Juliano Corulli Corrêa

NITROGEN AND SILICON FERTILIZATION OF UPLAND RICE

Silicon is not considered an essential element for plant development and growth, but its absorption brings several benefits to some crops, especially rice, by increasing cellular wall thickness, providing mechanical resistance to the penetration of fungi, improving the opening angle of leaves and making them more erect, decreasing self-shading and increasing resistance to lodging, especially under high nitrogen rates. To evaluate the effects of nitrogen and silicon fertilization on vegetative and yield components, plant height, and yield of rice cultivar IAC 202, an experiment was carried out combining three nitrogen rates (5, 75 and 150 mg N kg-1 soil) applied as urea, and four silicon rates (0, 200, 400 and 600 mg SiO2 kg-1 soil) applied as calcium silicate. Trial was set up in a completely randomized design 3 ´ 4 factorial scheme, (N = 5). Nitrogen fertilization increased the number of stems and panicles per square meter and the total number of spikelets, reflecting on grain productivity. Excessive tillering caused by inadequate nitrogen fertilization reduced the percentage of fertile stalks, spikelet fertility and grain mass. Silicon fertilization reduced the number of blank spikelets per panicles and increased grain mass, but did not affect grain productivity.

Correção da acidez e mobilidade de íons em Latossolo com aplicação superficial de escória, lama cal, lodos de esgoto e calcário

The experiment was carried out under field conditions in a no-tillage system from 2002 to 2005, aiming to evaluate liming, base saturation and nitrate, calcium and magnesium mobility in a dystrophic Clay Rhodic Hapludox soil. The possible interference of organic acid catering of black oat through surface application of flue dust, aqueous lime and sewage sludge from a centrifuge and a biodigestor were also evaluated at rates of zero (control), 2, 4 and 8 t ha -1 as well as an additional treatment of dolomitic limestone at the rate of 2 t ha -1 . Due to the increasing surface applications of flue dust, aqueous lime and sewage sludge from a centrifuge, soil pH value increased; these three residues and the sewage sludge from a biodigestor increased base saturation and availability of nitrate, calcium and magnesium up to the depth of 40 cm and within three months only. The low concentration of organic acid in the aerial part of the black oat did not explain the quicky nutrient leaching and soil acidity neutralization in depth. Flue dust, aqueous lime and sewage sludge from a centrifuge can be used as an acidity corrective and applied on the soil surface in no-tillage system.

Fósforo no solo e desenvolvimento de soja influenciados pela adubação fosfatada e cobertura vegetal

The efficiency of phosphate fertilizers can be affected by phosphate sources, soil properties, way of application and plant species. The objective of this work was to evaluate the effect of phosphorus levels and cover crops residues on phosphorus dynamics in the soil and soybean initial growth. The experiment was carried out in a greenhouse in pots containing a dystrophic Red Latosol (Typic Hapludox). The treatments consisted of three cover crop residues: pear millet ( Penisetum americanum L.), oats (Avena strigosa) and guinea sorghum (Sorghum bicolor) at 8 t ha -1 , interacting with 0, 50, 100 and 150 kg ha -1 of P , applied over straw mulch, as simple superphosphate. Phosphorus levels and the different residues affected P transport through the soil. Pear millet was more efficient in leaching available P while oats and guinea sorghum were more effective in leaching organic phosphorus.

Disponibilidade de metais pesados em Latossolo com aplicação superficial de escória, lama cal, lodos de esgoto e calcário

The objective of this work was to evaluate the soil chemical attributes and exchange of cadmium (Cd), chromium (Cr), nickel (Ni), mercury (Hg), lead (Pb) and arsenic (As) by DTPA extractor in an Oxisol with surface application of flue dust, aqueous lime, sewage sludge in rates of zero (control), 2, 4 and 8 Mg ha-1 and one additional treatment of dolomitic limestone at 2 Mg ha-1. The experiment was carried out in a randomized blocks design under field conditions, in a no-tillage system in 2003 and 2004. The surface applications of flue dust, aqueous lime and sewage sludge centrifuge and biodigestor at 8 Mg ha-1, as well as the application of limestone at 2 Mg ha-1, cause no problems of exchange to the environment, related to the heavy metals Cd, Cr, Hg, Pb, Ni and As, when applied on an Oxisol surface in no-till system. The bioavailability of heavy metals to soybean and black-oat cultures was zero, when were applied 8 Mg ha-1 sewage sludge, flue dust, and aqueous lime on soil surface in no-till system.

