Differential incidence of the lemma on seed germination among different Paspalum dilatatum genotypes

Nicolás Glison, Luis Viega, Pablo Speranza


Paspalum dilatatum Poir. is a promising perennial summer grass forage for temperate regions, but among other factors, slow stand establishment has hindered its adoption. One of the reasons may be seed dormancy. Intraspecific variability in seed dormancy has been reported in P. dilatatum, but the mechanisms underlying this variability remain unclear. In this paper, we focus on the role of seed external covering structures on germination, particularly the lemma. Seeds of apomictic and sexual biotypes of P. dilatatum were subjected to acid scarification and removal of the lemma to study their germination, imbibition rate and sensitivity to ABA. Seeds without lemma showed higher germination than other treatments in dormant genotypes. We found that the lemma delayed but did not prevent water uptake in any genotype. Comparing sexual biotypes, P. dilatatum subsp. flavescens showed higher lemma-imposed dormancy than P. dilatatum “Virasoro”, and also higher seed dormancy at the caryopsis level. The thickness of the lemma was not different between genotypes, so it is not a trait associated with germination. Intraspecific variability in germination behaviour in these and other panicoid grasses may not be solely determined by external coats, but they may explain some differences in seed dormancy among genotypes.


perennial warm-season forage grasses; seed dormancy; seed covering structures; acid scarification

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