• Authors:
    • Bellaloui, N.
    • Smith, J. R.
    • Mengistu, A.
    • Paris, R. L.
    • Wrather, J. A.
  • Source: Crop Science
  • Volume: 50
  • Issue: 5
  • Year: 2010
  • Summary: Phomopsis seed decay (PSD) of soybean ( Glycine max L. Merr) is primarily caused by Phomopsis longicolla. Currently, percent seed infection is used as a method for evaluating resistance to PSD. However, researchers need a common system for classifying soybean genotypes for their reaction to P. longicolla that is consistent across environments. The purpose of this research was: (i) to evaluate the reaction of a select set of soybean accessions to P. longicolla, and (ii) determine the effects of irrigation and two harvest regimes (normal and delayed) on seed infection. We propose a classification system for comparing reactions to P. longicolla among accessions based on a Phomopsis seed infection index (PSII), derived by dividing the percent seed infection of each accession by percent seed infection values of susceptible standards selected within early and late maturity groups. Percent seed infection by P. longicolla infection was greater when accessions were irrigated during the growing season and harvested at normal maturity. Some lines such as MO/PSD-0259 were rated as resistant to P. longicolla (7% seed infection) when not irrigated and harvested at maturity, but were rated as susceptible (39% seed infection) with irrigation and delayed harvest. The resistance ratings to P. longicolla using percent seed infection and PSII varied among accessions. SS93-6012, for example, had similar ratings for both (9% seed infection and 16% PSII). PI 416942 exhibited some resistance to P. longicolla based on percent seed infection (8%), but no resistance based on PSII (32%). Accessions PI 594478, Delmar, SS93-6012, SS93-6181, PI 594603A, and PI 594712 were classified by PSII as moderately resistant under irrigation and with delayed harvest. These results indicate that simple comparisons of percent seed infection among accessions without irrigation, without delayed harvest, and without a standard control of a similar maturity group might result in false conclusions about resistance to P. longicolla.
  • Authors:
    • Brennan, J. P.
    • Murray, G. M.
  • Source: Australasian Plant Pathology
  • Volume: 39
  • Issue: 1
  • Year: 2010
  • Summary: The incidence, severity and yield loss caused by 40 pathogens associated with 41 diseases of barley were assessed from a survey of 15 barley pathologists covering the winter cereal growing areas of Australia. The survey provided data on the frequency of years that each pathogen developed to its maximum extent, the proportion of the crop then affected in each growing area, and the yield loss that resulted in the affected crops with and without current control measures. These data were combined with crop production and grain quality data to estimate the value of the losses aggregated to the Northern, Southern and Western production regions. Pathogens were estimated to cause a current average loss of $252 x 10(6)/year or 19.6% of the average annual value of the barley crop in the decade 1998-99 to 2007-08. Nationally, the three most important pathogens are Pyrenophora teres f. maculata, Blumeria graminis f. sp. hordei and Heterodera avenae with current average annual losses of $43 x 10(6), $39 x 10(6) and $26 x 10(6), respectively. If current controls were not used, losses would be far higher with potential average annual losses from the three most important pathogens, P. teres f. maculata, H. avenae and P. teres f. teres, being $192 x 10(6), $153 x 10(6) and $117 x 10(6), respectively. The average value of control practices exceeded $50 x 10(6)/year for nine pathogens. Cultural methods (rotation, field preparation) were the only controls used for 14 pathogens and contributed more than 50% of the control for a further 13 pathogens. Breeding and the use of resistant cultivars contributed more than 50% of control for five pathogens and pesticides for four pathogens. The relative importance of pathogens varied between regions and zones.
  • Authors:
    • Portz, G.
    • Chagas, J. P.
    • Bagatini, T.
    • Cogo, Neroli P.
    • Portela, J. C.
