H.P. Haag

Níveis críticos de fósforo para o estabelecimento de gramíneas forrageiras em Latossolo Vermelho Amarelo, álico: II. Experimento de campo

The objectives of the present study, were to determine the critical levels of soil P by the Mehlich I and Resin extractors, and in the plant, for the establishment of Brachiaria decumbens Stapf., Brachiaria brizantha (Ilochst.) Stapf cv. Marandu and Panicum maximum Jack., in a Red Yellow Latosol. The experimental design was a randomized complete block with four replications and 21 treatments (7 levels of P x 3 species). The levels of P corresponded to 0, 20, 40, 80, 160, 320 e 640 kg of P205/ha. Two cuts of plant shoots were performed: the first, eighty days after sowing and the second, thirty days later. Differences in P requeriments for the establishment among the species, for 80% of maximum growth, were evident. The critical levels of soil P, in the first cut, were 4.7; 10.8 and 8.0 ppm (Mehlich I) and 10.7; 21.8 and 16.0 ppm (Resin), for the Brachiaria decumbens, Brachiaria brizantha and Panicum maximum, respectively. For the second cut, the levels were 3.0 and 3,5 ppm (Mehlich I) and 5.8 and 6.5 ppm (Resin), for Brachiaria decumbens and Panicum maximum, respectively. The critical levels of P in the plant were, in the same order, 0.08; 0.13 and 0.06% for the first cut and 0.09 and 0.08%, for the second cut.

Níveis críticos de fósforo para o estabelecimento de gramíneas forrageiras em Latossolo Vermelho-Amarelo, álico. I: ensaio em casa de vegetação

The objectives of the present study, carried out in a greenhouse, were to determine the critical levels of soil P, by the Mehlich I and Resin extractors, and in the plant, for the stablishment of pastures of Brachiaria decumbens Stapf., Brachiaria brizaniha (Ilochst.) Stapf cv. Marandu and Panicum maximum JACK., on a Red Yellow Latosol. The experimental design was a randomized complete block with four replications and 21 treatments (7 levels of P x 3 species). The levels of P were: 0; 17.5; 35.0; 70.0; 140.0; 280.0 and 560.0 ppm. Two shoot cuts of plants were done: the first, fifty days after sowing and the second, thirty days later. No differences in P requeriment for crop establishment were observed among the species, for 80% of maximum growth. The critical level of soil P, in the first cut, varied from 8.0 to 12.0 ppm (Mehlich I) and 13.0 to 18.0 ppm (Resin); for the second, cut, the levels were 11.5; 12.0 and 14.0 ppm (Mehlich I) and 18.0; 22.0 and 24.0 ppm (Resin), for the Brachiaria decumbens, Brachiaria brizaniha and Panicum maximum, respectively. The critical levels of P in the plant were, in the same order, 0.11; 0.13 and 0.12% for the first cut and 0.09; 0.12 and 0.10%, for the second cut.

Frutos de goiaba (Psidium guayava L.): desenvolvimento e extração de nutrientes

An orchard of guava (Psidium guayava L.) located in Alianca, SP, Brazil, had its fruits picked up at 15 to 90 days of age, in 15-day intervals. The soil was an Ultisol and the three varieties studied were: Okawa n° 2, Pedro Sato and Kumagai. The fruits were dried, weighed, grounded and analysed for all the macronutrients and for the micronutrients B, Cu, Fe, Mn and Zn. The highest fruit weights were obtained at 60 days of age for the Pedro Sato and Kumagai varieties, whereas the same happened at 75 days for the Okawa n° 2 variety. Fruits harvested from Pedro Sato and Kumagai plants removed more nutrients than those from Okawa n° 2 plants. The three varieties removed macronutrients in the following increasing order: Mg, Ca, P, S, N and K. Among the micronutrients, B, Zn and Fe had the highest amounts removed by fruits, whereas Cu had the lowest.

Nutrição mineral de hortaliças VII : absorção de nutrientes pela cultura da cebola

Plantas de cebola (Alium cepa L.var. Baia Piriforme Precoce de Piracicaba) foram cultivadas em vasos contendo silica e irrigadas com solucao nutritiva completa. Cada 15 dias a partir dos 70 dias da germinacao foram coletadas plantas e separadas em folhas e bulbo. Ate aos 85 dias o crescimento da cebola e lento intensificando-se apos esta idade ate o fim do ciclo. A absorcao dos nutrientes acompanha o crescimento. Uma producao de 36.700 kg de bulbo, correspondentes a um ha extrai as seguintes quantidades de nutrientes em kg: nitrogenio - 132,3, fosforo - 21,9, potassio - 177,0, calcio - 15,9, magnesio - 17,3, enxofre - 33,8.

Nutrição mineral de plantas ornamentais I : absorção de nutrientes pela cultura de gladíolos

Gladiulus corms no 3 (Gladiolus communis var. Itapetininga) were germinated in pots containing 7 kg of quertz. After germination the plants were irrigated several times a day with HOAGLAND & ARNON (1950) complete solution. Fifteen days after germination plant were harvested every ten days and subdivided in: aerial part, mother corms, daughter corm and bulbils. The different parts of the plants were weight and analysed for nitrogen, phosphorus, potassium, calcium, magnesium, sulphur, boron, copper, iron, manganese and zinco. It was observed that gladiulus plant show a fast growth period until fifty-five days. After this period is shows only increase in weight until seventy five days. A gladiulus plant at final cicle presents 362.6 mg of N; 78.4 mg of P; 536.4 mg of K;73.4 mg of Ca; 27.9 mg of Mg; 35.9 mg of S; 1,019.4 of B; 94.7 ug of Cu; 1,655.6 ug of Fe; 914.6 ug of Mn and 272.3 ug of Zn.

