Estudos sobre a nutrição mineral do milho: II - deficiências de macronutrientes na variedade Piranão

Corn plants, Piranão variety, were grown in nutrient solution, complete and with omission of one macronutrient each time, in order to gain information on the effects of treatments on growth, symptoms of deficiency, and mineral composition of the leaves. The following symptoms of deficiency were obtained: Nitrogen -- plants underdeveloped; "V" shaped chlorosis beginning in the older leaves followed by drying and necrosis; Phosphorus - older leaves dark green with a purple hve; Potassium - plants underdeveloped; marginal chlorisis and necrosis in the older leaves; iron induced chlorosis in the younger leaves; Calcium - plants very underdeveloped due to death of apical merystem; younger leaves showing tip and marginal chlorosis and afterwards necrosis and break down of the tissue; wide whitish areas in the younger leaves; Magnesium - plants very underdeveloped; internerval chlorosis in older leaves first, proceeding to the young ones; Sulfur - absence of marked symptoms, except for a slight chlorosis in the younger leaves. Dry matter production obeyed the following decreasing order: Complete, minus S, minus P, minus K, minus Mg, minus N and minus Ca. Ears were obtained only in treatments complete and minus S. Top/root ratio decreased according to this order: minus S, complete, minus K, minus Mg, minus N, minus P and minus Ca. The macronutrient content for the treatment complete was the following respectively for lower and upper, leaves: N - 2.76 and 2.52%; P - 0.59 and 0.53%; K - 2.25 and 2.26%;Ca - 2.17 and 1.85;Mg - 0.82 and0.66;S - 0.38 and 0.32. The values of the element corresponding to each treatment were: N - 1.84 and 1.22 (that is: lower leaves in the minus N plants had 1 84% N, whereas the upper leaves in same treatment had 1.22% N; P - 0.14 and 0.17%; K - 0.29 and 0.78%; Ca - 0.29 and 0.05; Mg -0.09 and 0.05%; S- 0.31 and 0.26%.Foram induzidos sintomas de carência de macronutrientes no milho, var. Piranão, exceto no caso do enxofre. Os níveis foliares de N, P, K, Ca, Mg e S foram determinados nas plantas sujeitos à nutrição completa e às deficiências de macronutrientes

Estudos sobre a nutrição mineral do milho. II. Efeito de doses crescentes de N, P e K no crescimento, produção e composição mineral da variedade Piranão em condições controladas.

O milho, var. Piranao, foi cultivado em solucao nutritiva com niveis crescentes de N, P e K. Houve resposta linear a adicao de N e assintotica as doses de P e de K. A determinacao a atividade da reductase de nitrato se correlacionou melhor com a producao total nas folhas, por sua vez refletiu melhor o estado nutricional que a determinacao de putrescina nas folhas

Estudos sobre a nutrição mineral do milho: II. efeito de doses crescentes de N, R e K no crescimento, produção e composição mineral da variedade Piranão em condições controladas

Maize plants, Piranão cultivar, were grown in nutrient solution with 5 levels each of N, R and K till harvest. Nitrate reductase activity and putrescine level were determined in leaves of plants in the N and K series, respectively, at silking stage. Upper and lower leaves were analysed for N, R and K in the corresponding treatments at the end of the life cycle. The main conclusions were the following : 5.1 There was a linear effect of level of N in the substrate on dry matter production. 5.2. High activities of nitrate reductase suggest that under natural conditions the variety should be very responsive to N fertilization. 5.3. An asymptotic response curve was found in the treatments with increasing levels of R in the medium, as well as in the case of the K treatments. 5.4. Curves of response of roots (dry matter) showed a tendency to level of as a function of increasing levels of element at lower concentrations than the components aeral part of the plant (leaves, stems, ears). 5.5. Determination of leaf putrescine did not of prove a better indicator of the K status leaf K. 5.6. The variety under study seems to be relatively more efficient in the utilization of N for yield components; the efficiency for utilization of K, is rather low and that for R is intermediate, findings that should have a bearing on the fertilization in field conditions.O milho, var. Piranão, foi cultivado em solução nutritiva com níveis crescentes de N, R e K. Houve resposta linear à adição de N e assintótica às doses de R e de K. A determinação da atividade da reductase de nitrato se correlacionou melhor com a produção da matéria seca que a do N total nas folhas. O teor de potássio total nas folhas, por sua vez refletiu melhor o estado nutricional que a determinação de putrescina nas folhas

Sharing local knowledge

This article was first published in ICT Update Feb: 2013, by the Technical Centre for Agricultural and Rural Cooperation (CTA) ACP-EU, P.O. Box 380, 6700 AJ Wageningen, the NetherlandsResearchers now use information & communications technology (ICT) to gather information more effectively from the field. Sander Muilerman, Juanita Schläpfer and Eugenio Tisselli discuss how ICTs can also give them the possibility to help share knowledge in local communities

Bioactive compounds in tomatoes: effect of organic vs conventional management in Parma in 2006

External and internal factors such as variety, season, location, ripening, growing conditions, technological and domestic processes could affect the content of bioactive compounds in food. The aim of this study was to evaluate the influence of different agronomical practices (organic vs conventional) on the nutritional quality of tomatoes. Fresh tomatoes (cv. Perfectpeel), cultivated under organic and conventional practices were analysed for vitamin C, lycopene, -carotene, chlorogenic acid, caffeic acid, coumaric acid, naringenin, rutin, quercetin, Total Antioxidant Capacity (TAC) and Ferric Reducing Ability of Plasma (FRAP). CaCO2 monolayer cell cultures were used for testing membrane damage by Trans Epithelial Electrical Resistance(TEER). Results showed that for lycopene, naringenin and rutin no significant differences were observed. For -carotene and coumaric acid significantly higher values were found in organic samples. Values of vitamin C, chlorogenic acid, caffeic acid, quercetin and TAC were significantly higher in conventional tomato, but the FRAP values were significantly higher in organic tomato. The observed TEER values were not significant different between organic and conventional tomato

Estudos sobre a nutrição mineral do milho. II. Efeito de doses crescentes de N, P e K no crescimento, produção e composição mineral da variedade Piranão em condições controladas.

O milho, var. Piranao, foi cultivado em solucao nutritiva com niveis crescentes de N, P e K. Houve resposta linear a adicao de N e assintotica as doses de P e de K. A determinacao a atividade da reductase de nitrato se correlacionou melhor com a producao total nas folhas, por sua vez refletiu melhor o estado nutricional que a determinacao de putrescina nas folhas.197