Studies on the mineral nutrition of the rice plant: XII. effects of the deficiencies of macronutrients on the varieties IAC-25 and IAC-47

Plantas de arroz, variedades IAC-25 e IAC-47, foram cultivadas em solução nutritiva completa e com deficiência de macronutrientes. Foram obtidos dados sobre a influência dos tratamentos na área foliar, produção de matéria seca e na composição mineral e observados os sintomas de carência. O estado nutricional das plantas deficientes em N foi também avaliado pela determinação da atividade da redútase de nitrato na folha.Rice plants, varieties IAC-25 and IAC-47 were grown in nutrient solution both in the presence and in the absence of macronutrients. Symptons of deficiency were observed in general agreement with description found in the literature. The deficiency of N affected most dry matter yield among the three major macronutrients. although the effect on grain production was greater when K was omitted. The following levels could be taken as indication of adequate nutrition when leaf samples are analysed at the boot stage (respectively) for var. IAC-25 and IAC-47): N - 4.18% and 3.54%; P - 0.36 and 0.27; K - 2.30 and 2.09; Ca - 1.22 and 1.00; Mg - 0.80 and 0.77; S - 0.24 and 0.18. Leaf nitrate reductase activity at the same physiological period correlated well both with N supply and dry matter production

Estudos sobre a nutrição mineral do arroz: XI. Marcha de absorção de micronutrientes pela variedade IAC-47

Dry matter yield and uptake of B, Cu, Fe, Mn and Zn by the rice variety IAC-47 were studied under controlled conditions, namely, by growing plants in nutrient solution and by falcing samples for analyses in set physiological periods. It was observed that only the curves describing dry matter production and accumulation of B and Fe was verified.A produção de matéria seca e a absorção de micronutrientes (B, Cu, Fe, Mn e Zn) pelo arroz var. IAC-47 foram estudadas usando-se plantas cultivadas em solução nutritiva. Verificou-se que: enquanto as curvas que descrevem o crescimento e a acumulação de B e Fe mostram tendência sigmóide, as demais não o fazem, evidência de redistribuição foi observada somente nos casos do B (diminuição no conteúdo foliar) e no do Fe (diminuição no conteúdo da raiz)