Nutrição mineral de seringueira. XII. Absorção de macro e micronutrientes nos primeiros 240 dias

Rubber plants were grown in a greenhouse and sampled at 60, 120, 180 and 240 days of growth. Samples were separated in leaves, stems and roots. Growth rate and nutrients concentrations were analyzed. The highest growth rate was obtained after 180 days of plant growth. Except for iron, the highest nutrient concentrations were determined in the leaves. Nutrient extractions per hectare at the 240 day were: N = 60kg; P = 12kg; K = 27,74kg; Ca = 8,97kg; Mg = 5,32 kg; S = 6,21kg; B = 45,52g; Fe = 544g; Mn = 337,74g and Zn = 77,30g.

Deficiência de macronutrientes, boro e ferro em Eucalyptus urophylla

Mudas de Eucalyptus urophylla foram cultivadas em solucoes nutritivas carentes nos macronutrientes e em boro e ferro, com a finalidade de se obter o quadro sintomatologico das carencias de N, P, K, Ca, Mg, S, B e Fe; aquilatar o efeito da omissao e presenca dos nutrientes sobre o crescimento e composicao quimica das folhas superiores, medianas e inferiores; assim como do caule e das raizes. Os autores obtiveram em quadro sintomatologico da omissao destes nutrientes, aliados aos seguintes niveis de carencia, expresso em funcao da materia seca: N - 0,69%; P - 0,04%; K - 0,14%; Ca - 0,04%; Mg - 0,05%; S < 0,05%; B - 8,0 ppm; Fe - 50 ppm. A omissao dos elementos da solucao nutritiva teve efeito depressivo no crescimento do Eucalyptus, com excecao do tratamento - S que nao deferiu do tratamento completo.

Nutrição mineral de plantas ornamentais: VII - absorção e deficiências de nutrientes pelo Chrysanthemum morifolium L., cv, 'Suzuki'

O presente trabalho teve como objetivo estudar aspectos da nutricao mineral de Crisântemo, cultivar Suzuki, no que concerne: - ao efeito da omissao e presenca de P, K, Ca, Mg e S, no crescimento das plantas; as quantidades de P, K, Ca, Mg, S, Cu, Fe, Mn e Zn extraidos em varias fases de seu desenvolvimento. Mudas de crisântemo foram transplantadas para vaso contendo silica. Foram submetidas a tratamentos, que constaram do cultivo de plantas em solucao nutritiva completa e omitindo um macronutriente por vez. Tambem foram cultivadas em condicoes de campo, coletando-se amostras de plantas periodicamente. Obtidos materiais de ambos os ensaios, processaram-se as analises quimicas. Sao discutidos os sintomas de deficiencia e apresentados os teores em cada orgao de plantas normais e carentes em cada elemento. Uma planta de crisântemo extrai: 231,24 mg de P; 1600,10 mg de K; 269,32 mg de Ca; 112,77 mg de Mg; 90,95 mg de S; 0,799 mg de Cu; 116,45 mg de Fe; 23,35 mg de Mn; 14,42 mg de Zn.

Disponibilidade de fósforo pelos extratores de Mehlich 1 e Resina em Latossolo Vermelho Amarelo, álico cultivado com três gramíneras forrageiras

This study was undertaken to compare the Mehlich 1 and Resin methods in the evaluation of available P in a Red Yellow Latossol, cultivated with Brachiaria decumbens Stapf., Brachiaria brizantha (Hochst.) Stapf cv. Marandu and Panicum maximum Jacq. Data of two experiments of P fertilization were utilized, one carried out in the greenhouse and the other in the field. Correlations between the amount of P extracted by each extrator with the relative production of dry matter and of the amount of P extracted by the plant and the level of P in the plant, were used to determine the efficiency of the extractors. The results showed that both extractors were efficient and similar for the evaluation of the P availability of the three grasses, but the resin method had a greater extraction capacity of the P applied.

Nutrição mineral de seringueira IV. Toxicidade de Boro em Hevea brasiliensis

Com frequencia observa-se no Brasil nas areas de seringueira sintomas visuais de deficiencia de boro, quer na fase de formacao das mudas em crescimento em viveiro, quer no jardim clonal e mesmo nos primeiros anos de desenvolvimento das plantas definitivas. Foi tambem constatado que estas deficiencias estao associadas com adubacao de N, P, K, Mg. Este fato levou os autores a determinar a resposta a plantulas de seringueira a niveis crescentes de boro no substrato (0,5; 1,0; 1,5; 2,0 e 2,5 ppm de B). Plantulas do clone Tjir 1 foram cultivadas em vasos contendo como substrato silica moida, acrescida de solucao completa com os niveis de boro acima indicadas. Nove dias apos o ensaio dos tratamentos o efeito do boro se fez notar. As plantas cresceram com menor intensidade e apareceram sintomas nas folhas, lembrando a carencia de potassio. Houve queda acentuada de folhas. As concentracoes de boro eram muito altas nas folhas variando entre 316 e 1300 ppm. No caule e nas raizes as concentracoes eram menores de 21 a 85 ppm. Os autores concluem que a seringueira e muito sensivel a toxicidade de boro, devendo ser dada uma atencao especial com este micronutriente nas plantacoes.