• Authors:
    • Mielniczuk, J.
    • Vezzani, F. M.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 35
  • Issue: 1
  • Year: 2011
  • Summary: Soil functions and quality are closely linked to soil structure. The effect of management practices on the recovery of the aggregation of a physically degraded soil was studied based on the distribution of water-stable aggregates and single particles (diameter classes 9.51-4.76, 4.76-2.00, 2.00-0.25, 0.25-0.053, <0.053 mm) and carbon stock (C) in the surface layer (0-7.5 cm) of a Paleudult in the Central Depression region of the state of Rio Grande do Sul, Brazil, under different management systems. The following systems were evaluated in experimental plots after 17 years: soil without plants and without tillage (fallow); no-till Lablab purpureus and maize ( Zea mays) (Lablab/m); no-till Cajanus cajan (pea/m) and maize; perennial pasture of Digitaria decumbens (Pangola grass). The following systems were evaluated after 15 years: conventional tillage and no-till Avena strigosa and maize (CT a/m and NT a/m, respectively) Avena strigosa+ Vicia sativa and maize+ Vigna unguiculata (CT av/μ and NT av/mu, respectively). A conventionally tilled area was also evaluated after 30 years of grain cultivation (crop) and native grassland (NGr), representing the degraded state and the native ecosystem of this soil, respectively. Undisturbed soil samples collected in two seasons (September 1999 to September 2000) were evaluated in six replications per management system. Data were analyzed by ANOVA and Tukey's test (5%) to detect differences between management systems. In the NGr, 76.4% of the soil aggregates consisted of 63.8% macroaggregates and of 23.6% of single particles, and a C stock of 20.0 Mg ha -1. The agricultural use with intense soil tillage and low residue application (crop) reduced the proportion of soil aggregates to 49.9% and raised single particles to 50.1%, while the C stock decreased to 11.8 Mg ha -1. From this condition, 15 years of the untilled system with greater diversity of plant species and high residue application (NT av/mc) raised the proportion of soil aggregates to 70.7% and of macroaggregates to 53.5%. Perennial pasture (Pangola) increased the proportion of soil aggregates to 74.1% and of macroaggregates to 61.8%, equaling NGr. The systems NT av/mc, pea/m and Lablab/m recovered C stocks to the level of NGr. Although Pangola had the highest soil aggregation rates, the C stock was lower than in the said systems, emphasizing the positive action of a dense root system in the recovery of soil aggregation.
  • Authors:
    • Sawargaonkar, G. L.
    • Gadade, G. D.
    • Shinde, V. S.
    • Gokhale, D. N.
    • Zade, K. K.
  • Source: Journal of Cotton Research and Development
  • Volume: 25
  • Issue: 2
  • Year: 2011
  • Summary: Field studies were carried out at Department of Agronomy, Marathwada Agricultural University, Parbhani during, 2007 to 2010 to explore the suitability of different soil moisture conservation and integrated nutrient management (INM) techniques in relation to yield and economics of Bt cotton under rainfed conditions. The results revealed that opening of furrow in alternate row recorded significantly highest seed cotton yield (2758, 2214 and 1452 kg/ha) as compared to cotton+straw mulching (2421, 2003 and 1233 kg/ha) and intercropping of cotton with soybean (2036, 1626 and 1106 kg/ha) treatments during the three year of experimentation respectively. However, intercropping of cotton+soybean recorded significantly highest seed cotton equivalent yield and thereby net returns and B:C ratio over wheat straw mulch and opening of furrow in alternate row. As regards to integrated nutrient management (INM) 100 per cent calculated RDF (100:50:30 N, P 2O 5 and K 2O kg/ha)+micronutrients (zinc, iron and boron) based on soil test recorded significantly highest seed cotton yield as compared to all other INM treatments. However, application of RDF with soil testing (75 per cent N, P 2O 5 and K 2O kg/ha through inorganic+25 per cent N, P 2O 5 and K 2O kg/ha through vermicompost) was next best treatment which recorded significantly highest seed cotton yield over rest of the treatments.
  • 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:
    • Mohamed, M.
    • Azam, A.
  • Source: Bulletin of Faculty of Agriculture, Cairo University
  • Volume: 62
  • Issue: 2
  • Year: 2011
  • Summary: The present study aimed at identifying the knowledge level of potato farmers regarding export conditions of potatoes to the European Union (EU), to determine the differences between the knowledge degrees of the farmers in two villages to identify farmer opinions regarding the environmental effects of the agricultural part of the Egyptian-European convention, and to identify the problems facing farmers since the implementation of the Egyptian-European convention. The study was conducted in the village of "Sayedna Solomon" in Nobariya area, Beharia Governorate as one of the largest areas inside the Pest Free Area (PFA), and the village of "Talia", Menofia Governorate as one of the largest areas outside the Pest Free Area (PFA). A random sample of 50 farmers was chosen from Sayedna Solomon village and 100 farmers from Talia village. Data were collected through personal interviews with respondents by using pre-tested questionnaires prepared specifically to achieve the study objectives. Frequencies, percentages, means, and standard deviations, in addition to "t" test were used to present and analysis of the obtained data. The most important results of the study were 1 - There was significant differences at 0.05 level between farmers' level of knowledge in the two studied villages regarding the export conditions of potatoes to the (EU). 2 - There was an increase in the negative environmental effects on small farmers resulting from applying the Egyptian-European convention as the investigated farmers expressed, and the differences between the two studied villages were significant at 0.01 level. 3 - There were main problems facing small farmers in the "Sayedna Solomon" village concerning the market of the crop locally, the low export prices, and the shortage of irrigation water in the summer, while the main problems in "Talia" village were concerning the lack of input supply and the high prices of the inputs, the irrigation problem, and the problem of marketing the crop locally.
