769 resultados para 070302 Agronomy
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The sugarcane borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae), is a key pest of sugarcane (Saccharum spp.). While damage caused by this pest has increased in the past 20 yr, studies investigating the insect-plant interactions are still lacking. Moreover, there is no information about the consequences of borer damage on the parameters of sugar quality. Therefore, two field experiments were performed during the 2010 and 2011 growing seasons in Brazil to compare the raw material and sugar quality of SP80-3280 sugarcane plants with and without the sugarcane borer. Plants were protected within screen cages and infested weekly during the 2010 and 2011 seasons, using egg masses starting at the second and third internode stage. At harvest, 25.77 and 19.01% of the internodes were bored by larvae (infestation intensity, II) in the first and second seasons, respectively. There was no correlation between the borer gallery total volume and II. The fiber content significantly increased with increasing II. The stalk biometric parameters, such as length, diameter, and yield, were not correlated with II. The sucrose yield significantly decreased with increasing II. Consequently, sugar yield losses were estimated at 8.83 and 19.80% per 1% bored internode for the first and second seasons, respectively. The concentration of phenolic compounds increased, and unclarified juice color quality decreased, with increasing II. Significant differences were detected in the quality of the sugar. These results should be confirmed for other sugarcane cultivars and incorporated into an economic injury level to enhance decision-making strategies for borer management. © 2013 by the American Society of Agronomy, 5585 Guilford Road, Madison, WI 53711. All rights reserved.
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Intercropping corn (Zea mays L.) with palisadegrass [Brachiaria brizantha (Hochst. ex A. Rich) Stapf] can result in high amounts of residue and improve nutrient cycling. Long-season corn hybrids will live longer, competing with palisadegrass, which may reduce both corn and forage biomass yields. This study, conducted in the state of São Paulo, Brazil, had the objective of evaluating nutrient concentration and yield of corn hybrids with different maturity ratings as affected by intercropped palisadegrass as well as forage dry matter production. Te experimental design was randomized blocks with a factorial arrangement of eight treatments consisting of two cropping systems (corn alone and intercropped with palisadegrass) and four corn hybrids (105-, 121-, 132, and 144-d relative maturity). Compared with corn grown alone, intercropping treatments resulted in corn grain yields of 107% (105-d hybrid) to 71.7% (144-d hybrid). In the corn-alone system, the 132- and 144-d corn hybrids provided the highest corn yields (9581 and 9606 kg ha-1, respectively). Corn yield was similar between the single-crop and intercrop systems when using 105-, 121-, and 132-d hybrids. Intercropping with the 144-d hybrid reduced forage production (6619 kg ha-1) and quality of palisadegrass (86 g kg-1 of crude protein) compared with the other hybrids. Te intercropping system with the 132-d hybrid allowed both the highest corn grain (8860 kg ha-1) and palisadegrass (8256 kg ha-1) yields. Therefore, intercropping palisadegrass with the earlier (105-, 121-, and 132-d) corn hybrids is a viable option for crop-livestock integration because it did not affect either corn or palisadegrass yield. © 2013 by the American Society of Agronomy, 5585 Guilford Road, Madison, WI 53711. All rights reserved.
