Controlled seed deterioration in Dalbergia nigra and Dimorphandra mollis, endangered Brazilian forest species

Publisher： International Seed Testing Association

ISSN： 1819-5717

Source： Seed Science and Technology, Vol.32, Iss.3, 2004-10, pp. : 813-823

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Abstract

This work aimed to study controlled seed deterioration in endangered Brazilian forest species »Jacaranda-dabahia« (Dalbergia nigra (Vell.) Fr. All. Ex Benth., Fabaceae, Atlantic Forest) and "Faveiro" (Dimorphandra mollis Benth., Caesalpiniaceae, "Cerrado"). The knowledge of those species' storability could assist seed conservation and availability. Seed moisture content (mc) was adjusted from initial values either by rehydration above water or by dehydration over silica gel. Seed subsamples of eleven mc for D. nigra (2.5, 2.8, 4.6, 5.3, 7.1, 9.5, 13.3, 14.3, 15.1, 17.4, 18.5%) and eight mc for D. mollis (1.6, 5.2, 6.9, 8.4, 9.2, 10.6, 11.4, 13.2%) were hermetically stored at 40, 50 and 65°C (±0.5°C), until complete survival curves were achieved. Both species had orthodox behaviour during storage, although D. mollis presented higher storability, probably due to hardseededness and different seed composition. An inverse relationship was observed between mc and seed longevity for the species. Viability constants for D. nigra and D. mollis were: K_E = 5.199, 6.282; C_W = 4.524, 3.838; C_H = 0.08175, 0.05405; C_Q = 0.001641, 0.001316. Lowest mc limits for application of the viability equation at 65°C appeared to be around 2.9 and 4.0% mc for D. nigra and D. mollis, respectively.