Combining Ability Analysis in Yellow Maize under Different Planting Dates and Nitrogen Rates

This investigation aimed to study the genetic behavior of ten yellow inbred lines and their F1 hybrids under nine different environments; three planting dates (D); D1 (1st May), D2 (1st June), D3 (1st July) and three nitrogen levels (N); N1 (90 kg N/fed.), N2 (120 kg N/fed) and N3 (150 kg N/fed.). In 2009 season, all possible combinations were made among ten inbred lines, in 2010 summer season the 45 F1 hybrids plus two commercial hybrids; SC162 and SC166 were evaluated at Sakha Agricultural Research Station, ARC, under three planting dates and three nitrogen levels. The nine different environmental conditions were designed as single experiments for each , i.e. D1N1, D1N2, D1N3, D2N1, D2N2, D2N3; D3N1, D3N2 and D3N3. The 47 entries were tested in each of the nine environmental conditions in a randomized complete block design, with three replications. The variations among entries in each environment were calculated. The superiority relative to the two check hybrids was calculated. The variations among hybrids were further partitioned into the general and the specific combining ability effects for the ten inbred lines and were computed according to Griffing’s method-4 model-1 (1956). The data was taken on grain yield (kg/plot) adjusted to (ard./fed.).