Júlio C. L. Neves

Eficiência de utilização de nutrientes e sustentabilidade da produção em procedências de Eucalyptus grandis e Eucalyptus saligna em sítios florestais do estado de São Paulo

Nutrient use efficiency and growth of three provenances of Eucalyptus grandis and three of E. saligna were evaluated, at 78 months of age, on various sites located in the counties of Angatuba, Itapetininga, Paraibuna, Sao Miguel Arcanjo and Sao Jose dos Campos, in the state of Sao Paulo, Brazil. There was a variation in biomass production among sites, with the highest yield being obtained in Sao Miguel Arcanjo, followed by Paraibuna. The other counties constituted a third group. The genetic materials revealed variations in nutrient use efficiency from site to site. E. grandis showed greater N, P, and Mg nutrient use efficiency than E. saligna. There were no appreciable differences in efficiency between the two species for Ca and K. High nutrient use efficiency is not necessarily related to high productivity. Ca and K are the nutrients that could most limit productivity of the next rotation, when harvesting the stem. However, this limitation can be substantially reduced, especially for Ca, if only stemwood is harvested.

Utilização de água residuária de origem doméstica na agricultura: estudo das alterações químicas do solo

Neste trabalho, teve-se como objetivo principal investigar as alteracoes quimicas do solo, em resposta a aplicacao de agua residuaria filtrada de origem domestica e comparar os resultados com aqueles obtidos com o manejo convencional. O experimento foi implantado na Unidade Piloto de Tratamento de Agua Residuaria e Agricultura Irrigada, localizada na Universidade Federal de Vicosa - UFV. O delineamento experimental constituiu-se de 18 unidades experimentais, cada uma composta de oito plantas. O experimento foi montado segundo o esquema de parcelas subdivididas, tendo nas parcelas os tipos de manejo adotados (convencional - MC e com agua residuaria de origem domestica - MR, com aplicacao de cinco diferentes lâminas) e, nas subparcelas as faixas de profundidade do solo (0 - 0,20; 0,20 - 0,40 e 0,40 - 0,60 m) no delineamento em blocos casualizados (linhas de plantio) com tres repeticoes. Os resultados obtidos permitiram concluir que a adocao do MR foi mais efetiva na melhoria das caracteristicas do solo que o MC.

Utilização de água residuária de origem doméstica na agricultura: estudo do estado nutricional do cafeeiro

The objective of this work was to investigate nutritional status of coffee in response to application of filtered domestic wastewater and to compare the results with conventional agricultural management. The experiment was carried out at the Sewer Treatment Pilot Plant (EPTE), DEA/UFV. The experimental design consisted of 18 plots, each with eight plants. The treatments were distributed in randomized blocks design (planting lines) with three repetitions. According to the results, it may be concluded that the adoption of the management with wasterwater was more effective to improve nutritional status of coffee in comparison to conventional management.

Mineral composition of two Brazilian corn cultivars as a function of cadmium in the nutrient solution

Abstract Plants from the Brazilian corn (Zea mays L.) cultivars CMS 54 and BR 473 were grown in nutrient solutions with 0.0, 0.05, 0.1, 0.5, and 1.0 mg cadmium (Cd) L‐1 for a ten day period. The experiment was a completely randomized block design with the treatments arranged in a 2×5×3 factorial, two corn cultivars, five Cd rates, and three replications. The influence of the Cd rates on the nutritional status of the corn plants was studied. Samples from roots and shoots were analyzed for their Cd, phosphorus (P), potassium (K), sulfur (S), calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), and copper (Cu) contents. At rates above 0.5 mg Cd L‐1, there was an influence of exogenous Cd on the elemental composition of the plants. It seems that with rates above 0.5 mg Cd L‐1, the influence of Cd on the P status of the shoots took place in the CMS 54 but not in the BR 473 cultivar. Similar results for K, Ca, Mg, and S were found. There was competition between the Cd and Zn ions at the absorption sites in the p...

TEORES FOLIARES DOS MACRONUTRIENTES CATIÔNICOS E SUAS RELAÇÕES COM O SÓDIO EM PLANTAS DE MILHO SOB ESTRESSE SALINO

O estresse salino representa um dos mais serios fatores que limitam o crescimento e a producao das culturas, induzindo a modificacoes morfologicas, estruturais e metabolicas nas plantas superiores. Com objetivo avaliar os efeitos da salinidade do solo sobre os teores nutricionais dos macronutrientes cationicos e suas relacoes com o sodio em uma variedade de milho, foi conduzindo em lisimetros de drenagem sob condicoes de casa de vegetacao, montado em delineamento inteiramente casualizado com sete tratamentos, sendo um irrigado com agua doce e sem lixiviacao e seis irrigados com agua salina de 1,2 dS m-1, com fracoes de lixiviacao de 40, 30, 20, 15, 10 e 5% da lâmina de irrigacao aplicada, e tres repeticoes. Os efeitos da salinidade do solo sobre a nutricao mineral da cultura do milho foram avaliados determinando o teor foliar dos macronutrientes cationicos e suas relacoes com o sodio aos 30, 60, 90 e 120 dias apos o plantio. No cultivar avaliado, o aumento da salinidade do solo decorrente da irrigacao com agua salina elevou os teores de sodio, as relacoes Na+/Ca2+, Na+/Mg2+, Na+/K+ e reduziu os teores de calcio, magnesio e potassio, refletindo dessa forma, o desequilibrio nutricional causado pelo estresse nutricional consequente do estresse salino progressivo.

