• Authors:
    • Tiwari, S.
    • Tomar, N. S.
    • Tripathi, N.
    • Deshmukh, R.
  • Source: Physiology and Molecular Biology of Plants
  • Volume: 18
  • Issue: 1
  • Year: 2012
  • Summary: Drought tolerance is the essential trait that needs to be incorporated in cereal crops, particularly those grown under the rainfed cultivation. Drought tolerance being contributed by several regions of the genome requires identification of these regions, using suitable molecular markers. Therefore, present investigation was aimed at analyzing the genetic diversity present among the cultivars of rainfed and the irrigated areas with respect to the drought tolerant trait. In all, 14 RAPD and 90 ISSR markers were used to identify these genomic regions. Out of 14 RAPD markers, one RAPD primer exhibited polymorphic banding pattern with 18.6% polymorphism, clearly separating drought tolerant and drought susceptible genotypes. Out of 90 ISSR primers, only 3 ISSR primers revealed polymorphism in relation to the drought tolerance trait exhibiting 21.38% polymorphism.
  • Authors:
    • Oliveira, E. B. de
    • Moraes, A. de
    • Pelissari, A.
    • Reis, E. F. dos
    • Ruaro, L.
  • Source: Pesquisa Agropecuária Brasileira
  • Volume: 47
  • Issue: 4
  • Year: 2012
  • Summary: The objective of this work was to assess the effect of soil management systems and winter cover crops on the number of propagules of Fusarium spp. in soil, the incidence of sudden death syndrome (SDS), and the productivity of the soybean cultivars CD 206 and FT Fenix. Two experiments were carried out in the 2006/2007 and 2007/2008 crop years. The experimental design was a randomized complete block in a split-split plot arrangement, with three replicates. Two soil tillage systems were evaluated: no-tillage and plowed soil at a depth of 25 cm. The soil covers used were: black oat, with two planting densities; black oat+vetch; ryegrass; and fallow. The incidence of the disease in the 2006/2007 crop year in the cultivar FT Fenix was lower than in CD 206. In the 2007/2008 crop, there was no significant difference. There was an increase in productivity, of 125 kg ha -1, in the plowed treatment, when compared to no-tillage. The cover with black oat+vetch showed a higher number of propagules of Fusarium spp. in soil in the 2006/2007 crop year. However, in the second year, this difference was not observed. The soil management systems and winter cover crops used do not influence the incidence of SDS in soybean cultivars or the number of Fusarium spp. propagules in soil. The plowed system provides an increase in soybean yield in the second year of management.
  • Authors:
    • Cai, L.
    • Padovan, B.
    • Lee, B.
    • Ren, Y. L.
  • Source: Pest Management Science
  • Volume: 68
  • Issue: 2
  • Year: 2012
  • Summary: BACKGROUND: Methyl bromide is being phased out for use on stored commodities, as it is listed as an ozone-depleting substance, and phosphine is the fumigant widely used on grains. However, phosphine resistance occurs worldwide, and phosphine fumigation requires a long exposure period and temperatures of > 15 degrees C. There is an urgent requirement for the development of a fumigant that kills insects quickly and for phosphine resistance management. This paper reports on a new fumigant formulation of 95% ethyl formate plus 5% methyl isothiocyanate as an alternative fumigant for stored grains. RESULTS: The formulation is stable for at least 4 months of storage at 45 degrees C. A laboratory bioassaywith the formulation showed that it controlled all stages of Sitophilusoryzae (L.), Sitophilusgranarius (L.), Tribolium castaneum (Herbst), Rhyzopertha dominica (F.), Trogoderma variabile Ballion and Callosobruchus maculatus (Fabricius) in infestedwheat, barley, oats and peas at 80 mg L-1 for 5 days, and in canola at both 40mg L-1 for 5 days and 80mg L-1 for 2 days at 25 +/- 2 degrees C. After an 8-14 day holding period, residues of ethyl formate and methyl isothiocyanate in wheat, barley, peas and canola were below the experimental permit levels of 1.0 and 0.1 mg kg(-1). However, fumigated oats needed an 18 day holding period. CONCLUSIONS: The findings suggest that the ethyl formate plusmethyl isothiocyanate formulation has potential as a fumigant for the control of stored-grain insect pests in various commodities. (C) 2011 Society of Chemical Industry
  • Authors:
    • Portela, S. I.
