Mineral concentration and distribution in tubers of fertilized and unfertilized potato cultivars Shepody and Russet Burbank as determined by VP-SEM/EDS

Abstract

Plant nutrients are difficult to measure in situ using traditional chemical methods. In this study, a variable pressure scanning electron microscope (VP-SEM) equipped with energy dispersive X-ray spectrometry (EDS) was used to map elemental nutrients in potato tissue. Samples were taken from tubers of the cultivars Shepody and Russet Burbank from fertilized and non-fertilized plots. Each sample was divided into eight segments from stem to bud. X-ray mapping showed a higher overall concentration of P, M g, and Ca in tubers from fertilized plots compared with those from unfertilized plots for Shepody and Russet Burbank. P content was correlated with Mg content in Shepody (r = 0.851) and in Russet Burbank (r = 0.748). An increasing gradient of P and Mg from stem end to center of tubers and decrease again towards the bud end was observed in Russet Burbank, but was not as noticeable in Shepody. Ca showed a steady decline from stem end to bud end of tubers and little or no correlation to P or Mg for both cultivars. Results obtained using VP-SEM/EDS showed good correlation to those found using traditional chemical methods. We demonstrated that VP-SEM/EDS can be successfully used for mapping of nutrients in potato tubers. This study gives support to this technique as an alternative to traditional chemical methods of measuring minerals and nutrients. Key words: Potato, scanning electron microscopy, energy dispersive X-ray spectrometry, distribution (mineral), P, Mg, Ca