• Authors:
    • Martius, C.
    • Lamers, J. P. A.
    • Ibragimov, N.
    • Kienzler, K.
    • Wassmann, R.
    • Scheer, C.
  • Source: Global Change Biology
  • Volume: 14
  • Issue: 10
  • Year: 2008
  • Summary: Land use and agricultural practices can result in important contributions to the global source strength of atmospheric nitrous oxide (N2O) and methane (CH4). However, knowledge of gas flux from irrigated agriculture is very limited. From April 2005 to October 2006, a study was conducted in the Aral Sea Basin, Uzbekistan, to quantify and compare emissions of N2O and CH4 in various annual and perennial land-use systems: irrigated cotton, winter wheat and rice crops, a poplar plantation and a natural Tugai (floodplain) forest. In the annual systems, average N2O emissions ranged from 10 to 150 mu g N2O-N m(-2) h(-1) with highest N2O emissions in the cotton fields, covering a similar range of previous studies from irrigated cropping systems. Emission factors (uncorrected for background emission), used to determine the fertilizer-induced N2O emission as a percentage of N fertilizer applied, ranged from 0.2% to 2.6%. Seasonal variations in N2O emissions were principally controlled by fertilization and irrigation management. Pulses of N2O emissions occurred after concomitant N-fertilizer application and irrigation. The unfertilized poplar plantation showed high N2O emissions over the entire study period (30 mu g N2O-N m(-2) h(-1)), whereas only negligible fluxes of N2O (< 2 mu g N2O-N m(-2) h(-1)) occurred in the Tugai. Significant CH4 fluxes only were determined from the flooded rice field: Fluxes were low with mean flux rates of 32 mg CH4 m(-2) day(-1) and a low seasonal total of 35.2 kg CH4 ha(-1). The global warming potential (GWP) of the N2O and CH4 fluxes was highest under rice and cotton, with seasonal changes between 500 and 3000 kg CO2 eq. ha(-1). The biennial cotton-wheat-rice crop rotation commonly practiced in the region would average a GWP of 2500 kg CO2 eq. ha(-1) yr(-1). The analyses point out opportunities for reducing the GWP of these irrigated agricultural systems by (i) optimization of fertilization and irrigation practices and (ii) conversion of annual cropping systems into perennial forest plantations, especially on less profitable, marginal lands.
  • Authors:
    • Paton, R. J.
    • Morton, J. D.
    • Littlejohn, R. P.
    • Houlbrooke, D. J.
  • Source: Soil Use and Management
  • Volume: 24
  • Issue: 4
  • Year: 2008
  • Summary: The North Otago Rolling Downlands (NORD) of New Zealand is currently undergoing a large change in land use with subsequent intensification as a result of a new large community irrigation scheme. To assess the effect of this change, a 4-year monitoring survey was established on two common Pallic soil types of the area to determine the influence of irrigation term (short, 5 years) and grazing animal (cattle vs. sheep) on a range of physical and organic matter soil quality parameters. This 4-year survey also included the historical land use of dryland sheep farming in the absence of irrigation water. Irrigation term had no significant (P > 0.05) effect on soil physical parameters (percentage macroporosity and bulk density) for 3 of 4 years and no significant effect (P > 0.05) on topsoil total carbon or nitrogen contents. However, irrigation term had a significant (P < 0.01) but biologically small effect on the ratio of carbon to nitrogen with narrowing of the range under longer term irrigation. A significant difference between the dryland and irrigated surveys was found for macroporosity (dryland sheep 17.3% v/v vs. irrigated sheep 13.4% v/v; P < 0.001) and for the C:N ratio (dryland sheep 10.7 vs. irrigated sheep 10.2; P < 0.05). The change in macroporosity under irrigation is likely to take effect within 1 or 2 years of land-use change as little discernable differences in soil physical properties were evident from land under short- or long-term irrigation.
  • Authors:
    • D'Ordine, R.
    • Navarro, S.
    • Back, S.
    • Fernandes, M.
    • Targolli, J.
    • Dasgupta, S.
    • Bonin, C.
    • Luethy, M. H.
    • Heard, J. E.
    • Salvador, S.
    • Kumar, G.
    • Abad, M.
    • Stoecker, M.
    • Harrison, J.
    • Anstrom, D. C.
    • Bensen, R. J.
    • Warner, D.
    • Castiglioni, P.
    • Carpenter, J. E.
  • Source: Plant Physiology
  • Volume: 147
  • Issue: 2
  • Year: 2008
  • Summary: An article about bacterial RNA chaperones conferring abiotic stress tolerance in plants and improved grain yield in maize under water-limited conditions.
  • Authors:
    • Ceccarelli, S.
    • Baum, M.
    • This, D.
    • Greco, A.
    • Grando, S.
    • Korff, M.