    • Andriulo, A. E.
    • Restovich, S. B.
  • Source: Field Crops Research
  • Volume: 128
  • Year: 2012
  • Summary: The agricultural system of the Humid Pampas consists of continuous cropping of soybean and maize under no tillage. This system may loose nitrogen (N) through leaching during the early and final stages of summer crops and during fallow. In this study (2005-2011) we evaluated the effect of fall-winter species (rescue grass, ryegrass, oats, barley, vetch, rape seed and forage radish) and a mixture of vetch and oats used as cover crops on water and N dynamics and main crop yield. Above-ground biomass production and N uptake by cover crops ranged from 1.1 to 11.9 Mg ha(-1) and from 17 to 223 kg N ha(-1), respectively, depending on sowing and killing dates and on the preceding crop. At killing, soil nitrate content in treatments with cover crops was 50-90% lower than in the control, reducing spring N leaching risk. When preceding maize, cover crops were killed in winter or early spring and their low C/N ratio (12-38) favored N release through residue decomposition. Vetch and rape seed as predecessors of fertilized maize increased residual N by approximate to 50 kg NO3-N compared to the control, posing the risk of fall N leaching. When preceding soybean, cover crops were killed in spring and, although their C/N ratios were higher (13-85), crucifers and legumes increased soil nitrate content. Maize yield was related to soil N availability at sowing (control and legumes > crucifers > grasses) which was inversely related to the preceding cover crop C/N ratio at killing. In normal to high rainfall years there were no differences in soybean yield among treatments. Water use by cover crops did not affect the main crop production except during an exceptionally dry year. Best synchronicity between N release from cover crop residues and harvest crop demand was achieved with the oats-vetch mixture before maize and with grasses before soybean. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • King, C. A.
    • Edwards, J. T.
    • Carter, T. E.
    • Purcell, L. C.
    • Ries, L. L.
  • Source: Crop Science
  • Volume: 52
  • Issue: 1
  • Year: 2012
  • Summary: Delayed wilting is observed in a few unusual soybean [ Glycine max (L.) Merr.] genotypes, but the reasons and importance of this trait for conferring agronomic drought tolerance are poorly understood. We hypothesized that soybean genotypes with delayed wilting conserve soil moisture by restricting transpiration and that this would be reflected in decreased radiation use efficiency (RUE) and/or improved water use efficiency (WUE). Water conserved when soil moisture was plentiful would be available later in the season when drought is usually more severe. Irrigated field experiments in eight environments compared RUE of genotypes known to wilt differently during drought. In addition, we measured stomatal conductance, carbon isotope discrimination (CID), volumetric soil-moisture content, stomatal density, and canopy temperature depression. In six of the eight environments, slow-wilting genotypes generally had lower RUE than fast-wilting genotypes, which is consistent with our hypothesis. Three of four slow-wilting genotypes had higher soil moisture immediately before irrigation than fast-wilting genotypes, which is also consistent with the hypothesis. Genotypic differences in CID (a proxy for WUE) were present but were not consistently related with slow wilting. No genotypic differences were detected in stomatal conductance or canopy temperature. These results suggest that multiple mechanisms involving RUE and WUE could result in soil-water conservation in these diverse genotypes.
  • Authors:
    • Gonzalez, B.
    • Rodriguez, E.
    • Campos, M.
