101. Phosphorus and irrigation application on the absorption and exportation of nutrients by cotton.; Aplicacao do fosforo e da irrigacao na absorcao e exportacao de nutrientes pelo algodoeiro.

• Authors:
  • Berger, P.
  • Santos, D.
  • Silva, T.
  • Aquino, R.
  • Aquino, L.
• Source: REVISTA BRASILEIRA DE ENGENHARIA AGRICOLA E AMBIENTAL
• Volume: 16
• Issue: 4
• Year: 2012
• Summary: This work aimed to evaluate the effect of phosphorus application in rainfed and irrigated crop on shoot dry matter, the absorption and nutrient exportation, and yield of cotton crop. The experiment was carried out in a Psament in the northeren part of Minas Gerais State, Brazil. The experimental design was in randomized blocks with four replications in a factorial arrangement of two doses of P 2O 5 * two cropping systems. Two additional treatments in each system without phosphorus application completed six studied treatments. Accumulation of dry biomass, absorption and exportation of nutrients, and yield of seed cotton were evaluated. Phosphorus levels did not influence the accumulation of shoot dry biomass. P supply increased the exportation of P, Ca, Mg, S, and Mn under irrigated and of N, K, and Fe regardless of the cropping system. Irrigation increased the dry biomass of leaves, stems, and shoots at 80 days after emergency, and the absorption of N, P, K, Ca, Mg, S, Cu, Fe, Mn, Zn, and B, as well as their exportation by the crop. There was an increase in the number of bolls per plant, fiber yield and productivity through the irrigation use. Increasing productivity with P application was conditioned to irrigation.

102. Spatial variability of leaf nutrient contents in a drip irrigated citrus orchard.

• Authors:
  • Ribeiro Junior, P.
  • Teixeira, M.
  • Coelho, R.
  • Armindo, R.
• Source: ENGENHARIA AGRICOLA
• Volume: 32
• Issue: 3
• Year: 2012
• Summary: This study aimed to evaluate the spatial variability of leaf content of macro and micronutrients. The citrus plants orchard with 5 years of age, planted at regular intervals of 8*7 m, was managed under drip irrigation. Leaf samples were collected from each plant to be analyzed in the laboratory. Data were analyzed using the software R, version 2.5.1 Copyright (C) 2007, along with geostatistics package GeoR. All contents of macro and micronutrients studied were adjusted to normal distribution and showed spatial dependence. The best-fit models, based on the likelihood, for the macro and micronutrients were the spherical and matern. It is suggest for the macronutrients nitrogen, phosphorus, potassium, calcium, magnesium and sulfur the minimum distances between samples of 37; 58; 29; 63; 46 and 15 m respectively, while for the micronutrients boron, copper, iron, manganese and zinc, the distances suggests are 29; 9; 113; 35 and 14 m, respectively.

103. Evapotranspiration and crop coefficient for sprinkler-irrigated cotton crop in Apodi Plateau semiarid lands of Brazil

• Authors:
  • dos Santos, C.
  • Sofiatti, V.
  • Bezerra, J.
  • da Silva, B.
  • Bezerra, B.
• Source: Agricultural Water Management
• Volume: 107
• Year: 2012
• Summary: During the twentieth century, the cotton crop was the main agricultural product in the semiarid regions of Brazil, with over 3.2 million hectares planted. However, due to structural problems, this activity became uncompetitive and economically unfeasible, being virtually wiped out in the eighties. The revival of cotton growing in semiarid lands of Brazil is important to the regional economy. However, the adoptions of new technologies mainly related to the water use efficiency are needed. Thus, accurate ETc estimates are required for efficient irrigation management. The K-c method is a practical and reliable technique for estimating ETc, and has been vastly applied by the farmers in the semiarid lands of Brazil. However, the use of K-c values listed in FAO-56 can contribute to ETc estimates that are substantially different from actual ETc. Hence the importance of determining K-c values experimentally. A field study on sprinkler-irrigated cotton was carried out during the dry seasons of 2008 and 2009 years in the Apodi Plateau, Brazilian semiarid lands. This study aims to determine ETc and the K-c curve values using the Bowen Ratio Energy Balance (BREB) technique. The locally developed K-c curves are compared with generalized FAO K-c values adjusted for local climate and management. The ETc values were 716 mm and 754 mm in 2008 and 2009, respectively. These values were higher than those observed in other areas of Brazilian semiarid. These differences are attributed to weather heterogeneity in the region. The average of K-c values were 0.75, 1.09 and 0.80 for initial, middle and end, of growing season, respectively. These values were lower than the Kc-FAO-Adjusted to local conditions. For this reason, ETc values obtained from Kc-FAO-Adjusted were overestimated by 12% in both the years. The irrigation scheduling based on the Kc-FAO-Adjusted increases production cost and yield loss. (C) 2012 Elsevier B.V. All rights reserved.

