The endosperm and cotyledon tissues of Ricinus communis seeds and young seedlings were examined for changes in the mineral nutrient composition of globoids during early seedling growth. The effect on globoid composition of providing mineral nutrients to the developing seedling was also investigated. Globoids in endosperm and cotyledon tissues of castor bean seeds contained P, Mg and K, as well as trace amounts of Ca, Fe and Zn. Irrespective of the addition of mineral nutrients, K content in globoids of endosperm and cotyledon tissues declined significantly during initial seedling growth. During early seedling growth, amounts of Fe, Zn and Ca increased in cotyledon globoids. Ca contents of globoids of endosperm tissues also increased. The changes in Fe, Zn and Ca globoid contents were not influenced by providing mineral nutrients to growing castor bean seedlings.

Mineral nutrient stores in cereal grains are mainly phytate, a salt of the phosphorus-rich compound phytic acid. Quantitative measures of total phosphorus, phytic acid-phosphorus, potassium, magnesium, calcium, iron, manganese and zinc were obtained for whole grains, embryos and rest-of-grain portions of cv. Kaybonnet rice (wild type) (Oryza sativa L.) and a low phytic acid (lpa1–1) mutant strain with a 45% reduction in phytic acid. P, K and Mg were present in higher amounts than Ca, Mn, Fe and Zn in both grain types. Whole-grain amounts of total P, Ca, Mn and phytic acid-phosphorus were lower in whole lpa1–1 grains than in wild-type grains; K, Mg and Fe amounts were similar, and Zn was higher. Embryos, which comprise 3.5% or less of grain dry weight, were comparatively rich in all measured elements. The lpa1–1 mutation influenced the phytic acid content of the embryo more than that of the aleurone layer. Aleurone-layer cells of wild-type grains had many phosphorus-rich globoids 2μm or larger in diameter, whereas lpa1–1 grains contained more of the smaller globoids. The reduction in globoid size was consistent with the reduction in phytate. Energy-dispersive X-ray analysis of both aleurone-layer cells and sections of globoids in aleurone-layer cells revealed that P, K and Mg were the main mineral nutrient elements present in both grain types; traces of Ca, Mn, Fe or Zn were present. Starchy endosperm cells contained virtually no P, K or Mg, whereas scutellum cells were rich in these elements.

Cucurbita maxima Duch. cv. Warted Hubbard, which produces large fruits with many seeds, was used as a test system to study changes in several mineral nutrients during seed formation. Developing embryos increased markedly in weight, size and oil content. Energy dispersive X-ray (EDX) analysis was carried out on mineral nutrient storage globoids in developing Cucurbita cotyledons from 4 to 9 weeks after pollination. Phosphorus peak-to-background (p/b) and potassium p/b ratios increased slightly after the fourth week, while magnesium p/b ratios remained unchanged. The calcium p/b ratio was statistically higher at 4 weeks than in the subsequent weeks. Traces of iron and zinc were found in most of the globoids at all fruit ages. The zinc p/b ratio was higher in globoids at 4 weeks than at 9 weeks. Traces of manganese were detectable in only 18% of the globoids at 4 weeks and not detectable in any globoids at 9 weeks. The frequency of the small globoids of 0.25 μm in diameter was the highest at 4 weeks and was zero at 9 weeks. The frequency of the larger globoids increased progressively from 4 to 9 weeks. As the spherical globoids increased in size and hence in volume, there was a 6.4-fold increase in the embryo phytic acid, which is the main component of globoids. On a whole embryo basis, P content increased 4.5-fold, K 3.3-fold, Mg 5.4-fold and Ca 3.2-fold from the fourth to the ninth week.