Thermal requirements and germination niche breadth of Polygonum ferrugineum Wedd. from southeastern Brazil

• Published in: Seed science research Vol. 31; no. 2; pp. 91 - 97
• Main Authors: Marques, Andréa R., Gonçalves, Ana Letícia B. R., Santos, Fábio S., Batlla, Diego, Benech-Arnold, Roberto, Garcia, Queila S.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.06.2021
• Subjects: Aquatic plants; Brazil; cold; Dormancy; Environmental conditions; Floods; Geographical distribution; Germination; High altitude; High temperature; Niche breadth; Parascyllium ferrugineum; Polygonum; Regression analysis; Research Paper; seed dormancy; Seed germination; Seeds; Stratification; temperature; Temperature effects; Temperature requirements; Brazil; seed dormancy; germination niche; base temperature; Polygonaceae; stratification; thermal time requirement
• ISSN: 0960-2585; 1475-2735; 1475-2735
• DOI: 10.1017/S0960258521000106

Temperature may regulate seed dormancy and germination and determine the geographical distribution of species. The present study investigated the thermal limits for seed germination of Polygonum ferrugineum (Polygonaceae), an aquatic emergent herb distributed throughout tropical and subtropical America. Seed germination responses to light and temperature were evaluated both before (control) and after stratification at 10, 15 and 20°C for 7, 14 and 28 d. Germination of control seeds was ~50% at 10 and 15°C, and they did not germinate from 20 to 30°C. The best stratification treatment was 7 d at 10°C, where seed germination was >76% in the dark for all temperatures, except at 30°C, and < 60% in light conditions. A thermal time approach was applied to the seed germination results. Base temperature (Tb) was 6.3°C for non-dormant seeds and optimal temperature (To) was 20.6°C, ceiling temperature (Tc (<50)) was 32.8°C, and thermal time requirement for 50% germination was 44.4°Cd. We concluded that a fraction of P. ferrugineum seeds is dormant, has a narrow thermal niche to germinate (10 and 15°C) and that cold stratification (10°C) alleviated dormancy and amplified the thermal range permissive for germination of the species. Consequently, P. ferrugineum is expected to occur in colder environments, for example, at high altitudes. Higher temperatures decrease the probabilities of alleviate dormancy and the ability of their seeds to germinate.