• Authors:
    • Kripa, S.
    • Singh, R.
  • Source: Annals of Plant Protection Sciences
  • Volume: 18
  • Issue: 2
  • Year: 2010
  • Summary: Field studies were conducted in Uttar Pradesh, India, during the 2007/08 and 2008/09 rabi seasons, to determine the effect of intercropping on the mustard aphid ( Lipaphis erysimi) incidence. Indian mustard was intercropped with wheat, barley, pea, chickpea, lentil, linseed and radish, with a sole crop of Indian mustard as the control. The aphid population was determined and yield was recorded at harvest. Results showed that mustard intercropped with barley registered minimum mean aphid population index (2.35) and maximum mean yield of mustard (2.67 q/ha), followed by mustard + wheat, having mean aphid index of 2.53 q/ha and 2.67 q/ha, respectively. Mustard intercropped with linseed and chickpea were also better than the control in checking the incidence of mustard aphid, having 2.88 and 3.09 mean aphid indexes, respectively. However, the mustard intercropped with pea, lentil and radish were at par with the control.
  • Authors:
    • Mitchell, J. P.
    • Summers, C. G.
    • Stapleton, J. J.
    • Prather, T. S.
  • Source: PHYTOPARASITICA
  • Volume: 38
  • Issue: 1
  • Year: 2010
  • Summary: Experiments were conducted in laboratory bioreactors and in field plots to test effects of certain cultivated members of the grass family (Poaceae=Gramineae), including wheat ( Triticum aestivum cv. Yolo), barley ( Hordeum vulgare cv. UC337), oats ( Avena sativa cv. Montezuma), triticale ( X Triticosecale), and a sorghum-sudangrass hybrid ( Sorghum bicolor * S. sudanense="sudex", cv. Green Grazer V) for soil disinfestation potential. Soilborne pest organisms tested for effects on survival and activity included the phytopathogens Sclerotium rolfsii, Pythium ultimum and Meloidogyne incognita, and a variety of weed taxa. Following soil amendment, bioreactors were incubated for 7 days at ambient (23°C) or elevated, but sublethal (38°C day/27°C night), soil heating regimens. Addition of each of the poaceous amendments to soil at 23°C resulted in inconsistently reduced tomato root galling (49-97%) by M. incognita, or reduced recovery of S. rolfsii and P. ultimum (0-100%) fungi in soil, after 7 days' incubation ( P≤0.05). When the organisms were exposed to the poaceous soil amendments at the 38°/27° temperature regimen, nematode galling and recovery of active fungi were consistently and significantly reduced by 98-100%. These results demonstrated feasibility of soil disinfestation ("biofumigation") by activity of poaceous amendments, further aided by combining plant residues with soil heating (e.g. solarization). Results from three field experiments with sudex cover crops, conducted throughout the growing season, demonstrated biocidal activity on a range of weedy plants, including Amaranthus retroflexus, Calandrinia ciliata, Cerastium arvense, Digitaria sanguinalis, Echinochloa crus-galli and Poa annua. Both shoots and roots of sudex provided allelopathic weed biomass reductions of 35-100%, and for at least 106 days after shredding. Deleterious activity of shredded residues incorporated in soil was less persistent. These properties in poaceous crops can be useful for soil disinfestation; however, harmful phytotoxicity to subsequent crops may also result. In order to take full advantage of these low-input measures for controlling soilborne diseases and pests, further understanding of their properties must be gained, and user guidelines developed.
  • Authors:
    • Meena, B.
    • Swaminathan, S.
    • Verma, T.
  • Source: Annals of Plant Protection Sciences
  • Volume: 18
  • Issue: 1
  • Year: 2010
  • Summary: Field studies were conducted in India, during the 1999/2000 and 2000/01 rabi seasons, to detemine the impact of intercrops on the incidence of Lipaphis erysimi on Indian mustard. The treatments comprised Indian mustard+wheat (2:3; 3 rows of intercrop and 2 rows of Indian mustard), Indian mustard+barley (2:3), Indian mustard+chickpeas (2:2) and Indian mustard. Aphid populations were recorded from 5 randomly selected plants from each plot at weekly intervals from initial appearance to harvest. Visual counts of aphids were made to record the populations on wheat, barley and chickpeas. Higher aphid numbers were recorded on Indian mustard and Indian mustard+chickpea intercrop. The average number of aphids was higher during the 1999/2000 season and lower during the 2000/01 season. The peak population was observed during the second and fourth weeks of February. The Indian mustard+chickpea intercrop had significantly higher aphid populations (320.35), followed by Indian mustard (234.71) during the 1999/2000 season possibly due to the plant height and the extra nitrogen made available by chickpeas resulting in better succulence of Indian mustard. The range of aphid populations was 153.60-320.35/5 plants during the 1999/2000 season and 118.88-125.81/5 plants during the 2000/01 season.
  • Authors:
    • Hayes, P.
    • Talbert, H.
    • Surber, L.
    • Kanazin, V.
    • Bowman, J.
    • Abdel-Haleem, H.
    • Blake, T.
