|Seeds and Plant Propagation. Agroforestry Technology Information Kit (IIRR, 1992, 105 p.)|
Many agroforestry species have hard seed coats which are impermeable to water and air or which prevent the emergence of seed parts. Hardseededness tends to be promoted with delayed harvesting and prolonged drying. Hastened seed germination is essential for rapid and uniform seedling establishment and to shorten the time of exposure of seedlings to pests and other stresses. The following procedures are some pre-germination treatments which may be carried out singly or in combination to enhance germination of hardseeds.
TAP WATER TREATMENT
Soak seeds in tap water for 1248 hours (depending on species) before planting. Sow only seeds that absorb water. If a large portion does not absorb water, other treatments should be used.
BOILING WATER TREATMENT
1. Place seeds (and a stick to stir them with) in cloth bags or used socks.
2. Dip and stir seeds in boiling water (5-10 parts water to 1 part seed) for 3-15 seconds. Longer time is needed for seedlots with thicker coats or with more hardseeds. Boiling water may also be poured into a container with seeds.
HOT WATER TREATMENT
1. Pour hot water (boiling water allowed to cool for about 10-15 minutes) into a container with seed (10 parts water to 1 part seed).
2. Let stand for 3-10 minutes or until water cools off. Seeds may be left soaked overnight in cold or tap water.
Nick-off seedcoat with a knife or nailclipper, or rub with sandpaper, file, or any rough material, taking care not to injure the internal portion especially the radicle (rootend). This technique is practical only for small seedlots.