• Authors:
    • Kephart, K. D.
    • Klouser, L.
    • Johnston, J. A.
    • Johnston, R. H.
    • Hogg, A. C.
    • Dyer, A. T.
  • Source: Phytopathology
  • Volume: 100
  • Issue: 1
  • Year: 2010
  • Summary: Caused by a complex of Fusarium species including F. culmorum, F. graminearum, and F. pseudograminearum, Fusarium crown rot (FCR) is an important cereal disease worldwide. For this study, Fusarium population dynamics were examined in spring wheat residues sampled from dryland field locations near Bozeman and Huntley, MT, using a quantitative real-time polymerase chain reaction (qPCR) Taqman assay that detects F. culmorum, F. graminearum, and F. pseudograminearum. Between August 2005 and June 2007, Fusarium populations and residue decomposition were measured eight times for standing stubble (0 to 20 cm above the soil surface), lower stem (20 to 38 cm), middle stem (38 to 66 cm), and chaff residues. Large Fusarium populations were found in stubble collected in August 2005 from F. pseudograminearum-inoculated plots. These populations declined rapidly over the next 8 months. Remnant Fusarium populations in inoculated stubble were stable relative to residue biomass from April 2006 until June 2007. These two phases of population dynamics were observed at both locations. Relative to inoculated stubble populations, Fusarium populations in other residue fractions and from noninoculated plots were small. In no case were FCR species observed aggressively colonizing noninfested residues based on qPCR data. These results suggest that Fusarium populations are unstable in the first few months after harvest and do not expand into noninfested wheat residues. Fusarium populations remaining after 8 months were stable for at least another 14 months in standing stubble providing significant inoculums for newly sown crops.
  • Authors:
    • Nachit, M. M.
    • Mori, M.
    • Inagaki, M. N.
  • Source: Cereal Research Communications
  • Volume: 38
  • Issue: 4
  • Year: 2010
  • Summary: The drought stress in the rain-fed regions of West Asia and North Africa strongly depends on residual soil water available for the reproductive plant growth. The water uptake ability (i.e. water consumption per unit dry matter per day) of three synthetic-derived bread wheat genotypes, SYN-8, SYN-10 and SYN-15, and their parental variety Cham 6 were examined under controlled conditions. In addition, yield performance was compared under one artificial environment with supplemental irrigation and ten rain-fed environments at two locations over five cropping seasons. Large differences were found in water uptake ability among the four wheat genotypes; SYN-8 had the highest and SYN-10 the lowest ability. These differences were reflected in decrease of soil water content and increase of leaf temperature after irrigation. Under field conditions of supplemental irrigation, there were no significant differences in grain yield among genotypes Cham 6, SYN-8 and SYN-10; however, SYN-15 had lower grain yield due to low harvest index. Significant differences of the grain yield were found between SYN-8 and SYN-10 grown in rain-fed conditions. Lower water uptake ability was associated with higher grain yield; this speculates that intensive extraction of water from soil during vegetative growth might increase biomass production, but leave inadequate available soil moisture for reproductive growth and grain production. The balancing of water consumption by plants with stored soil moisture over the whole growing period is a major attribute of drought adaptation in these synthetic-derived wheat genotypes.
  • Authors:
    • Rayar, A. J.
    • Senthivel, T.
    • Kannan, N.
    • Frank, M.
  • Source: Agricultural Water Management
  • Volume: 97
  • Issue: 5
  • Year: 2010
  • Summary: The study explores the potential of introducing an additional crop during dry season in Rwanda, comparing the efficiency of in situ soil moisture conservation techniques to sustain rain-fed agriculture. Comparative study of in situ soil moisture conservation techniques in bench terraces and unterraced field with maize crop had been conducted from June 2007 to October 2007. Bench terrace increased the average soil moisture content in 90 cm soil depth by more than 50% than that of unterraced land. Within the bench terraced field compartment bund and ridges and furrows increased soil moisture by 19.5% and 27.9% higher than plain bed. In terms of efficiency of moisture conservation, ridges and furrows performed well with 85.8% followed by compartment bund with 75.9% in terraced field. Unterraced field conserved moisture very poorly with 13.9% efficiency inferring importance of bench terraces for soil moisture conservation. No maize grain yield was recorded in all the techniques because soil water depleted to 60% and above from the beginning of the cropping period inferring the need of supplementary irrigation. Analysis of rainfall, crop water demand and in situ moisture conservation reveals exciting opportunities for water productivity enhancements by integrating components of water management within the context of rain-fed farming through water harvesting and supplemental or microirrigation for dry spell mitigation. Detailed analysis is needed for feasibility of lift irrigation with different crops under different altitudes to derive suitable policy for hill land irrigation.
  • Authors:
    • Starkey, S.
    • Reese, J.
    • Viswanathan, P.
    • Orozco, G. V.
    • Cardona, P. S.
    • Khan, S. A.
    • Murugan, M.
