Center for Cropping Systems

Northam, Australia

Center for Cropping Systems

Northam, Australia
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Lo-Pelzer E.,French National Institute for Agricultural Research | Bousset L.,French National Institute for Agricultural Research | Jeuffroy M.H.,French National Institute for Agricultural Research | Salam M.U.,Center for Cropping Systems | And 3 more authors.
Field Crops Research | Year: 2010

To durably control phoma stem canker (Leptosphaeria maculans/. Leptosphaeria biglobosa) in oilseed rape by preserving the efficacy of specific resistances, the design of cropping systems is required, combining different aspects of crop management over time and at the regional scale. Modelling is a practical means to do so. To this end, the structure of SIPPOM, a Simulator for Integrated Pathogen POpulation Management, is presented. By linking epidemiological, population and crop model approaches, it simulates both the quantitative evolution (size) and qualitative evolution (genetic structure) of L. maculans population under the influence of various cropping systems. It involves five sub-models: (i) primary inoculum production; (ii) ascospore dispersal; (iii) crop development; (iv) plant infection, disease severity, and yield loss; and (v) changes in the genetic structure of pathogen populations over time. The input variables are weather data, soil characteristics, the description of cropping systems (crop sequence and winter oilseed rape crop management, including cultivars, sowing, fungicide, and tillage) and their spatial distribution (the model is spatially explicit), plus the initial size and genetic structure of pathogen populations. The genetic evolutionary forces taken into account are migration, selection, and recombination. The model simulates disease severity and the genetic structure of the pathogen population, in addition to the attainable yield less yield loss caused by the disease. The economic and environmental performances of the simulated strategies are computed using technical operation costs, crop prices, and yields. The underlying hypotheses are discussed in light of advantages and possible improvements of the model. Possible uses of SIPPOM are proposed with respect to the design of collective strategies for the durable control of phoma stem canker on winter oilseed rape at a regional scale. © 2010 Elsevier B.V.

Lo-Pelzer E.,French National Institute for Agricultural Research | Aubertot J.N.,French National Institute for Agricultural Research | Bousset L.,French National Institute for Agricultural Research | Salam M.U.,Center for Cropping Systems | Jeuffroy M.H.,French National Institute for Agricultural Research
Field Crops Research | Year: 2010

SIPPOM, a simulator for integrated pathogen population management, has been developed to assess and rank Integrated crop management (ICM) strategies, at the regional scale. The input variables are weather data, soil characteristics, the description of cropping systems (crop sequence and winter oilseed rape crop management) and their spatial distribution, plus the initial size and genetic structure of pathogen populations. Here, we use SIPPOM to simulate phoma stem canker severity, the genetic structure of the pathogen populations, and the yield loss caused by the disease. Sensitivity analysis is conducted to quantify how strongly state variables (sub-model output variables) respond to variations in parameters. The results indicate which parameters need to be more accurately estimated, and it elucidates the steadiness of the rankings of contrasting control strategies under various weather conditions when parameters were varied. Due to the complexity of SIPPOM, the scope of this work was limited to a sensitivity analysis of each sub-model independently. Three values of each parameter were tested under various environmental conditions and crop management according to their expected or known effects on disease and yield. Qualitatively speaking, variations in input variables and parameters provided sub-model output variables that behaved as expected by experts. Parameters with the greatest effect on state variables and that need to be estimated more accurately are for instance those related to pseudothecia maturation and disease severity index estimates. Improvements are foreseen (e.g., the calculation of both the number of phoma leaf spots and the severity disease index). Because the ranking of the simulated control strategies remained steady, despite large variations in the simulated variables linked with variations in parameters, the sensitivity analysis shows that the model, as it stands, can be used to compare and rank ICM strategies with respect to their effectiveness. Possibilities of a sensitivity analysis of the overall model are discussed. © 2010 Elsevier B.V.

Borger C.P.D.,Western Research Institute | Hashem A.,Center for Cropping Systems | Powles S.B.,University of Western Australia
Weed Research | Year: 2016

Light is an important resource that crops and weeds compete for and so increased light interception by the crop can be used as a method of weed suppression in cereal crops. This research investigated the impact of altered availability of photosynthetically active radiation (PAR) (from crop row orientation or seeding rate) on the growth and fecundity of Lolium rigidum. Wheat and barley crops were sown in an east-west (EW) or north-south (NS) direction, at a high or low seeding rate, in three field trials in 2010 and 2011 (at Merredin, Wongan Hills and Katanning, Western Australia). The average PAR available to L. rigidum in the inter-row space of EW crops compared with NS crops was 78% to 91% at crop tillering, 39% to 56% at stem elongation, 28% to 53% at boot/anthesis and 41% to 59% at grain fill. Reduced PAR in the EW crop rows resulted in reduced L. rigidum fecundity in five of the six trials (average of 2968 and 5705 L. rigidum seeds m-2 in the EW and NS crops). Availability of PAR was not influenced by seeding rate, but the high seeding rate reduced fecundity in three of the six trials (average of 3354 and 5092 seeds m-2 in the crops with high and low seeding rate). Increased competitive ability of crops (through increased interception of PAR or increased crop density) was highly effective in reducing L. rigidum fecundity and is an environmentally friendly and low cost method of weed suppression. Weed Research © 2016 European Weed Research Society..

