Biofortificação simultânea em Zn e Fe em trigo mole - avaliação nutricional da semente

Since its origin the main goal of X-ray Microanalysis was the quantitative analysis in Metalurgy. The quantitative analysis is almost impossible in the large majority of the biological materials (Ruste, 1983) although a qualitative and semi- quantitative analysis can be achieved. The preparation of the biological material is also important being indispensable 1) to preserve all the elements we want analyse avoiding any migration or extraction 2) do not add elements that difficult the analysis (Halpern, 1983). Bread wheat grains (Triticum aestivum L. cv Nabão) obtained from plants growing with different treatments (0Ts; 2Ts; 2T5s; 2T7s; 2T10s; 2T13s) under environmental controlled conditions, were immersed in ethanol 30% during 10-15s and after that transversally sectioned approximately in the middle of the equatorial region. With a Scanning Electron Microscope Jeol T330A coupled with a X-ray Microanalyser Tracor Northern Series II, the distribution of the Zn, Fe, P, Ca, K, Mg, Cu and Mn throughout a transect in the grain endosperm was studied. The results allow us to conclude that in the large majority of the cases did not exist a homogeneous distribution of the nutrients throughout the grain endosperm (between Periphery and Centram area), varying largely according the element and the treatment of the plants. When analysing the ratio Fe/Zn a progressive increase until the 27Ts treatment was verified (0Ts – 0.70; 2Ts – 0.88; 2T5s – 0.98; 2T7s – 1.48), decreasing after that (2T10s – 1.10; 2T13s – 0.67). This data partially agrees with the Fe/Zn ratios obtained by Atomic Absorption Spectrophotometry- 0Ts – 1.7; 2Ts – 0.66; 2T5s – 0.94; 2T7s – 1.8; 2T10s – 1.7; 2T13s – 2.0 (Fernando et al. 2011). The use of this methodology in the analysis of the Fe/Zn ratio can be extremely useful in field studies where a large quantity of seeds must be regularly monitorized.