HETEROSIS AND COMBINING ABILITY STUDIES IN SWEET CORN (Zea mays L. saccharata)

The present investigation has been undertaken in sweet corn to carry out the combining ability analysis and to estimate heterosis as well as to understand nature of gene action, genetic parameters, character association of yield and yield contributing characters. Eight divergent parents were selected and crossed in diallel fashion excluding reciprocals during Kharif, 2010. The resulting 28 crosses along with parents and a standard check Sugar 75 and Madhuri were evaluated in Randomized Block Design replicated thrice, during Rabi, 2010-11 at Agricultural Research Institute, Rajendranagar, Hyderabad. The data were collected on days to 50 per cent tasseling, days to 50 per cent silking, days to maturity, plant height, ear height, ear length, ear girth, number of kernel rows per ear, number of kernels per row, green cob yield, 100 kernel (dry) weight and seed yield (wet) per plant, green fodder yield and sugar content in percentage. The combining ability analysis revealed importance of both additive and non-additive gene actions in governing the characters but non-additive gene action was found predominant. Among the parental lines, 6122-1 and 6100-2 were good general combiners for earliness viz., days to 50 per cent tasseling, days to 50 per cent silking and days to maturity and the parents 6100 and 6100-2 for seed yield (wet) per plant. The parental lines 6100, 6100-2 and 6104 contributed maximum favourable genes. Considering all the characters, the parents 6100, 6100-2 and 6122-1 can be given status of good combiners. The hybrids, 6104 x 6100, 6127 x 6100 and 6122-1 x 6100-2 were the good specific combiners for seed yield (wet) per plant. Hence, these crosses could be advanced further for isolation of transgressive segregants and also to develop good inbred lines. Estimates of heterosis, heterobeltiosis and standard heterosis were variable among crosses in desirable direction and some of them turned out to be best specific crosses. The cross combinations 6127 x 6100 (20.09%) and 6104 x 6100 (19.65%) for seed yield (wet) per plant were found to be superior to the standard check Madhuri. The hybrids 6072-3 x 6069, 6072-3 x 6100-2, 6069 x 6122-1, 6122-1 x 6127, 6072-3 x 6127 and 6104 x 6082 performed well over standard Madhuri for sugar content in kernel. But none of the character (except sugar content in some hybrids like 6072-3 x 6069, 6072-3 x 6100-2 and 6069 x 6122-1) was significant when compared with standard check Sugar 75. Character association among seed yield (wet) per plant and yield contributing characters exhibited that 100 seed (dry) weight, number of kernels per row, number of kernel rows per ear, ear girth, ear length, plant height, green cob yield and ear height had significant and positive correlations with grain yield. Path coefficient analysis had shown direct positive relationship of number of kernels per ear, ear height, ear length, 100 seed (dry) weight (phenotypic), number of kernels per row and green cob yield with grain yield. The indirect effect of these characters on grain yield influenced more by green cob yield and number of kernels per row. The identified four superior cross combinations (6104 x 6100, 6127 x 6100, 6100 x 6100-2 and 6122-1 x 6100-2) in the present investigation, based on heterosis and combining ability, which performed well for seed yield (wet) per plant and yield contributing characters may be used as single cross hybrids after evaluation in multi location trials.