711 research outputs found
Copper modulates the biochemical and enzymatic activity and growth of tomato cultivars grown in vitro
Received: August 25th, 2020 ; Accepted: December 17th, 2020 ; Published: February 09th, 2021 ; Correspondence: [email protected] (Cu) is a micronutrient that is neglected for tomato growth. This study sought
to identify the effects of exposure to Cu on the growth and biochemical activity of two tomato
cultivars. Tomato seeds of ‘Carolina’ and ‘Cereja’ cultivars were disinfected and inoculated in
MS medium plus copper sulfate concentrations (CuSO4) (default MS, 25, 50, and 100 µm) and
had their growth monitored for 30 days. It was estimated that the growth and biomass
accumulation of tomato plants ‘Carolina’ and ‘Cereja’, both from the aerial part and the roots,
were benefited by 25 e 50 µm of CuSO4. However, it was observed that these concentrations were
inefficient in controlling hyperhydricity and leaf deformation. There was a reduction of these
phenomena in the treatment with 100 µm, in both cultivars. Tomato of ‘Carolina’ cultivar
subjected to 100 µm showed an increase in anthocyanins and superoxide dismutase (SOD)
activity in the root system. There was a reduction of catalase (CAT) activity in shoots exposed to
Cu. ‘Cereja’ tomatoes subjected to 100 µm showed an increase in CAT and SOD activity in
shoots and roots, respectively. It was concluded that the ‘Carolina’ and ‘Cereja’ tomatoes have
their growth impaired when exposed to 100 µm CuSO4. Concentrations higher than 50 µm of
CuSO4 cause an increase in the antioxidant activity in the shoot of tomato plants from the
‘Carolina’ cultivar. Concentrations higher than 50 µm CuSO4 increase SOD activity in the root
system of tomato plants from the ‘Cereja’ cultivar
Acumulação diferencial de nutrientes por cinco cultivares de milho (Zea mays L.): I - acumulação de macronutrientes
The objective of the present work was to examine the differences in growth, yield, accumulation and transport of nutrients between the cultivars Agroceres 256, Agroceres 504, Centralmex, H-7974 and Piranão. The experiment was carried out in the municipality of Piracicaba, State of São Paulo, Brazil. The soil type was a sandy oxisol of medium fertility, expect for K which was low. The experimental set-up was a randon block design with four replications. Common cultivation practices were followed, and the fertilizer used consisted of 83 g of a formula: 30-120-70, per meter length at planting, and 33 g of the formula: 50-0-45 per meter length as dressing 22 days after germination. The plant population density was 50,000 per hectare. Plants were collected for analysis at 20 days after germination, and there after at intervals of 20 days up to 120 days. The plants were divided into "stems + leaves", tassels, and ears for chemical analysis of N, P, K, Ca, Mg and S. Conclusions: Growth - The cultivars produce maximum quantities of dry matter of 327 to 381 g per plant at the age of 100 to 106 days. - Differences between cultivars in terms of dry matter accumulation in the vegetative parts of the plant is not necessarily relate to the dry weight of the ear. Accumulation of nutrients - There are no differences in the quantity of N, P and K taken-up by the cultivars, although during the period of rapid growth some differences may appear. - Differences in the accumulation of Ca, Mg and S are detected when the quantities of these nutrients approach the maximum. The cultivar H-7974 presented the highest quantities of Ca and Mg where as Agroceres 504 was richest in S. - The maximum level of nutrients are attained in the following period in days: N (89-100); P (101 -120); K (58-66); Ca (75-94); Mg (100-120) and S (93-95). - The maximum quantities taken-up in mg/plant are:N (3,169-3,878);P (541-642); K (3,850-4,693); Ca (582-782); Mg (654-943); S (444-799). Yield - No differences were found between cultivars for grain production. Transport of nutrients - The re were no differences in the amounts of nutrients in the grain between cultivars. - The transport of nutrients into the ears of the different cultivars are the following order (per hectare harvested, 50,000 plants): N (111-143 kg); P (22-30 kg); K (30-45 kg); Ca (0.7-1.1 kg); Mg (10-12 kg) and S (9-13 kg).No presente trabalho, os