Aplicação superficial de diferentes fontes de corretivos no crescimento radicular e produtividade da aveia preta

Em solos acidos, a pratica da calagem superficial favorece o crescimento radicular, principalmente na superficie do solo, bem como a produtividade das culturas em condicoes normais de precipitacao pluviometrica. Entretanto, pouco se sabe sobre a adocao desta pratica e suas eventuais acoes, no solo e nas plantas, em relacao a outras fontes de corretivos. O objetivo do trabalho foi avaliar o efeito da aplicacao superficial de diferentes corretivos nos atributos quimicos do solo, no crescimento radicular, da parte aerea e na produtividade da aveia preta. O trabalho foi desenvolvido em campo sobre Latossolo Vermelho distrofico, durante o ano agricola de 2004, dois anos apos a aplicacao superficial dos corretivos, no sistema plantio direto. Os tratamentos constituiram da aplicacao superficial de calcario dolomitico, escoria de aciaria - E, lama cal - Lcal, lodo de esgoto centrifugado - LC e sem aplicacao de corretivo, em delineamento em blocos casualizados com quatro repeticoes. A aplicacao superficial de calcario, escoria de aciaria, lama cal, lodo de esgoto centrifugado permitiu o aumento nos valores de pH, no teor de Ca, na maior disponibilidade de P e na reducao dos teores de Al no solo. O crescimento do sistema radicular, o desenvolvimento da parte aerea e a produtividade da aveia preta foram incrementados com a aplicacao superficial dos corretivos de acidez no sistema plantio direto.

Enraizamento de estacas de azaléia tratadas com concentrações de ANA em diferentes substratos

De acordo com a necessidade de aumentar a producao de mudas de azaleia por meio da propagacao vegetativa, em menor intervalo de tempo, foi proposto estudar os efeitos de diferentes substratos e concentracoes de ANA (acido naftalenoacetico). O experimento foi conduzido em esquema fatorial 3X4 com tres substratos (areia grossa lavada, casca de arroz carbonizada e humus) e quatro concentracoes de ANA na forma de po (0; 2,5; 5,0 e 7,5%). Utilizaram-se estacas de 100 mm de comprimento retiradas da porcao apical do ramo, sem gema apical e com corte em bisel na parte superior, deixando um par de folhas cortadas ao meio. Essas foram colocadas para enraizar em bandejas de isopor de 128 celulas, por um periodo de 90 dias, nas quais avaliaram-se: comprimento, superficie, volume e diâmetro radicular e a porcentagem de estacas enraizadas, sobreviventes, mortas e numero de brotos. Pode-se concluir que a maior porcentagem de enraizamento foi obtida no substrato de casca de arroz carbonizada e com ANA na concentracao de 5%.

Doses de boro e crescimento radicular e da parte aérea de cultivares de arroz de terras altas

Appropriate boron (B) availability in soils favors root growth, and a sufficient supply of this micronutrient is very important for adequate rice development and yield in upland fields, depending on the cultivars and soil type. This study aimed at evaluating the influence of B addition on growth of roots and shoot of three upland rice cultivars. The experiment was carried out in a greenhouse, in 10 L pots containing 8 kg of an Hapludox; the experiment was in a completely random 3 x 3 factorial design, with four replications. The treatments consisted of three rice cultivars (Caiapo, Primavera, and Maravilha) and three B rates (0, 3 and 6 mg dm-3), as borax. The B rate of 6 mg dm-3 boron was deleterious to dry matter yield of both roots and shoot in upland rice. Besides the greater absorption capacity, cultivar Maravilha was more tolerant to high B doses in the soil, thus root length, diameter and surface were not negatively affected.

Resposta de plantas de alho livres de vírus ao nitrogênio em ambiente protegido

Nitrogen fertilization associated to the utilization of bulb free of virus enhances garlic yield and quality and it can incentive growers to invest in the crop whereas it allows a better economic return. The aim of this research was to evaluate the relative chlorophyll index (RCI), plant nutrition and total and commercial garlic yield and verify the correlation among these variables in relation to nitrogen fertilization. The experiment was carried out under greenhouse from May to September 2006. The experimental design consisted of randomized blocks with six replications. The treatments were application of crescent levels of nitrogen corresponding to 0, 20, 40, 80, 160, and 320 kg N ha-1. The N source was ammonium nitrate; 25% of the dose was applied when plants presented 3 or 4 leaves, 25% when plants presented 5 or 6 leaves, and 50% after the differentiation. The application of crescent levels of nitrogen proportioned higher relative chlorophyll index (RCI), increased the N content and reduced P and K content in leaves, enhanced total and commercial yield without secondary growth.

Boron rates for triticale and wheat crops

No reports are registered on responses to boron fertilization nutrient deficiency and toxicity in triticale crops. The aim of this study was to evaluate triticale response to different rates of boron in comparison to wheat in an hapludox with initial boron level at 0.08 mg dm-3 4 ´ 4 factorial design trial completely randomized blocks design (n = 4). Boron rates were 0; 0.62; 1.24 and 1.86 mg dm-3; triticale cultivars were IAC 3, BR 4 and BR 53 and IAPAR 38 wheat crop was used for comparison. The wheat (IAPAR 38) crop presented the highest boron absorption level of all. Among triticale cultivars, the most responsive was IAC 53, presenting similar characteristics to wheat, followed by BR 4; these two crops are considered tolerant to higher boron rates in soil. Regarding to BR 53, no absorption effect was observed, and the cultivars was sensitive to boron toxicity. Absorption responses differed for each genotype. That makes it possible to choose and use the best-adapted plants to soils with different boron rates.