Light and fluctuating temperatures are two important factorstriggeringseed germination.The aim of thiswork was to: (1) elucidate the effect of temperature, light regime and storage time on seed germination in nine taxaofVerbascum spp.,collectedfromdifferenthabitats in the Mediterranean area; and (2) estimate threshold temperatures for seed germination. For all taxa, germination assays were performed at constant and fluctuating temperatures, both in continuous darkness (D) and in alternating light/dark (L/D; 12h photoperiod). Final germinated proportions (FGPs), base (Tb), optimal (To) and cut-off (Tc) temperatures were derived. At constant temperatures, seed germination was strongly suppressed under the D regime. In L/D, the effect of storage time was very small and the highest FGPs were observedfrom15to308C(40–100%),dependingonthe species. Tb ranged from below 7 to above 108C and it appeared to be constant within each seed lot. To and Tc showed some within-lot variability and were higher for fast-germinating seeds in each lot. Considering fluctuatingtemperatures,germinationappearedtobequicker and more complete than at constant temperatures. The germination of Verbascum spp. is favoured in L/D and fluctuating temperatures, which explains their pioneer character when positioned near the soil surface and under a low vegetation canopy. V. arcturus and V. pinnatifidum were shown to be less favoured by L and fluctuating temperatures, which might explain their ability to germinate in rocky areas or sandy dunes, even when they are not directly exposed to the light.

Threshold temperatures for seed germination in nine species of Verbascum (Scrophulariaceae)

CRISTAUDO, Antonia Egidia
Co-primo
;
GALESI, Rosario;
2016

Abstract

Light and fluctuating temperatures are two important factorstriggeringseed germination.The aim of thiswork was to: (1) elucidate the effect of temperature, light regime and storage time on seed germination in nine taxaofVerbascum spp.,collectedfromdifferenthabitats in the Mediterranean area; and (2) estimate threshold temperatures for seed germination. For all taxa, germination assays were performed at constant and fluctuating temperatures, both in continuous darkness (D) and in alternating light/dark (L/D; 12h photoperiod). Final germinated proportions (FGPs), base (Tb), optimal (To) and cut-off (Tc) temperatures were derived. At constant temperatures, seed germination was strongly suppressed under the D regime. In L/D, the effect of storage time was very small and the highest FGPs were observedfrom15to308C(40–100%),dependingonthe species. Tb ranged from below 7 to above 108C and it appeared to be constant within each seed lot. To and Tc showed some within-lot variability and were higher for fast-germinating seeds in each lot. Considering fluctuatingtemperatures,germinationappearedtobequicker and more complete than at constant temperatures. The germination of Verbascum spp. is favoured in L/D and fluctuating temperatures, which explains their pioneer character when positioned near the soil surface and under a low vegetation canopy. V. arcturus and V. pinnatifidum were shown to be less favoured by L and fluctuating temperatures, which might explain their ability to germinate in rocky areas or sandy dunes, even when they are not directly exposed to the light.
germination; storage time ; thermal-time; Verbascum plant species
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.11769/45245
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