    • Smith, C. M.
  • Source: Journal of Economic Entomology
  • Volume: 103
  • Issue: 3
  • Year: 2010
  • Summary: The Russian wheat aphid, Diruaphis noxia (Kurdjumov) (Hemiptera: Aphididae), is globally one of the most devastating pests of bread wheat, Tritium aestivum L.; durum wheat, Triticum turgidum L.; and barley, Hordeum vulgare L. Host plant resistance is the foundation for cereal insect pest management programs, and several sources of D. noxia resistance have been incorporated in cultivars to manage D. noxia damage. The emergence of D. noxia North American biotype 2 (RWA2) in Colorado has made all known Dn genes vulnerable except the Dn7 gene from rye, Secale cereale, and has warranted exploration for sources of resistance to both RWA1 and RWA2. The category of resistance in resistant donor plants may exert selection pressure over the aphid population to form a new virulent population. In the current study, we report tolerance and antibiosis resistance to RWA1 and RWA2 in the barley genotype 'Stoneham'. The rate and degree of expression of resistance in Stoneham against RWA1 and RWA2, although not similar, are greater than the partial resistance in 'Sidney'. Antixenosis resistance to RWA1 or RWA2 was not observed in Sidney or Stoneham. The tolerance identified in Stoneham is encouraging because it may delay D. noxia biotype selection and fits well in a dryland barley cropping system.
  • Authors:
    • McLaughlin, M. J.
    • McBeath, T. M.
    • Noack, S. R.
  • Source: Crop & Pasture Science
  • Volume: 61
  • Issue: 8
  • Year: 2010
  • Summary: Although not commonly used in dryland cropping systems to date, foliar phosphorus (P) fertilisation may allow a tactical response to prevailing seasonal climatic conditions, with the added benefit of reduced input costs at sowing. However, variable outcomes have been reported from field trials predominantly conducted in the USA, and to a lesser degree in Australia. The effectiveness of foliar P is dependent on soil P status, soil water status, crop type, fertiliser formulation and prevailing climatic conditions. This review argues that the potential of foliar P fertilisation in Australian dryland cereal cropping could be enhanced by altering formulations for enhanced leaf penetration using adjuvants, and by accurately assessing the responsiveness of sites before application. This review demonstrates that it is important to use appropriate techniques such as isotopic labelling, to measure the efficacy and mode of action of foliar formulations.
  • Authors:
    • Maraseni, T. N.
    • Cockfield, G.
    • Maroulis, J.
  • Source: The Journal of Agricultural Science
  • Volume: 148
  • Year: 2010
  • Authors:
    • Yu Qiang
    • Wang Enli
    • Chen Chao
  • Source: Agricultural Water Management
  • Volume: 97
  • Issue: 8
  • Year: 2010
  • Summary: In the North China Plain (NCP), while irrigation using groundwater has maintained a high-level crop productivity of the wheat-maize double cropping systems, it has resulted in rapid depletion of groundwater table. For more efficient and sustainable utilization of the limited water resources, improved understanding of how crop productivity and water balance components respond to climate variations and irrigation is essential. This paper investigates such responses using a modelling approach. The farming systems model APSIM (Agricultural Production Systems Simulator) was first calibrated and validated using 3 years of experimental data. The validated model was then applied to simulate crop yield and field water balance of the wheat-maize rotation in the NCP. Simulated dryland crop yield ranged from 0 to 4.5 t ha -1 for wheat and 0 to 5.0 t ha -1 for maize. Increasing irrigation amount led to increased crop yield, but irrigation required to obtain maximum water productivity (WP) was much less than that required to obtain maximum crop yield. To meet crop water demand, a wide range of irrigation water supply would be needed due to the inter-annual climate variations. The range was simulated to be 140-420 mm for wheat, and 0-170 mm for maize. Such levels of irrigation applications could potentially lead to about 1.5 m year -1 decline in groundwater table when other sources of groundwater recharge were not considered. To achieve maximum WP, one, two and three irrigations (i.e., 70, 150 and 200 mm season -1) were recommended for wheat in wet, medium and dry seasons, respectively. For maize, one irrigation and two irrigations (i.e., 60 and 110 mm season -1) were recommended in medium and dry seasons, while no irrigation was needed in wet season.
  • Authors:
    • Bertrand, N.
    • Parent, L. É.
    • MacDonald, J. D.
    • Chantigny, M. H.
    • Angers, D. A.
    • Fallon, E.
    • Tremblay, N.
    • Rochette, P.