  • Source: Bulletin of Insectology
  • Volume: 65
  • Issue: 1
  • Year: 2012
  • Summary: The use of cover crops is the most effective method to combat soil degradation due to erosion in olive cropping in Spain. Within the framework of Integrated Pest Management (IPM), a compelling question is how cover crops would affect elements of the olive-agroecosystem such as natural enemies. Accordingly, the objective of this study was to examine the effects of cereal cover cropping on natural enemy communities in olive groves. Samples of the anthropod communities were collected in olive groves under tillage and cover cropping systems at five different locations in the same province. Cereal cover crops significantly increased the abundance of parasitoids in the olive canopy, especially Ageniaspis fuscicollis Dalman (Hymenoptera Encyrtidae) a parasitoid of the olive moth Prays oleae Bernard (Lepidoptera Yponomeutidae), the most common insect pest of olive trees. However, parasitoid abundance and structure depended on olive grove location suggesting the importance of crop surroundings in parasitoid community dynamics. Predators numbers were slightly higher in tilled olive groves but no significant differences were found between the two soil management systems.
  • Authors:
    • Marins, A. C. de
    • Souza, S. N. M. de
    • Santos, R. F.
    • Veloso, G.
    • Secco, D.
    • Rosa, H. A.
    • Borsoi, A.
  • Source: Food, Agriculture and Environment (JFAE)
  • Volume: 10
  • Issue: 2 part 3
  • Year: 2012
  • Summary: Certain soil physical characteristics such as resistance to penetration (Rs) and bulk density (Ds) are extremely important, and are also indicators of the soil structural quality. This paper aims at evaluating the use of four cover crop species in the reduction of density and soil resistance to penetration in areas where a no-till farming system is applied. The so-called "regenerator" species, which act in soil structure, were considered treatments, and consisted of four species: showy rattlebox ( Crotalaria spectabilis), moha grass ( Setaria italica), pigeon pea ( Cajanus cajan), sorghum ( Sorghum bicolor), and yet the control (an area without crops). Soil bulk density evaluations were carried out according to the methodology recommended by EMBRAPA, in the following depths: 0.0-0.1, 0.1-0.2 and 0.2-0.3 m. Sampling was carried out with five replications for the crop row and five for the spacing between each crop row, in each experimental unit (5 m * 5 m), up to 0.40 m in depth. An experimental design was 5*4*2 factorial, meaning 5 treatments, 4 depths and 2 sampling conditions. The species studied, especially the pigeon pea and the sorghum, showed a great potential to improve soil structural state, for they showed figures to Ds and Rs that were lower than the ones from the area without crops.
  • Authors:
    • Isla, R.
    • Urrego, Y. F.
    • Salmeron, M.
    • Cavero, J.
  • Source: Agricultural Water Management
  • Volume: 113
  • Issue: October
  • Year: 2012
  • Summary: Typical field conditions under sprinkler irrigation include low irrigation uniformity and non-uniform plant density, which can affect the crop yield and the environmental impact of irrigation. The effect of the uniformity of sprinkler irrigation and plant density on the variability of maize grain yield under semi-arid conditions was evaluated, and the relevance of the spatial variability of these two variables on the simulation of maize grain yield was tested with the DSSAT-CERES-Maize model (V 4.5). Experimental field data from three maize growing seasons (2006, 2009 and 2010) with nighttime or daytime sprinkler irrigation were used to test the model performance. Yield, irrigation depths and plant density distribution were measured in 18 m * 18 m plots divided in 25 sub-plots. Regression analysis showed that the variability of plant density and seasonal irrigation depth (due to irrigation non-uniformity) was able to explain from 28 to 77% of the variability in maize grain yield for the experiments with a relatively high coefficient of uniformity (CU) (73-84%) and high plant density (more than 74,844 plants ha -1). Taking into account irrigation depth distribution improved maize yield simulations compared to simulations with the average irrigation water applied. The root mean square error ( RMSE) decreased from 637 to 328 kg ha -1. Maize yield was over-predicted by 3% when irrigation depth distribution was not considered. Including plant density distribution in the simulations did not improve maize yield simulations. The simulated decrease in maize yield with decreasing CU of irrigation from 100 to 70% varied from year to year and caused reductions in yield ranging from 0.75 to 2.5 Mg ha -1. The ability of the model to simulate CU effects on maize yield is shown.