  • Source: Theoretical and Applied Genetics
  • Volume: 117
  • Issue: 5
  • Year: 2008
  • Summary: The objective of the present study was to identify quantitative trait loci (QTL) influencing agronomic performance across rain fed Mediterranean environments in a recombinant inbred line (RIL) population derived from the barley cultivars ER/Apm and Tadmor. The population was tested in four locations (two in Syria and two in Lebanon) during four consecutive years. This allowed the analysis of marker main effects as well as of marker by location and marker by year within location interactions. The analysis demonstrated the significance of crossover interactions in environments with large differences between locations and between years within locations. Alleles from the parent with the higher yield potential, ER/Apm, were associated with improved performance at all markers exhibiting main effects for grain yield. The coincidence of main effect QTL for plant height and yield indicated that average yield was mainly determined by plant height, where Tadmor's taller plants, being susceptible to lodging, yielded less. However, a number of crossover interactions were detected, in particular for yield, where the Tadmor allele improved yield in the locations with more severe drought stress. The marker with the highest number of cross-over interactions for yield and yield component traits mapped close to the flowering gene Ppd-H2 and a candidate gene for drought tolerance HVA1 on chromosome 1H. Effects of these candidate genes and QTL may be involved in adaptation to severe drought as frequently occurring in the driest regions in the Mediterranean countries. Identification of QTL and genes affecting field performance of barley under drought stress is a first step towards the understanding of the genetics behind drought tolerance.
  • Authors:
    • Whitmore, J.
    • Chen, X.
    • Jackson, E.
    • Erickson, C.
    • Windes, J.
    • Wesenberg, D.
    • Evans, C.
    • Obert, D.
  • Source: Journal of Plant Registrations
  • Volume: 2
  • Issue: 2
  • Year: 2008
  • Summary: 'Lenetah' (Reg. No. CV-338, PI 652440) two-rowed spring feed barley ( Hordeum vulgare L.) was developed by the Agricultural Research Service, Aberdeen, ID, in cooperation with the Idaho Agricultural Experimental Station and released in December 2007. Lenetah was selected from the cross 94Ab12981/91Ab3148. 94Ab12981 has the pedigree 85Ab2323/'Camas'. 85Ab2323 has the pedigree 79Ab19042/'Crystal'. 79Ab19042 is a selection from the cross 'Klages'/'Hector'. Camas is a selection from the cross ND5976/ND7159. ND5976 has the pedigree 'Maris Concord'/Klages//ND2679-4 and ND7159 has the pedigree Klages/ND1244/3/ND2685/ND1156//Hector. 91Ab3148 has the pedigree 'Gallatin'/'Targhee'//'Bowman'. Lenetah was selected as an F 5:6 line in 2001 and given the experimental designation 01Ab11107. It was released due to its superior yield and test weight compared to 'Baronesse', the most widely grown feed barley in Idaho and Montana. The yield advantage over Baronesse is especially pronounced in northern Idaho and eastern Washington and under dryland conditions.
  • Authors:
    • Diekmann, J.
    • Ryan, J.
    • Pala, M.
    • Singh, M.
  • Source: Experimental Agriculture
  • Volume: 44
  • Issue: 4
  • Year: 2008
  • Summary: With increasing land-use pressure in semi-arid, dryland Middle Eastern agriculture, fallow-based cereal production has given way to cropping intensification, including legume-based rotations along with conservation tillage and on-farm straw disposal. Such agronomic developments can only be biologically and economically assessed in multi-year trials. Thus, this 10-year study examined the influence of tillage systems (conventional and shallow or conservation) and variable stubble management, including compost application, on yields of barley and vetch grown in rotation. Barley yielded higher with compost applied every two or four years than with burning or soil-incorporating the straw and stubble. Barley straw and grain yields were generally higher with the mouldboard plough. Similarly with vetch, treatments involving compost application yielded significantly higher than burning or incorporating the straw and stubble. Despite yearly differences between crop yields, the pattern of treatment differences was consistent. Thus, the cereal-vetch rotation system is sustainable, while excess straw could be used as compost with benefit to the crop. Though there was no clear advantage of the shallow conservation-type tillage, the energy costs are less, thus indicating its possible advantage over conventional deep tillage in such rotational cropping systems.
  • Authors:
    • Chamorro, L.
    • Romero, A.
    • Xavier Sans, F.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 124
  • Issue: 1/2
  • Year: 2008
  • Summary: A comparative survey of weed vegetation in organic and conventional dryland winter cereal fields was performed in central Catalonia (NE Spain) in order to assess the effects of agricultural intensification on the diversity, structure and composition of weed communities. A total of 36 cereal fields were surveyed in nine agricultural sites, where a pair of one long-established organic and one conventional farms were selected. Weed surveys were carried out before harvest in 2003 and 2004, taking into account the spatial pattern. Organic practices produced an increase in weed cover, species richness and Hill's first order diversity (but not in equitability), as well as a shift in weed vegetation composition, which favoured potentially rare arable, broad-leaved, insect-pollinated and legume weeds. Weed diversity was concentrated in the crop edges, especially in the weed communities of conventional cereal fields, which were found to be more spatially heterogeneous than the organic ones.
