Júlio César Lima Neves

Crescimento e qualidade de mudas de Anadenanthera macrocarpa (Benth.) brenan em resposta à saturação por bases do substrato

RESUMO – O presente trabalho foi desenvolvido com o objetivo de verificar a influencia da saturacao por bases do substrato sobre o crescimento e a qualidade de mudas de Anadenanthera macrocarpa (angico-vermelho). O delineamento experimental utilizado foi inteiramente casualizado, com quatro repeticoes por tratamento. Foram empregados tres solos como substrato, e para cada um deles a saturacao por bases original foi elevada aos seguintes valores: Latossolo Distrofico, 30,0; 50,0; e 70,0%; Latossolo Alico, 25,0; 45,0; e 65,0%; e Argissolo, 50,0; 60,0; e 70,0%. Foram avaliados os parâmetros morfologicos das mudas, suas relacoes e o indice de qualidade de Dickson. A saturacao por bases nao teve influencia em nenhum dos parâmetros avaliados quando o substrato utilizado foi o argissolo. Exceto no diâmetro do coleto, a elevacao da saturacao por bases exerceu influencia significativa, com padrao linear sobre os parâmetros morfologicos, suas relacoes e no indice de qualidade de Dickson para mudas produzidas no Latossolo Distrofico. No Latossolo Alico foi observado influencia significativa com um comportamento quadratico sobre as caracteristicas avaliadas, sendo os melhores crescimentos e qualidade encontrados quando a saturacao por bases estava proxima de 50,0%.

Crescimento de mudas de angico-vermelho (Anadenanthera macrocarpa (Benth.) Brenan) sob diferentes doses de macronutrientes

Neste trabalho, objetivou-se avaliar, por meio de caracteristicas morfologicas, o efeito de doses de macronutrientes no crescimento e desenvolvimento de mudas de angico- vermelho (Anadenanthera macrocarpa (Benth.) Brenan) produzidas em amostras de tres classes de solo (Argissolo Vermelho-Amarelo, Latossolo Vermelho-Amarelo alico e Latossolo Vermelho-Amarelo distrofico). As mudas foram plantadas em vasos com capacidade para 2,1 dm3. O experimento foi conduzido no periodo de dezembro de 2004 a maio de 2005. Os tratamentos foram delimitados segundo uma matriz baconiana, em que se variaram os macronutrientes em tres doses diferentes, mais dois tratamentos adicionais (zero e base), com quatro repeticoes. As fontes de N, K e S foram parceladas em quatro vezes (0-30-60-90 dias). Em termos gerais, o maior crescimento das plantas ocorreu no Latossolo Vermelho-Amarelo alico. O nutriente que mais surtiu efeitos significativos foi o P, sendo recomendadas doses de 150 a 250 mg dm-3. Para a aplicacao de N, recomendam-se doses minimas de 50 mg/dm3. A aplicacao de S deve ser de 20 a 80 mg dm-3. As respostas a aplicacao dos demais nutrientes (Ca, Mg e K), em muitos casos, nao ocorreu, evidenciando-se que a especie tem baixo requerimento por eles. Entretanto, partindo desse estudo, sugerem-se novos estudos com os nutrientes K e Ca, para producao de mudas da referida especie nesses solos.

Transporte de boro no solo e sua absorção por eucalipto

The mechanism and magnitude of B transport to plant roots depend on both water and B soil contents. The contribution of mass flow and diffusion to the B transport in soil to eucalypt roots was evaluated in response to the water potential and B rates. Two water potentials (-10 and -40 kPa) and six B levels (0; 0.5; 1; 2; 3 and 5 mg dm-3 of B) were evaluated. The plants were grown in 2.5 dm3 plastic pots with soil, in a greenhouse. The water potential was controlled by a tensiometer in each pot and soil moisture adjusted with distilled water. The maximum root dry weight was produced at rates of 0.98 and 2.38 mg dm-3 of B, at potentials of -10 and -40 kPa, respectively, and the maximum shoot dry weight at rates of 0.96 and 1.82 mg dm-3 of B, at potentials of -10 and -40 kPa, respectively. Positive and highly significant relationships were observed between B rates, soil extractable B, B in soil solution and B plant content at both water potentials. Mass flow was the predominant mechanism for B transport in soil, supplying 100 % of the plant demand in the soils treated with the highest B rates. Diffusion was a complementary mechanism, but its relative increased substantially under conditions of low soil B and greater water deficit.