  • Source: Euphytica
  • Volume: 172
  • Issue: 3
  • Year: 2010
  • Summary: More than half of the barley grown in the USA is used for livestock feed, with the remaining stocks diverted for human food and malting purposes. The use of barley grain as a major source of cattle feed has been criticized because of its rapid digestion in the rumen, which can result in digestive disorders in cattle. In sacco dry matter digestibility (ISDMD) and particle size (PS) after dry rolling have been found to play a role in the feedlot performance of barley as a feed grain. Reducing the rate of ISDMD is predicted to result in significantly improved animal health and average daily gain. A recombinant inbred line population derived from a cross between a high ISDMD, two-rowed barley cultivar (Valier) and a six-rowed Swiss landrace line (PI370970) exhibiting far slower ISDMD has been developed for studying the underlying genetic locations and mechanisms of these traits. To detect associated quantitative trait loci (QTLs), we collected and analyzed data from irrigated and rain-fed environments. A significant negative correlation was observed between ISDMD and PS. High heritability estimates for ISDMD and PS suggest that early selection for these traits during breeding would be achievable. Four QTLs were identified on chromosomes 2H, 6H, and 7H, explaining 73-85% of ISDMD phenotypic variation, while three QTLs on 2H and 7H were associated with variation in PS and explained 58-77% of its variation. A major QTL on chromosome 2H tightly linked to the morphology-modifying gene vrs1 was found to dramatically control 35-62% of the phenotypic variation of ISDMD and 26-53% of that of PS. The impact of the vrs1 locus on ISDMD was validated in two populations representing different genetic backgrounds. Our results suggest that it may also be advantageous to simultaneously overlap these QTLs around the vrs1 locus.
  • Authors:
    • Matic, T.
    • Todorovic, M.
    • Albrizio, R.
    • Stellacci, A.
  • Source: Field Crops Research
  • Volume: 115
  • Issue: 2
  • Year: 2010
  • Summary: The understanding of the interactive effect of water and N availability, associated with the ability of crops to efficiently use these resources, is a crucial issue for stabilizing cereal production in Mediterranean areas. A 3-year side by side experiment on durum wheat and barley, under different water regimes and nitrogen levels, was carried out in a typical Mediterranean environment of Southern Italy, to identify the outstanding features of these species that contribute to enhanced grain yield and improved water and nitrogen use efficiency. Wheat and barley response was assessed under three water supply regimes ( I100, I50, I0: full irrigation, 50% of full irrigation and rainfed) coupled with two N fertilizer levels (high N: 120 kg ha -1 and low N: not fertilized). In order to evaluate barley yield response under lower N rates, 60 kg ha -1 were applied in 2006. The occurrence of abundant rainfall during the experimental period determined only mild water stress during most of the growing season, especially in 2006 and 2007. Under these conditions, nitrogen fertilization was the main factor affecting crop response, and different crop traits in response to irrigation were primarily evident on tissue N concentrations. Grain number per unit land area explained a high proportion of grain yield and it was mainly influenced by N fertilization. Water availability enhanced N absorption: the response of both crops to N fertilization, in terms of N uptaken and grain N concentration, was higher in the year characterized by greater water availability during the most sensitive stages to drought stress. Under unfertilized conditions, the two crops showed similar response in terms of number of grains per unit land area; under N fertilization, barley exhibited a higher increase in number of grains per unit land area, but wheat achieved similar yields as consequence of the higher grain weight. In years characterized by similar average productivity of wheat, barley did not show further increase in number of seeds, even doubling the rate of N supplied. By increasing irrigation water supply, the two crops showed a similar yield response, but a different N partition, as confirmed by the lower nitrogen harvest index values for barley over 2007-2008. At similar total availability of N, barley reached higher N utilization efficiency than wheat, mainly because of a lower N concentration in the grain rather than a higher efficiency in using the available N.
  • Authors:
    • Al-Naeem, M.
  • Source: American Journal of Plant Physiology
  • Volume: 5
  • Issue: 3
  • Year: 2010
  • Summary: A field study was carried out to determine the effect of irrigation scheduling on growth parameters and Water Use Efficiency (WUE) of barley and faba bean crops for optimum production during the winter seasons of 2001-02 and 2002-03. Four irrigation treatments T 1 (application of water at field capacity soil moisture), T 2, T 3 and T 4 irrigation at 15, 30 and 45% soil moisture depletion of the available water at field capacity of soil, respectively were tested on a loamy-sand soil. Plant growth parameters of both the crops were significantly affected by the different irrigation treatments. Mean barley grain yield ranged from 4.52-6.72 Mg ha -1 and the faba bean seed yield from 0.86-1.45 Mg ha -1 in different irrigation treatments. The WUE, based on total grain/seed yield ranged between 0.90-148 kg m -3 of water for barley and 0.17-0.30 kg m -3 of water for faba bean in different irrigation treatments. There was no significant difference in WUE of barley and faba bean crops between T 1 and T 2 treatments. The WUE was slightly higher in T 2 (irrigation at 15% soil moisture depletion) than T 1 (irrigation at soil moisture of field capacity level). In conclusion, appreciable grain yield of barley and faba bean seed can be achieved if irrigated at 15% soil moisture depletion. The study provided useful information for scheduling irrigation of barley and faba bean crops under arid environment for efficient water use and management.
