Evaluating Indigenous Practices for Petai (Parkia speciosa Hassk.) Seed Germination: The Effect of Seed Shelling and Seed Cutting on Germination, Growth, and Survival

Parkia speciosa Hassk. (petai, pete, sator, and stink bean) is a medium to large tree native to Southeast Asia with various medicinal, wood, and shade tree uses. Its seed is an important component of Indonesian, Malaysian, and Thai cuisines. Petai is a common component of smallholder tree gardens throughout Indonesia. Indigenous propagation practices for this species are removal of the seed coat, cutting off ¼ to ½ of the seed, or both, before sowing in prepared beds or containers. These practices are thought by farmers to accelerate seed germination and improve seedling growth. Seed cutting is also practiced to retain part of the seed for household consumption. A research trial was implemented to document the effect of seed shelling and seed cutting on seed germination, seedling growth, and seedling survival. Results indicate that both treatments accelerate—but do not increase—seed germination. Nine days after sowing, the treatments increased germination by 27–32% over the controls; the combination of the treatments increased germination by up to 70%. However, by 35 days all treatments and combinations achieved 100% germination. Seed cutting had a negative effect on seedling diameter and height growth. The combination of no shelling and ½ cutting indicated higher seedling mortality over the study period. The findings support the use of the indigenous seed shelling practice but suggest discontinuation of seed cutting practices.