Mineral analyses of storage reserves of Cucurbita maxima and Cucurbita andreana pollen

Abstract

Cucurbita maxima and Cucurbita andreana are so closely related that hybridization is possible. These two species also have been shown to have very different levels of calcium storage in their seeds. Our neutron activation analysis studies have shown that the total amount of P, Ca, K, and Mg in pollen of the two species was similar. Energy dispersive X-ray analysis studies also showed that the composition of electron-dense particles in the tube cells of the two species was similar. Thus the differences in Ca levels in phytate reserves in the seeds of these two Cucurbita species do not appear to be paralleled by differences in mineral reserves in the pollen of the two species. Specimen preparation studies demonstrated that even though elements such as P, K, Mg, and Ca are mostly retained by an anhydrous fixation and embedding protocol, thin-sectioning of such blocks on a water-filled microtome boat resulted in major loss of elements. Key words: pollen, mineral nutrients, energy dispersive X-ray analysis, neutron activation analysis, phytate, Cucurbita.