Eduardo Lima

Teores e acúmulo de nutrientes durante o ciclo da mandioquinha-salsa em função da aplicação de nitrogênio, fósforo e potássio

The arracacha (Arracacia xanthorrhiza Bancroft) culture, in spite of already being cultivated for a long time in Brazil, has still low information on its nutritional aspect, and the field development. The study of the nutrient distribution inside the plant and their behavior along the vegetative cycle is important to establish a correct fertilizer recommendation, and to provide nutritional information, besides to obtain best commercial root production. The macro and micro nutrient levels and accumulation in the crop were evaluated through a field experiment accomplished with three levels of N, P, and K, in Nova Friburgo, Rio de Janeiro State, using a random blocks experimental design with four repetitions. Four sample periods were observed along the crop cycle, where three sections of the plant (leaves, corm, and roots) were collected; also, changes in nutrient levels of the plant sections were monitored along the time periods. Correlation of the nutrient levels was not observed in the plant parts, in the sampling times, with the commercial roots production. Larger accumulations of the nutrients were observed between the 150 and 210 DAT in the leaves, 210 DAT in the corm and 300 DAT in the roots. The levels were influenced by the applied treatments, but an answer was not observed in the increase of commercial roots production.Apesar da cultura da mandioquinha-salsa (Arracacia xanthorrhiza Bancroft) ser cultivada ha bastante tempo no Pais, informacoes referentes aos seus aspectos nutricionais e seu desenvolvimento no campo sao ainda incipientes. O estudo dos teores de nutrientes e seu comportamento ao longo do ciclo ontogenetico e importante para se estabelecer uma correta recomendacao de fertilizantes, niveis criticos e consequentemente uma maior producao de raizes comerciais. Com o objetivo de avaliar os teores e o acumulo de macro e micronutrientes na cultura durante seu desenvolvimento, foi realizado um experimento de campo com tres niveis de N, P e K, na regiao de Nova Friburgo-RJ, utilizando um delineamento experimental de blocos ao acaso com quatro repeticoes. Foram realizadas quatro amostragens ao longo do ciclo da cultura e coletadas tres partes da planta (folhas, propagulo e raizes), observando-se ao longo do tempo o comportamento dos teores e o acumulo dos nutrientes nessas partes. Nao foi observada correlacao dos teores de nutrientes nas partes da planta, nas epocas de amostragem, com a producao de raizes comerciais. Maior acumulo de nutrientes foi observado entre os 150 e 210 DAT nas folhas, aos 210 DAT nos propagulos e aos 300 DAT nas raizes. Os teores foram influenciados pelos tratamentos aplicados no plantio do experimento, mas nao foi observada resposta no aumento de producao de raizes comerciais.

Impacto dos nutrientes N e K e de açúcares solúveis sobre populações de Diabrotica speciosa (Germar) (Coleoptera, Chrysomelidae) e Agrotis ipsilon (Hüfnagel) (Lepidoptera, Noctuidae) na cultura da batata, Solanum tuberosum L. (Solanaceae)

The occurrence of Diabrotica speciosa (Germar, 1824) and Agrotis ipsilon (Hufnagel, 1767) on the potato cultivars Achat and Monalisa, influenced by nitrogen and potassium dosage, and minimum theor of soluble sugars, was studied. The following parameters were evaluated: concentration of mineral nutrient and sugar in green leaf, senescent leaf, leaf in abscission, stem, tubercle and total plant using extracts of infusion in ethanol 80%. The largest infestation of D. speciosa larvae was on Monalisa cultivar at 150 kg.ha-1 of N + K with 27.03% at P< 0,05. It was observed that the effect of the dosage of N + K in the increment of the concentration of soluble sugars increased the damages in the tubercles and stems by A. ipsilon. The infestation by these species increased to 58.82% on the Monalisa cultivar, when the nitrogen dosage increased from zero to 150 kg.ha-1, in the absence of potassium. On the other hand, high dosage of K reduced the damages by A. ipsilon on Monalisa cultivar. However, it did not influence the storage of soluble sugar. The results indicated that in Achat cultivar the accumulated soluble sugar was reduced, probably sensibilized by elevation of potassic fertilization dosing, differing from Monalisa cultivar, in which the influence was by nitrogen dosing.

