Indian Agricultural Research Institute, New Delhi
* Part II of Studies of Problems in Producing Hybrid Rice. Part I appeared in the Indian J. Genet. 39: (1979).
A large rice collection made from North East Indian hills was studied to estimate the extent of variability for various components of flowering behaviour which included panicle emergence, time of blooming initiation and its duration as well as the mechanism and the angle of glume opening. The study, in general, revealed a wide variation for all the traits. The degree of synchrony of panicle emergence and blooming initiation appeared to be related to the duration of the variety. In majority of the short duration varieties panicle emergence was relatively more synchronised while blooming initiation was earlier and uniform as compared to long duration varieties. Initiation of blooming and angle of separation of lemma and palea appeared to be related to the type of spikelets to some extent. Short coarse spikelets had early initiation and wider angle than long fine grain types. Cultures such as IARI 6193-B and IARI 7216 showed two flushes of anthesis per day as against the rule of single flush per day in rice. Cultures like IARI 5818 showed markedly longer duration of anthesis of 90 minutes as against the normal range of 50-70 minutes in the rest of the material.
