Germination responses with different treatments, seed vigour and seedling growth of Pterolobium stellatum (Forssk.) provenances stored from 19 to 30 years

Genet Resour Crop Evol https://doi.org/10.1007/s10722-023-01784-5 RESEARCH ARTICLE Germination responses with different treatments, seed vigour and seedling growth of Pterolobium stellatum (Forssk.) provenances stored from 19 to 30 years Shiferaw Alem · Hana Habrová · Kateřina Houšková Received: 22 May 2023 / Accepted: 18 October 2023 © The Author(s) 2023 Abstract Knowledge of the genetic variability of different species for conservation purposes and quality seedling production after longer storage time is important. The aim of the research paper was to examine the effect of longer seed storage periods (19–30 year) on seed viability, seed vigour and initial growth of seedlings from five provenances of Pterolobium stellatum (Forssk). Seeds collected from Dabena, Gambo, Agaro, Bishofitu, and Merti localities and stored for 19, 19, 21, 25, and 30 years, respectively used for the study. Different seed dormancy-breaking treatments such as; soaking in cold water for 48 h (CW-48); soaking in hot water for 10 min (HW-10); 20 min (HW-20) and mechanical scarification; i.e., nicking (NK) used for the germination of the seeds. A randomized complete block design was used for the experiment and the study undertaken in a greenhouse. For each treatment, S. Alem (*) · H. Habrová Department of Forest Botany, Dendrology and Geobiocoenology, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemědělská 1, 613 00 Brno, Czech Republic e-mail: H. Habrová e-mail: K. Houšková Department of Silviculture, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemědělská 1, 613 00 Brno, Czech Republic e-mail: four replications and for each replication, 50 seeds were used. One-way analysis of variance was used for germination index, early seedling growth and seed vigour index data. The results showed that for all the provenance seeds stored for different periods, NK treatment resulted relatively in a higher mean germination percentage and germination indices as compared to the other pre-treatments. The seed vigour index result showed significant differences among the different provenances (P < 0.001). Similarly, there were significant differences among the early growth of seedlings germinated from different provenance seeds (P < 0.001). The seeds collected from Merti provenance and stored for 30 years and Dabena provenance, stored for 19 years, have relatively resulted in higher mean germination index, seed vigour and seedling growth relative to the other studied provenance seeds. We observed that provenance had a more significant influence on germination, seed vigour and seedling growth than the seed storage period for the P. stellatum. Finally it is recommended that despite there is inter population variation, the seeds of P. stellatum can be stored for a longer time and application of nicking as a dormancy breaking treatment could enhance seed germination of the species. Keywords Dormancy · Germination percentage · Germination index · Seed vigour Vol.: (0123456789) 13 Genet Resour Crop Evol Introduction Pterolobium stellatum (Forssk.) Brenan, which belongs to the Fabaceae family, is a perennial tall scandent woody species. It is an evergreen dicotyledonous flowering plant and semierect multistemmed climbing woody thorny shrub that can reach 2–15 m high (Janson and Cardon 2005; Ward and Spellenberg 1988). The species is native to Africa, and its distribution extends from South Africa to Eastern Africa (Janson and Cardon 2005; Teketay 1998). Traditionally, the species is used as a medicinal plant to treat tuberculosis, pneumonia, and other related respiratory diseases (Kigen et al. 2016; Getahun 1976). Leaves and bark are used for ink production (Janson and Cardon 2005). It is also used to treat infertility, epilepsy, and neuroglia (Kigen et al. 2016; Ragunthan and Abay 2009) and to treat sexually transmitted diseases (Njoroge and Bussmann 2006). Some chemical analyses of the plant parts showed that the species possess cytotoxic and anti-diarrhoea properties (Andualem et al. 2014). The plant is also used for animal fodder, live fences, firewood, charcoal, ornamental tree, and soil conservation purposes to have a healthy environment (Alemayehu et al. 2015; Zegeye et al. 2005). The storage of seeds for a long time is one of the strategies of ex-situ conservation. Keeping seed viability in a conducive environment is an excellent alternative for maintaining or minimizing the loss of physiological quality of seeds during storage until sowing as an ex-situ conservation strategy (Solberg et al. 2020a, b; Silva et al 2019; Vijay 2015; Pradhan and Badola 2008; Ellis et al. 1991). For the conservation of plant genetic resources through exsitu conservation, knowledge of the characteristics of the seed is important (Pradhan and Badola 2012). Different factors, such as temperature, nature of the seeds, moisture, insects, etc., could affect the viability of the seeds in a storage room, and pre-storage conditions also affect seed longevity (Mdlalose et al. 2021; Solberg et al. 2020a, b; De Vitis et al. 2020; Rao et al. 2017; Pradhan and Badola 2012; Delouche et al. 1973). Seed moisture, vigour, germination percentage, rate of germination, etc., are some of the most important parameters for assessing the seed quality of a species after storage of the seed (Mdlalose et al. 2021). Seed dormancy problems could also affect the germination of the seeds of different species. Seed coat-imposed dormancy Vol:. (1234567890) 13 is an ecological mechanism that allows the seed to germinate only when conditions are favourable for supporting seedling growth (Argel and Paton 1999). In the case of legume species, the impermeable seed coat is considered to be the main dormancy problem for the germination of seeds (Grubb and Coomes 1997; Albrecht 1993). Therefore, to break seed dormancy problems using pre-sowing treatments, rapid and uniform germination and high germination capacity can be obtained (Huang and Gutterman 2000; Schutz and Rave 1999; Teketay and Tigabu 1996; Teketay 1996). Different pre-sowing treatments, such as cold stratification, mechanical disruption, or acid and hot water treatments are widely used to break seed dormancy problems, and these techniques can improve the germination of seeds within a short period (Tadros et al. 2011). Research shows that the seeds of P. stellatum have a prolonged dormancy problem, which is associated with the hard seed coat cover of the species (Jemaneh 2019; Teketay 1998). Some authors have indicated that if the seed of P. stellatum is stored properly and placed in airtight containers, cool, dry areas and insect-free places, it can stay for a longer period without losing its viability (Teketay 1998; Bein et al. 1996). However, knowledge of the seed longevity of the species of the different provenances of P. stellatum and its effect on the germination, seed vigour and seedling growth are lacking. Such knowledge is necessary for conservat (...truncated)