• Authors:
    • Garcez, F.
    • Bacchi, L.
    • Gavassoni, W.
    • Silva, F.
  • Source: Summa Phytopathologica
  • Volume: 37
  • Issue: 3
  • Year: 2011
  • Summary: The effects of crop residues and their extracts on Sclerotinia sclerotiorum are not well documented. Three experiments were conducted with crop residues and their ethanol and partition extracts. Oat, vetch, bean, pearl millet, corn and wheat were assessed under controlled conditions. Sclerotia covered with oat, vetch, bean and pearl millet residues did not germinate carpogenically. Ethanol extracts of oat and vetch residues were efficient in inhibiting carpogenic germination whereas pearl millet and wheat did not differ from control. All partitioned ethanol extracts inhibited germination. Crop residues negatively affected the number of apothecia per sclerotium.
  • Authors:
    • Carneiro, L.
    • Furtini Neto, A.
    • Silva, T.
    • Paludo, V.
  • Source: SEMINA-CIENCIAS AGRARIAS
  • Volume: 32
  • Issue: 4
  • Year: 2011
  • Summary: This work aimed to evaluate biomass production and phosphorus uptake by cover crops growing in two different soil types fertilized with two different sources of phosphorus. The experiment was carried out under greenhouse condition, at the Department of Soil Science, Federal University of Lavras. The experimental set up was a completely randomized design, in a 5*2*2 factorial scheme, testing five cover crops ( Brachiaria decumbens, Brachiaria brizantha cv. Marandu, Panicum maximum cv. Tanzania, Avena strigosa - oat cv. Common and Lupinus albus L. - lupine cv. Common), two P fertilizers (triple superphosphate - ST and rock phosphate araxa - FA), and two soil types (Oxisol - LVdf and Entisol - RQo), with four replications. Doses of phosphate used were 90 and 50 mg.dm -3 of P, based on the total P 2O 5 in LVdf and RQo, respectively. Plants were harvested 70 days after seedling emergence. In both soils, shoot and root biomass was higher in the ST treatment than in FNA treatment. This was probably due to the higher P accumulation in the plants. Satisfactory vegetative cover was observed when oat was cultivated using ST as a P source. For lupine, best results were obtained using FA as a P source.
  • Authors:
    • Costa, O.
    • Ziech, M.
    • Nornberg, J.
    • Bermudes, R.
    • Viegas, J.
    • Skonieski, F.
    • Meinerz, G.
  • Source: REVISTA BRASILEIRA DE ZOOTECNIA-BRAZILIAN JOURNAL OF ANIMAL SCIENCE
  • Volume: 40
  • Issue: 3
  • Year: 2011
  • Summary: The objective of this work was to evaluate the influence of species intercropped with ryegrass on the botanical and structural composition and the nutritional values of pastures in an agroecological transition system. It was evaluated ryegrass ( Lolium multiflorum Lam.) intercropped with black oats ( Avena strigosa Schreb.), white clover ( Trifolium repens L.) and forage peanut ( Arachis pintoi Krapov. & Gregory). It was used a complete random design with three treatments and three repetitions. The first grazing was done 21 days after emergence of the plants on the pastures with ryegrass and black oats and ryegrass and forage peanuts and 28 days after emergence on the pasture of ryegrass+white clover. The second grazing, on the pasture with ryegras+black oats, occurred 30 days after the first one, whereas on the other pastures, grazing occurred 37 days later. The rates of dry matter (DM) accumulation, from the beginning of period of exclusion until maximal production of dry matter were: 77.7; 75.0 and 71.3 kg/ha/day of DM for the pastures intercropped with white clover, forage peanut and black cover, respectively. Leaf/culm ratio until second grazing, was high on all pastures. Reduction on contents of crude protein according to exclusion days on ryegrass+black oat pasture is lower than on pastures of ryegrass intercropped with white clover or forage peanut.
  • Authors:
    • Urashima, A.
    • Silva, C.
