Storage period, husking and seed treatment effects on germination of Rhodes grass (Chloris gayana L.) seeds

Abstract

Seed dormancy is among the major problems associated with pasture establishment from Rhodes grass. Two experiments were conducted with the aim to assess the effects of storage period (years), husking and seed treatment on germination rate of Rhodes grass seeds of two cultivars, Callide and Masaba, at Kulumsa and Debre Zeit Research Centers. The first experiment included two seed lots (harvested in years 2013 and 2014) and two husking treatments (husked and with husk) laid out in split plot design with four replications. The second experiment had three seed lots (harvested in 2012, 2013 and 2014), three chemical treatments (KNO₃, Ethanol, and H₂O) and untreated control for each lot in randomized complete block design with three replications. In the first experiment, germination rate ranged from 13.5% in freshly harvested seeds with husk to 85.5% in aged seeds without husk. Husking improved germination and this may be attributed to improved access of embryo to water, exclusion of empty husks and elimination of physical barriers to germination. In the second experiment, germination rate ranged from 3.3% in untreated fresh seeds to 21.1% in seeds harvested in 2012 and pre-treatment with KNO₃ solution. In conclusion, freshly harvested seeds of Rhodes grass have very low germination rate in both experiments while husk removal and pre-soaking in KNO₃ solution improved performance in new as well as older seed stocks. However, it is recommended that further study should be carried out to come up with comprehensive information on the period required in months to achieve maximum possible germination rate; the interactive effects of husking, chemical treatment, and genotype; and the underlying mechanism of dormancy.

Keywords: Chloris gayana L., Dormancy, Seed priming, Germination