• Authors:
    • Lee, Y.
    • Kwak, Y.
    • Lee, S.
    • Choi, K.
    • Seo, Y.
    • Kim, M.
    • Yang, S.
  • Source: World Journal of Microbiology and Biotechnology
  • Volume: 28
  • Issue: 4
  • Year: 2012
  • Summary: The present study evaluated the changes of soil microbial communities that were subjected to no-till and compared the results to those subject to tillage for organic farming in a controlled horticultural field by fatty acid methyl ester. Fungi ( P<0.001), gram-positive bacteria ( P<0.001), arbuscular mycorrhizal fungi ( P<0.01), and actinomycetes ( P<0.01) in the no-till soils were significantly larger than those in the tillage soils. The no-till in the subsoil had a significantly lower ratio of cy17:0 to 16:1omega7c compared to that of tillage, indicating that microbial stress decreased because the soils were not disturbed ( P<0.05). Fungi should be considered as a potential factor responsible for the obvious microbial community differentiation that was observed between the no-till and tillage areas in a controlled horticultural field.
  • Authors:
    • Everts, K. L.
    • Zhou, X. G.
  • Source: Plant Disease
  • Volume: 96
  • Issue: 3
  • Year: 2012
  • Summary: Multiple applications of fungicides are used to manage anthracnose caused by Colletotrichum orbiculare and gummy stem blight caused by Didymella bryoniae, the two most common and destructive diseases on watermelon ( Citrullus lanatus) in the mid-Atlantic region of the United States. To develop a sustainable, nonchemical management option, a split-plot experiment was conducted over 3 years to evaluate the effects of a no-till hairy vetch ( Vicia villosa) cover crop on disease severity, plant growth, and fruit yield compared with two conventional bedding systems and fungicide application. The main plots were bedding strategies consisting of bare ground, polyethylene covering, or a hairy vetch cover crop that was planted in the fall, killed the following spring, and left on the soil surface as an organic mulch. The subplots were a nonfungicide control or a weekly application of a standard fungicide program. Hairy vetch mulch provided greater than a 65% reduction in the area under the disease progress curves of anthracnose and gummy stem blight and greater than an 88% decrease in diseased fruit compared with bare ground or polyethylene mulch. The reductions were comparable with those achieved by fungicide applications. Watermelon vine lengths in plots with hairy vetch were similar to or greater than those in plots with polyethylene or bare ground that were treated with fungicides. Marketable fruit in plots with hairy vetch was higher compared with bare ground in 2 of 3 years and was similar to that in plots treated with fungicides in all 3 years. Addition of fungicide application to hairy vetch treatment further reduced anthracnose in 1 year and gummy stem blight in 2 years but did not significantly increase fruit yield in all 3 years. This is the first demonstration that a no-till hairy vetch production system can reduce anthracnose and gummy stem blight on watermelon and that the production system has the potential to mitigate damage caused by these diseases.
  • Authors:
    • Reinhardt, C. F.
    • Bezuidenhout, S. R.
    • Whitwell, M. I.
  • Source: Weed Research
  • Volume: 52
  • Issue: 2
  • Year: 2012
  • Summary: No information is available on the effect of cover crops on weed growth in maize production in KwaZulu-Natal, South Africa. In a field experiment, the influence of two preceding cover crops, stooling rye and annual ryegrass, on the growth of maize and the weed Cyperus esculentus were compared with herbicides and weed control by hoeing. Maize emergence and early growth were delayed in the presence of physical residues of both cover crop species, especially annual ryegrass. Growth of C. esculentus was significantly inhibited in the inter-row maize planting lines by the cover crops for the first 16 days after maize emergence, but this effect had diminished by day 28. In a pot experiment, the influence of the same two cover crops on maize and C. esculentus growth was evaluated together with oats and two additional annual ryegrass cultivars. Here, the growth of maize and C. esculentus were suppressed, especially by the root residues of the annual ryegrass, in particular the cultivar Midmar. Chemical analysis of the leachate of the root residues indicated the presence of phenolic acids and benzoxazolin-2(3 H)-one. To achieve effective weed control, a weed management strategy combining the mulch retained on the soil surface, with a possible reduction in the type and amount of herbicide, should be implemented.
  • Authors:
    • Wang, J.
    • Kimmins, J.
    • Cao, F.
