Seed dormancy and pre-treatments to enhance germination in selected Albizia species.
An experiment was conducted to find the best pretreatment to improve the germination and vigour of Albizia odoratissima, Albizia procera, and Albizia falcataria [Paraserianthes falcataria] seeds. Physical treatments were nicking, seed coat removal and scarification, and chemical treatments soaking in sulfuric acid, hydrogen peroxide, acetone, potassium nitrate, thiourea, gibberellic acid (GA3) and water. Soaking nicked seeds of A. odoratissima or mechanically scarified seeds of P. falcataria in flowing water gave the maximum germination percentage and vigour. Scarification with concentrated H2SO4 for 10 or 20 min gave the largest germination percentage and vigour in A. procera. The seed coat extract of these seeds inhibited the germination of seeds of yardlong bean (Vigna unguiculata), okra (Abelmoschus esculentus), brinjal (Solanum melongena) and rice (Oryza sativa). Thin layer chromatography showed the presence of a coumarin-like substance with a RF value of 0.22 in the seed coat of A. odoratissima; the presence of a further substance was also indicated.