Waxy corn breeding program in Thailand is in the beginning stage with high potential
in commercializing to new varieties. Thein corn is one of waxy corn with small ear and
popularly consumed as fresh corn. Plant breeders are currently interested in improving
varieties for desired characteristics and high yield. Study on heterosis in 10 Thein corn
varieties aimed to classify varieties to heterotic groups for reciprocal recurrent selection.
The results found that the studied Thein corn varieties showed significant differences on
yield and ear size. Varietal cross between TNW and TSW gave the highest green yield and
marketable dehusked yield of 14.5 and 8.2 Mg ha-1 respectively, and 19 crosses from 45
crosses gave green yield over than 12.5 ton/ha. For yield heterosis, the values were
between -21 % (TNW/TMP) and 69 % (TLO/TSW) for green yield and between -25%
(TNW/TMP) and 115% (TLO/TSW) for marketable dehusked yield. The SCA for GY and
MDY ranged from -4.9 to 3.2 Mg ha-1 and -2.4 to 1.5 Mg ha-1, respectively. TLO and TSW
also had significantly positive GCA effects of 0.6* and 0.9** Mg ha-1 for marketable
dehusked yield. TKKU1 and TPR gave positive significant SCA effect for dehusk yield,
they are recommended for reciprocal recurrent selection program for yield improvement.
For ear size (ear width, ear length and seed row number), its heterosis was -14 to 30%.