POLYMORPHISM IN POLLEN CHARACTERS OF ORYZA MALAMPUZHAENSIS KRISHN ET CHANDRN

摘要

Palynological study has been carried out in seven accessions of Oryza malampuzhaensis. SEM studies of pollen grains showed variation in the apertural morphology and exine pattern among the accessions. The various genotypes showed a gradation series from elongate to circular. The variations in exine pattern revealed extremes of evolutionary changes with the finely granulate being more primitive and the matted form as the most advanced. The wide range of variations and appearance of new pollen morphotypes suggest the hybrid origin of this tetraploid taxon. The role of introgression from related wild Oryza species and subsequent selection at different localities are considered as possible centres of the evolution of different genotypes.