SELECTION BY SEED SIZE WITHIN F3 BULK FAMILIES OF WHEAT

Abstract

In order to know the efficiency of the bulle F₃ family selection (FMF₃) to improve seed size in a segregating population of wheat, three cycles of screening for larger seed were practiced during the bulk advance of the F3 families derived from F₂ plants until the F₆ generation. The generacional advance of bulked families from F₃ to F₆ was conducted under droughted conditions. Average of three environments, and based on seed size and grain yield, it was observed that seed size was fixed since the first generation of screening. The selection response was of 23.34 and 11.82% for seed weight and the volume of 1000 seeds, respectively; of 14.43% for hectoliter weight, and 18.9% for grain yield. The genetic advance of the first generation of screening was 11.5, 11.0, 15.8 and 13.8% for the same characters, respectively. The FMF₃ method was efficient in maintaining significant variation among families in each generation of selection, allowing for additional gains through family selection. The genetic advance in seed size was based on a higher frecuency of larger seeds, but not on increased seed size.