autores apresentam os resultados de um ensaio de campo empregando os cultivares Agroceres 256, Agroceres 504, Centralmex, H-7974 e Piranão no sentido de aquilatar diferenças no crescimento, produção e acumulação e exportação de nutrientes. O ensaio foi conduzido num regossol de fertilidade mediana, exceto em relação ao K que é baixo, situado no Município de Piracicaba, SP. O delineamento experimental utilizado foi de blocos ao acaso com 4 repetições. Foram seguidas as práticas culturais comuns, e a adubação constituiu de 83 g da fórmula 30-120-70 por metro linear por ocasião do plantio e 33 g por metro linear da fórmula 50-0-4, em cobertura 22 dias após a germinação. Plantas foram coletadas a partir dos 20 dias após a germinação, em intervalos de 20 dias até os 120 dias. As plantas foram divididas em "colmo + folhas", pendão e espiga e analisadas para N, P, K, Ca, Mg e S. Concluíram os autores que diferenças entre cultivares na acumulação de matéria seca na parte vegetativa não se traduzem, necessariamente, por um aumento de peso da matéria seca na espiga. Os cultivares atingem o máximo da quantidade de nutrientes nas seguintes épocas, em dias: N (89-100); P (101-120); K (58-66); Ca (74-94); Mg (100-120); S (93-95). Verificaram, ainda, que as quantidades máximas extraídas em mg/planta são: N (3169-3878); P (541-642); K (3850-4693); Ca (582-782); Mg (654-943); S (444-799). Finalmente, a exportação de nutrientes nas espigas por hectare (50.000 plantas) colhidas é: N (111-143 kg); P (22-30 kg); Ca (0,7-1,1 kg); Mg (10-12kg); S(9-13kg)
Acumulação diferencial de nutrientes por cinco cultivares de milho (Zea mays L.): III - diagnose foliar
The objective of the present work was to examine the differences in nutrients levels between the cultivars Agroceres 256, Agroceres 504, Centralmex, H-7974 and Piranão. The experiment was carried out in the municipality of Piracicaba, State of São Paulo, Brazil. The soil type was a sandy "Regossol" of medium fertility. Common cultivation practices were followed, and the fertilizer used consisted of 83 g of a formula: 30-120-70, per meter length at planting, and 33 g of the formula 50-0-45 per meter length as a dressing. The plant population density was 50,000 per hectare. Sixty days after planting and at flowering the leaves (+4) and the ear leaf, respectively, were harvested for diagnostic purposes. It was observed that differences exist in the concentrations of P, K, Ca, Mg and Fe in the leaf (+4) dry matter of the cultivars at 60 days after planting, and in the concentrations of P, K, Cu and Fe during flowering. Such differences did not affect the production of grain. The extent of the differences between cultivars in the levels of nutrients in the leaves depends on the period of sampling. The harvestry of leaves at determined physiological periods tend to dimi-nuish these differences. Cultivars with similar yield potential may be regarded equally in relation to their leaf analysis, provided that one adopts an adequate range of nutrient levels.O trabalho foi desenvolvido com a finalidade de se aquilatar diferenças nos níveis críticos entre os cultivares Agroceres 256, Agroceres 504, Centralmex, H-7974 e Piranão. O ensaio foi conduzido no Município de Piracicaba, SP, tendo como suporte um Regossol arenoso de média fertilidade. Foram seguidas as práticas culturais comuns e a adubação constuiu de 83 g da fórmula 30-120-70, por metro linear no plantio e 33 g/ /metro linear da fórmula 50-0-45 em cobertura. A população de plantas foi de 50.000 por hectare. Aos 60 dias após o plantio e no florescimento foram coletadas as folhas (+4) e da inserção da espiga, para fins de diagnose. Foram observadas diferenças nas concentrações de P, K, Ca, Mg e Fe, na matéria seca das folhas (+4) dos cultivares aos 60 dias após o plantio, e nas concentrações de P, K, Cu e Fe na folha da inserção da espiga, na fase de florescimento. Diferenças estas que não afetam a produção de grãos. A extensão das diferenças entre cultivares nos níveis foliares dos nutrientes depende da época de amostragem. As coletas feitas em épocas fisiológicas determinadas tende a diminuir estas diferenças. Cultivares com potenciais de produção semelhantes podem ser tratados igualmente em relação à análise de folhas, desde que se adote uma faixa de teores adequados
