• Authors:
    • Teixeira Junior, T.
    • Colombo, G. A.
    • Afferri, F. S.
    • Cancellier, L. L.
    • Pires, L. P. M.
    • Peluzio, J. M.
    • Ribeiro, G. R. dos S.
  • Source: Ciência Rural
  • Volume: 42
  • Issue: 3
  • Year: 2012
  • Summary: In order to evaluate the genetic divergence among soybean cultivars, an assay was carried out at Formoso do Araguaia, TO, Brazil, in off-season of 2007, in irrigated lowland conditions. The experimental design were randomized blocks with 12 treatments and three replications. Genetic divergence was evaluated by multivariate procedures: Mahalanobis distance, Tocher clustering method's and nearest neighbor method. It was observed the formation of two distinct groups by the dendrogram of genetic dissimilarity, which were identical to those groups formed by Tocher's method. The Tocher optimization method and the nearest neighbor agreed among themselves. The traits number of days to maturity, plant height and weight of 100 seed were the ones that most contributed for genetic dissimilarity. The presence of genetic variability allowed the identification of dissimilar cultivars with high average for the evaluated traits. The hybridations 'DOKO' * 'CONQUEST' and 'DOKO' * 'FT-2000' are promising to obtain segregating populations with high variability.
  • Authors:
    • Cornet, D.
    • Gaiser,T.
    • Srivastava, A. K.
    • Ewert, F.
  • Source: Field Crops Research
  • Volume: 131
  • Year: 2012
  • Summary: Soil fertility restoration and crop performance in many developing countries with low input agriculture strongly relies on fallow duration and management. More precise information about the availability of fallow land may provide a way to improve the simulation of yarn (Dioscorea spp.) yields at the regional scale which has hardly been considered in prevailing approaches to model regional crop production. The probable reason behind this is scarce availability of data on fallow duration and variation across the farms in a region. Therefore, this study attempts to estimate effective fallow availability for yam production at the regional scale and to simulate the effect of fallow on regional yam yield. Yam growth and yield were simulated with the EPIC model which was incorporated into a Spatial Decision Support System (SDSS) covering a typical catchment with variable land use intensity within the sub-humid savannah zone of West Africa. Yarn-fallow rotations were simulated within 1120 quasi-homogenous spatial units (LUSAC = Land Use-Soil Association-Climate units) and aggregated to the 121 sub-basins and ten districts within the catchment under three different scenarios of fallow availability: (Si) Total savannah area was available as fallow land, (S2) 50% of the bush savannah was available as fallow land and (S3) 25% of the bush savannah was available as fallow land. The aggregation procedure adopted in this study was based on changes in the frequency of fallow-cropland classes within the sub-basins to render the SDSS sensitive to changes in fallow availability. Comparison of the average simulated tuber yield with the observed mean yield over the entire catchment showed that the simulations slightly overestimated the yields by 0.4% for scenario S1, whereas, underestimated by 14.2% and 36.8% in scenario S2 and S3 respectively. When compared with the effective fallow availability to maize, it was concluded that, (1) due to farmers preferences to plant yam mainly on virgin savanna land and as the first crop in the rotation after fallow, the effectively available fallow area for yam is higher than for maize and (2) the applied approach is suitable to derive effective fallow availability for yarn production at the district scale. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • de Ridder, N.
    • Vanlauwe, B.
    • Pypers, P.
    • Guto, S. N.
    • Giller, K. E.
  • Source: Agronomy Journal
  • Volume: 104
  • Issue: 1
  • Year: 2012
  • Summary: Soil fertility gradients develop on smallholder farms due to preferential allocation of inputs. A multi-location on-farm trial was conducted in Meru South, Central Kenya whose overall aim was to test minimum tillage and crop-residue retention practices in socio-ecological niches across heterogeneous smallholder farms. We identified three soil fertility classes together with the farmers, namely: good, medium, and poor. In each soil fertility class, two tillage (minimum or regular) and two crop residue (removed or retained) practices were tested for four consecutive seasons. Maize (Zea mays L.) grain yields in the good fields were above 2.5 Mg ha(-1) across cropping seasons and cumulated yields were not influenced by tillage or crop residue management. The grain yields in the medium fields ranged between 1.3 and 5.4 Mg ha(-1) and were greater with crop residue retention. In the poor fields, grain yield was
  • Authors:
    • Gamba, F.
    • Cruz, G.
    • Scattolini, A.
    • Prieto, V.
