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

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, 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.