Acumulação diferencial de nutrientes por cinco cultivares de milho (zea mays L): II - acumulação de micronutrientes
The objective of the present work was to examine the differences in growth, yield, accumulation and transport of nutrients between the cultivars Agroceres 256, Agroceres 504, Centralmex, H-7974 and Piranão. The experiment was carried out in the municipality of Piracicaba, State of São Paulo, Brazil. The soil type was a sandy oxisol of medium fertility, except for K which was low. The experimental set-up was a randon block design with four replications. Common cultivation practices were followed, and the fertilizer used consisted of 83 g of a formula: 30-120-70, per meter lenght at planting, and 33 g of the formula: 50-0-45 per meter lenght as dressing 22 days after germination. The plant population density was 50,000 per hectare. Plants were collected for analysis at 20 days after germination, and there after at intervals of 20 days up to 120 days. The plants were divided into "stems + leaves", tassels, and ears for chemical analysis of Cu, Fe, Mn and Zn. Conclusions: Accumulation of nutrients - Differences in the accumulation of micronutrients appeared before the period of rapid growth (20 days) although afterwards no differences were detectable. - The maximum level of nutrients are attained in the following period (in days): Cu (101 -104); Fe (106-120); Mn (82-94); Zn (87-108). - The maximum quantities taken-up (in mg/plant) are: Cu (2.06-3.49); Fe (26.66- -36.29); Mn (9.92-14.39); Zn (5.88-6.69). Transport of nutrients - The transport of nutrients into the ears of the different cultivars are (per ha harvested): Cu (26-35 g); Fe (200-220 g); Mn (90-140 g); Zn (160-250 g).No presente trabalho, os autores apresentam os resultados de um ensaio de campo empregando os cultivares Agroceres 256, Agroceres 504, Centralmex, H-7974 e Piranao no sentido de aquilatar diferenças na acumulação e exportação de micronutrientes. O ensaio foi conduzido num regossol de fertilidade mediana, exceto em relação ao K que é baixo, situado no município de Piracicaba, SP. O delineamento experimental utilizado foi de blocos ao acaso com 4 repetições. Foram seguidas as práticas culturais comuns e a adubação constituiu de 83 g da fórmula 30--120-70 por metro linear por ocasião do plantio e 33 g por metro linear da fórmula 50-0-4, em cobertura 22 dias após a germinação. Plantas foram coletadas a partir dos 20 dias após a germinação, em intervalos de 20 dias até os 120 dias. As plantas foram divididas em "colmo + folhas", pendão e espiga e analisadas para B, Cu, Fe, Mn e Zn. Concluíram os autores que diferenças na acumulação de micronutrientes manifestam-se antes da fase de crescimento intenso. Os cultivares atingem o máximo da quantidade dos nutrientes nas seguintes épocas, em dias:Cu (61-85); Fe (71-76); Mn (82-94); Zn (87-108). Verificaram, ainda, que as quantidades máximas extraídas em mg/planta são:Cu (2,06--3,49); Fe (26,66-36,28); Mn (9,92-14,39); Zn (5,88-6,69). Finalmente a exportação de nutrientes nas espigas por hectare (50.000 plantas) colhidas é: Cu (26-35 g); Fe (200-220 g); Mn (90-140 g) e Zn (160-250 g)
Universal Critical Behavior of Aperiodic Ferromagnetic Models
We investigate the effects of geometric fluctuations, associated with
aperiodic exchange interactions, on the critical behavior of -state
ferromagnetic Potts models on generalized diamond hierarchical lattices. For
layered exchange interactions according to some two-letter substitutional
sequences, and irrelevant geometric fluctuations, the exact recursion relations
in parameter space display a non-trivial diagonal fixed point that governs the
universal critical behavior. For relevant fluctuations, this fixed point
becomes fully unstable, and we show the apperance of a two-cycle which is
associated with a novel critical behavior. We use scaling arguments to
calculate the critical exponent of the specific heat, which turns out
to be different from the value for the uniform case. We check the scaling
predictions by a direct numerical analysis of the singularity of the
thermodynamic free-energy. The agreement between scaling and direct
calculations is excellent for stronger singularities (large values of ). The
