Seven wheat varieties that differed in origin and their 19 F1 hybrids were studied to investigate the extent of heterosis. This study showed that the manifestation of heterosis in F1 hybrids over better parent was present for grain yield and yield components only, viz., number of spike per plant, number of spikelet per spike and 100-kemel weight. In general, negative hybrid vigour was observed for plant height, leaf area and days to earing. On an average, maximum heterosis was observed for grain yield (42.5 per cent.) which varied from 19.1 to 72.9 per cent. and was followed by spike number (19.0 per cent.), number of spikelets per spike (4.1 per cent.) and 100-kernel weight (0.9 per cent.). Further, the F1 hybrids gave 31.3 to 50.6 per cent, more grain yield than the highest yielding variety of the area, Kalyan 227. The best combination involved Kalyan 227 and an exotic stock, USA 255.
The increase in grain yield in F1 hybrids seems to be due to the high manifestation of hybrid vigour in the yield components. The present investigation also suggests that the crosses between the parents of diverse origin manifest greater heterosis than the crosses between closely related parents.
