Paspalum dilatatum (dallisgrass).

Paspalum dilatatum is a perennial grass native to South America that has been introduced into tropical and subtropical areas as a forage species/fodder. It is reported as invasive in Japan, Malaysia, Taiwan, Vietnam, Indonesia, Philippines, Hawaii, American Samoa, Australia, Fiji, French Polynesia, New Caledonia, New Zealand, Niue, Norfolk Island, Solomon Islands and the Minor Outlying Islands. In Hawaii and New Zealand, it forms dense stands that smother and prevent recruitment of native species.

Agrostological novelties in Valladolid province (Spain)

Se aportan datos corológicos de nueve especies de plantas vasculares, incluidas en la familia Gramineae, presentes en la provincia de Valladolid (España). De ellas, cinco son primeras citas provinciales: Bromus lanceolatus Roth, Koeleria crassipes Lange, Lamarckia aurea (L.) Moench, Panicum capillare L. y Paspalum dilatatum Poir. Además, se muestran algunos registros fotográficos. Chorological data of nine species of vascular plants included in the Gramineae family and present in Valladolid province (Spain) are provided. Among them, we must highlight Bromus lanceolatus Roth, Koeleria crassipes Lange, Lamarckia aurea (L.) Moench, Panicum capillare L. and Paspalum dilatatum Poir., for they are new records in the province. Besides, photographic records are shown.

The forage grass Paspalum dilatatum tolerates partial but not complete submergence caused by either deep water or repeated defoliation

Grazing, flooding and their combination are major disturbances that could affect plant performance in humid grasslands. We performed two experiments to study the tolerance of the forage grass Paspalum dilatatum Poir. to different submergence depths and defoliation frequencies. First, we addressed whether this species can shift from the escape strategy to ‘quiescence’ when completely submerged for 30 days. Second, we explored to what extent partial or complete submergence produced by defoliation compromises plant regrowth. The results showed that regardless of the depth of water at submergence, P. dilatatum always responded by attempting to expose its leaf area above water, by increasing the tiller angle and/or blade length (i.e. tiller height). Partially submerged plants showed a reduction in starch concentration (89%) but biomass was unaffected, whereas completely submerged plants did not survive. After one defoliation event, 77% of aerial biomass of partially submerged plants was removed and the concentration of carbon reserves (water-soluble carbohydrates and starch) decreased to half that of control plants. A second event of defoliation (20 days later) of plants with few reserves removed 50–52% of shoot biomass and compromised plant survival, with plants dying before the end of the experiment. In conclusion, P. dilatatum does not tolerate prolonged conditions of complete submergence caused by either deep water columns or repeated defoliation.

Taxonomical and chorological notes 11 (112–125)

The present part of the series provides new records of 14 taxa of which 8 are native and 6 introduced in Europe. Three vascular plants are newly reported from Kosovo (Corrigiola litoralis, Dysphania pumilio, Equisetum pratense) and one (Chamaecytisus purpureus) from Northern Macedonia. The occurrence of one species (Corydalis pumila) is confirmed in Northern Macedonia. Amendments to the known distribution of vascular plants are reported from Albania (Ambrosia artemisiifolia, Gratiola officinalis, Onosma heterophylla, Paspalum dilatatum), Hungary (Euphorbia lathyris), Lithuania (Ophioglossum vulgatum), and Slovakia (Duchesnea indica, Panicum dichotomiflorum, Pilosella cymosa).

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

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 these biotypes, so this trait did not explain differences in dormancy. Intraspecific variability of seed dormancy in this species may be attributable to the lemma incidence, however differences in the caryopsis component of seed dormancy should be considered.