Produtividade do milho em condições de diferentes manejos do solo e de doses de nitrogênio

Research has been conducted to identify the best nitrogen (N) rate for maize in most diverse types of soil management. However, there is no agreement on the results, once the dynamic of N is influenced by soil management and cover crops. This study evaluated dry mass production and nutrient uptake by cover crops, agronomic parameters and grain yield of maize in response to soil management and N rates. Field trials were carried out in Selvíria, Mato Grosso do Sul State, Brazil, in the growing seasons of 2009/2010 and 2010/2011, on a clayey Rhodic Haplustox (20º 20' S and 51º 24' W, 340 m asl). Thirty-six treatments were established with four replications, in a randomized blocks design, with the combination of cover crops (millet, Crotalaria juncea and millet + Crotalaria juncea), soil management systems (tillage with chisel plow + lightweight disking, heavy disking + lightweight disking, and no-tillage) and topdressing N rates (0, 60, 90 e 120 kg ha-1 - urea as source). Maize hybrid DKB 350 YG® was used and N applied at stage V5 (fifth expanded leaf). A linear increase with the increase of N rates was observed for chlorophyll leaf index, leaf N content, ear length and diameter, and grain weight and yield. Previously grown sunn hemp and millet + sunn hemp grown, associated with 120 kg ha-1 N for maize, induced a higher grain yield after two growing seasons.

Coberturas vegetais, manejo do solo, doses de nitrogênio e seus efeitos na nutrição mineral e nos atributos agronômicos do milho

Research has investigated the best nitrogen rate for maize under the most diverse types of soil management. The aim of this study was to evaluate the influence of cover crops, soil management and topdressed N rates on the dry matter production, nutritional status, plant lodging, plant height and first-ear insertion of maize. Field experiments were carried out in Selvíria, Mato Grosso do Sul State, Brazil, in the growing seasons of 2009/2010 and 2010/2011, on a clayey Rhodic Haplustox (20º 20' S and 51º 24' W, at 340 m asl). Thirty-six treatments were established with four replications, in a randomized blocks design, to test combinations of cover crops (millet, Crotalaria juncea and millet + Crotalaria juncea), soil management (tillage with chisel plow + lightweight disking, heavy disking + lightweight disking, and no-tillage system) and N rates (0, 60, 90 e 120 kg ha-1 - urea as source). The maize hybrid DKB 350 YG® was used and topdressing N applied at stage V5 (fifth expanded leaf). Previously grown sunn hemp and millet + sunn hemp resulted in a higher shoot dry matter, P leaf content and total N, P and K uptake. In the no-tillage system, the initial and final population and shoot dry were highest, and first-ear insertion and plant height lower. The application of 120 kg ha-1 topdressed N increased the P leaf content, N and P in the entire plant, shoot dry matter, total N, P and K uptake, plant height, and the first-ear insertion of maize.

Physiological indexese macro- and micronutrients in plant tissue and essential oil of Mentha piperita L. grown in nutrient solution with variation in N, P, K and Mg levels

Mentha piperita L. is an aromatic and medicinal species of the family Lamiaceae, known as mint or peppermint, and its leaves and branches produce essential oil rich in menthol. This study aimed to evaluate physiological indexes, macro- and micronutrients inthe shootsand essential oil of Mentha piperita L. grown in nutrient solution number 2 of Hoagland and Arnon (1950) with different N, P, K and Mg levels. Shoot length, dry mass of the different organs, total dry mass, leaf area, essential oil yield and composition, and macronutrient (N, P, K, Mg, Ca, S) and micronutrient (Mn, Cu, Fe, Zn) contents in the shoot were evaluated. Plants treated with 65%N/50%P/25%K/100%Mg had a tendency towards longer shoot, greaterroot and leaf blade dry masses, higher essential oil yield, higher menthol levels and lower menthone levels. The results showed that Mentha can be grown in nutrient solution by reducing 65% N, 50% P, 25% K and 100% Mg. This solution had better development compared to the other tested treatments. Therefore,we recommendMentha piperita L. to be grown with such nutrient levels.

