Provenance variation in seed storability of jabon (Neolamarckia cadamba) and their response to seed invigoration by priming and gamma irradiation treatments

Abstract

Jabon (Neolamarckia cadamba (Roxb.) Bosser) is a tree species native to Indonesia with a wide growth distribution and high economic potential, but the cultivation of this species is often hampered by low seed viability and vigor, especially for seeds that have undergone storage. This study aims to examine the provenance variation in seed germination and storability of N. cadamba and the effectiveness of invigoration treatments on the stored seed for 5 years. Hydro-priming, osmo-priming, hormone-priming, and gamma irradiation were tested to improve seed germination and seedling growth. The results showed that intra-population variation in seed germination and storability is quite high, ranging from 53.5%-82.8% for germination capacity and rate of germination decline ranging from 0.7%-61.6% after 5 years of storage. Pomalaa provenance had the best seed germination and storability compared to other provenances. The invigoration treatment significantly affected germination and seedling growth of all provenances. Hydro-priming with aquades for 48 hours gave the best germination capacity for Pomalla and Batuhijau provenances. For low initial germination, such as seed from Kapuas, Alas Purwo, and Kampar, the GA3 500 ppm for 48 hours and PEG-1.2 MPa for 24 hours treatments could improve seed viability and vigor. GA3 and gamma irradiation gave the best seedling growth, although other treatments, such as PEG-0.8 MPa for 24 hours, also could increase seedling height and biomass of Kampar provenance. In general, the effectiveness of the invigoration treatment depends on the initial physiological conditions, the invigoration method, and its concentration.