Agronomic performance of green cane fertilized with ammonium sulfate in a coastal tableland soil

The recent approach of eliminating the usage of fire for sugarcane harvesting resulted in managing the crop on a trashblanketed soil, to which a proper recommendation of N fertilization is lacking, a problem that remains in the coastal tablelands of the Espirito Santo State, Brazil. This study aimed at evaluating the effect of increasing N rates on stalk and sugar yields and the N use efficiency by the crop. The experimental area planted with sugarcane, at the first ratoon, is located in Linhares, Espirito Santo State. The treatments consisted of N rates varying from 80 to 160 kg N∙ha−1 as ammonium sulphate, and a control without N, in a completely randomized blocks experimental design. Stalk yield increased with the N rate, and fitting the results to a quadratic function suggests no response to fertilizer rates above 130 kg N∙ha−1. The highest margin of agricultural contribution was obtained at the rate of 100 kg N∙ha−1. The N use efficiency decreased from almost 49 to 38%, when the N rate increased from 100 to 160 kg N∙ha−1. There was no effect of increasing N rates on the sugar concentration, although the sugar yield response was positive and strongly influenced by the stalk production. Results showed the importance of reassessing the adequate N rate for maximizing yield in green cane production systems.

Soil organic matter fractions affected by N-fertilizer in a green cane management in Brazilian Coastal Tableland

The recent approach of eliminating the use of fire for sugarcane harvesting (green cane) resulted in managing the crop on a trash-blanketed soil, which changed the content and dynamic of carbon and the nitrogen requirement. These alterations are relevant due to economic and environmental aspects of sugarcane production systems. This study aimed to evaluate changes in total organic carbon (TOC), total nitrogen (TN) and soil organic matter fractions with the application of N-fertilizer on the residues of green cane. The experiment was with sugarcane at the fourth ratoon in Linhares, Espírito Santo State, Brazil. The soil is a Xanthic Dystrudults, originated from Barreiras Group sediments in the coastal tableland region. The treatments were set in a completely randomized blocks experimental SOIL AND PLANT NUTRITION Article Soil organic matter fractions affected by N-fertilizer in a green cane management in Brazilian Coastal Tableland Shirlei Almeida Assunção*, Ana Paula Pessim Oliveira, Lúcia Helena Cunha dos Anjos, Marcos Gervasio Pereira, Eduardo Lima Universidade Federal Rural do Rio de Janeiro Departamento de Solos Seropédica (RJ), Brazil. *Corresponding author: shirleiaassuncao@gmail.com Received: Sept. 4, 2017 – Accepted: Oct. 24, 2017 design and consisted of N (as ammonium sulphate) dosages varying from 80 to 160 kg N.ha–1 and the control. The application of increasing N doses resulted in accumulation of TOC and carbon in the humic, granulometric and oxidizable fractions of soil organic matter (SOM). It was obtained a model adjustment for quadratic regression for TOC, NT and SOM fractions. The doses between 80 and 100 kg N.ha–1 were the most favorable to accumulate carbon and the SOM fractions. N doses higher than 100 kg N.ha–1 favored SOM mineralization. The SOM fractions were responsive to application of N-fertilizer on harvesting residues of the green cane management area.

Avaliação da infestação de insetos-praga associados à batata (Solanum tuberosum L.) sob efeito de nutrientes nitrogenados e potássicos e teores acumulados de aminoácidos livres nas cultivares Achat e Monalisa

Evaluation of insect-pest infestation associated to potato (Solanum tuberosum L.) under effect of nitrogen and potassium fertilizers and the accumulated amount of free aminoacids in Achat and Monalisa cultivars. The objective of this work was to evaluate the occurence of insect-pests on potato plants influenced by dosages of nitrogen and potassium accumulated in plant organs. A total of 169 plants of the Achat and Monalisa cultivars were evaluated to determine the presence-absence of Diabrotica speciosa Germar, 1824 and Agrotis ipsilon Hufnagel, 1767. The experiment was carried out and executed at the Universidade Federal Fluminense, and the delineation was complete randomized block design, with four replication and nine treatments, using three fertilization level (0; 75 and 150 Kg/ha) with N-urea + KCl. The aminoacid levels were adjusted by the Leucine standard-curve (µg/l), using the Ninhydrin method, at 570 nm. The results showed that the tubercles of Monalisa accumulated high free aminoacid levels with 7,95% in the treatment N1K2 and 7,75% in the N2K1.These treatments, induced the infestation by D. speciosa larvae in 27,03%, when the aminoacid level was 2,01 ± 0,58% (X ± EP), with probability of 0,0196<P<0,05. The studied cultivars showed a diferential behavior, especially, in relationship to the N and K metabolism, resulting in the accumulation of free aminoacids, and consequently in the pest infestation increment. The results indicated that the aminoacid level increasing affects the tubercles production, mainly in the Monalisa cultivar, in winter cropping with long dry periods.