The influence of the soil phosphate capacity factor on soil and plant phosphorus critical levels of different vegetables

A glasshouse experiment was carried out to study the effect of soil characteristics on soil and plant critical levels of P for the growth of tomato (Lycopersicum esculentum) and peruvian carrot (Arracacia xanthorrhiza), in a first cultivation, and cucumber (Cucumis sativus) or lettuce (Lactuca sativa) in a second cultivation. Samples of six soils received six rates of soluble P (0, 100, 200, 450, 700, and 1000 mg of P dm−3 of soil). Soil available P was determined by Mehlich-1 and Bray-1 extractants. Plant tops were harvested, oven dried, and total-P was determined. For lettuce, leaf tissue inorganic P (Pi), organic P and total acid soluble P (Pts) were determined. Soil and plant P critical levels varied for species and soils, and both varied inversely with the phosphate capacity factor (PCF). Critical concentrations of Pts and Pi; varied inversely with soil characteristics associated with soil P adsorption and accounted for the correlation verified between plant critical level and PCF.

Growth of Brazilian Cotton Cultivars in Response to Soil Applied Boron

ABSTRACT The growth of cotton (Gossypium hirsutum L.) was evaluated in a 6 × 5 factorial experiment with 6 boron (B) levels (0.0, 0.5, 1.0, 1.5, 2.0, and 3.0 mg dm−3), 5 cultivars (‘CNPA 8H’, ‘BRS Aroeira’, ‘BRS Antares’, ‘BRS Sucupira’, ‘BRS Ipe’), and 3 replications. As B increased in the soil, leaf B concentrations increased linearly in ‘BRS Aroeira’ and ‘CNPA 8H’, and quadratically in ‘BRS Ipe’ and ‘BRS Sucupira’. The concentrations of B in the leaves and in the soil increased with the B increasing in the soil. The agronomic characteristics evaluated showed ‘BRS Aroeira’ and ‘BRS Sucupira’ responding more and BRS responding less to the B doses applied. The variation in the effFiciency of B utilization was: ‘BRS Aroeira’ > ‘CNPA 8H’ = ‘BRS Antares’ > ‘BRS Sucupira’ > ‘BRS Ipe’. Cultivar ‘BRS Aroeira’ had the greatest potential to respond positively to the addition of B to the soil.

Zinc deficiency affects physiological and anatomical characteristics in maize leaves

Zinc (Zn) is an essential microelement involved in several plant physiological processes. Therefore, it is important to identify Zn deficiencies promptly--before extensive damage occurs to the plant. The diagnostic tools that are used to identify Zn deficiencies are very important in areas where Zn deficiencies occur. Such diagnostic tools are vital for nutritional management and fertilizer recommendations. The current study investigated the effects of Zn deficiency on maize plants by recording a number of physiological and anatomical parameters. A Zn omission trial (from 0 to 22 days) was carried out to produce plants that had varying degrees of Zn deficiency. Typical symptoms of Zn deficiency (e.g. chlorotic stripes and purple shades on the edges and leaf sheath) appeared 16 days after the omission of Zn from nutrient solutions. As the time of Zn omission increased, there were significant decreases in net photosynthesis, stomatal conductance, maximal efficiency of photosystem I (evaluated by Fv/Fm), biomass (dry weight) and Zn concentrations in plants. Zinc-deficient plants also had a lower vascular bundle proportion coupled with a higher stomata density. These physiological and anatomical changes negatively impacted plant growth. Moreover, they occurred before visible symptoms of Zn deficiency were observed. Zinc concentrations were recorded for younger leaves, rather than for more mature leaves, which is usually recommended for plant analysis. The results demonstrate that the analysis of Zn in young leaves of maize is a very sensitive indicator of Zn status.

Germination, vigor and growth of bean cultivars in saline solutions

To isolate the effects of high concentrations of different salts in solution, response of osmotic pressure, kind of salts, and pH two trials were performed with two bean cultivars: Diamante Negro and OPNS 331. The treatments consisted of NaNO3, NaCl, NaHCO3, KNO3, KCl, or KHCO3 solutions, and a control without salts, in a randomized block design, with four replicates. In the first trial, germination and vigor were studied in 60 mmol L-1 solutions and growth in a nutrient solution enriched with salts at the indicated concentration. In the second trial, the seeds were germinated in deionized water and the seedlings were transplanted to nutrient solution with 60 mmol L-1 salts at the indicated pH, with an additional treatment in which the pH of the nutrient solution with NaCl was raised to 8.5 to coincide with the bicarbonate solution. The plant growth variables were evaluated for the two bean cultivars studied. The salinity promoted reductions in growth and the harmful effects caused by high salt concentrations and pH, in both common bean varieties under study, may be ranked in the order: osmotic pressure > alkalinity > bicarbonate ≈ chloride > sodium.

Cadmium, Lead, Copper, Zinc, and Nickel in Lettuce and Dry Beans as Related to Mehlich-3 Extraction in Three Brazilian Latossols

ABSTRACT Lettuce (Lactuca sativa L.) and dry beans (Phaseolus vulgaris L.) were grown in three Brazilian Red-Yellow Latossols (Oxisols) in greenhouse conditions with cadmium (Cd), lead (Pb), copper (Cu), zinc (Zn), and nickel (Ni) applied to soils in treatments arranged as a randomized complete block design. Plant metals were analyzed in lettuce shoots and dry beans roots, stems, leaves, and seeds. After plant growth, soil samples from the pots were extracted with Mehlich-3 (M-3) for metal availability evaluation. The release of Ni in the M-3 extraction was dependent on the soil exchangeable aluminum (Al3 +). Mehlich-3 was efficient for determination of availability of Cd, Pb, Cu, Zn, and Ni for dry beans and availability of Cd and Ni for lettuce. The dry bean leaves Cd, Pb, Cu, Zn, and Ni were highly correlated with their recovering from soils with M-3. The same was observed for Cd and Ni in lettuce shoots and the M-3 recovered metals from soils.