104. Damage caused by citrus canker on Valencia sweet orange yield.

• Authors:
  • Maringoni, A.
  • Verona, L.
  • Nesi, C.
  • Theodoro, G.
  • Brugnara, E.
• Source: IDESIA
• Volume: 30
• Issue: 1
• Year: 2012
• Summary: The citrus canker, caused by Xanthomonas axonopodis pv. citri, is one of the main citrus diseases and has threatened the world's citriculture. In this study, the damage caused by citrus canker was quantified in a sweet orange culture, cv. Valencia [ Citrus sinensis (L.) Osb.], grafted over 15 year-old Rangpur lime ( C. limonia Osb.), in the municipality of Guatambu, SC, Brazil, in the crop of 2004/05. Evaluations of the number of fruits per plant (NF), fruit yield per plant (P), citrus canker incidence on the fruit (IFR), and incidence (IL) and severity (SV) of citrus canker on 80 leaves per orange tree were performed in the harvest period, applying diagrammatical scales. Plants had large variation in SV (0.16%-1.09%), IL (12.50%-56.25%) and IFR (12.30%-56.09%). Linear regressions were significant between IL * SV, NF * SV, P * IFR, and NF * IFR. There was no significant difference (p>0.05) between the mean estimated values of IL in different quadrants of the crowns of the orange trees (N, S, L and O). Each 1% increase in IFR reduced 2.16 kg and 21.3 fruits per tree.

105. Rootstocks for high fruit yield and quality of 'Tahiti' lime under rain-fed conditions.

• Authors:
  • Silva, S.
  • Stuchi, E.
  • Mourao Filho, F.
  • Cantuarias-Aviles, T.
  • Espinoza-Nunez, E.
  • Bremer Neto, H.
• Source: Scientia Horticulturae
• Volume: 142
• Year: 2012
• Summary: Despite considerable research conducted on 'Tahiti' lime [ Citrus latifolia (Yu Tanaka) Tanaka] in several countries, few long-term studies have focused on rootstock effects on fruit production and quality under non-irrigated conditions. As for many other fruit crops, rootstock studies for 'Tahiti' lime are often based on the evaluation of several horticultural responses simultaneously, instead of considering multivariate statistical approaches which may provide with more comprehensive information. Consequently, a trial was installed to evaluate the horticultural performance of non-irrigated 'Tahiti' lime trees budded onto the following 12 rootstocks: 'HRS 801' and 'HRS 827' hybrids; 'Rubidoux', 'FCAV' and 'Flying Dragon' trifoliates; 'Sun Chu Sha Kat' and 'Sunki' mandarins; 'Cravo Limeira' and 'Cravo FCAV' 'Rangpur' limes; 'Carrizo' citrange, 'Swingle' citrumelo, and 'Orlando' tangelo. The trial was installed in 2001, in an 8 m * 5 m spacing with no supplementary irrigation. Measurements of yield, fruit quality oriented to different consuming markets, canopy volume and tree tolerance to drought, were performed. A multivariate cluster analysis identified both 'Rangpur' lime rootstocks as those inducing larger cumulative yield and higher percentage of fruits for the domestic market, with highest drought tolerance to the trees. Despite of their high susceptibility to drought stress under non-irrigated conditions, the 'Flying Dragon' and 'FCAV' trifoliate rootstocks performed outstandingly for 'Tahiti' lime, inducing higher yield efficiency, early bearing and larger percentage of high-quality fruits for foreign markets, with smaller trees more suitable for high-density plantings.

106. Partial root drying of lemon under semi-arid conditions in the north of Minas Gerais, Brazil.

• Authors:
  • Oliveira, P.
  • Coelho Filho, M.
  • Coelho, E.
• Source: Acta Horticulturae
• Issue: 928
• Year: 2012
• Summary: Meeting the increased water requirement in agriculture due to the increases of irrigated areas in order to provide food for growing populations, relies on the application of water with increased efficiency. This work evaluated the partial root drying technique for lemon 'Tahiti' trees under semi-arid climate conditions in the north of Minas Gerais. The experiment was carried out in randomized block design with nine treatments and four replicates. Treatments were based on percentages of reduction of calculated irrigation water depth, i.e., 25% corresponding to the reduction of irrigation on one quarter of the area occupied by the plant and 50% corresponding to the reduction of irrigation on half of the plant area during three phonological phases (I, II and III) of lemon 'Tahiti'. The results showed that irrigation scheduling using the partial root drying method may be performed with any of the treatments evaluated. The larger yields and water use efficiencies were obtained for treatments T7 and T8 which were a reduction of 25% of total irrigation every 7 or 15 days during flowering followed by a reduction of 50% of total irrigation every 7 or 15 days in phases II and III.