  • 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:
    • Hebbar, K. B.
    • Mayee, C. D.
  • Source: Current Science
  • Volume: 100
  • Issue: 11
  • Year: 2011
  • Summary: There are several reasons why plants wilt. Some of them are over-watering, lack of water, too much sun, not enough sun, too many/much fertilizers, diseases caused by infection, etc. Wilt due to lack of water or other environmental factors generally occurs gradually and hence, the cause of those can be studied and accordingly it can be controlled by devising appropriate management strategies. Moreover, plants recover with appropriate control measures and continue to yield. In this review, we discuss a typical wilt which is sudden and occurs within a few hours. Hence, understanding the cause and devising a control measure are difficult. Its sporadic distribution and untimely occurrence further complicate the effort to find the cause of this wilt. Unlike the wilt mentioned above which occurs due to lack of water, sudden wilt occurs when the soil is suddenly saturated by a downpour of rain and the sun later shines bright and hot. Paradoxically, the physiological responses, i.e. wilt symptoms to those induced by either drought or flooding are similar. However, the causal mechanism is different. Here, we demonstrate that the imbalance in uptake and loss of water under flooding is the cause of sudden/parawilt of cotton. We also discuss how plants with rapid growth rate and climate factors like bright sunshine and high temperature accentuate the problem of parawilt in cotton.
  • Authors:
    • Jansirani, R.
  • Source: Journal of Cotton Research and Development
  • Volume: 25
  • Issue: 2
  • Year: 2011
  • Summary: The study was conducted at Kovilpatti block of Tuticorin district of Tamil Nadu with the specific objective of studying extent of adoption of production technologies in Bt cotton by the growers. The area was selected based on the major cultivation of Bt areas and production of Bt cotton under irrigated condition. The selected respondents for this study were 90, who have adopted Bt cotton and non Bt cotton i.e 45 growers in each category by using simple random sampling method. The collected data were analyzed using percentage analysis. All the growers adopted Bt varieties and 95.55 per cent of the growers adopted appropriate time of planting. About 80.00 per cent of the growers adopted spacing. Three fourths (77.77%) of the growers adopted regular plucking intervals during harvest and 75.55 per cent of the growers adopted proper irrigation management followed by pest and diseases management (73.33%). More than fifty (66.66%) of the growers adopted preparation of fields to required tilth and formation of trenches followed by manures and fertilizers (62.22%) and number of split doses (57.77%). Out of ten technologies nine technologies were adopted more than fifty per cent by the growers due to the reasons that private firms have agreed to buy the produce from the farmers offering a minimum support prices. State Department of Agriculture has also introduced contract farming to assure remunerative prices to farmers.
  • Authors:
    • Robles-Gonzalez, M. M.
    • Virgen-Calleros, G.
    • Vazquez-Garcia, M.
    • Medina-Urrutia, V. M.
  • Source: Acta Horticulturae
  • Issue: 894
  • Year: 2011
  • Summary: This work was carried out to determine the influence of seasons of vegetative shoots on the time of flowering and to known the intervals from flowering to fruit harvest of Mexican lime trees. Two experiments on a seven years old Mexican lime trees budded on Sour Orange rootstock were established. In experiment 1, the number of vegetative (VS) and reproductive shoots (RS) on each one of 10 trees were registered weekly during one year, using a metallic ring of one square meter area placed on the tree 1.75 m from the ground. Minimum temperature and rainfall data were also recorded every week. In experiment 2, monthly, ten new vegetative shoots on each one of ten trees were tagged. These shoots were observed every week until they bloom. During the most important periods of blooming, five flowering shoots per tree were chosen to determine interval to harvest. In experiment 1, four VS and two RS flushes were observed. The first period of VS and RS started in autumn and was associated to the initiation of irrigation. The second and more important was registered in January when temperatures were the lowest of the year. Half RS and half VS were recorded during this period. The third and four flushes were mainly VS and occurred during summer months with highest temperatures and the rainy season. In experiment 2, from the vegetative shoots emerging in January, 52% formed reproductive shoots 60-85 days later and 25% also flowered sparsely four to six months later. The remaining shoots (23%) repeated their vegetative activity during June and July. Most of the vegetative shoots initiated in February showed again a vegetative activity during May to July, and only 20% of them changed to reproductive. New vegetative shoots appeared from March to July showed a vegetative activity during the next two to six months. From the vegetative shoots emerged from July to September very few (15%) transformed to reproductive during November-December and the majority became vegetative again, however, most of them changed to reproductive from January to April. Fruits initiating during the winter time lasted 130 to 145 days until harvest. But those fruits emerged during the late spring and summer months reached complete development 90 to 120 days later. These combined phenological characteristics explain the long period of harvest showed by the MLT under tropical semiarid conditions.