Genetic analysis of the developmental characteristics related to the earliness of head formation in cabbage (Brassica oleracea L.)

To clarify the effect of heterosis for the earliness of head formation in cabbage, we applied the diallel analysis to four developmental characteristics that were highly correlated with the earliness of head formation: leaf position at which the head formation started (LPH), length of the 5th wrapper leaf (L5), width of the 15th wrapper leaf (W15) and leaf shape index (width/length) of the 15th wrapper leaf (LSI15). LPH showed large additive and average dominant effects, high broad and narrow sense heritabilities, and incomplete dominance directed to low. Both L5 and W15 showed remarkably large dominance effect, low narrow sense heritability, and overdominance directed to long and wide. LSI15 showed large additive effect, comparatively high broad and narrow sense heritabilities, and incomplete dominance. From these results, we discussed bow to raise the early head forming F, hybrid cabbage by taking into account the mode of inheritance of these developmental characteristics.