Panicle characteristics of some Glaberrima cultivars.

Results of the study showed that all characters except culm thickness varied widely among cultivars. Number of primary branches was generally higher in glaberrimas than in sativas. Number of primary branches among the glaberrimas ranged from 8.0 in Acc. 104233 and Acc. 104254 to 16.3 in Acc. 104003 (the highest). The sativas, mostly IR cultivars, had higher numbers of secondary branches. The ratio of secondary to primary branches did not exceed 2 in the glaberrimas (except in Acc. 104233, 104235, and 104254), but in the sativas, the ratio was more than 2. Acc. nos. 103350, 103443, 102198, and 103997 had high numbers of primary branches with very few secondary branches; spikelets on secondary branches totalled less than 20% of total spikelets. Acc. 104001 and Acc. 104003 had high numbers of primary and secondary branches with spikelets on secondary branches totalling only 30% of the total spikelets. In the sativas, spikelets on secondary branches totalled 58% or higher. The number of vascular bundles from just below the neck node is usually correlated with the number of primary branches. Acc. 103443 had the highest number of inner and outer vascular bundles and also high numbers of primary branches, possibly indicating a better transport system. Acc. 103443 also had the largest culm diameter and medullary cavity. The number of primary branches and spikelets on primary branches were positively correlated with number of inner and outer vascular bundles. These two characters had no relation with number of secondary branches or spikelets on secondary indicating scope for increasing the number of spikelets on the primary branch without significantly increasing those on the secondary branch. Medullary cavity was positively correlated with the number of inner and outer vascular bundles and with culm diameter. Culm thickness had no relation with any of the characters, and had minimum variability.