Abstract

                                That heterosis is a genetic phenomenon cannot be doubted. Recently many have however, studied the specific physiological-biochemical reactions and mechanisms responsible for the superior growth and develop. ment in the hybrids of various crops. For studying these specific reactions responsible for hybrid vigour, attention should be focussed on the actual stage at which the heterosis is manifested in growth and the degree of its manifesta- tion. The study of relative growth rate, leaf area and dry matter accumulation are interesting fields for understanding the phenomenon of heterosis and the stage of manifestation of hybrid vigour.

Key words :