Marcela Campanharo

Rates of urea with or without urease inhibitor for topdressing wheat

The urease inhibitor NBPT(N-(n-butyl) thiophosphoric triamide) is a management alternative to increase urea efficiency in topdressing because it reduces NH3 volatilization. The objective of this study was to evaluate N recovery and yield performance of wheat ( Triticum aestivum L.) ‘BRS 254’ fertilized with different urea or urea + NBPT rates in topdressing. The experiment was conducted from May to September 2007 in Vicosa, Minas Gerais, Brazil. Treatments followed a 5 × 2 + 1 factorial design consisting of five N fertilizer rates (30, 60, 90, 120, and 150 kg ha-1) as urea or urea + NBPT (Agrotain® ) applied as topdressing and a control without N. The experiment was a randomized complete block design with four replicates. Adding NBPT to urea resulted in better N utilization by wheat plants. The 100 kg N ha-1 topdressing rate provided the best apparent N recovery by wheat plants, whereas 90 kg ha-1 provided the best N use efficiency.

Rates of nitrogen and growth retardant trinexapac-ethyl on wheat

The objective in this study was to evaluate the effects of nitrogen rates in association with rates of the growth retardant trinexapac-ethyl on wheat. The experiment was conducted in Vicosa, MG and arranged in a 5×4 factorial, randomized block design, with four repetitions. A combination of five nitrogen rates (30, 60, 90, 120 and 150kg ha-1) with four rates of trinexapac-ethyl (0, 62.5, 125 and 187.5g ha-1) were tested. Trinexapac-ethyl promotes reduction of soot dry mass and grain yield at the lowest N rates, but at the highest N rates there is increase in these characteristics. The combination between N and trinexapac-ethyl rates that promotes higher shoot dry mass is 150kg ha-1 and 187g ha-1 but that promotes higher grain yield is 100kg ha-1 and 120g ha-1, respectively.

Urease inhibitor (NBPT) and efficiency of single or split application of urea in wheat crop

O NBPT (N-(n-butil) tiofosforico triamida) e uma substância inibidora da urease, que se vem apresentando como das mais promissoras para a maximizacao do uso do nitrogenio da ureia em sistemas agricolas. O objetivo deste estudo foi avaliar o desempenho produtivo do trigo irrigado, submetido a fertilizacao com ureia ou ureia+NBPT aplicadas em dose unica ou parcelada. O experimento foi conduzido, de junho a outubro de 2006, em Vicosa-MG, Brasil. Seguiu-se o esquema fatorial 2×2, em que a ureia ou ureia+NBPT foram combinadas com duas formas de aplicacao: dose total na semeadura (60kg ha-1) ou parcelada (20kg ha-1 na semeadura + 40kg ha-1, em cobertura, no perfilhamento). O delineamento experimental foi o de blocos ao acaso com dez repeticoes. Conclui-se que o parcelamento da fertilizacao nitrogenada nao promove incremento de produtividade do trigo, sob as condicoes de cultivo empregadas; o uso de inibidor de urease aumenta a produtividade da cultura do trigo, quando a ureia e aplicada, em cobertura, durante o perfilhamento, mas, seu uso nao promove aumento da produtividade quando a ureia e aplicada no sulco, durante a semeadura.