  • Source: Agrociencia (Montevideo)
  • Volume: 16
  • Issue: 1
  • Year: 2012
  • Summary: Citrus canker, caused by Xanthomonas citri pv citri, affects all Citrus production regions worldwide with tropical or subtropical climate. This work studies the relationship between rain, temperature, susceptibility of lemon leaves, and the appearance of symptoms of canker The evolution of citrus canker symptoms during five months of vegetative growth in a lemon Lisbon type orchard with disease background were analyzed. The data used were generated in the assessment of three growth flushes in plots with six (Treatment I) and ten (Treatment II) copper oxide sprays respectively. Daily rainfall and temperature were registered every 20 minutes. The parameters of the logistic curve of disease progress were calculated. Shoot age at disease outbreak and maximum disease value were determined. Rain was assumed to initiate an infection event from which a model of hour-degree accumulation was applied to predict the date for new symptoms appearance. Under the conditions of local infection, only the rains over 10 mm produced symptoms at the predicted date according to the model used. It was demonstrated that tissue susceptibility became a secondary factor once the environmental conditions became favourable to dissemination and symptoms expression. The method used demonstrated to be an useful tool to predict the risk of new symptoms appearance and to plan monitoring of the disease.
  • Authors:
    • Dabar, S.
    • Soni, S. N.
  • Source: Journal of Soils and Crops
  • Volume: 22
  • Issue: 1
  • Year: 2012
  • Summary: After the green revolution and the development stage of cotton production in India the acceptance of improved cotton production technology/practices was getting the prime attention for increasing their production and productivity. Cotton research schemes and several extension education programmes were introduced to offer the education and training to farmers in respect of adopting the viable and proven improved cotton production technology/practices for their practical utilization in order to increase the income. In this context study was conducted in Dhar district. Madhya Pradesh to know the technological adoption level of cotton growers and to find out the association between socio personal and economic attributes of cotton growers with level of adoption. The study was conducted in the year of 2008-09. The study revealed that in respect of overall technology adoption, maximum cotton growers 50.22% adopted high level of technology followed by 34.11% respondents who adopted medium level and 15.67% respondents adopted low level of improved cotton production technology on their farms. The high level of adoption were reported in various extent i.e. in case of irrigation management (60.00%) followed by insect control measure (58.00%), rhizobium culture (58.00%), seed treatment (55.00%), recommended dose of fertilizer (52.00%), method of sowing (47.00%), weed management (46.00%), pest control measure (41.00%) and improved variety of seed (35.00%) respectively. The Study also revealed postive nature of phenomena the relationship between socio personal and economic characteristics of cotton growers and adoption level of improved cotton production technology. The zero order correlation coefficient of characteristic of cotton growers depicted in respect of age was 0.470**, for caste 0.283**, for level of income 0.392**, for level of employment 0.468**, for social participation 0.289** and for size of family 0.431. These characteristics were found to positively significant with adoption level of cotton production technology at 0.01 level of probability respectively. On the other hand, the characteristics like size of land holding had the correlation coefficient value of 0.200*, for material possession 0.248*, for economic motivation 0.201*, for attitude towards improved practices 0.215* and for extension participation 0.247* and these values were found positively significant with adoption level of cotton production technology at 0.05 level of probability respectively.
  • Authors:
    • Srinivasan, G.
  • Source: Journal of Cotton Research and Development
  • Volume: 26
  • Issue: 1
  • Year: 2012
  • Summary: Field experiment was conducted at Cotton Research Station, Srivilliputtur during 2005-2008 to study the response of summer irrigated cotton to the preceding crop, residue management and INM practices. The results revealed that maize as a preceding crop was advantageous with its stalk incorporated with the highest seed cotton yield of 1573 kg/ha and was comparable with maize as a preceding crop with stalk removed. With regard to INM practices, application of 100 per cent RD of fertilizers+azophos registered the highest seed cotton yield and was comparable with 75 per cent RD of fertilizers+azophos, 100 per cent RD of fertilizers+FYM and 100 per cent RD of fertilizers alone indicating that 75 per cent RD of fertilizers+azophos was optimum to get economic yield.
  • Authors:
    • van den Bergh, I.
    • Staver, C.
    • Reinhardt, D. H.
    • Gubbuk, H.
    • Albrigo, L. G.
    • Wuensche, J. N.
  • Source: ISHS Acta Horticulturae
  • Issue: 928
  • Year: 2012
  • Summary: This proceedings contains 54 papers dealing with cultivation and production of citrus, bananas and other tropical fruits in the subtropics. Topics discussed include the effects of climate change, different substrates, thinning, girdling, heavy pruning, fertilizer application, irrigation and water stress; grafting; pollination strategies; mechanical harvesting; postharvest treatment; drying; storage; breeding; fruit drop, set and quality; growth and physiology; as well as pests, diseases and weeds.
  • Authors:
    • Begue, A.
    • Dubreuil, V.
    • Meirelles, M.
    • Arvor, D.
    • Shimabukuro, Y. E.
