A line X tester analysis of combining ability involving five male sterile (ms) lines of Indian cultivars and four exotic restorers of spring wheat revealed that D2 sca was higher than D2 gca for almost all the characters in both sets. Therefore gene action was found mainly non-additive type for these traits. Inset II, D2 gca was higher than D2 sca for days to heading, duration of grain filling and plant height indicating additive gene action for these characters. Preponderance of non additive gene action was also indicated from D2 gca/D2 sca which are less than unity for most of attributes. In set I, among lines, msUP 368 and msWH 157 for duration of grain filling, tillers/plant and spikes/plant; msHD 2204 for plant height; msUP 368 for days to heading and among testers, W 8156 and 3401/478466 for duration of grain filling showed high gca effects. In set II, among lines, RJ-401 for days to heading and duration tillers/plant and spikes/plant showed high gca effects. It was observed that best general combiners were not always present in best specific cross combinations. The degree and direction of MP and SP heterosis varied greatly for different character and crosses. There was lack of definite relationship between sca effects and estimates of heterosis.
Hybrid wheat, combining ability, cytoplasmic male sterility, exotic restorer, line x tester, heterosis, Triticum timopheevi