  • Source: Revista Brasileira de Ciência do Solo
  • Volume: 34
  • Issue: 4
  • Year: 2010
  • Summary: Soil structure plays a prominent role in plant growth and erosion control, and consequently in food production and soil and water conservation. This research was developed with the objective of implementing and accompanying the restoration process of the structure of a degraded soil, by planting crop sequences under no-tillage (autumn-winter and spring-summer, grass and legume, in single and intercropped systems), and later verifying the relations with water and soil losses caused by rainfall erosion, under distinct surface physical conditions (untitled soil, with and without crust; freshly-tilled soil by chiseling and by chiseling followed by disking after one month, and crop residue covering 100, 18, and 0 %). The field study was developed under simulated rainfall, at the Agriculture Experimental Station of the Federal University of Rio Grande do Sul (EEA/UFRGS), in Rio Grande do Sul State, Brazil, from May 2004 to Decembe, 2007. The six erosion tests, in intervals of about a week, were performed from October to December, 2007. The soil used is an Ultisol, with a sandy clay loam texture in the surface layer and 0.115 in m(-1) average slope steepness, and an advanced degree of degradation. The rains were applied with a rotating-boom rainfall simulator, at a constant intensity of 64 mm h(-1), for 1-3 h. For this study, water and soil loss data were adjusted to a rainfall duration of 1.5 h. Properties of soil and plants were measured in the experimental plots and water erosion in the surface runoff The crop sequences and erosion tests influenced the results of the study significantly, with greater differences in the latter than in the former. The erosive process was more influenced by the external or soil surface than the internal or subsurface physical conditions. In general, all crop sequences were effective in restoring the soil structure in the experimental period. The sequence involving teosinte controlled the rainfall erosion process most effectively with regard to soil and water loss and the one involving corn+cowpea and pearl millet with regard to soil loss. The highest soil and water losses in the study were observed from the soil surface with no mobilization and little crop residue cover, regardless of the presence or type of crust, but especially when this latter was slightly cracked prior to rainfall application. The soil surface entirely covered by crop residue, be it untilled or freshly chiseled, controlled runoff effectively and impeded erosion completely. Soil and water losses from the freshly-disked soil surface chiseled a month earlier, although the soil was the most mobilized of all and bare, were practically zero, opposite to what was expected.
  • Authors:
    • Arriaga, F. J.
    • Rogers, H. H.
    • Runion, G. B.
    • Prior, S. A.
  • Source: Journal of Environmental Quality
  • Volume: 39
  • Issue: 2
  • Year: 2010
  • Summary: Increasing atmospheric CO(2) concentration has led to concerns about potential effects on production agriculture. In the fall of 1997, a study was initiated to compare the response of two crop management systems (conventional tillage and no-tillage) to elevated CO(2). The study used a split-plot design replicated three times with two management systems as main plots and two atmospheric CO(2) levels (ambient and twice ambient) as split plots using open-top chambers on a Decatur silt learn soil (clayey, kaolinitic, thermic Rhodic Paleudults). The conventional system was a grain sorghum [Sorghum bicolor (L.) Moench.] and soybean (Glycine max (L.) Merr.] rotation with winter fallow and spring tillage practices. In the no-tillage system, sorghum and soybean were rotated, and three cover crops were used [crimson clover (Trifolium incarnatum L.), sunn hemp (Crotalaria juncea L.), and wheat (Triticum aestivum L.)]. Over multiple growing seasons, the effect of management and CO(2) concentration on leaf-level gas exchange during row crop (soybean in 1999, 2001, and 2003; sorghum in 2000, 2002, and 2004) reproductive growth were evaluated. Treatment effects were fairly consistent across years. In general, higher photosynthetic races were observed under CO(2) enrichment (more so with soybean) regardless of residue management practice. Elevated CO(2) led to decreases in stomatal conductance and transpiration, which resulted in increased water use efficiency. The effects of management system on gas exchange measurements were infrequently significant, as were interactions of CO(2) and management. These results Suggest that better soil moisture conservation and high rates of photosynthesis can occur in both tillage systems in CO(2)-enriched environments during reproductive growth.
  • Authors:
    • Razafimpamoa, L. H.
    • Randrianaivoarivony, J. M.
    • Rahetlah, V. B.
    • Ramalanjaona, V. L.
  • Source: African Journal of Food, Agriculture, Nutrition and Development
  • Volume: 10
  • Issue: 10
  • Year: 2010
  • Summary: Forage availability and quality during the dry and cool season is a major constraint to dairy development in the Highlands of Madagascar. The objective of the present study was to determine optimal seeding of oat and common vetch mixtures for increased production and quality of forage. The study was conducted under irrigated conditions in two agro-ecological zones of the Vakinankaratra region in the Highlands of Madagascar. Seed proportions studied were oat-vetch 100:0; 0:100; 50:50 and 50:75. Pure stands of oat and vetch were seeded at the rate of 100 and 60 kg ha -1, respectively. Standard fertilization for forage oat production was uniformly applied on each plot. Pure stands and mixtures were given two successive cuts at flag leaf stage of oat. For both sites and their average, dry matter (DM), feed unit for lactation (UFL), crude protein (CP), and protein digested in the small intestine (PDI) yields were not significantly (p>0.05) different among mixtures and pure stands. The highest yields were obtained from the 50:50 mixture at the first site and from the 50:75 mixture at the second site. According to the two sites' results' average, the highest DM (7.71 t ha -1), UFL (6.08*103 units ha -1), CP (1.64 t ha -1) and PDI (597.1 kg ha -1) yields were obtained from 50:50 mixture. There were no significant differences (p>0.05) in forage quality characteristics except for CP and protein digested in the small intestine when rumen-fermentable nitrogen is limiting (PDIN). Mean CP concentration varied from 15.20% for pure stand of oat to 27.01% for pure stand of vetch. The highest value (178.8 g/kg DM) and the lowest value (103.5 g/kg DM) in PDIN content were obtained from pure stand of oat and pure stand of vetch, respectively. Mixtures had 4.6 to 6.3% more CP content and 15.6 to 39.1% more PDIN content than pure stand of oat. Combined land equivalent ratio values exceeded unity in both mixtures which showed an advantage of intercropping over sole system in terms of the use of environmental resources. As intercropping of oat with vetch at 50:50 (50:30 kg ha -1) mixture achieved maximum yield advantage and forage quality, it could be used as alternative practice of oat sole cropping for high forage and protein production in the Vakinankaratra region.