Borger C.P.D.,Western Research Institute | Hashem A.,Center for Cropping Systems | Pathan S.,0 Doney Street
Weed Science | Year: 2010

Crop rows oriented at a right angle to sunlight direction (i.e., east-west within the winter cropping system in Western Australia) may suppress weed growth through greater shading of weeds in the interrow spaces. This was investigated in the districts of Merredin and Beverley, Western Australian (latitudes of 31° and 32°S) from 2002 to 2005 (four trials). Winter grain crops (wheat, barley, canola, lupines, and field peas) were sown in an east-west or north-south orientation. Within wheat and barley crops oriented east-west, weed biomass (averaged throughout all trials) was reduced by 51 and 37%, and grain yield increased by 24 and 26% (compared with crops oriented north-south). This reduction in weed biomass and increase in crop yield likely resulted from the increased light (photosynthetically active radiation) interception by crops oriented east-west (i.e., light interception by the crop canopy as opposed to the weed canopy was 28 and 18% greater in wheat and barley crops oriented east-west, compared with north-south crops). There was no consistent effect of crop row orientation in the canola, field pea, and lupine crops. It appears that manipulation of crop row orientation in wheat and barley is a useful weed-control technique that has few negative effects on the farming system (i.e., does not cost anything to implement and is more environmentally friendly than chemical weed control). © 2010 Weed Science Society of America.

Borger C.P.D.,Western Australian Department of Agriculture and Food | Riethmuller G.P.,Western Australian Department of Agriculture and Food | Hashem A.,Center for Cropping Systems
Crop and Pasture Science | Year: 2010

Enteropogon ramosus is a native, perennial, C4 grass species found within the wheatbelt of Western Australia. Emergence, survival, seed production and seed dormancy of E. ramosus was investigated in a continuous pasture rotation, a pastureminimum tillage wheat rotation, and a pastureminimum tillage wheat rotation where a cultivation event at the beginning of the pasture year was used to kill all E. ramosus plants. The results indicated that E. ramosus could germinate throughout the year, although plant density (ranging annually from 0 to 17plantsm-2) was lowest in conditions of low rainfall (summerautumn drought). Seed production (estimated from seed head production, r≤91.7, P0.001) ranged from 0 to 2274m-2 and was greatest in spring, in the continuous pasture rotation. Seed germinability reached 8089%, following an initial 3 months of dormancy directly after seed production. Cultivation at the beginning of the pasture-crop rotation killed all plants, reduced emergence and prevented seed production for the 2-year period of the experiment. Soil disturbance from minimum tillage crop sowing reduced but did not eliminate E. ramosus plants. As a result, E. ramosus grew throughout the year in the minimum tillage cropping system. Further research is required to determine the competitive effect of E. ramosus on crop growth. © 2010 CSIRO.

Salam M.U.,Bentley Delivery Center | Galloway J.,Center for Cropping Systems | Diggle A.J.,Bentley Delivery Center | MacLeod W.J.,Bentley Delivery Center | Maling T.,Bentley Delivery Center
Australasian Plant Pathology | Year: 2011

Ascochyta blight is the most destructive foliar pathogen of field peas. The amount of yield loss resulting from the disease in Australia is mainly driven by primary infection from wind-borne ascospores of Didymella pinodes. In this study, a model was developed to predict the spread of ascospores from the ascochyta blight infected field pea stubble of previous season's crops. The model was adapted from a previously developed spatiotemporal model and calibrated with field experimental data consisting of release events of ascospores of D. pinodes from known source for 21 consecutive weeks, under natural environmental conditions, in a 400 m by 400 m area. The model was then applied in a 30.9 km by 36.8 km area in a major field pea growing region of Western Australia to show the magnitude and spatial diversity of the dispersal of ascospores, generated in previous season's field pea stubble, could differ between growing seasons. This simulation was only tested subjectively. It is concluded that a properly validated simulation of this type has potential for understanding the value of physical separation of the current season field pea crop from previous season's stubble, visualising the scale and diversity of ascospore dispersal as an educational tool for growers and consultants, and deriving the "magic figure" of the intensity of field pea area that could result in the presence of ascospores everywhere in a region. © 2011 Australasian Plant Pathology Society Inc.

