Identifying dormancy class and storage behaviour of champak (Magnolia champaca) seeds, an important tropical timber tree

Magnolia champaca is a culturally important tree in the tropics with a high commercial value. Its natural regeneration is rare. Hence, the species is usually propagated from seeds but with great difficulties. The class of dormancy in M. champaca seeds has been reported to be physical, physiological, and morphological. Their storage behaviour as orthodox, intermediate, and recalcitrant has been reported by various authors. During the present research, seeds of this species in Sri Lanka were collected to determine their dormancy class and storage behaviour. Both scarified and non-scarified seeds imbibed water; however, high germination occurred only on gibberellic acid (GA3) showing the presence of physiological dormancy. Embryos elongated inside of seeds at warm temperatures before radicle emergence indicating morphological dormancy. Thus, seeds have morphophysiological dormancy (MPD) and probably the non- deep simple level. The moisture content of fresh mature seeds was 25 %. Low germination occurred on GA3 for seeds dried to 10 % moisture content, and the seeds stored dry at 4 and -1 ºC for 1 month did not germinate. Thus, the storage behaviour may be best classified as intermediate. Knowing that the seeds of this species have MPD allows future studies to partition the factors driving embryo growth, unblocking physiological dormancy, and stimulating germination in nature and in propagation. But the storage behaviour may limit seed usage in propagation programmes relying on stored seeds.

DOI: http://dx.doi.org/10.4038/jnsfsr.v41i2.5708

J.Natn.Sci.Foundation Sri Lanka 2013 41(2):141-146