  • Authors:
    • Nepomuceno, A. L.
    • Oliveira, G. M. de
    • Neumaier, N.
    • Rakocevic, M.
    • Farias, J. R. B.
  • Source: Pesquisa Agropecuária Brasileira
  • Volume: 45
  • Issue: 7
  • Year: 2010
  • Summary: The objectives of this work were to determine the heliotropic movements of the upper trifoliates for two soybean cultivars, BR 16 and Embrapa 48, during a daily cycle, in three phenological stages and two water regimes, and to estimate the impact of irrigation and daily leaflet movements on agronomic characteristics and grain yield. Heliotropic movements were studied in three phenological stages: V4-V6, V7-V10, and R5 in irrigated and non-irrigated plots. For each stage, the leaflet elevation and azimuth were measured hourly. Under a low (V4-V6 stage) and mid (V7-V10 stage) leaf area index (LAI) the diaheliotropism was slightly more frequent and intensive in non-irrigated than in irrigated plants, only at early morning and late afternoon hours. At R5 stage (high LAI) the paraheliotropism of superior trifoliates was predominant and more intensive in non-irrigated plants. The heliotropic movements are correlated to carbon gain, but not to environment (light intensity or temperature), for measurements at 11 h. 'Embrapa 48' expresses greater paraheliotropism than 'BR 16' at high LAI, while 'BR 16' displays lower heliotropic plasticity under irrigation. In spite of significant heliotropic differences, genotype and water availability treatments did not influence the final grain yield.
  • Authors:
    • Srivastva, A. K.
    • Mina, B. L.
    • Kundu, S.
    • Bhattacharyya, R.
    • Chandra, S.
    • Pandey, S. C.
    • Gupta, S.
    • Saha, S.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 86
  • Issue: 2
  • Year: 2010
  • Summary: To date, the sustainability of wheat ( Triticum aestivum)-soybean ( Glycine max) cropping systems has not been well assessed, especially under Indian Himalayas. Research was conducted in 1995-1996 to 2004 at Hawalbagh, India to study the effects of fertilization on yield sustainability of irrigated wheat-soybean system and on selected soil properties. The mean wheat yield under NPK+FYM (farmyard manure) treated plots was ~27% higher than NPK (2.4 Mg ha -1). The residual effect of NPK+FYM caused ~14% increase in soybean yield over NPK (2.18 Mg ha -1). Sustainable yield index values of wheat and the wheat-soybean system were greater with annual fertilizer N or NPK plots 10 Mg ha -1 FYM than NPK alone. However, benefit:cost ratio of fertilization, agronomic efficiency and partial factor productivity of applied nutrients were higher with NPK+FYM than NPK, if FYM nutrients were not considered. Soils under NPK+FYM contained higher soil organic C (SOC), total soil N, total P and Olsen-P by ~10, 42, 52 and 71%, respectively, in the 0-30 cm soil layers, compared with NPK. Non-exchangeable K decreased with time under all treatments except NPK. Total SOC in the 0-30 cm soil layer increased in all fertilized plots. Application of NPK+FYM also improved selected soil physical properties over NPK. The NPK+FYM application had better soil productivity than NPK but was not as economical as NPK if farmers had to purchase manure.
  • Authors:
    • Dalal, R. C.
    • Blamey, F. P. C.
    • Rao, A. S.
    • Rao, D. L. N.
    • Mohanty, M.
    • Reddy, K. S.
    • Dixit, S. K.
    • Pandey, M.
    • Menzies, N. W.
