Effect of mass selection in nil-competition conditions on some traits of four cabbage populations

Mass selection with controlled pollination for heading, resistance to early bolting, fewer frame leaves relative to head size and few cover leaves, wa s applied for three cycles in four Greek open-pollinating populations (OPPs ) of cabbage in nil-competition conditions (honeycomb method). The cycle 0 OPPs with their respective cycle 3 OPPs were tested under competition condi tions (growers density), in two successive years, to assess the selection r esponse for heading, resistance to early bolting, number of cover leaves an d yield. In most cases, the selection response was significant at P = 0.01 or even at P = 0.001. For example, the mean increase of yield estimated ove r all OPPs across 2 years was 36%, without any undesirable changes in dry m atter and soluble solids contents.