Observations on seed embryo and germination, seedling morphology and development of Vitellaria paradoxa (C. F. Gaertn.)

Abstract

Cotyledon morphology and subsequent establishment of V. paradoxa seedlings that account for its cryptohypogeal germination were studied. To identify the embryonic axis, fresh and partially dry seeds were deshelled and their distal ends transversely cut off. Cut seeds were immersed in 1.0 % tetrazolium chloride (TTC) solution for 24 hours and kept in the dark for staining. To study cotyledon morphology, 50 seeds were deshelled, air-dried for 3–5 days and split open from the distal end. Another batch of 50 seeds were sown directly. The sprouted seeds or seedlings were sampled at 5-day intervals and their cotyledonary tubes sectioned to observe morphological and anatomical features. Morphologically the seed bears a cotyledonary raphe, which lies vertically with distally schizocotylous and proximally syncotylous cotyledons. Large seeds sprouted earlier (7 days) followed by seedling emergence within 61 days, while small seeds sprouted almost a week later (12 days) with seedling emergence within 75 days. The location of the embryos at the proximal ends cause germinating seeds to produce long cotytedonary tubes which bury the plumules deep into the soil, a protection against bushfires. This germination study will enhance nursery establishment for plantation development of V. paradoxa.