Autecological studies on Audouinia capitata 7. Seed Nutrition

Autecological studies on Audouinia capitata (Bruniaceae). 7. Nutritional aspects in the mature seed
J.H.de Lange G.R.Thompson C.R.Swart 1993 South African Journal of Botany 59: 178-187 https://doi.org/10.1016/S0254-6299(16)30751-7

Lipids and proteins are the major storage compounds present in the starchless endosperm of dormant A. capitata seed. Calcium oxalate crystals are present in protein bodies of the epidermal endosperm, and in the pericarp cells. The globoid inclusions of protein bodies are a major source of P, K, Cl and Mg and the epidermal endosperm crystals, a major source for Ca. No crystalloids are found in the protein bodies. The seeds store N and P. They also contain substantial concentrations of Cu, Zn and Mn. Lower amounts of these elements are present in the pericarp. Nutrients in the pericarp of the indehiscent fruit are probably utilized by the developing seedling. The high N, P and lipid content in the seed, and also the distribution pattern of calcium oxalate crystals in the seed and pericarp, seem to be beneficial evolutionary adaptations. Lipids in seeds from the soil seed bank differ quantitatively from those in fresh seeds. Low densities of protein bodies are found in many seeds resulting in deficiencies of proteins and mineral elements. This may partially explain high incidence of pre-emergent seedling mortality contributing to the rarity of the species.

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"The two major nutrient reserves in A. capitata seeds are lipids and proteins. No starch is found in dormant seeds. The 55.4% oil recorded in fresh A. capitata seeds is high when compared to that found in most other plants. The high oil content and the absence of starch in the small A. capitata seeds could be an evolutionary adaptation. The energy released during oxidation of fatty acids is approximately 2.2 times the energy released by the same volume of carbohydrates
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A. capitata occurs on heathlands which have generally nutrient-poor soils, particularly deficient in Nand P (Kruger 1979; Groves 1981; Low & Bristow 1983). The high concentrations of Nand P in the seeds of A. capitata, as well as in the seeds of other plants in the fynbos and Australian heathlands, appear to ensure seedling establishment in
nutrient-poor environments."

Publicado el junio 16, 2022 08:14 TARDE por tonyrebelo