Characterization of Early Maturing F1 Hybrid Varieties in Cabbage (Brassica oleracea L.)

Abstract

A cabbage plant forms a mature head during the continuous process of vegetative growth, suggesting that head formation is affected by developmental characteristics before harvesting. We investigated characteristics of early maturing F1 hybrid varieties using 27 F1 hybrids composed of 21 F1 hybrids of mixed reciprocal combinations of 42 diallel crosses of 7 inbred lines and 6 commercial F1 hybrids. We estimated the number of days it took for the head to attain the target weight from transplantation (head-maturing period, HMP). The HMP to reach 1250 g (HMP1250), the most marketable weight in Japan, varied from 60 to 88 days among the materials and corresponded to their estimates based on grower’s experience. We thus considered that the HMP1250 was a valid measure of cabbage maturity. Correlation analysis between HMP1250 and developmental characteristics clarified that HMP1250 was correlated with the leaf shape index (width/length) of wrapper leaves, the leaf position at which head formation started and the size of wrapper leaves. This result suggested that cabbage maturity could be divided into those developmental characteristics. That is to say, early maturing F1 hybrid varieties had the following developmental characteristics; change to a large leaf shape index from the low leaf position, low leaf position at which their head formation started and large leaf size.