  • Source: Journal of Phytopathology
  • Volume: 159
  • Issue: 11/12
  • Year: 2011
  • Summary: Blast caused by Magnaporthe grisea ( Pyricularia grisea) is a disease that occurs in many important gramineous plants in Brazil such as rice, wheat, triticale and barley. In 2005, the presence of this disease was reported on black oat ( Avena strigosa) at different locations of Parana state. Due to little information of M. grisea that is infecting this host, this work aimed to characterize it at molecular, sexual and pathogenic level. DNA analysis showed that M. grisea from black oat formed a homogenous and genetic distinct group of its own, different from other hosts, including rice, wheat, triticale and barley. Isolate 15720 was an exception, because it was similar to wheat isolate. There was no sexual compatibility between M. grisea from oat and other tested hosts. In pathogenic terms, isolates of M. grisea from oat infected triticale, wheat, rye, millet, barley, sorghum and rice; cross-inoculation was positive with wheat, triticale, rice and barley.
  • Authors:
    • Evangelista, A.
    • Silva, T.
    • Silva, C.
    • Folegatti, M.
    • Alves Junior, J.
  • Source: Engenharia Agricola
  • Volume: 31
  • Issue: 2
  • Year: 2011
  • Summary: The aim of this study was to evaluate the effect of different irrigation levels on canopy and root growth, productivity, and fruit quality of young Tahiti acid lime trees. The experiment was installed in Piracicaba, Brazil in a 1.0-ha orchard plot with 'Tahiti' acid lime trees, grafted on Swingle citrumelo rootstock and carried out from August of 2002 to May 2005. Each treatment was assigned to a drip irrigation level, based on ETc as follows: (T1) non-irrigated, (T2) 25%, (T3) 50%, (T4) 75% and (T5) 100% of ETc determined by weighing lysimeter presented in the orchard plot. Trunk diameter and tree height were evaluated monthly. The roots were evaluated when the trees were 30 and 48 months old. The yield and fruit quality was evaluated in 2004 and 2005. The results showed that irrigation did not influence root distribution in depth, and trees irrigated with 75% and 100% ETc showed horizontal root distribution concentrated until 0.6 m from the trunk. Irrigation did not improve the quality of fruit. Yield increased in all irrigated treatment, but the most efficient yield mean per unit of water applied was the 25% ETc treatment.
  • Authors:
    • Batista, C.
    • Lima, T.
    • Neves, J.
    • Oliveira, R.
    • Berger, P.
    • Aquino, L.
  • Source: REVISTA BRASILEIRA DE ENGENHARIA AGRICOLA E AMBIENTAL
  • Volume: 15
  • Issue: 5
  • Year: 2011
  • Summary: The objective was to evaluate the application of phosphorus doses in parcels in the cotton crop in the systems of cultivation under irrigation and rainfed, being aimed the higher efficiency of phosphate fertilization, in comparison to the traditional application, only at sowing. The experiment was carried out in Quartzanic Neossoil, in the North region of Minas Gerais. The adopted design was randomized blocks, with three replicates. The treatments were the doses of 50 and 120 kg ha -1 of P 2O 5 applied in four ways: PS, P1, P2 and P3 [100/0; 75/25; 50/50; 25/75% of the dose of phosphate fertilizer applied, respectively at the sowing and at 35 days after the emergence (DAE)], in the irrigated and rainfed crops. Two additional treatments, without P, in the crop without and with irrigation, completed the eighteen studied treatments. The increase of the P doses increased the dry mass of aerial part and the number of reproductive structures at 80 DAE, the relative efficiency of the phosphate fertilization and the productivity of cotton in bull. The response to P doses occurred only under irrigation. The parceled application of the phosphate fertilizer did not increase the efficiency of the fertilization in the cotton farm in Quartzanic Neossoil.
  • Authors:
    • Santos Junior, V.
    • Silva, H.
    • Aquino, L.
    • Batista, C.
    • Pacheco, D.
  • Source: Bioscience Journal
  • Volume: 27
  • Issue: 2
  • Year: 2011
  • Summary: This paper objective was to evaluate P levels in irrigated crops or rainfed in productivity and P uptake by cotton plant. The experiment was conducted at the Instituto Federal do Norte de Minas (IFNMG), Campus Januaria. The treatments consisted of three P rates (0, 50 and 120 kg ha -1 of P 2O 5) and three cropping systems (Sprinkler, Dripping and Rainfed). It was adopted the randomized block design in factorial design with three replications. At 80 days after emergence (DAE), leaves, stems, and reproductive structures were collected. Each organ was dried, crushed, and P content determined. P content of each organ was calculated. The macro and micronutrients levels in the fifth fully expanded leaf from the apex to the base (leaf index) were determined. The P and S contents were higher in irrigated plants by dripping. The P and Mg highest values were obtained with 120 kg ha -1 de P 2O 5. The irrigated plants had higher P content in shoots compared to those under rainfed. Regardless of the method, irrigation and the highest P rates increased the quantity of reproductive structures, the quantity of the bolls per plant, and seed cotton productivity.
