Effects of panicle position on seed viability and vigor in some selected castor seed accessions

Abstract

Castor bean is widely cultivated around the world because of the commercial importance for its oil. The fruits of castor are set on a panicle-like structure called raceme. The racemes are classified into the primary, secondary and tertiary racemes as a result of their different time of initiation on the mother plant. The possibility that the raceme initiation points could affect seed viability attributes through its association with time to seed set exists. This study, therefore, determines variation in seed viability and vigor of seeds originating from different racemes positions on the same mother plant. The germination study was conducted in a screen house with 7 castor accessions using sand as a substratum. They were planted in the field under rain-fed conditions in a randomized complete block design with three replications. The castor seeds were planted in 3 rows plot with intra- and inter-row spacing of 1 m. Three seeds from each accession were sown per hole. The racemes were found to be statistically similar in terms of germination ability. However, secondary racemes had the highest mean (64.4%) for the germination percentage and germination rate index (GI) of 5.9. Accession NKAN had the higher germination ability with mean germination percentage of 68.9 and germination rate index (GI) of 6.4. In conclusion, the seed viability and vigor of castor seeds are not significantly affected by raceme positions on the mother plant.