Evaluation and selection in wheat segregation populations and preliminary yield trial.

Segregation of traits in hybrids of bread wheat begins from F2 population and continues until several generations later. At first, the best combinations of hybrids were selected and then from among of them base of traits: plant height, strong tillers, uniformity of tillers, spike form, resistance to shattering, suitable leaf angle, resistance to preharvest sprouting and reaction to diseases such as yellow rust, leaf rust, powdery mildew, septoria leaf blotch and scab were selected individual plant. In this study, in F2 generation 702 population, F3 generation 181 numbers, f4 generation 201, F5 generation 182, F6 generation 332 and F7 generation 271 numbers of bread wheat were evaluated in modified pedigree-bulk method. At first, from among of F2 generation were selected 6000 individual plant base of morphological traits in the field, then thrashing and discarding the shriveled seeds. The seeds remain from each number bulked together that they were 411 numbers for F3 generation. Among of 181 numbers F3 in Mogan 71 numbers were selected to selection in hot and dried condition of weather in Gonbad for next cropping season. In F4 and F5 generations suitable individual plants for each number in the field were selected. Number of plants in F4 and F5 generations were 900 and 117 respectively. After thrashing and discarding the shriveled seeds, remain seeds for each number bulked together for F5 and F6 generations. Finally base of pedigree method 649 and 360 numbers were selected as a F5 and F6 generations respectively. In F6 generations at first were selected 152 combinations then 5 spikes from each combination were selected and after thrashing and discarding the shriveled seeds 500 numbers remained for F7 generation that will plant in pedigree method. Among of 271 numbers in F7 generation after checking all of plants, 160 numbers of them that were the best for all traits were selected. After thrashing and checking finally all of 128 pure lines were selected for studying in 1384-1385 preliminary tests(PWSN). In this study 213 bread wheat lines from Gorgan crosses in 1383-1384 year were planted and evaluated with Tajan, Shiroudy , N-80-6 and N-81-18 cultivars (as a checks). Area of each plot was 7.2 m2. Morphological and agronomy traits and reaction of lines to leaf diseases were measured. Selection of lines was done based on seed yield and morphological traits and reactions to diseases. Finally, 125numbers of the best lines were selected to evaluate in the PRWYT experiment in 1385-1386 year.