Determinação de Fe, Zn, Cu e Mn extraídos do solo por diferentes extratores e dosados por espectrofotometria de emissão ótica em plasma induzido e espectrofotometria de absorção atômica

In an attempt to enhance the precision of chemical analyses of soil fertility and quantify different elements simultaneously, some laboratories have opted to use the technique of inductively coupled plasma for optical emission spectrometry (ICP) instead of the technique of Atomic Absorption Spectrometry (AAS), which currently is the most commonly used in soil analysis laboratories. In this study we compared the precision of the two dosage techniques, their repeatability and the magnitude of the concentrations of the micronutrients Fe, Zn, Cu and Mn, extracted through Mehlich-1, Mehlich-3 and DTPA-TEA; Additionaly, we aimed to select the wavelengths of lowest spectral interferences with the ICP. Thirty-six soil samples (0 to 0.2 m) from the states of Minas Gerais and Bahia, Brazil, with varied micronutrient concentrations were used. To define the ICP wavelengths and to evaluate the precision and repeatability of the dosage methods, three of the 36 collected soils were selected. The wavelengths with the lowest spectral interferences in the ICP were: 259.939 nm for Fe in Mehlich-1 and DTPA-TEA and 234.349 nm in Mehlich-3; 213.857 nm for Zn and 324.752 nm for Cu in the three extractors; and 259.372 nm for Mn in Mehlich-1 and DTPA-TEA and 260.568 nm in Mehlich-3. Both ICP and AAS were precise and reproducible for Fe and Mn dosage, while ICP, owing to the lower detection limit, was more precise and reproducible in the Zn and Cu dosages. The dosage methods differed statistically (p < 0.01) by the identity test applied for the Zn, Cu, and Mn dosages, using Mehlich-1, Mehlich-3 and DTPA-TEA, which affected the interpretation of the ICP results, based on the critical levels of AAS.

Influência da saturação por bases e da relação Ca:Mg do substrato sobre o crescimento inicial de jacarandá-da-bahia (Dalbergia nigra (Vell.) Fr. All. ex Benth.)

