Translocação e redistribuição de enxofre em plantas de milho e de soja

Abstract

Resumo -O objetivo deste trabalho foi estudar a translocação e a redistribuição de S pelo transporte acrópeto e basípeto em plantas de milho e de soja. Plantas das duas espécies foram cultivadas em solução nutritiva contendo 35 S em casa de vegetação. O 35 S aplicado em uma única raiz foi prontamente absorvido e translocado para a parte aérea, assim como para as demais raízes cultivadas na ausência de enxofre. O radioisótopo aplicado em uma única folha foi transportado tanto na direção acrópeta quanto na basípeta. Entretanto, o milho e a soja mostraram comportamentos diferentes na absorção e na redistribuição do enxofre. O milho, apesar de ter apresentado maior absorção radicular, reteve grande parte desse elemento na raiz, enquanto a soja absorveu consideravelmente menos, porém apresentou maior eficiência de translocação. Nas plantas de soja, as folhas superiores, principalmente as mais novas, mostraram ser os principais drenos fisiológicos do enxofre.Termos de indexação: Zea mays, Glycine max, transporte de nutrientes, raiz, absorção. Translocation and redistribution of sulphur in corn and soybean plantsAbstract -The objective of this work was to study the S translocation and redistribution by acropetal and basipetal transport in corn and soybean plants. Plants of both species were cultivated in nutritive solution containing labeled 35 S, in a greenhouse. The 35 S applied to only one root was absorbed quickly and transported to the shoot, as well as to the other roots cultivated in non-labeled solution. The 35 S applied to only one leaf was transported both to acropetal and basipetal direction. However, corn and soybean showed different behaviors in S absorption and redistribution. In spite of having larger root absorption, corn retained great part of that S in the root, while soybean absorbed considerably less, but presented greater translocation efficiency. The upper leaves, mainly the youngest, showed to be the main physiologic sinks for S in soybean plants.

Nutritional Disorders of Macronutrients in Bletia catenulata

“…The treatment resulted in the development of nutritional disorder symptoms in B. catenulata plants, with new leaves that were light green (Supplemental Fig. 1E), demonstrating the main physiological S sink (Silva et al, 2003). This result is consistent with those reported by Malavolta (1997), who confirmed the yellowing of younger leaves as a typical symptom.…”

Use of Gypsum for Crop Grain Production under a Subtropical No‐Till Cropping System

“…Given that wheat grain yield in 2005 was positively related to the Ca ( r = 0.79, p < 0.05) and S ( r = 0.70, p < 0.05) leaf contents and that corn grain yield in 2004–2005 was also positively related to Ca ( r = 0.71, p < 0.05) and S ( r = 0.89, p < 0.01) leaf contents, it is considered more probable that yield benefits imparted by gypsum resulted from increased Ca and SO 4 –S availability to the cereal crops. The explanation for this effect may be due to the lower cation exchange capacity of roots (CECR) in grasses than in legume plant species (Asher and Ozanne, 1961) and to the different behaviors in S uptake and redistribution by plants (Silva et al, 2003). Williams and Coleman (1950) found that the CECR was double in soybean as compared with corn.…”

“…Therefore, corn and wheat plants are less efficient than soybean plants in Ca uptake from the soil solution. In contrast, corn retains a greater part of the S absorbed in the root, while soybean presents greater translocation efficiency (Silva et al, 2003). Thus, corn and wheat crops require less Ca and/or SO 4 –S than the soybean crop, but they respond more to greater soil Ca and SO 4 –S availability because they are less efficient in both Ca uptake and S translocation.…”

Fontes, modo de aplicação e translocação de enxofre no desenvolvimento inicial do milho

“…As plantas de milho apresentam maior absorção radicular de S quando comparado a soja, retendo grande parte desse nutriente na própria raiz enquanto o S aplicado via folhar é transportado para todas as partes da planta. Sendo assim, a fertilização deste nutriente via foliar na cultura do milho pode ser importante em solos com baixos teores de enxofre, porém na prática existe carência de trabalhos apresentando resultados sobre o assunto (SILVA et al, 2003).…”