critical exponents do not depend on the strengths of the exchange interactions.Comment: 4 pages, 1 figure (included), RevTeX, submitted to Phys. Rev. E as a
Rapid Communicatio
Hidden non-Fermi liquid behavior due to crystal field quartet
We study a realistic Kondo model for crystal field quartet ground states
having magnetic and non-magnetic (quadrupolar) exchange couplings with
conduction electrons, using the numerical renormalization group method. We
focus on a local effect dependent on singlet excited states coupled to the
quartet, which reduces the non-magnetic coupling significantly and drives
non-Fermi liquid behavior observed in the calculated quadrupolar
susceptibility. A crossover from the non-Fermi liquid state to the Fermi liquid
state is characterized by a small energy scale very sensitive to the
non-magnetic coupling. On the other hand, the Kondo temperature observed in the
magnetic susceptibility is less sensitive. The different crystal-field
dependence of the two exchange couplings may be related to the different
dependence of quadrupolar and magnetic ordering temperatures in
CeLaB.Comment: 7 pages, 5 EPS figures, REVTe
Decomposition and nutrient release of leguminous plants in coffee agroforestry systems.
Leguminous plants used as green manure are an important nutrient source for coffee plantations, especially for soils with low nutrient levels. Field experiments were conducted in the Zona da Mata of Minas Gerais State, Brazil to evaluate the decomposition and nutrient release rates of four leguminous species used as green manures (Arachis pintoi, Calopogonium mucunoides, Stizolobium aterrimum and
Stylosanthes guianensis) in a coffee agroforestry system under two different climate conditions. The initial N contents in plant residues varied from 25.7 to 37.0 g kg-1 and P from 2.4 to 3.0 g kg-1. The lignin/N, lignin/polyphenol and(lignin+polyphenol)/N ratios were low in all residues studied. Mass loss rates were highest in the first 15 days, when 25 % of the residues were decomposed. From 15 to 30 days, the decomposition rate decreased on both farms. On the farm in Pedra Dourada (PD), the decomposition constant k increased in the order C. mucunoides < S. aterrimum < S. guianensis < A. pintoi. On the farm in Araponga (ARA), there was no difference in the decomposition rate among leguminous plants. The N release rates varied from 0.0036 to 0.0096 d-1. Around 32 % of the total N content in the plant material was released in the first 15 days. In ARA, the N concentration in the S. aterrimum residues was always significantly higher than in the other residues. At the end of 360 days, the N released was 78 % in ARA and 89 % in PD of the initial content. Phosphorus was the most rapidly released nutrient (k values from 0.0165 to 0.0394 d-1). Residue decomposition and nutrient release did not correlate with initial residue chemistry and biochemistry, but differences in climatic conditions between the two study sites modified the decomposition rate constants
Green manure in coffee systems in the region of Zona da Mata, Minas Gerais: characteristics and kinetics of carbon and nitrogen mineralization.
The use of green manure may contribute to reduce soil erosion and increase the soil organic matter content and N availability in coffee plantations in the Zona da Mata, State of Minas Gerais, in Southeastern Brazil. The potential of four legumes (A. pintoi, C. mucunoides, S. aterrimum and S. guianensis)to produce above-ground
biomass, accumulate nutrients and mineralize N was studied in two coffee plantations of subsistence farmers under different climate conditions. The biomass production of C. mucunoides was influenced by the shade of the coffee plantation.C. mucunoides tended to mineralize more N than the other legumes due to the low polyphenol content and polyphenol/N ratio. In the first year, the crop establishment of A. pintoi in the area took longer than of the other legumes, resulting in lower biomass production and N2 fixation. In the long term, cellulose was the main
factor controlling N mineralization. The biochemical characteristics, nutrient accumulation and biomass production of the legumes were greatly influenced by
the altitude and position of the area relative to the sun
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