RESUMO n Com o objetivo de verificar a influŒncia da saturaAao por bases do substrato sobre o crescimento e qualidade de mudas de Dalbergia nigra (jacarandAE-da-bahia), desenvolveu-se este trabalho. O delineamento experimental utilizado foi inteiramente casualizado com quatro repetiAies por tratamento, e cada vaso com uma planta foi considerado uma repetiAao. Foram utilizados trŒs tipos de solo como substrato (dois latossolos e um argissolo), e em cada um deles a saturaAao por bases original foi elevada para os seguintes valores: latossolo distrUfico: 30,0, 50,0 e 70,0%; Latossolo AElico: 25,0; 45,0; e 65,0%; Argissolo: 50,0; 60,0; e 70,0%. Para avaliar os efeitos das diferentes relaAies Ca:Mg do corretivo, elevou-se a saturaAao por bases do solo para 60,0% no argissolo, 50,0% no latossolo distrUfico e 45,0% no latossolo AElico, utilizando como corretivo uma mistura de CaCO 3 e MgCO 3 nas seguintes relaAies estequiomOtricas: 1:0, 1:1, 2:1, 3:1 e 4:1. Foram avaliados os par‚metros morfolUgicos das mudas, suas relaAies e o Indice de qualidade de Dickson. Observou-se uma resposta linear quando as diferentes relaAies Ca:Mg do corretivo foram analisadas em funAao da variaAao do peso de matOria seca da parte aOrea, bem como o peso de matOria seca total quando o substrato era o Argissolo, porOm nos demais substratos e caracterIsticas nao houve influŒncia significativa. Pode-se concluir que, quando a saturaAao original do solo for igual ou superior a 14,0% no Latossolo distrUfico e 4% no Latossolo AElico, nao hAE necessidade de se proceder ‡ correAao do solo, enquanto no Argissolo as mudas de melhor qualidade sao obtidas quando a saturaAao estAE em torno de 60,0%. Palavras-chave: SaturaAao por bases, jacarandAE-da-bahia e qualidade de mudas. GROWTH AND SEEDLING QUALITY OF Dalbergia nigra (VELL.) FR. ALL. EX BENTH.) IN RESPONSE TO BASE SATURATION IN THE SUBSTRATE ABSTRACT n The objective of this work was to verify the influence of the base saturation in the substrate on growth and seedling quality of Dalbergia nigra (Brazilian rosewood). The experiment was arranged in a complete randomized design with four replicates per treatment. Three soils were used as substrate and each one had the original saturation increased as follows: Dystrophic Latosol, 30.0, 50.0 and 70.0%; Alic Latosol, 25.0, 45.0 and 65.0%; Clay soil, 50.0, 60.0 and 70.0%. Seedling morphological parameters, their relationships and the Quality Index of Dickson were evaluated. A linear response was obtained when the different Ca:Mg ratios in lime were analyzed as a function of the dry matter of the aerial part, as well the total dry matter weight when the substrate was argisol, however, there was no significant influence of basis saturation. It can be concluded that when the original saturation in the soil is equal or above 14.0% for the Dystrophic Latosol and 4% for the Alic Latosol there is no need for liming, while in the Clay soil the best seedlings are obtained when the saturation is around 60.0%.

Crescimento de mudas de jacaré (Piptadenia gonoacantha J.F. Macbr.) em diferentes tipos de solos e fontes e doses de nitrogênio

The objective of the present work was to evaluate the growth and the quality of seedlings of Piptadenia gonoacantha in response to nitrogen sources and doses produced in samplings of three different types of soil. The experiment was arranged in a randomized design (DBC), in a factorial scheme (3x5x3), corresponding to three sources (ammonium nitrate, calcium nitrate and ammonium sulphate), and five doses of nitrogen (0, 50, 100, 150 and 200 mg/dm≥ N), applied in a solution in four equal parts 25, 50, 75 and 100 days after seed saving), and three types of soil (Latisol, Argisol and Cambisol) with four repetitions. The morphologic parameters, Dickson quality index, root system nodulation, both active and total and their relations were analyzed. The substrates Argisol and Cambisol and ammonium sulphate provided greater means for the morphologic characteristics evaluated. In r elation to the N doses evaluated in this study, the better means for the morphologic parameters were achieved with the doses varying from 151 to 200 mg/dm 3 N.

Consumo de água em plantios de eucalipto: parte 2 modelagem da resistência estomática e estimativa da transpiração em tratamentos irrigados e não-irrigados

This paper concludes the last part of the work aimed to calculate water consumption in eucalypt plantations. Stomatal resistance was modeled as a function of the following ambient variables: global solar irradiance, vapor pressure deficit and temperature. Based on stomatal resistance modeled from the values observed in the first part of this work, eucalypt transpiration by the Penman-Monteith method could be calculated in some days during the humid and dry periods of the year. Correlation between stomatal resistance and ambient variables was verified. The models generated by this relation proved efficient in calculating the diurnal variation of stomatal resistance as well as hourly and daily transpiration totals.