  • Authors:
    • Carvalho, L.
    • Lima, M.
    • Sofiatti, V.
    • Brito, G.
    • Silva Filho, J.
  • Source: Acta Scientiarum - Agronomy
  • Volume: 33
  • Issue: 1
  • Year: 2011
  • Summary: The objective of this study was to identify physiological traits that could distinguish between cotton genotypes that were tolerant or sensitive to water deficits. The experiment was conducted in a completely randomized design through a factorial combination to analyze four genotypes (BRS 187 8H and ACALA SJ-4 - water deficit tolerant; CNPA 7H and SU-0450/8909 - water deficit sensitive) and two water regimes (watered/always irrigated and stressed/with a water deficit imposed at flowering). Irrigation was suspended for the plants in the water deficit treatment groups when their first flowers appeared. Leaf water potential (psipd) was monitored until the plants reached -3.0 MPa predawn, at which point leaf samples were collected for analysis. The plants were reirrigated and monitored for a recovery to 50% of leaf water potential. The maximum photochemical efficiency ( Fv/Fm), chlorophyll content (SPAD index), relative water content (RWC), disruption of the cell membrane via membrane leakage, carbon isotope composition (delta 13C), seed cotton yield and fiber quality were evaluated. The trends in membrane leakage and carbon isotope composition were different between the tolerant and sensitive genotypes under a water deficit, which makes these physiological traits suitable for screening for tolerance to water deficits in cotton.
  • Authors:
    • Carneiro, P. T.
    • Melo, A. S. de
    • Soares Filho, W. dos S.
    • Gheyi, H. R.
    • Brito, M. E. B.
    • Fernandes, P. D.
  • Source: Acta Scientiarum Agronomy
  • Volume: 33
  • Issue: 2
  • Year: 2011
  • Summary: Water and soil salinity affects the growth, development and production of fructiferous species, such as citrus. The use of tolerant rootstocks can guarantee the agribusiness of citrus under such conditions. Thus, the sensibility to salinity during the phase of rootstock formation of varieties and selected hybrids was studied. The experiment was carried out in a greenhouse, with five levels of irrigation water salinity [control, tap water with electrical conductivity (EC w) of 0.41 dS m -1, and water with EC w of 1.0, 2.0, 3.0 and 4.0 dS m -1] and seven genotypes, in a randomized block design and five replications each consisting of four plants, during 150 day period. Growth and physiologic variables were evaluated. Significant effects of genotypes and salinity in the variables were observed. The most expressive reduction was found for total dry matter with unit increase of EC w. A linear reduction was observed in hybrids LVK * LVA-009 and TSK * TRENG-256. Among the evaluated genotypes 'Volkamer' lemon was the least sensitive to saline stress.
  • Authors:
    • Trentin, G.
    • Maldaner, I. C.
    • Radons, S. Z.
    • Heldwein, A. B.
    • Grimm, E. L.
    • Bosco, L. C.
  • Source: Revista Brasileira de Engenharia Agrícola e Ambiental
  • Volume: 15
  • Issue: 2
  • Year: 2011
  • Summary: The objective of this study was to determine the effect of different levels of irrigation and chemical control on yield and occurrence of Late Blight in potato cv. Asterix, at Santa Maria - RS. Two experiments were conducted at the Crop Science Department, Federal University of Santa Maria. One experiment was carried out during spring-summer, 2005/2006 and the second, during fall 2006. The experimental design was a complete randomized, with four replications. The Blitecast model was used to indicate the timing of spraying, by accumulating severity values (VS). Sprinkler irrigation was used corresponding to 1.0, 0.75, 0.50 ETm and no irrigation. Results showed that in dry and high temperature periods, yield was affected by irrigation, mainly when crop water demand was supplied with 100% ETm. During wet periods, yield was affected by the efficient control of Late Blight. The Blitecast model with a severity value of 18 (Bli18) was the most efficient for controlling the disease. Irrigations applied at least every three days did not affect Late Blight incidence and development.