant genes (BBJJ). The most interesting result of our experiments, in the view of breeding practice, is that the hybrids derived through the crossing of genetically diverse, ecologically and geographically distant forms segregate, producing new material in breeding for genotypes of various heights.

English

0409|AGRIS 0401|AL-Wheat Program

Juan Carlos Mendieta

CIMMYT Publications Collection