  • Authors:
    • Oehler, F.
    • Ferchaud, F.
    • Durand, P.
    • Salmon-Monviola, J.
    • Sorel, L.
  • Source: Computers and Electronics in Agriculture
  • Volume: 81
  • Issue: February
  • Year: 2012
  • Summary: Assessing the environmental impacts of agricultural practices at the catchment scale increasingly involves the use of spatially distributed models that include cropping systems as input. Use of these models for diagnosis and evaluation requires large datasets at large spatial and temporal scales. The description of spatial dynamics of cropping systems at a fine resolution (i.e. field level) is particularly needed. As these data are scarce or not available, our objective was to propose a model that first reconstructs spatial dynamics of past cropping systems from available data, and second constructs alternative spatial cropping systems, corresponding to agricultural practice scenarios. Classification systems for farms and fertilisation practices were defined to classify farm-level organisation for crop-succession and crop management strategies, in particular nitrogen fertilisation. Winter cover crops and multiple strategies per crop at the farm level can be represented with this model. Cropping systems are modelled in three steps: we modelled crop cover succession in summer with Markov chains based on empirical data and in winter with rules based on expert agronomic knowledge: lastly a Knapsack-based algorithm was used to allocate a crop management system to fields with constraints on several crop management strategies per crop type. Results of a case study performed on the Fremeur catchment (western France) show that this model respects the main constraints for cropping system modelling to assess agricultural practices at the catchment scale. From a scenario discussed with stakeholders and regional authorities characterised by stable areas of summer crops, the decrease in bare soil area in winter and overall reduction in total nitrogen fertilisation for different types of crops and farms we demonstrate the model's ability to simulate coherent cropping systems. Thus, if faced with a lack of data or knowledge about the local factors that drive changes in cropping systems, the model can construct the spatial dynamics of cropping systems, which can be used as input to distributed nitrate transfer models to assess agricultural practices at the catchment scale. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Saoub, H. M.
    • Akash, M. W.
    • Ayad, J. Y.
  • Source: Research on Crops
  • Volume: 13
  • Issue: 1
  • Year: 2012
  • Summary: In Jordan, the improvement of vetch production is becoming one of the main objectives as its growing areas are decreasing either because of environmental or cropping system changes. However, there is no literature concerning the assessment of genetic diversity of vetches landraces that harbour important genes for the development of new adapted varieties. The present study aimed at collecting, evaluating and characterizing vetch landraces covering different parts of Jordan. Twenty-six vetch landraces were collected from different parts of Jordan during a period extended from April to May in 2006-07 growing season and assessed in the field during 2008-09 growing season. The experiment was conducted at three stations (Ghwier Agricultural Research Station, Rabba Agricultural Research Station and Jubeiha Agricultural Research Station, The University of Jordan). Results indicated that grain yield of Vicia erivillia landraces was higher than grain yield of Vicia sativa landraces, regardless of the growing location. However, biological yield obtained from V. sativa entries [671 kg/ha (entry no. 6) upto 2514 kg/ha (entry no. 1)] was higher than that obtained from V. erivillia entries [536 kg/ha (entry no. 10) upto 2125 kg/ha (entry no. 23)]. Similar trend was shown for straw yield where V. sativa entries had more vegetative growth compared to V. erivillia entries. These differences attributed to the dissimilarity in genetic make-up of the two species. For example, some researchers mention that V. erivillia produces more grain yield due to its ability to tolerate drought when compared to V. sativa. The identification of these superior adapted local landraces is the first step in fulfilling the objective of the national vetch breeding programme.