Total soil electrical conductivity and critical soil K+ to Ca2+ and Mg2+ ratio for potato crops

Soil K+ to Ca2+ and Mg2+ ratio as well as the total salinity were evaluated in response to potassium fertilizer application onto potato. Potassium was applied at six different rates (0, 60, 120, 240, 480 and 960 kg ha-1 of K2O), as K2SO4, and was placed during planting time in the furrow. Soil from the 0-200 mm layer was collected in the furrow, 20 and 48 days after plant emergence (DAE) to evaluate soil pH, K+, Ca2+ and Mg2+ contents and the total electrical conductivity (EC). A factorial design (6x2), with six K rates and two sampling times was set up in a randomized block design with four replications. The application of K fertilizer increased exchangeable K, did not affect pH and exchangeable Ca and Mg contents, but caused a linear increase of the soil K+/(Ca2++Mg2+)1/2 ratio as well as EC. At 20 DAE, the critical soil K+/(Ca2++Mg2+)1/2ratio and the EC associated with maximum tuber yield (30.5 Mg.ha-1, with 353.4 kg ha-1 of K2O) were 1.79 and 1.6 dS m-1, respectively. The highest soil K+/(Ca2++Mg2+)1/2 ratio and EC were obtained with the highest application of K fertilizer, which led to a reduction in the potato tuber yield.

Crescimento de mudas de garapa em resposta à calagem e ao fósforo

RESUMO – Este trabalho teve por objetivo avaliar o desempenho inicial da garapa (Apuleia leiocarpa (Vogel) Macbride) em condicoes diferenciadas de disponibilidade de fosforo (P) no solo e de saturacao por bases (V). Os tratamentos foram arranjados em esquema fatorial combinando seis doses de P (0, 100, 200, 300, 400 e 500 mg dm-3) e cinco niveis de calagem empregando o criterio da saturacao por bases, para calculo (original = 24, 40, 50, 60 e 70%). O delineamento foi em blocos ao acaso com cinco repeticoes. Aos 120 dias apos a semeadura, mediram-se a altura e diâmetro do coleto de todas as plantas, as quais foram colhidas, separadas em raiz e parte aerea e secas, para obtencao de massa seca constante. Os resultados permitiram a conclusao de que o nivel de calagem recomendado para a formacao de mudas de garapa e aquele que proporciona a elevacao da saturacao por bases a 60%, sendo, nessas condicoes, a dose recomendada de P de 54 mg dm -3 . O nivel critico de P no solo foi influenciado pelo valor da saturacao por bases, variando de 6 (V = 60 %) a 33 mg dm -3 (V = 40 %). O nivel critico de P na materia seca da parte aerea tambem foi influenciado pela saturacao por bases, variando de 0,11 (V = 60%) a 0,18 dag kg -1 (V = 50%).

Acúmulo de ácido oxálico e cristais de cálcio em ectomicorrizas de eucalipto.: II- formação de cristais de oxalato de cálcio induzida por fungos ectomicorrízicos em raízes laterais finas

Eucalypt is efficient at taking up Ca from the soil, however little is known about the contribution of ectomycorrhizas and organic acids to this process under field conditions. The accumulation of calcium oxalate crystals (CaOx) was evaluated in, approximately, 2,100 fine lateral roots and ectomycorrhizas of a 2.5-year-old Eucalyptus grandis x Eucalyptus urophylla hybrid, grown in a mountainous area at Vicosa, MG, Brazil. Optical and scanning electron microscopy techniques were used for CaOx observation. Abundant accumulation of calcium as druses or grains in the root cortex cells was observed in 73.7 % of the fine lateral roots. The conspicuous presence of CaOx was observed in 56.2 % of the ectomycorrhizal and in 17.5 % of the nonmycorrhizal fine lateral roots, evidencing the role of the ectomycorrhizal association in calcium storage of eucalypt roots. In the ectomycorrhizal root, druses were the predominant CaOx form, while in nonmycorrhizal roots crystalline grains were more frequent. The 10 ectomycorrhizal morphotypes observed varied in relation to the CaOx content in the root cortex, possibly representing distinct capacities of each ectomycorrizal fungi to supply Ca to the host plant. The analysis of the mantle surface of the different ectomycorrhizal morphotypes by scanning electron microscopy did not detect the presence of CaOx in this structure, confirming that under the conditions evaluated, CaOx accumulation in the association is limited to the root cortex. This is the first report on the occurrence of CaOx in eucalypt ectomycorrhizas in Brazil, with data that demonstrate the existence of calcium storage mechanisms in the ectomycorrhizas in areas with low calcium availability.