  • Authors:
    • Pala, M.
    • Rashid, A.
    • Masri, S.
    • Matar, A.
    • Singh, M.
    • Ibrikci, H.
    • Ryan, J.
  • Source: European Journal of Agronomy
  • Volume: 28
  • Issue: 2
  • Year: 2008
  • Summary: Given the complex nature of rainfed cropping systems in Mediterranean agriculture and the dynamic nature of phosphorus (P) in soils, agronomic assessment of P fertilization must be long term in order to consider residual effects. Thus, a 9-year study involved initial relatively large applications of P (0, 50, 100, 150, 200 kg P 2O 5 ha -1) and yearly smaller dressings (0, 15, 30, 45, 60 kg P 2O 5 ha -1) in a trial involving dryland cereals (wheat/barley) in rotation with legumes (chickpea, lentil, or vetch) at three locations with varying mean annual rainfall in northern Syria; Breda (270 mm), Tel Hadya (342 mm) and Jindiress (470 mm). Assessment was made of grain, straw and total biomass yield and crop P uptake and available P (Olsen). While crop responses varied due to seasonal rainfall fluctuations, they tended to decrease with increasing initial available soil P levels (2.7, 6.2, and 4.4 mg kg -1 for Breda, Tel Hadya and Jindiress, respectively). Residual P was not significant for cereals or legumes at any site, but direct P was significant for both crops at Breda and Jindiress, as well as for legumes at Tel Hadya. In contrast, residual and direct P significantly influenced Olsen-P and seasonal and total P uptake. With no P fertilizer, or where minimal amounts (15 kg P 2O 5 ha -1) were applied annually, the balance between applied P and crop P offtake became increasingly negative; after 8 years without applied P, the P balance was -54, -38, -27, -17, and +7 kg ha -1 for the initial (residual) P application of 0, 50, 100, 150, and 200 kg P 20 5, respectively. This was counterbalanced by the higher annual application rates and to a lesser extent the amounts of P applied initially. The study demonstrated the highly variable nature of crop responses to fertilizer P under semi-arid field conditions over several years, with soil moisture from seasonal rainfall being the dominant influence on overall yields. While crop responses may not occur in any given year, especially if available P is near or above critical threshold levels, dryland cropping without P fertilizer is unsustainable in the long run.
  • Authors:
    • Ibrikci, H.
    • Grando, S.
    • Ceccarelli, S.
    • Masri, S.
    • Ryan, J.
  • Source: Journal of Plant Nutrition
  • Volume: 31
  • Issue: 2
  • Year: 2008
  • Summary: Barley is traditionally grown in the Mediterranean region as a dryland crop, invariably under drought-stressed conditions and often without inputs such as fertilizer. Following research that demonstrated the benefits of fertilization, even under less-than-favourable rainfall condition, fertilizer use on cereals has increased dramatically in the past few decades in countries of West Asia-North Africa. With developments in breeding new barley cultivars for higher yield, combined with disease resistance and environmental adaptability, it is crucial to assess the extent to which such cultivars respond to fertilizer inputs as this may affect aspects of a breeding strategy, particularly the choice of germplasm for adaptation in any particular environment. Thus, we assessed the yield potential of 30 barley cultivars with a range of germplasm types, including new cultivars and landraces, in a greenhouse in two soil types with and without adequate nitrogen and phosphorus fertilizer, i.e., low and high fertility. By comparison with the unfertilized low fertility soils, the fertilizer treatment increased yield parameters by about 10-fold. However, the rankings of some cultivars changed markedly with fertilization; some increased, others showed poor responses and decreased relatively, and two performed well with and without fertilizer. Based on the differential responses at the initial screening stage in the greenhouse, it is possible to identify lines or cultivars that are highly responsive to fertilizers and to incorporate such germplasm for further development to produce high-yielding cultivars for commercial adoption by farmers.
  • Authors:
    • Easley, S.
    • Sheedy, J.
    • Smiley, R.
  • Source: Plant Disease
  • Volume: 92
  • Issue: 12
  • Year: 2008
  • Summary: Dryland field crops in the Pacific Northwest United States are commonly produced in silt loams infested by the root-lesion nematodes Pratylenchus neglectus and P. thornei. Soils at 30 sites in Oregon were sampled from 0 to 120 cm depth to examine the vertical distribution of these Pratylenchus spp. Both species were distributed through entire soil profiles of all cropping systems. Populations were generally greatest in the surface 30 cm, but sometimes high populations were detected at depths greater than 45 cm. Sampling to 30 cm depth allowed detection of more than 50% of the population in most sites, while sampling to 45 cm depth yielded more than 75% of the population in over 75% of the sites evaluated. Therefore, soil samples should be collected to 30 to 45 cm depth to accurately estimate populations of Pratylenchus spp. in dryland crops produced on silt loams in the Pacific Northwest. Populations of Pratylenchus spp. were found to be related to the most recently planted crop, with populations after barley, after wheat, and during summer fallow being detected in ascending order.