Absorção de fosfatos mono e diâmonico marcados com radiofósforo, em presença e ausência de uréia, pela parte aérea de mudas de abacaxizeiro (Ananas comosus (L.) Merr.)

One per cent (w/v) solutions of monoammonium and diammonium phosphates either in the presence or absence of 1% urea were applied in the axyl of the "D" leaves of young plants grown in soil filled pots. There was no statistical difference between the two P sources. On the other hand, the presence of urea showed tendency to decrease internal transport of the applied phosphates irrespective of the source used.O presente trabalho, desenvolvido em casa-de-vegetação com abacaxizeiro cultivar "Smooth cayenne", para observação do efeito de MAP e OAP com e sem uréia adicionados em solução a 1%, via axila da folha D, mostrou que: ambas as fontes tiveram efeitos semelhantes no suprimento de fósforo e a uréia não melhorou a eficiência de absorção, mostrando ainda uma tendência negativa na distribuição do 32p entre as partes estudadas

Efeitos das deficiências de macronutrientes em duas variedades de soja (Glycine max (L.) Merr.), Santa rosa e UFV-1, cultivadas em solução nutritiva

Two soybean varieties were grown in nutrient solution in the presence and in conditions of deficiency of macronutrients (supplied at 1 tenth of full strength level). During the life cycle samples were taken for leaf analyses, as well as for the determination of the activity of nitrate reductase (NO3R). At the end of the pod filling, periodical mineral analyses were carried out in all the organs of the plants under the "complete" tratment; only leaves were analysed in teh remaining plants. The main conclusion were the following (1) symptoms of deficiency which showed up (N, P, K and Ca) are in agreement with those described in the literature; (2) plants deficient in N,P, K or Ca did not produce any pods; (3) there was a differential response in quantitative terms, of the two varieties to the deficiency of elements in the substrate; (4) the adequate levels of N, P, K, Ca, Mg and S are not the same for the two varieties; (5) quick tests provided and indication of the nutritional status; (6) NO3R activity reflected the level of N in the nutrient solution.Duas variedades de soja, Santa Rosa e UFV-1 foram cultivadas em solução nutritiva deficiente em macronutrientes. Foi possível obter sintomas de carência, verificar o efeito das deficiências no crescimento, composição mineral e produção de vagens. Fez-se a diagnose foliar no caso de N, P e K e verificou-se o efeito do nivel de N na solução sobre a atividade da redutase de nitrato