Estimativa da área foliar de Euphorbia heterophylla

Leaf area estimate may contribute to understand the relationships of interference among weeds and crops. The objective of this research was to obtain a mathematical equation to estimate the leaf area of Euphorbia heterophylla based on linear measures of the leaf blade. Correlation studies were carried out using the real leaf area and leaf length (C) and the maximum leaf width (L) of 200 leaf blades which were collected from several agroecosystems at Universidade Estadual Paulista in Jaboticabal, SP, Brazil. The evaluated statistic models were: linear Y = a + bx; simple linear Y = bx; geometric Y = ax b; and exponential Y = ab x. All of the evaluated models can be used for E. heterophylla leaf area estimation. The simple linear regression model is suggested using C*L and taking the linear coefficient equal to zero. Thus, an estimate of the leaf area of E. heterophylla can be obtained using the equation Af' = 0.6816*(C*L).

Adubação fosfatada no crescimento inicial e na nutrição de mudas de pinhão-manso

Physic nut (Jatropha curcas L.) is a perennial oilseed species that has aroused economic interest for biodiesel production. Among other factors, it is essential to determine the nutritional demands of this species to facilitate raising it as a crop. This study aimed to evaluate the early growth and mineral nutrition of physic nut, as well as soil fertility, as affected by phosphorus fertilization. The study was carried out in a plastic greenhouse in a completely randomized block experimental design with four replicates. The plants were grown in plastic pots filled with 50 dm³ of Latossolo Vermelho (Rhodic Hapludox). Application rates of 0, 50, 100, 150 and 200 mg dm-3 of P were tested, plus a control. Evaluations of plant height and root collar diameter were performed monthly. The experiment was ended 150 days after transplant of the seedlings, at which time leaf area, dry weight, leaf contents and total accumulation of macro- (N, P, K, Ca, Mg and S) and micronutrients (B, Cu, Fe, Mn and Zn) were performed, and soil chemical properties were analyzed. We concluded that absence of P fertilization alone is as limiting to early growth of physic nut as simultaneous absence of soil amendment and fertilization. The rate of 57 mg dm-3 of P may be recommended for initial growth of physic nut. The total accumulation of nutrients in physic nut seedlings exhibited the following order: K>N>Mg>Ca>P>S>Fe>Mn>B>Zn>Cu. Phosphorus fertilization resulted in increased soil cation exchange capacity (CEC).

Estimativa da área foliar de Panicum maximum usando dimensões lineares do limbo foliar

The objective of this study was to obtain a mathematical equation to estimate the leaf area of Panicum maximum using linear measures of leaf blade. Correlation studies were conducted involving the real leaf area (Sf), the main vein leaf length (C), and the maximum leaf width (L). The linear and geometric equations related to C provided good leaf area estimates. For practical reasons, the use of an equation involving only the C*L product is suggested. Thus, an estimate of P. maximum leaf area can be obtained by the equation Sf = 0.6058 (C*L), with the coefficient of determination R = 0.8586.

Níveis de adubação N-K do abacaxizeiro 'BRS Imperial' no extremo Sul da Bahia

Pós-graduação em Agronomia (Ciência do Solo) - FCAV

Qualidade de sementes, teor de nitrogênio e expressão gênica em genótipos de milho inoculados com Azospirillum brasilense

Pós-graduação em Agronomia (Genética e Melhoramento de Plantas) - FCAV

Arranjo de plantas, características agronômicas e produtividade de soja

Pós-graduação em Agronomia (Agricultura) - FCA

Fungicidas e reguladores vegetais nas características fisiológicas e produtivas de alface ‘Vera’

Pós-graduação em Agronomia (Horticultura) - FCA

Aplicação foliar de indutor de resistência em feijoeiro comum: efeito sobre desempenho da cultura, qualidade fisiológica e sanitária das sementes

Pós-graduação em Agronomia - FEIS

Anatomia foliar e análise de EDX de Costus spiralis (Jacq.) Roscoe de ambiente impactado e não impactado do litoral de São Paulo.