  • Source: Agroforestry Systems
  • Volume: 84
  • Issue: 3
  • Year: 2012
  • Summary: Intercropping Ginkgo and crop species in southern China is receiving increasing attention because it offers potential advantages for resource utilization, higher economic income to farmers and increased sustainability in crop production, We carried out a 2-year field intercropping system composed of Ginkgo with wheat, broad bean, and rapeseed, respectively, to determine the competitive interactions between the different species, and productivity and the economic yield of each intercropping system. The density of Ginkgo and crop species was varied systematically in a two-way density matrix composed of three monoculture densities and nine intercropping of all possible pairwise combinations of monoculture densities. Intercropping systems were assessed on the basis of several intercropping indices such as land equivalent ratio, relative crowding coefficient, relative competition intensity and vector competition analysis. The results showed that the combined biomass production of the component crop species was significantly greater in the Ginkgo/crop mixtures than in monocultures crops (Ginkgo, broad bean, wheat, and rapeseed). Ginkgo:rapeseed ratio 24:12, Ginkgo:bread bean ratio 24:5, and Ginkgo:wheat ratio 24:200 had the best total biomass production. Ginkgo:rapeseed (and broad bean) ratio 24:5 and Ginkgo:wheat ratio 24:200 in respective Ginkgo/crop mixtures had the maximum economic yield. Vector competition analysis showed that Ginkgo/rapeseed mixture exhibited an antagonistic interaction type and therefore is not suitable for intercropping. Ginkgo/broad bean mixture demonstrated the most beneficial effects among the three intercropping systems.
  • Authors:
    • Li, B.
    • Qiao, B.
    • Zhang, C.
    • Chang, J.
  • Source: Journal of Fruit Science
  • Volume: 29
  • Issue: 2
  • Year: 2012
  • Summary: To improve ecological efficiency of Chinese jujube orchard and to further dig out its productive potentiality, comparative tests between intercropping wheat with Chinese jujube and single-cropping wheat were conducted. The results showed that intercropping wheat with Chinese jujube could obviously decrease dry-hot winds in wheat field; Bulk density and temperature of the soil were decreased, and the total porosity, capillary porosity, capillary moisture capacity and moisture capacity were apparently improved ( P
  • Authors:
    • Pauletti, V.
    • Favaretto, N.
    • Molin, R.
    • Mellek, J. E.
    • Dieckow, J.
    • Da-Silva, V. L.
    • Vezzani, F. M.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 36
  • Issue: 3
  • Year: 2012
  • Summary: The quality of no-tillage systems depends on an adequate soil management that promotes soil structure improvements. This is associated to the cropping system adopted. This study investigated the effect of long-term no-tillage systems (18 years) on the structural quality of a sandy-clay to clay Oxisol (Latossolo Vermelho) in the region of Campos Gerais, Parana, Brazil. Five cropping systems were assessed: wheat-soybean [Wt-So], black oat-maize-wheat-soybean [Ot-Mz-Wt-So], vetch-maize-wheat-soybean [Vt-Mz-Wt-So], ryegrass-maize-ryegrass-soybean [Rg-Mz-Rg-So]; and alfalfa-maize [Alf-Mz]. Soil was sampled from the layers 0-5, 5-10 and 10-20 cm, in cylinders and in blocks with undisturbed structure. In the 0-5 cm layer, bulk density was lowest in the Ot-Mz-Wt-So (0.96 Mg m -3) and Vt-Mz-Wt-So systems (0.93 Mg m -3). In the 5-10 and 10-20 cm layers, the bulk density tended to be lowest in Alf-Mz systems (1.14 and 1.17 Mg m -3, respectively). A similar trend was observed for macroporosity, which in the top layer was greater in Ot-Mz-Wt-So (0.29 m 3 m -3) and Vt-Mz-Wt-So (0.30 m 3 m -3) and in the 5-10 and 10-20 cm layers tended to be greater in the Alf-Mz system (0.19 m 3 m -3). No clear trend was observed for microporosity. The saturated hydraulic conductivity was directly related with macroporosity, and was highest for Vt-Mz-Wt-So in the 0-5 cm layer (224 mm h -1) and Alf-Mz in the layers 5-10 (170 mm h -1) and 10-20 cm (147 mm h -1). In the Vt-Mz-Wt-So system, the mean weight diameter of aggregates was lowest in the 0-5 cm layer (2.39 mm) and highest (3.04 mm) in the Wt-So. The highest cone index values were observed in the Wt-So system, with over 1.5 MPa in the 7.5-22.5 cm layer. The compaction degree was lowest in the Alf-Mz system (0.2 MPa cm). Results were attributed mainly to the role of the crop roots of the systems and to the intensity of machinery traffic. Considering the 0-20 cm layer as a whole, the capacity to promote soil structural quality improvements was greater for the semi-perennial Alf-Mz system than for systems based on annual species. Bi-annual rotation systems, based on cover crops such as black oat and vetch, promote soil structural quality improvements compared to the wheat - soybean succession.
  • Authors:
    • Oliveira, P. S. R. de
    • Costa, A. C. T. da
    • Demetrio, J. V.
