Efficiency of Two Cycles of Pedigree Line Selection in Bread Wheat (Triticum aestivum L) under Late Sowing Date

Abstract

The current study aimed to assess the efficiency of two cycles of pedigree line selection in bread wheat (Triticum aestivum L) in late sowing date during four successive seasons from 2011/2012 to 2014/2015 at Fac. Agric. Farm, Assiut University, Egypt. The genetic materials were two segregating bread wheat populations i.e. Debeira x Sahel and Giza 165 x Sakha 93. The genotypic (gcv) and phenotypic (pcv) coefficients of variation for grain yield/plant decreased from 14.90 and 17.12 in base population (F4) to 3.98 and 6.16% after two cycles (F6) of selection in population I and from 21.93 and 22.65 (F4) to 2.68 and 8.85% (F6) in population II, respectively. The same trend could be found for correlated traits in both populations. Grain yield/plant and number of spikes/plant in the two populations showed low heritability after two cycles of selection compared to their values in base populations. After two cycles of pedigree line selection for grain yield/plant, selections mean in the F6 was 17.82 g for population I compared to their parents Debeira (15.83 g) and Sahel (11.94 g) as well as the bulk sample (13.38 g). Also, the selections of population II averaged 18.78 g compared to the less values of 12.41, 15.09 and 14.19 g for both parents Giza 165, Sakha 93 and the bulk sample; respectively. The selected families in the F6 surpassed the better parent and unselected bulk sample for number of spikes/plant, biological yield/plant, weight of spikes/plant, plant height, spike length and number of spikelets/spike. The observed direct responses of pedigree line selection for grain yield/plant (selection criterion) were 33.18 and 32.35; 12.57 and 24.45; and 36.58 and 28.39% over two cycles of selection as accounted from unselected bulk sample, better parent and mid parents in population I and II, respectively. The results revealed that the mean of family score for selection response (FSSR) over all selected F6 family of Model 1 recorded the highest value (34.57 and 36.19%), followed by Model 2 (31.50 and 33.12%) and Model 7 (29.52 and 31.12%) in population I and II, respectively. In general, the obtained results revealed that the direct pedigree line selection for grain yield/plant in wheat scaled to be powerful tool in late sowing date for improving the grain yield and be effective to get high yielding lines.