  • Source: Proceedings of the 19th World Congress of Soil Science, Soil Solutions for a Changing World, 1–6 August 2010, Brisbane, Australia
  • Year: 2010
  • Summary: The Mother Baby Trial (MBT) approach is an on-farm participatory mechanism to introduce and test technology options suited to a heterogeneous community. In this study, the MBT concept was followed with integrated nutrient management (INM) technology in a soybean-wheat system. Seven treatments were tested in Mother trials in 2005-06 and 2006-07 on farmers' fields in the Rajgarh and Bhopal districts of Central India. In 2007-08, 100 Baby trials were conducted by farmers in 10 surrounding villages to demonstrate and test the INM technology. The Baby trials were based on the results of Mother trials which showed that INM using 50% of the recommended NPKS fertilizer+5 t FYM/ha+ Rhizobium to soybean and 75% of the recommended NPKS fertilizer+P-solubilizing bacteria to wheat produced higher soybean yield by 46% and higher wheat yield by 24% over the farmers' practice. In the Baby trials, there was a wide variation in soybean yield obtained with INM, balanced fertilization (BF) using inorganic fertilizers, and farmers' practice; in poorer yielding trials, some problems were evident in the control of weeds and insect pests. Wheat responded well to BF and INM in trials irrigated 3-4 times. The MBT approach proved valuable in demonstrating higher productivity of the soybean-wheat system, and the value of INM and BF technologies, but only with proper weed and pest management in soybean, and adequate irrigation in wheat, as a package of practices.
  • Authors:
    • Wrather, A.
    • Shannon, G.
    • Stevens, G.
    • Rhine, M. D.
    • Sleper, D.
  • Source: Irrigation Science
  • Volume: 28
  • Issue: 2
  • Year: 2010
  • Summary: Furrow irrigating soybean prior to a large, unexpected rainfall event can reduce nitrogen fixation and crop yield. The objective of this study was to evaluate the tolerance of soybean cultivars to waterlogged alluvial soils. Five cultivars were selected, which showed a range of tolerances to excessive soil water. Flood duration and flood timing experiments were conducted on clay and silt loam soils. Main plots were flooding duration and flood timing and subplots were soybean cultivars. Most cultivars were able to withstand flooding for 48-96 h without crop injury. Cultivars flooded during the V5 growth stage suffered the least amount of yield loss. The greatest yield losses from flooding occurred at the R5 growth stage. Soybean yields from cultivars flooded at R5 were reduced by 20-39% compared to non-flooded checks. Pioneer 94B73 (cv.) had no significant change in yield from flooding for 192 h at any of the three growth stages, compared to non-flooded controls.
  • Authors:
    • Rogers, D. J.
    • Brier, H. B.
  • Source: Crop Protection
  • Volume: 29
  • Issue: 1
  • Year: 2010
  • Summary: The response of vegetative soybean (Glycine max) to Helicoverpa armigera feeding was studied in irrigated field cages over three years in eastern Australia to determine the relationship between larval density and yield loss, and to develop economic injury levels. Rather than using artificial defoliation techniques, plants were infested with either eggs or larvae of H. armigera, and larvae allowed to feed until death or pupation. Larvae were counted and sized regularly and infestation intensity was calculated in Helicoverpa injury equivalent (HIE) units, where 1 HIE was the consumption of one larva from the start of the infestation period to pupation. In the two experiments where yield loss occurred, the upper threshold for zero yield loss was 7.510.21 HIEs and 6.431.08 HIEs respectively. In the third experiment, infestation intensity was lower and no loss of seed yield was detected up to 7.0 HIEs. The rate of yield loss/HIE beyond the zero yield loss threshold varied between Experiments 1 and 2 (-9.440.80 g and -23.173.18 g, respectively). H. armigera infestation also affected plant height and various yield components (including pod and seed numbers and seeds/pod) but did not affect seed size in any experiment. Leaf area loss of plants averaged 841 and 1025 cm 2/larva in the two experiments compared to 214 and 302 cm 2/larva for cohort larvae feeding on detached leaves at the same time, making clear that artificial defoliation techniques are unsuitable for determining H. armigera economic injury levels on vegetative soybean. Analysis of canopy leaf area and pod profiles indicated that leaf and pod loss occurred from the top of the plant downwards. However, there was an increase in pod numbers closer to the ground at higher pest densities as the plant attempted to compensate for damage. Defoliation at the damage threshold was 18.6 and 28.0% in Experiments 1 and 2, indicating that yield loss from H. armigera feeding occurred at much lower levels of defoliation than previously indicated by artificial defoliation studies. Based on these results, the economic injury level for H. armigera on vegetative soybean is approximately 7.3 HIEs/row-metre in 91 cm rows or 8.0 HIEs/m 2.