In the present Study the nature and extent of heterosis was examined for 18 characters in a 7 parent half diallel of durum wheats. The average heterosis over the mid parent was 57, 31, 22. 19, 10 and 9 per cent for grain yield, extrusion peduncle length, third internode length, ears per plant, 100-grain weight and plant height in that order. Two crosses, HD 3578 × HD 4501 and N 1200 × HD3578 significantly outyielded the best durum check. Heterosis in complex character was neither due' to heterosis in all of its components nor due to differences in reciprocal components. Heterosis in grain yield was related mainly to its direct components. Heterosis in leaf area, plant height and its components was not related to that for grain yield. There was a general lack of heterosis for most of the characters where parents with high level of expression were involved.
Triticum durum, macaroni wheat, heterosis, diallel cross