  • Source: European Journal of Soil Science
  • Volume: 61
  • Issue: 2
  • Year: 2010
  • Summary: Drainage and cultivation of organic soils often result in large nitrous oxide (N2O) emissions. The objective of this study was to assess the impacts of nitrogen (N) fertilizer on N2O emissions from a cultivated organic soil located south of Montreal, QC, Canada, drained in 1930 and used since then for vegetable production. Fluxes of N2O were measured weekly from May 2004 to November 2005 when snow cover was absent in irrigated and non-irrigated plots receiving 0, 100 or 150 kg N ha(-1) as NH4NO3. Soil mineral N content, gas concentrations, temperature, water table height and water content were also measured to help explain variations in N2O emissions. Annual emissions during the experiment were large, ranging from 3.6 to 40.2 kg N2O-N ha(-1) year(-1). The N2O emissions were decreased by N fertilizer addition in the non-irrigated site but not in the irrigated site. The absence of a positive influence of soil mineral N content on N2O emissions was probably in part because up to 571 kg N ha(-1) were mineralized during the snow-free season. Emissions of N2O were positively correlated to soil CO2 emissions and to variables associated with the extent of soil aeration such as soil oxygen concentration, precipitation and soil water table height, thereby indicating that soil moisture/aeration and carbon bioavailability were the main controls of N2O emission. The large N2O emissions observed in this study indicate that drained cultivated organic soils in eastern Canada have a potential for N2O-N losses similar to, or greater than, organic soils located in northern Europe.
  • Authors:
    • Gross, J. R.
    • Tanaka, D. L.
    • Liebig, M. A.
  • Source: Soil Science Society of America Journal
  • Volume: 74
  • Issue: 2
  • Year: 2010
  • Summary: The inclusion of cover crops during fallow (i.e., green fallow) may mitigate greenhouse gas (GHG) emissions from dryland cropping systems. An investigation was conducted to quantify the effects of chemical and green fallow on soil organic C (SOC) and CO2, CH4, and N2O flux within spring wheat (Triticum aestivum L.)-fallow (chemical fallow) and spring wheat-safflower (Carthamus tinctorius L.)-rye (Secale cereale L.) (green fallow) under no-till management in west-central North Dakota. Using static chamber methodology, flux measurements were made during 19 mo of the fallow period of each cropping system. Soil samples collected before initiation of flux measurements indicated no difference in SOC in the surface 10 cm between cropping systems. Additionally, differences in gas flux between cropping systems were few. Emission of CO2 was greater under green fallow than chemical fallow during spring thaw until the termination of rye (P = 0.0071). Uptake of atmospheric CH4 was the dominant exchange process during the evaluation period, and was significantly (P = 0.0124) greater under chemical fallow (-2.7 g CH4-C ha-1 d-1) than green fallow (-1.5 g CH4-C ha-1 d-1) following the termination of rye. Cumulative fluxes of CO2, CH4, and N2O did not differ between the chemical- and green-fallow phases during the 19-mo period (P = 0.1293, 0.2629, and 0.9979, respectively). The results from this evaluation suggest there was no net GHG benefit from incorporating a rye cover crop during the fallow phase of a dryland cropping system under no-till management.
  • Authors:
    • Pepo, P.
  • Source: 45th Croatian & 5th International Symposium on Agriculture
  • Year: 2010
  • Summary: In non-irrigated treatment the maximum yields of winter wheat were 5590 kg ha -1 in biculture (maize-wheat) and 7279 kg ha-1 in triculture (peas-wheat-maize) in 2007 year characterized by water-deficit stress. In 2008 (optimum rain amount and distribution) the maximum yields were 7065 kg ha -1 (biculture) and 8112 kg ha -1 (triculture) in non irrigated conditions. The fertilization surpluses of wheat were 2853-3698 kg ha -1 (non-irrigated) and 3164-5505 kg ha -1 (irrigated) in a dry cropyear (2007) and 884-4050 kg ha -1 (non-irrigated) and 524-3990 kg ha -1 (irrigated) in an optimum cropyear (2008). The optimum fertilizer doses varied N150-200+PK in biculture and N50-150+PK in triculture depending on cropyear and irrigation. The optimalization of agrotechnical elements provides 7,8-8,5 t ha -1 yields in dry cropyear and 7,1-8,1 t ha -1 yields of wheat in good cropyear, respectively. Our scientific results proved that in water stress cropyear (2007) the maximum yields of maize were 4316 kg ha -1 (monoculture), 7706 kg ha -1 (biculture), 7998 kg ha -1 (triculture) in non irrigated circumstances and 8586 kg ha -1, 10 970 kg ha -1, 10 679 kg ha -1 in irrigated treatment, respectively. In dry cropyear (2007) the yield-surpluses of irrigation were 4270 kg ha -1 (mono), 3264 kg ha -1 (bi), 2681 kg ha -1 (tri), respectively. In optimum water supply cropyear (2008) the maximum yields of maize were 13 729-13 787 (mono), 14 137-14 152 kg ha -1 (bi), 13 987-14 180 kg ha -1 (tri) so there was no crop-rotation effect. We obtained 8,6-11,0 t ha -1 maximum yields of maize in water stress cropyear and 13,7-14,2 t ha -1 in optimum cropyear on chernozem soil with using appropriate agrotechnical elements.