We evaluated the effect of phosphorus application rates from various sources and in the presence or absence of filter cake on soil phosphorus, plant phosphorus, changes in acid phosphatase activity, and sugarcane productivity grown in Eutrophic Red Ultisol. Three P sources were used (triple superphosphate, Araxa rock phosphate, and Bayovar rock phosphate) and four application rates (0, 90, 180, and 360 kg ha−1 of P2O5) in the presence or absence of filter cake (7.5 t ha−1, dry basis). The soil P, the accumulated plant P, the leaf acid phosphatase activity and straw, the stalk productivity, the concentration of soluble solids in the juice (Brix), the juice sucrose content (Pol), and the purity were the parameters evaluated. We found that P applications increased levels of soil, leaf, and juice phosphorus and led to higher phosphorus accumulation and greater stalk and straw productivity. These levels were highest in the presence of filter cake. Acid phosphatase activity decreased with increasing plant phosphorus concentration. Phosphate fertilization did not show effect on sugarcane technological quality. We concluded that P application, regardless of source, improved phosphorus nutrition and increased productivity in sugarcane and, when associated with filter cake, reduced the need for mineral fertilizer.

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Resumo -O gesso agrícola pode ser utilizado como fonte de enxofre, desta forma, melhorando a nutrição e promovendo ganhos na produtividade da cultura da soja em sistema de plantio direto. Objetivou-se com este trabalho avaliar os efeitos do enxofre (S) aplicados na forma de gesso agrícola na cultura da soja em sistema de plantio direto com e sem adubação potássica. O experimento foi conduzido no município de Guairá-SP em solo da classe LATOSSOLO VERMELHO Eutrófico. O delineamento experimental utilizado foi o de blocos ao acaso, em esquema fatorial 2 x 5, com quatro repetições. Os tratamentos foram obtidos pela combinação de dois níveis de K (0 e 60 kg ha -1 de K 2 O), fonte cloreto de potássio; e cinco doses de enxofre (0, 30, 60, 90 e 120 kg ha -1 de S), fonte gesso agrícola. Foram avaliados os teores foliares de potássio, cálcio e enxofre, além da produção de grãos e o teor de óleo presente nos grãos. O enxofre aplicado no solo melhora o estado nutricional da cultura da soja aumentando os teores de potássio, cálcio e enxofre, sem influenciar a produtividade de grãos, independente da adubação potássica. A aplicação de enxofre no solo aumenta o teor de óleo nos grãos da soja com ou sem adubação potássica.Palavras-chave -Enxofre. Nutrição de plantas. Sistema conservacionista. Abstract -The gypsum can be used as a sulfur source, thereby improving nutrition and promoting gains in yield of soybeans in no-tillage system. The objective of this study was to evaluate the effects of sulfur applied as gypsum in the soybean culture under the no-tillage system with and without potassium fertilization. The experiment was conducted in the city of Guaíra-SP in an OXISOL. The experimental design used was randomized blocks in factorial scheme 2 x 5 with four replications. The treatments were obtained by combining two levels of K (0 and 60 kg ha -1 K 2 O), applied as potassium chloride, and five doses of sulfur (0, 30, 60, 90 and 120 kg ha -1 S) applied in the form of gypsum. Foliar potassium, calcium and sulfur, in addition to grain yield and oil content in the grains were evaluated. It was observed that the application of sulfur in the soil improved the nutritional status of soybean in potassium, calcium and sulfur, without affecting grain yield, independent of potassium fertilization. The presence of sulfur in the soil increased the oil content in soybean grain with or without potassium fertilization.

The far red light insensitive (fri) mutant of tomato, which is phytochrome A (phyA) deficient, displays some characteristics that have recently indicated important functions of this photoreceptor in water relations. With respect to the relationship between nutrition and water relations, we investigated the growth and nutritional status of fri supplied with Hoagland's complete solution and solutions with the individual omission of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and sulfur (S). For this purpose, 20-day-old tomato plants of the WT (cv. Moneymaker) and fri mutant were transplanted into pots (one plant per pot) that contained Hoagland and Arnon (1950) solution diluted to 50 per cent in the first week and to 100 per cent from the second week of cultivation until the end of the experiment (50 DAT O) from a balanced nutrient solution. The experiment was arranged in a completely randomized factorial design with two genotypes and seven types of nutrient solutions with three replications. Upon harvest, the following measurements were performed: the height of the plants, measured from the base of the stem of each plant to the insertion of the first fully expanded leaf; the stem diameter; the total number of leaves per plant; an indirect chlorophyll measurement, which we called the green color index, and the leaf area. Statistical analysis was performed using analysis of variance (ANOVA) followed by Tukey's test. First, based on growth analyses, fri showed an enhanced dry weight of the shoot, root and whole plant in complete solution compared with the wild type (WT). In addition, the phyA mutant had a multifaceted response compared with that of the WT when the nutrients were omitted. For the fri mutant, the height and green color index were reduced without N and K; the leaf area without P, K and S; the dry weight of the root and shoot without N, P, K and S, and the root, shoot and total plant dry weight without P, K and S. On the other hand, the green color index of the fri mutant was enhanced without Ca and Mg. Together, these results show that in addition to revealing an altered response to nutrition in the fri mutant, phyA can play a role in light signaling in the nutrition and nutritional stress of tomato.

RESUMOObjetivou-se com este estudo avaliar os efeitos da aplicação de zinco no desenvolvimento e na nutrição do capimtanzânia. O delineamento experimental foi inteiramente casualizado, constituídos de seis doses de zinco (0,15,30, 60, 120 e 240 mg dm -3 ) e quatro repetições. Cada unidade experimental foi constituída de vaso preenchido com Latossolo Vermelho distrófico (Zn = 0,4 mg dm -3 ). Foram realizados dois cortes, o primeiro após 53 dias da transplantação das mudas e o segundo 35 dias após o primeiro corte. Avaliou-se a concentração de zinco no solo, o teor de zinco foliar, o número de perfilhos, número de folhas, altura de plantas, massa seca da parte aérea, do sistema radicular e da planta inteira. As doses de zinco influenciaram a concentração de zinco no solo e na planta, e a produção de massa seca do capim-tanzânia, especialmente do primeiro corte. O capim-tanzânia apresenta alta tolerância à toxicidade de zinco, apresentando nível crítico tóxico de 273 mg kg -1 . Palavras-chave: Panicum maximum; fertilidade; micronutriente; nutrição; pastagem; solo. ABSTRACTIt was aimed to assess the effects of zinc in the development and nutrition of Tanzania grass. The experimental design used was fully randomized, consisting of six doses of zinc (0, 15, 30, 60, 120 and 240 mg dm -3 ) and four repetitions. The experimental unit was formed in a vase filled with a Red Latosol dystrophic (Zn = 0.4 mg dm -3 ). There were two cuts, the first after 53 days of transplanting seedlings and the second 35 days after the first cut. Was evaluated the concentration of zinc in the soil, the content of zinc leaf, the number of tillers, number of leaves, plant height, the dry mass of the shoot, root system and the whole plant. The doses of zinc influenced the concentration of zinc in soil and plant, and production of dry mass of Tanzania grass, especially the first cut. The Tanzania grass shows high tolerance to the toxicity of zinc, and toxic critical level of 273 mg kg -1 .