Scanlan C.A.,University of Western Australia | Scanlan C.A.,Center for Cropping Systems | Hinz C.,University of Western Australia
Plant and Soil | Year: 2010

Root radius frequency distributions have been measured to quantify the effect of plant type, environment and methodology on root systems, however, to date the results of such studies have not been synthesised. We propose that cumulative frequency distribution functions can be used as a metric to describe root systems because (1) statistical properties of the frequency distribution can be determined, (2) the parameters for these can be used as a means of comparison, and (3) the analytical expressions can be easily incorporated into models that are dependent upon root geometry. We collated a database of 96 root radii frequency distributions and botanical and methodology traits for each distribution. To determine if there was a frequency distribution function that was best suited to root radii measurements we fitted the exponential, Rayleigh, normal, log-normal, logistic and Weibull cumulative distribution functions to each distribution in our database. We found that the log-normal function provided the best fit to these distributions and that none of the distribution functions was better or worse suited to particular shapes. We derived analytical expressions for root surface and volume and found that they are a valid, and simpler method for incorporating root architectural traits into analytical models. We also found that growth habit and growth media had a significant effect on mean root radius. © 2010 Springer Science+Business Media B.V.

Paynter B.H.,Center for Cropping Systems | Clarke G.P.Y.,Baron Hay Court
Genetic Resources and Crop Evolution | Year: 2010

Coleoptile length is related to maximum seeding depth. The coleoptile length of 44 spring barley cultivars (Hordeum vulgare L.) was determined by laying seeds on moistened filter paper and incubating at 15°C for 13 days. Significant differences in coleoptile length were noted between cultivars (P < 0.05). Most cultivars had a coleoptile length between 60 and 80 mm. Five cultivars (Buloke, Dash, Harrington, Morrell and Tallon) had a coleoptile length shorter than 60 mm. Seven cultivars (CM72, Doolup, Finniss, Fleet, Hannan, Haruna Nijo and Macumba) had a coleoptile length longer than 80 mm. No relationship was found between early growth habit or plant height and coleoptile length. The impact of different dwarfing genes on coleoptile length was discussed. Differences in coleoptile length observed should be exploited by breeders to improve the tolerance of barley to deep seeding and stubble retention. This would be a useful tool in managing climate variability and would assist barley growers to sow closer to the optimum sowing time in situations where moisture is present at depth but not on the soil surface. © Springer Science+Business Media B.V. 2009.

Sharma D.L.,Center for Cropping Systems | D'Antuono M.F.,3 Baron Hay Court
Agronomy Journal | Year: 2011

Wheat growers in Western Australia (WA) value flowering date predictions for risk aversion from frost and terminal stresses. Currently used statistical models such as the "flowering calculator" (referred to as photothermal model as programmed by Tennant and Tennant [2000] [TT]) are less robust in colder regions and/or higher latitudes of WA. We developed a new statistical model (named DM) that includes a vernalization component in addition to photoperiod and temperature components, the three biological drivers of reproductive growth and development in wheat (Triticum spp.). The model assumes that heatsums required for flowering comprise a variety specific minimum, plus some more that are linearly contingent on sowing day, daylength, and the statistical summaries of daily temperature profiles. The vernalization opportunity was quantified using a term named "coldsum" calculated as equal to the sum of daily periods under 5°C in hourly temperature profile, while "heatsum" referred to the periods above 0°C. Environments were characterized using a log-log transformation on heatsums and a segmented-lines approach on coldsums. The model coefficients were estimated using data from four sowing dates spanning prevalent sowing times in WA over 4 yr at three diverse locations. The DM predictions were statistically far superior to TT (F probability < 0.001; RMSD 6.1 and 17.4, respectively) in all respect of location, season, sowing date, and cultivar factors when compared in independent datasets from six cultivar × sowing date trials across WA wheatbelt. Since DM relies on a structured application of seasonal profiles, it should be applicable to other geographic areas, cultivars, and crops. © 2011 by the American Society of Agronomy.

Paynter B.H.,Center for Cropping Systems
Weed Technology | Year: 2010

Field studies compared the grain yield of four two-row spring barley cultivars at four sites when sown at two-row spacing in competition with two densities of rigid ryegrass. The sites chosen had low background populations of rigid ryegrass. Although the four cultivars sown differed in their grain yield, row spacing did not influence cultivar performance. Doubling the row spacing decreased barley grain yield at three of the four sites. The impact of row spacing on grain yield was more noticeable when doubled to 48 or 50 cm compared with 36 cm. Rigid ryegrass competition reduced barley grain yield at two of the four sites. At both locations the influence of weed competition on barley grain yield was the same at both narrow and wide row spacing and at one location the impact of weed competition was modified by cultivar. Planting barley in wide rows was found to favor rigid ryegrass production through an increase in both rigid ryegrass biomass production and tiller number. The development of farming systems for barley on the basis of a row spacing greater than 25 cm is likely to be associated with an increase in weed productivity unless good integrated weed management principles are implemented. Modifications to the current system may allow an increase in row spacing without any yield loss or increased weed seed set. Nomenclature: Rigid ryegrass, Lolium rigidum Gaudin LOLRI 'Safeguard'; barley, Hordeum vulgare L. 'Baudin', 'Dash', 'Gairdner', and 'Vlamingh'. © 2010 Weed Science Society of America.

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