Four single cross corn hybrids, selected on the basis of the chemical element accumulation characteristics of their inbred parents in single‐cross hybrids, were grown under greenhouse conditions to determine the effect of different rates of calcitic and dolomitic limestone at two rates of K on accumulations of Ca, Sr, Mg, and K. As was predicted from the performance of the inbred parents in other single cross hybrids, the four hybrids used in this experiment differed with respect to the concentrations of Ca, Sr, K, and Mg accumulated. Partial genetic control of chemical element accumulation by these hybrids was apparent. With respect to Ca and Sr accumulation the hybrids could be compared at any constant level of lime above 1/2 the L.R. with no significant change in rank order. At the lower rates of lime hybrid IV was relatively low in accumualtion of Ca, and addition of K to the soil caused a greater decrease in Ca accumulation by hybrid IV than was observed for the other hybrids. Hybrid II was a higher accumulator of Ca under all conditions than were hybrids I and III. On the other hand, the capacity of hybrid IV to accumulate Ca increased more with additions of calcitic limestone and decreased more with addition of K than was observed for the other three hybrids. Within rates and sources of lime, accumulation of Ca and Sr were highly related, indicating that no genetic mechanism was operative in these hybrids to cause differential accumulation of these two elements. The observations discussed suggest that antagonistic effects of one element added to soil on accumulation of other elements as well as accumulation levels of each element by these hybrids were under partial genetic control.

Four single‐cross corn hybrids (Zea mays L.) which differ with respect to their accumulations of Ca, Sr, Mg, and K were grown under greenhouse conditions in soil treated with 0, 100, 200, and 400 ppm of Sr as SrNO3. The investigation was conducted to determine if these hybrids would exhibit variable selectivity for Sr compared with Ca and Mg. All hybrids responded substantially to Sr additions to the soil. The concentrations of Sr in hybrids I and IV increased more with increasing rates of Sr than was observed for the other two hybrids. Relative to concentrations of Ca plus Mg in the plants, hybrid IV accumulated more Sr than did hybrid III with the other two hybrids being intermediate. Results for selectivity ratios indicated that Sr was removed as readily by hybrid IV as were Ca and Mg, while other hybrids were selective for Ca and Mg in preference to Sr. It was concluded that although variable selectivity was evident among the hybrids, the concentrations of Sr accumulated by the hybrids were predominantly a function of the availability of Sr in the soil and the Sr and Ca accumulation characteristics of the hybrids. It is not likely that hybrids can be developed which accumulate high concentrations of Ca and low concentrations of Sr.

Nunca como hoje a alimentação esteve na ordem do dia, seja nos órgãos de comunicação social, seja na imensidão da internet, seja determinante da nossa saúde. Neste contexto, temos assistido a uma de alguns produtos alimentares. Neste caso concreto, os alimentos em causa são as bebidas açucaradas e conhecemos já a proposta do Orçamento de Estado para 2017 de incluir uma taxa adicional em