COMPOSIÇÃO MINERAL DE GRÃOS DE TRIGO SUBMETIDOS A DOSES DE SULFATO DE AMÔNIO E TRINEXAPAC-ETIL

Grain mineral composition is important for the establishment of appropriate fertilizer levels, as well as to define the nutritional quality of food and physiological quality of seeds. The objective of this study was to evaluate the effect of ammonium sulfate (AS) and trinexapac-ethyl rates on mineral composition of wheat grains ( Triticum aestivum L.) cv. Pioneiro. The experiment was carried out in Vicosa, Minas Gerais State, Brazil, from June to October 2006. The treatments consisted of five AS rates (150 kg ha -1 , 300 kg ha -1 , 450 kg ha -1 , 600 kg ha -1 , and 750 kg ha -1 ) combined with four trinexapac-ethyl rates (0 g ha -1 , 62.5 g ha -1 , 125 g ha -1 , and 187.5 g ha -1 ). The experiment was arranged in a randomized block design with four replications. AS rates increased the concentrations of total-N (protein), Ca, S, Cu, and Zn and decreased the concentrations of P, K, and Mn (at AS rates above 457 kg ha -1 ). The Mg and Fe concentrations were not influenced by AS rates. Trinexapac-ethyl increased total-N, P, and Mn; reduced Ca; and had no influence on the concentrations of K, S, Cu, Zn, Mg, and Fe. It can be concluded that AS application improves the nutritional quality of grains, while the use of the growth retardant trinexapac-ethyl has no influence on its mineral composition. KEY-WORDS: Triticum aestivum L.; nutrition; growth retardant.

Adubação potássica aplicada na axila foliar e no solo em coqueiro anão verde

Potassium (K) directly influences the productivity of coconut dwarf to be activator of enzymes involved in respiration and photosynthesis, among other functions. However in many cases their implementation on the ground has not provided adequate leaf levels. It was evaluated the influence of doses of KCl applied via soil and via leaf axil on the leaf nutrient concentration in green dwarf coconut tree (Cocos nucifera L.). The experiment was driven at a commercial orchard in Campos dos Goytacazes, Brazil, in a Typic Quartzipsamments, in the period from May 31, 2007 to May 31, 2008, using a randomized complete block design with five treatments and sixteen replicates. Treatments consisted of two application ways (on soil and on the axil of the leaf number nine) and two levels of KCl (1666 and 3333 g of KCl per plant, per year) level 1 and 2 for soil and (833 and 1666 g per plant, per year) level 1 and 2 in for plant axil, with three month interval applications), besides a control, without KCl. Leaf samples were collected before the first fertilization and three months after each fertilization. Application of KCl increased leaf concentrations of K and Cl and it reduced Mg concentration in plant tissue. Leaf concentrations of N; P; Ca; S; B; Cu; Fe; Mn and Zn were not influenced by treatments. Potassium application in the frond axils is an alternative due to better absorption of nutrients compared to conventional fertilization. In addition, frond axils fertilization minimizes loss of nutrients and it is possible to reduce the amounts of potassium applied.

Toxicity symptoms of nickel in common bean

Despite the importance of nickel (Ni) in the N metabolism of legumes, common bean (Phaseolus vulgaris L.) is considered very sensitive to Ni doses. The objective in this study was to characterize the toxicity symptoms of Ni in common bean cv. Perola. The experiment was conducted in greenhouse in the campus of the Universidade Estadual do Norte Fluminense - Darcy Ribeiro, Campos dos Goytacazes - RJ. Solutions containing 0; 20; 40; 60 and 100 mg L -1 of Ni, in the form of nickel chloride hexahydrate (NiCl 2 .6H 2 O), were applied to shoots of common bean plants at the rate of 2.5 mL of solution per plant of common bean, 25 days after sowing. Plants of common bean treated with 0; 20; 40 and 60 mg L -1 of Ni sh owed no toxicity symptoms. Plants treated with 100 mg L -1 of Ni sh owed chlorotic leaves with

Produção de massa seca e teores de nutrientes do feijoeiro comum submetido à deriva de glyphosate em duas classes de solo

, a deriva de glyphosate pode atingir ate 160m alem do local considerado alvo colocando em risco as culturas vizinhas. Assim, o objetivo deste trabalho foiavaliar a materia seca e os teores de nutrientes do feijoeiro comum (Phaseolus vulgaris L.) cv. Perola submetidoa deriva de glyphosate. O experimento foi conduzido em casa de vegetacao na Universidade Estadual do NorteFluminense Darcy Ribeiro - UENF, Campos dos Goytacazes - RJ, utilizando o feijoeiro comum. Utilizou-se odelineamento em blocos casualizados em esquema fatorial 4 x 2 com quatro repeticoes, sendo o primeiro fatorconstituido pelas subdoses de 0; 14,4; 43,2 e 86,4g ha