Studies on Hetrotic Effects of Crosses of Onions with Different Skin Colored Onion Lines

The study was carried out to investigate the heterotic effects for eight important characteristics of 12 crosses among four different skin colored lines. A set of 4 X 3 diallel crosses was made using yellow (Y), white (W), red (R) and chartreuse (C) skin colored lines. The highest parental heterosis for fresh bulb weight was being of the order of 234% in the cross A-240 X C-44 (W/Y) showing generally higher heterosis in white colored maternal lines, whereas chartreuse colored maternal line showed the lowest heterosis.  The heterosis of bulb shape ranged from -16% (A-240 X C-44, W/Y) to 16% (A-261 X C-270, C/R) and C/Y cross showed higher heterosis than others. In all the crosses, the heterosis for parental lines with soluble solide content (SSC) ranged from -19%  to 20% and heterosis for plant height, leaf numbers, pseudostem length and pesudostem diameter  was -10 ~ 58%, -14 ~ 49%, -88 ~ 49%, -21 ~ 28%, respectably.  Overall, fresh bulb weight exhibited the most significant positive heterosis among eight characteristics.