Seed germination : patterns of some asteraceae species from two regions with contrasting precipitation north-central Nepa

Abstract

Germination is an important seed feature connected to a species' regeneration niche, and it can influence the distribution and abundance of species in communities. The germination of seeds in plants is governed by several environmental processes, leading to less research about their growth, adaptation, and changes in their germination behavior influenced by climate change. Present study compared germination ecology of three species of Asteraceae from moist region (Cremanthodium reniforme, Dubyaea hispida, Synotis alata) and closely related three species from dry region (Cremanthodium arnicoides, Synotis penninervis and Taraxacum eriopodum of the Annapurna Conservation Area in north-central Nepal. Seeds were germinated under different light (12-h photoperiod and continuous dark), temperature (low: 25/15℃ and high: 30/20℃) and water stress (0, ˗0.25, ˗0.5, ˗0.75 and ˗1 MPa) to determine germination percentage, Timson’s index (germination rate) and mean germination time (MGT). Higher seed mass was found in Cremanthodium arnicoides and larger seed size was found in Dubyaea hispida. Seeds of all species germinated in both photoperiod and continuous dark condition. At low temperature and all levels of water stresses, Cremanthodium arnicoides and Synotis penninervis exhibited higher Germination Percentage (%), while Cremanthodium reniforme showed higher Mean Germination Time (MGT) and Taraxacum eriopodum had higher values for Timson’s Index (TI). However, at high temperature significantly higher germination percentage was found in Dubyaea hispida and Synotis alata, higher MGT was found in Synotis penninervis and higher TI was found in Dubyaea hispida. No germination was recorded in five species below -0.5 MPa water potential but seeds of Cremanthodium arnicoides germinated up to -0.75 MPa. These finding give a clear indication about the germination traits of the species from wet and dry regions, while also providing a clear understanding about their germination patterns, survival of the plants, and effect of climate change. Key words: Annapurna Conservation Area, Environmental tolerance, Himalaya precipitation gradient, Mean Germination Time, Timson’s Index