  • Source: Pesquisa Agropecuaria Tropical
  • Volume: 42
  • Issue: 2
  • Year: 2012
  • Summary: In the crop-livestock integration system, improper oat management can result in low biomass yield. This study aimed to evaluate the effect of cutting management systems on the biomass yield of five oat cultivars with potential use in the crop-livestock integration system. A completely randomized blocks design with four replications, in a split-plot scheme, was used. The plots were represented by the oat cultivars Preta Comum, IAPAR 61, IPR 126, FAPA 2, and FUNDACEP FAPA 43. The Preta Comum cultivar features a short cycle, while the others have a long one. The sub-plots were represented by the following cutting systems: one single cut in the flowering stage, one cut in the vegetative and other in the flowering stage, two cuts in the vegetative and other in the flowering stage, and three cuts in the vegetative and other in the flowering stage. The long cycle cultivars (IAPAR 61, IPR 126, FAPA 2, and FUNDACEP FAPA 43) reached high forage yield, without affecting the subsequent fodder yield for soil covering, pointing out its ability to be used in crop-livestock systems. The management systems with three cuts in the vegetative stage maximizes the forage yield, however, concerning fodder yield, the best results were obtained by using up to two cuts in the vegetative stage, or a single one in the flowering stage.
  • Authors:
    • Ferrari, J. V.
    • Furlani Junior, E.
    • Ferrari, S.
    • Alberton, J. V.
  • Source: Revista Brasileira de Ciencias Agrarias
  • Volume: 7
  • Issue: 2
  • Year: 2012
  • Summary: The fiber quality, productivity and favorable climate are considered key points for the development of the cotton crop in the Brazilian Cerrado. This study aimed to evaluate the effect of cover crops and N application in pre-sowing on the cotton crop growth and yield. The experimental design was randomized blocks, consisting of a - three cover crops (radish, white oat and black oat) implanted during the winter period, b - four nitrogen levels (0, 30, 60 and 90 kg ha -1 of N) applied to the millet residues and before cotton sowing. In April 2008, evaluations were realized of plant development and also harvesting was performed of experimental plots of cotton plants. The results showed that the radish provides increased length of branches and cotton bolls of cotton crop, without yield increase, and the use of increasing doses of N up to 90 kg ha -1 decreased the amount of carima per plant, increasing the number of reproductive branches and cotton yield.
  • Authors:
    • Handoo, Z. A.
    • Cram, M. M.
    • Fraedrich, S. W.
    • Zarnoch, S. J.
  • Source: Nematology
  • Volume: 14
  • Issue: 4
  • Year: 2012
  • Summary: Tylenchorhynchus ewingi, a stunt nematode, causes severe injury to slash pine seedlings and has been recently associated with stunting and chlorosis of loblolly pine seedlings at some forest tree nurseries in southern USA. Experiments confirmed that loblolly pine is a host for T. ewingi, and that the nematode is capable of causing severe damage to root systems. Initial population densities as low as 60 nematodes (100 cm 3 soil) -1 were sufficient to damage the root systems of loblolly pine seedlings. Populations of T. ewingi increased on pine from two- to 16-fold, depending on the initial population density. Evaluations of various cover crops used in southern forest tree nurseries indicated that legumes, rye and several varieties of sorghum were excellent hosts for T. ewingi. Other small grains such as ryegrass, oats and wheat were poorer hosts. A cultivar of pearl millet was a non-host for T. ewingi, and a cultivar of brown top millet appeared to be either a very poor host or a non-host. Nurseries that have seedling production losses caused by T. ewingi should consider rotating with non-host cover crops such as pearl millet or leaving fields fallow as part of their pest management programme.
  • Authors:
    • Rodrigues, J. G. L.
    • Fernandes, D. M.
    • Bicudo, S. J.
    • Nascimento, F. M.
    • Fernandes, J. C.
    • Furtado, M. B.
  • Source: Revista Brasileira de Ciencias Agrarias
  • Volume: 7
  • Issue: 1
  • Year: 2012
  • Summary: The main goal of this research was to evaluate the response of maize crop in succession to maize+oat crops, with the anticipation of the increasing doses of nitrogen application in the oat culture, in no-tillage system. The experiment was carried out under field conditions at FCA/UNESP, Botucatu Campus, Sao Paulo, Brazil. The experimental design was arranged in randomized blocks with four replications, in split-plots. The plots were the nitrogen doses applied on the oat crop (0, 20, 40 e 60 kg ha -1), and split-plots, the nitrogen doses applied in the cover (60, 80, 100 e 120 kg ha -1), divided into two different crop stages of the maize crop. The dry matter weight and the C/N ratio were assessed on the oat and maize crops. On the maize crop, the plant nitrogen was quantified before the first covering and 15 days after the second covering, when the dry matter weight of the maize plants was determined. After the harvest, the yield was also calculated. Results indicate that the maize development and yield under no-till system were related to the straw C/N ratio, and the maize crop response to the anticipated N fertilization anticipation varied according to the N doses and application periods. The dry matter weight of the maize plants were influenced by the rates and periods of N applications.