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Physical fractions (free light fraction, intra-aggregate light fraction and heavy fraction) of soil organic matter (SOM) are good indicators of soil quality for sustainable land use. The objective of this study was to evaluate the effect of cover crops on total organic carbon (TOC) and physical fractions of soil organic matter in soil under a no-tillage system (NTS) and a conventional tillage system (CTS, one plowing and two disking). A three-year field experiment was carried out as a cover crop-rice (Oryza sativa)-cover crop-rice rotation. Treatments included cover crops (Panicum maximum, Brachiaria ruziziensis, Brachiaria brizantha, and pearl millet (Pennisetum glaucum), fallow, till or no till. The SOM was physically fractionated in free light fraction (FLF), intra-aggregates light fraction (IALF) and heavy fraction (HF). The levels of C in whole soil were also evaluated, as well as C in the light fractions (FLF+IALF) and in the HF. Results indicated that concentrations of C in the FLF and IALF in surface soils (0-0.05m) were much higher (10.8 and 1.95gkg-1, respectively) than that in the 0.05-0.1m soil depth (7.68 and 1.54gkg-1, respectively) and in the 0.1-0.2m soil depth (4.98 and 1.24gkg-1, respectively). The NTS resulted in higher levels of FLF (12.2gkg-1) and IALF (2.19gkg-1) than with CTS (1.37-7.30gkg-1). Millet had the highest C (19.5gkg-1) and N (1.1gkg-1) concentrations in soil. There was an accumulation of TOC and total N in the surface soil with cover crops, and concentrations of TOC were higher in the HF (79.0%) than in the light fractions (21.0%). Although SOM changed little during the two years of this experiment, the various C fractions were significantly affected by the tillage treatments. We conclude that SOM physical fractionation allowed seeing significant differences caused by the soil management in the organic matter dynamics in a short period of time. © 2013 Elsevier B.V.
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For many years, composting has been used as a result of the recycling of organic matter. There is significative animal carcasses accumulation from teaching and researching activities of the university veterinary hospital. Every year, Unesp University needs to dispose correctly about 180 tones of this waste and the composting seemed to be the most sustainable alternative. Piles of animal carcasses were prepared using peanut hulls and tree pruning as bulking agent and water to the first phase of this process. The extracts pH values no impediments for offering germination and indicated a good addition to the soil management. The germination index showed no impediment to the seeds germination on any type of compost and the extracts concentrations not influenced this biological process. No parameters studied assigns risks of contamination of carcasses for the compost development in Unesp according to the proposed design. © 2013 Taylor & Francis Group.
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Sorghum is an excellent alternative to other grains in poor soil where corn does not develop very well, as well as in regions with warm and dry winters. Intercropping sorghum [Sorghum bicolor (L.) Moench] with forage crops, such as palisade grass [Brachiaria brizantha (Hochst. ex A. Rich) Stapf] or guinea grass (Panicum maximum Jacq.), provides large amounts of biomass for use as straw in no-tillage systems or as pasture. However, it is important to determine the appropriate time at which these forage crops have to be sown into sorghum systems to avoid reductions in both sorghum and forage production and to maximize the revenue of the cropping system. This study, conducted for three growing seasons at Botucatu in the State of São Paulo in Brazil, evaluated how nutrient concentration, yield components, sorghum grain yield, revenue, and forage crop dry matter production were affected by the timing of forage intercropping. The experimental design was a randomized complete block design. Intercropping systems were not found to cause reductions in the nutrient concentration in sorghum plants. The number of panicles per unit area of sorghum alone (133,600), intercropped sorghum and palisade grass (133,300) and intercropped sorghum and guinea grass (134,300) corresponded to sorghum grain yields of 5439, 5436 and 5566kgha-1, respectively. However, the number of panicles per unit area of intercropped sorghum and palisade grass (144,700) and intercropped sorghum and guinea grass (145,000) with topdressing of fertilizers for the sorghum resulted in the highest sorghum grain yields (6238 and 6127kgha-1 for intercropping with palisade grass and guinea grass, respectively). Forage production (8112, 10,972 and 13,193Mg ha-1 for the first, second and third cuts, respectively) was highest when sorghum and guinea grass were intercropped. The timing of intercropping is an important factor in sorghum grain yield and forage production. Palisade grass or guinea grass must be intercropped with sorghum with topdressing fertilization to achieve the highest sorghum grain yield, but this significantly reduces the forage production. Intercropping sorghum with guinea grass sown simultaneously yielded the highest revenue per ha (€ 1074.4), which was 2.4 times greater than the revenue achieved by sowing sorghum only. © 2013 Elsevier B.V.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Pós-graduação em Agronomia (Energia na Agricultura) - FCA
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Pós-graduação em Agronomia (Horticultura) - FCA
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Pós-graduação em Ciência da Informação - FFC
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Pós-graduação em Fisiopatologia em Clínica Médica - FMB
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Pós-graduação em Agronomia - FCAV