  • Authors:
    • Slafer, G. A.
    • Mariano Cossani, C.
    • Savin, R.
  • Source: Crop and Pasture Science
  • Volume: 61
  • Issue: 10
  • Year: 2010
  • Summary: In semiarid Mediterranean environments, low nitrogen (N) and water availabilities are key constraints to cereal productivity. Theoretically, for a given level of N or water stress, crops perform better when co-limitation occurs. Empirical evidence of this theoretical concept with field crops is rather scarce. Using data from field experiments we evaluated whether N-use efficiency (NUE) and water-use efficiency (WUE) in small grain cereals increases with the degree of co-limitation. Four field experiments were carried out during three growing seasons including factorial combinations of bread wheat, durum wheat and barley, grown under different N fertiliser rates and water regimes. Yield gap was calculated as the difference between maximum attainable yield and actual yield while stress indices for N (NSI) or water (WSI) were calculated as the ratios between actual N uptake or water use and those required to achieve maximum yields, respectively. Water and N co-limitation was calculated as CWN=1-|NSI-WSI|. The relationships of yield gap, NUE and WUE with the different co-limitation indices were evaluated. Yield gap (range from -3.8 to -8.1 Mg ha -1) enlarged (was more negative) with the highest levels of stress and, as expected from theory, it was reduced with the degree of co-limitation. WUE ranged from 6.3 to 21.8 kg ha -1 mm -1 with the maximum values observed under conditions in which co-limitation increased. Reduction in yield gap with increased degree of co-limitation was mainly due to a positive effect of this variable on WUE.
  • 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:
    • Ristolainen, A.
    • Sarikka, I.
    • Hurme, T.
    • Alakukku, L.
  • Source: Agricultural and Food Science
  • Volume: 19
  • Issue: 4
  • Year: 2010
  • Summary: Surface water ponding and crop hampering due to soil wetness was monitored in order to evaluate the effects of conservation tillage practices and perennial grass cover on soil infiltrability for five years in situ in gently sloping clayey fields. Thirteen experimental areas, each having three experimental fields, were established in southern Finland. The fields belonged to: autumn mouldboard ploughing (AP), conservation tillage (CT) and perennial grass in the crop rotation (PG). In the third year, direct drilled (DD) fields were established in five areas. Excluding PG, mainly spring cereals were grown in the fields. Location and surface area of ponded water (in the spring and autumn) as well as hampered crop growth (during June-July) were determined in each field by using GPS devices and GIS programs. Surface water ponding or crop hampering occurred when the amount of rainfall was clearly greater than the long-term average. The mean of the relative area of the ponded surface water, indicating the risk of surface runoff, and hampered crop growth was larger in the CT fields than in the AP fields. The differences between means were, however, not statistically significant. Complementary soil physical measurements are required to investigate the reasons for the repeated surface water ponding.
  • Authors:
    • Bryan, B. A.
    • King, D.
    • Wang, E.
  • Source: Global Change Biology Bioenergy
  • Volume: 2
  • Issue: 6
  • Year: 2010
  • Summary: First-generation biofuels are an existing, scalable form of renewable energy of the type urgently required to mitigate climate change. In this study, we assessed the potential benefits, costs, and trade-offs associated with biofuels agriculture to inform bioenergy policy. We assessed different climate change and carbon subsidy scenarios in an 11.9 million ha (5.48 million ha arable) region in southern Australia. We modeled the spatial distribution of agricultural production, full life-cycle net greenhouse gas (GHG) emissions and net energy, and economic profitability for both food agriculture (wheat, legumes, sheep rotation) and biofuels agriculture (wheat, canola rotation for ethanol/biodiesel production). The costs, benefits, and trade-offs associated with biofuels agriculture varied geographically, with climate change, and with the level of carbon subsidy. Below we describe the results in general and provide (in parentheses) illustrative results under historical mean climate and a carbon subsidy of A$20 t−1 CO2−e. Biofuels agriculture was more profitable over an extensive area (2.85 million ha) of the most productive arable land and produced large quantities of biofuels (1.7 GL yr−1). Biofuels agriculture substantially increased economic profit (145.8 million $A yr−1 or 30%), but had only a modest net GHG abatement (−2.57 million t CO2−e yr−1), and a negligible effect on net energy production (−0.11 PJ yr−1). However, food production was considerably reduced in terms of grain (−3.04 million t yr−1) and sheep meat (−1.89 million head yr−1). Wool fiber production was also substantially reduced (−23.19 kt yr−1). While biofuels agriculture can produce short-term benefits, it also has costs, and the vulnerability of biofuels to climatic warming and drying renders it a myopic strategy. Nonetheless, in some areas the profitability of biofuels agriculture is robust to variation in climate and level of carbon subsidy and these areas may form part of a long-term diversified mix of land-use solutions to climate change if trade-offs can be managed.