Several plants show morphological changes when exposed to environmental stress. We aimed to analyze comparative anatomy and EDX (energy dispersive x-ray detector) of Costus spiralis (Jacq.) Roscoe leaves from Jureia-Itatins Ecological Station (Peruibe, Sao Paulo), a preserved area, and Mogi River Valley (Cubatao, Sao Paulo) an affected area by pollution from the industrial complex of Cubatao. There were some significant differences in the leaves from the affected area, where they had a smaller abaxial hypoderm, larger size of adaxial hypoderm and larger central vascular core. There were damages in epicuticular wax deposition. The EDX analyses presented only differences in calcium and potassium concentration and presence of manganese in Cubatdo samples. Those leaves presented crystal deposition in the vascular core, probably because of the phosphogypsum residues from fertilizer industries.

Resposta do cafeeiro à inoculação de fungos micorrízicos arbusculares, em latossolo vermelho, do cerrado

The aim of this study was evaluate the response of two coffee cultivars (tolerant and sensitive to aluminum - Al), inoculated or not by two arbuscular mycorriza fungi (AMF), Gigaspora margarita and Glomus etunicatum, in cerrado Oxisol, with different base saturation. This experiment was conducted under greenhouse conditions, with a complete randomized design, in a 2x3x2 factorial scheme, consisting of 2 cultivars (tolerante and sensitive to Al), 3 treatments with mycorrhizal (inoculated with two species of AMF and without inoculation) and 3 levels of soil base saturation (30, 45 and 53 V%), with five replicates per treatment. The variables were: plant height, stem diameter, leaf area, shoot dry weight, root fresh weight, nitrate reductase activity, chlorophyll concentration, root colonization and number of AMF spores. Mycorrhizae isolates promoted greater response of coffee plants, in acid soil with high concentration of Al, but this response was observed for both cultivars when plants were colonized by G. margarita. The cultivars evaluated showed no differences in Al tolerance when non inoculated.

Produção de chicória da amazônia cultivada sob densidades de cultivo e poda do pendão floral

Chicory is a vegetable Amazon unconventional flavor that has attracted the attention of researchers for its great versatility, which makes it a promising vegetable. However, jobs are scarce in the literature on cultivation techniques for the species. This study aimed to evaluate the effect of pruning tassel floral and different spacing, the yield on Amazon chicory. Three different spacings: E1 = 0.15 x 0.15 m, with 44 plants m(2), E2 = 0.20 x 0.20 m, with 25 plants m(2), and E3 = 0.25 x 0.25 m, with 16 plants m(2), with and without pruning floral tassel. The experiment was conducted in a randomized block design in a split plot design 3 x 2, with six replications. The characteristics evaluated were: number of leaves, fresh weight and dry weight of shoots, number of tassel floral tassel floral fresh weight, yield (kg m(-2)), and leaf area index (LAI). The largest production of chicory Amazon was obtained in plants grown at a spacing of 0.25 x 0.25 m subjected to pruning floral tassel. The highest yield for Amazon chicory was obtained in plants grown at a spacing of 0.15 x 0.15 m submitted pruning floral tassel.

Modelagem da área foliar de duas cultivares de amendoim em função das dimensões lineares dos folíolos

The purpose of this study was to determine a shape factor to estimate area of leaflets of two peanut cultivars (IAC TATU ST, IAC RUNNER 886). Correlation studies were conducted involving real leaf area (Sf) and leaf length (C), maximum leaf width (L) and the product between C and L. For each cultivar was determined a form factor (f) by means of regression analysis between the product of the length by the width and the actual area of leaves and the correlation between leaf area estimated by the correction factor and direct measurement. All evaluated models (linear, exponential or geometric) provided good estimates of leaf area (above 87%). Linear models had the best fit, passing or not through the origin. From a practical viewpoint, it is suggested to use the linear model involving the C and L product, using a linear coefficient equal to zero, with values of factor f equal to 0.7111 and 0.7266 for IAC RUNNER 886 and IAC TATU ST, respectively. The method of dimensions is feasible for the estimation of leaf area for both peanut cultivars, for showing good r(2) values (0.97), with errors below 3%, even when used with independent data.