Accumulation of Mineral Nutrients by Developing Fruits of Prickly Plume Grevillea (Grevillea annulifera F. Muell.)

Abstract

The nutrition of developing fruits of Grevillea annulifera was studied in its natural habitat on sandy heathland 600 km N. of Perth, W.A. Seeds made up 33% of the dry matter of the fruit at maturity and accumulated over 70% of the Mg, Cu, N, Zn and P, 42-61% of the S, K, Fe, Ca and Mn but less than 20% of the Na. Follicles lost most of their P, Zn and N during fruit ripening and small quantities of Mg and Cu. Dry matter, K, S, Ca, Na, Fe and Mn were not withdrawn from follicles. Retranslocation from follicles could have provided from 24 to 41% of the P, Zn and N in seeds. The seed coat made up 60% of the dry matter of seeds and had most of the K, Ca, Na, Fe and Cl; the embryo had most of the N, P, S, Mg, Zn, Mn and Cu. Levels of most nutrients in embryos of G. annulifera were very high when compared with those in seeds of crop species. Leaves had low levels of most nutrients. The results suggest that G. annulifera has the nutritional characteristics common to xeromorphs and the ability to transport nutrients very efficiently to fruits, and especially to embryos. An ecological survey of nutrient levels in fruits at three localities revealed that within-locality variation was as great as or greater than that between localities. Nutritional information is discussed in relation to flower and fruit shedding by the species. It is suggested that spatial restrictions to fruit growth contribute partly to fruit shedding.