Dynamics of Macro- and Micronutrients in Cuphea

ABSTRACT

Temporal dynamics of nutrient densities, their interrelationships, and remobilization from leaves to seeds of cuphea were quantified in growth chamber and field studies. Temporal nutrient densities in leaf samples exhibited large levels of variation, whether remobilized and largely accumulated in the seed [copper, (Cu), potassium (K), phosphorus (P), sulfur (S) and zinc (Zn)], remobilized and accumulated in the seed coat [boron (B), calcium (Ca), iron (Fe), magnesium (Mg), manganese (Mn), and sodium (Na)] or almost excluded from the seed [barium (Ba), selenium (Se) and strontium (Sr)]. The temporal seed-to-leaf nutrient density “[S]/[L]” ratios and the proportion of variance unique to each nutrient separated the nutrients into a group (Cu, Fe, S, and Zn) with large [S]/[L] ratios and large unique variances, and another group (B, Ca, Mg, Mn and Sr) with small [S]/[L] ratios and small unique variances; the first group was selectively stored in the developing embryo. Nutrients with large densities in leaves at harvest may constitute a resource potentially available for subsequent crops.

Keywords:

• cuphea
• oil crop
• nutrient density
• nutrient homeostasis

ACKNOWLEDGMENTS

We thank Beth Burmeister for her excellent editorial assistance.

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Notes

^†Leaf (L1-L5) and seed sampling dates expressed in growing degree days (GDD in °C).

^‡Ratio of nutrient density in seed [S] and mean nutrient density in leaf [L].

^§Upper and lower rows within each nutrient are nutrient densities in leaves and seed of field and growth chamber studies, respectively; Means, within each row, followed by the same letter do not differ significantly (p < 0.05, Tukey's HSD).

^¶Individual nutrients in seed and leaf (L5) differed significantly from each other (p < 0.05) using a t-test.

^†Nutrient means in embryo and seed coat, within each row, followed by the same letter do not differ significantly (p < 0.05, Tukey's HSD).

^‡,

∗,

∗∗ significant at p < 0.05 and p < 0.01, respectively.

^§Seed classes: Light(2.4 mg/seed), Medium(3.1 mg/seed), Heavy(3.5 mg/seed).