  • Source: Applied Geography
  • Volume: 32
  • Issue: 2
  • Year: 2012
  • Summary: The Amazonian state of Mato Grosso is the main production area for soybeans in Brazil and contains 31.3% of the national production as of 2009. The rapid evolution of the agricultural systems in this area shows that the region is experiencing a rapid agricultural transition. In this paper, we broke down this transition process into three steps: crop expansion, agricultural intensification and ecological intensification. We used remote sensing products to develop and compute satellite-derived indices describing the main agricultural dynamics during the cropping years from 2000-2001 to 2006-2007. Our results indicated that Mato Grosso is continuing to expand its agricultural sector, with a 43% increase in the net cropped area during the study period. Although this expansion mainly occurred in the cerrado ecoregion until the early 2000s, the forest ecoregion is experiencing expansion at this time. We observed that 65% of the crop expansion in Mato Grosso from 2000 to 2006 occurred in this ecoregion. However, we did not identify this crop expansion as the major driver of deforestation in Mato Grosso because only 12.6% of the cleared areas were directly converted into croplands. Agricultural intensification also evolved rapidly, as the proportion of the net cropped area cultivated with double cropping systems harvesting two successive commercial crops (i.e., soybean and corn or soybean and cotton) increased from 6% to 30% during the study period. Finally, we found that ecological intensification occurred because the region's farmers planted a non-commercial crop (i.e., millet or sorghum) after the soybean harvest to prevent soil erosion, improve soil quality, break pest cycles, maintain soil moisture and set the conditions for high-quality no-tillage operations. In 2006-2007, 62% of the net cropped area was permanently covered by crops during the entire rainy season. This practice allowed the farmers to diversify their production, as shown by the positive evolution of the Area Diversity Index. Future scholars can use the method proposed in this paper to improve their understanding of the forces driving the agricultural dynamics in Mato Grosso.
  • Authors:
    • Ortega, A. L.
  • Source: Archives of Agronomy and Soil Science
  • Volume: 57
  • Issue: 6
  • Year: 2011
  • Summary: The permanent bed planting system for wheat ( Triticum aestivum L.) production has recently received additional attention. Studies using hard red spring wheat (cultivar Nahuatl F2000) were conducted at two locations in central Mexico. The studies included the installation of three furrow diking treatments, two granular N timing treatments and three foliar N rates applied at the end of anthesis. The objective was to evaluate the effect of these factors on wheat grain yield, yield components and grain N in a wheat-maize ( Zea maize L.) rotation with residues of both crops left as stubble. Results indicated that diking in alternate furrows increased both grain yield and the final number of spikes per m 2. The split application of N fertilizer enhanced the number of spikes per m 2 and grain N uptake, but the effect on grain yield was inconsistent. Similarly, grain protein increased with the foliar application of 6 kg N ha -1, depending upon the maximum temperature within the 10 days following anthesis. The normalized difference vegetative index (NDVI) readings collected at four growth stages were generally higher for the split N application than for the basal N application at planting. Grain N uptake was associated to NDVI readings collected after anthesis.
  • Authors:
    • de Assis, R. L.
    • Madari, B. E.
    • Petter, F. A.
    • Pacheco, L. P.
    • Leandro, W. M.
    • Barbosa, J. M.
    • Oliveira de Almeida Machado, P. L.
  • Source: Revista Brasileira de Ciência do Solo
  • Volume: 35
  • Issue: 5
  • Year: 2011
  • Summary: The cover crops in no-till system can contribute to the formation of mulch and nutrient cycling to annual crops in succession. The objective of this study was to evaluate biomass production and nutrient cycling of cover crops sown in the second growing season, in crop rotation after upland rice and soybean, in no-tillage and conventional tillage systems, on a Red Latassol of Rio Verde, state of Goias, from April 2008 to April 2010. The experiment was evaluated in randomized strips, in a 5 x 6 factorial design, with four replications. In the horizontal strips two soil management systems (after three years of no-tillage and conventional systems) were evaluated and the cover crops in the vertical strips. Biomass and ground cover and nutrient cycling rates were only evaluated in the no-till treatments, in a 5 x 6 factorial arrangement, where the plots were subdivided, corresponding to six harvest dates of dried biomass 0, 15, 30, 60, 90 and 120 days after cutting of the cover crops. The following cover crops were sown in the second growing season: Brachiaria ruziziensis, Pennisetum glaucum and B. ruziziensis + Cajanus cajan and a fallow treatment as reference. Biomass production and the rates of soil cover and nutrient accumulation and release by cover crops as well as rice and soybean yield were evaluated. B. ruziziensis and B. ruziziensis + C. cajan performed best in biomass production, ground cover and nutrient accumulation at the end of the cover crops. The nutrients N and K had the highest concentration in the biomass, and the highest nutrient release to the soil was observed for K and P. The highest rice yield was observed when grown in no-tillage on crop residues of P. glaucum and B. ruziziensis, while soybean yields did not differ in the treatments.