107. Phosphorus Split Application on Irrigated Cotton

• Authors:
  • Batista Almeida de Aquino, R.
  • Lima, T.
  • Lima Neves, J.
  • Berger, P.
  • de Aquino, L.
• Source: Pesquisa Agropecuaria Tropical
• Volume: 42
• Issue: 1
• Year: 2012
• Summary: PHOSPHORUS SPLIT APPLICATION ON IRRIGATED COTTONMost regions where cotton is cultivated in Brazil present low soil fertility, especially concerning the available phosphorus (P). This study aimed to evaluate the phosphorus split application on irrigated cotton, for reaching a higher phosphate fertilization efficiency, in comparison to the traditional application at sowing. The experiment was conducted in Quartzarenic Neosol with 22 mg dm(-3) of P (medium availability), in the north region of the Minas Gerais State, Brazil. The design used was randomized blocks, in a (4x3) + 3 factorial scheme, with three replications. Treatments consisted of P2O5 doses (0 kg ha(-1), 30 kg ha(-1), 60 kg ha(-1), 120 kg ha(-1), and 180 kg ha(-1)) and three split applications (80% and 20%; 60% and 40%; 40% and 60% of the P dose applied respectively at sowing and at 35 days after emergence (DAE)), plus the application of 0 kg ha(-1), 60 kg ha(-1), and 120 kg ha(-1) of P2O5 at sowing. The P source was the granulated triple superphosphate, and the P content in the shoots increased according to the doses applied. Nutrient contents in the index leaf, except for P, were not influenced by P levels and split applications. The P content in the index leaf and the number of cotton bolls per plant increased with the increment of P doses, but were not affected by the phosphate fertilizer split application. The application of 40% of the P dose at sowing and the remaining amount split at 35 DAE decreased the cotton boll yield, with no significant effect for the other split applications.

108. Cotton yield as a function of salinity and seeds treatment with growth regulator

• Authors:
  • da Silva Soares, L.
  • Freire, A.
  • Alves de Oliveira, F.
  • de Medeiros, J.
  • de Oliveira, F.
• Source: Revista Ciencia Agronomica
• Volume: 43
• Issue: 2
• Year: 2012
• Summary: This study was conducted to evaluate the effect of different salinity levels of irrigation water and seed treated with growth regulator on the yield of cotton. It was used an entirely statistical randomized design, in a factorial scheme 5 x 2, with four replications. The treatments resulted from the combination of four salinity levels of irrigation water (S-1-0.5; S-2-2.0; S-3-3.5; S-4-5.0 and S-5-6.5 dS m(-1)) in treated and untreated seeds with growth regulator. The variables were: production of cotton, seed and fiber, 100 seed weight and percentage of fiber. There was not interaction between salinity levels and seed treated. The parameters of cotton production are reduced with the use of water salinity from 3.5 dS m(-1), independent of seed treated or not with growth regulators. Agronomic traits 100 seed weight, percentage of fiber and seed cotton production are not influenced by mepiquat chloride. The seed treatment with growth regulator do not affects the adverse effect of salinity.

109. Sensibility of cotton crops to mepiquat chloride under saline conditions

• Authors:
  • Freire, A.
  • Teixeira de Oliveira, M.
  • Alves de Oliveira, F.
  • de Medeiros, J.
  • de Oliveira, F.
• Source: Revista Ciencia Agronomica
• Volume: 43
• Issue: 3
• Year: 2012
• Summary: This work was carried out to evaluate the effect of irrigation water at different salinity levels, and of seed treatment with plant growth regulator, on the development of the cotton plant. The experimental design used was completely randomized, arranged in a 5 x 2 factorial scheme with four replications. The treatments resulted from the combinations of five levels of salinity of the irrigation water (S-1-0.5, S-2-2.0, S-3-3.5, S-4-5.0 and 6.5 dS m(-1)) on seeds, both treated and not treated with growth regulator. The evaluated characteristics were: number of leaves, leaf area, height, dry mass of stems, leaves and vegetative parts, specific leaf area and leaf area ratio. There was an interaction between salinity and seed treatments with mepiquat chloride, but only for leaf area and leaf area ratio. All other characteristics decreased with the increasing salinity of the irrigation water, with greater reductions in leaf area (mean of 65.8%) and dry mass of vegetative parts (64%). Seed treatment with mepiquat chloride affected plant development, independent of salinity.

110. Graded potato yield in response to interplant spacing and fertilizer recommendation criteria.; Producao classificada de batata em resposta ao espacamento e criterio de recomendacao da adubacao.

• Authors:
  • Moreira, M. A.
  • Nunes, J. C. S.
  • Fontes, P. C. R.
• Source: Bioscience Journal
• Volume: 28
• Issue: 3
• Year: 2012
• Summary: Two independent experiments were established in a Red Yellow Argisol Cambic soil objecting to evaluate potato yield and tuber size distribution profile in response to interplant spacing and fertilizer recommendation criteria. One experiment was sprinkler irrigated and the other one was drip-irrigated. Six treatments resulting from the combination of three interplant spacing (29, 36, and 50 cm) and two fertilizer recommendation criteria (by area or by plant number in the area) were evaluated in a completely randomized block design and five replications. In both experiments, marketable potato yield (tuber number and mass) exponentially decreased with the increase in row spacing and it was affected by recommendation criteria. The combination of fertilizer recommendation by area with narrower space optimizes marketable tuber yield by increasing medium and small tubers and also increases fertilizer use efficiency. Environmental, economic and practical implications of the results to potato production are discussed.