• Authors:
    • Yogo, Y.
    • Asai, M.
  • Source: Journal of Weed Science and Technology
  • Volume: 55
  • Issue: 3
  • Year: 2010
  • Summary: Paraquat is an herbicide that inhibits germination and seedling growth of grasses, including wild oat ( Avena fatua L.), a problematic weed in winter cereals. Outdoor pot experiments were conducted to determine the influence of paraquat on wild oat seedling emergence to evaluate the efficacy of this herbicide as a tool for an integrated management system. A diquat+paraquat liquid formulation (7.0% diquat dibromide and 5.0% paraquat dichloride) was sprayed at a rate of 1,000 ml/10 a directly onto wild oat seeds placed on the soil surface, and the soil was not disturbed during the following year. Fewer viable wild oat seeds were recovered from the diquat+paraquat treatment relative to a glyphosate ammonium salt (41.0%, 500 ml/10 a) treatment. A treatment of diquat+paraquat greater than 3,000 ml/10 a markedly reduced wild oat seedling emergence if the seeds were incorporated into the soil soon after the application. However, when the wild oat seeds were covered with chopped straw, no suppression of emergence could be detected with diquat+paraquat application even at a rate of 4.6 times the recommended dose. Increasing the dilution water volume also decreased the effectiveness of emergence suppression. Our results suggest that diquat+paraquat spray following wheat harvest would not be effective for reducing wild oat germination and seedling emergence in the summer.
  • Authors:
    • Lithourgidis, A.
    • Dordas, C.
  • Source: Crop Science
  • Volume: 50
  • Issue: 5
  • Year: 2010
  • Summary: Annual cool-season grain legumes like faba bean ( Vicia faba L.) grown in mixtures with winter cereals such as wheat ( Triticum aestivum L.), barley ( Hordeum vulgare L.), or rye ( Secale cereale L.) may offer advantages over cereal-alone crops grown for forage production. A 2-yr field study was conducted to evaluate the effects of intercropping faba bean with each of the above cereals in three seeding ratios (i.e., 75:25, 50:50, and 75:25) on growth rate, plant height, chlorophyll content, forage yield, and N uptake. Growth rate of faba bean and cereals was lower in the mixtures than in the monocultures, especially in the faba bean-barley mixtures because of the strong competitive ability of barley. Chlorophyll content was lower in faba bean compared with the cereals, and there was no difference among seeding ratios. Plant height of faba bean was higher in the intercrops compared with its monocrop at 3 wk after tillering (WAT), whereas at 6 WAT, the trend was different since faba bean plants in the monocrop were higher than in the intercrops. Rye monocrop and rye-faba bean intercrops provided the greatest forage yield. Although the three intercrops of faba bean with rye had lower crude protein (CP) content than the faba bean monocrop, they provided the highest CP yields per hectare because of their higher forage yield than the faba bean monocrop.
  • Authors:
    • Crozat, Y.
    • Pineau, S.
    • Corre-Hellou, G.
    • Naudin, C.
    • Jeuffroy, M. H.
  • Source: Field Crops Research
  • Volume: 119
  • Issue: 1
  • Year: 2010
  • Summary: Cereal-legume intercrops are a promising way to combine high productivity and several ecological benefits in temperate agro-ecosystems. However, the proportion of each species in the mixture at harvest is highly variable. The aim of this study was to test whether the timing of small application of N fertilizer is an effective way of influencing the dynamic interactions between species during crop growth and affecting the percentage of each species in the biomass of the mixture without greatly disturbing N 2 fixation. The influence of timing of nitrogen fertilization in pea-wheat intercrops was studied as regards (i) the dynamics of crop growth, (ii) nitrogen acquisition of each species, (iii) the inhibition and recovery of symbiotic N 2 fixation (SNF) after N application and (iv) final performance (yield, % of wheat, grain protein content). This was assessed in winter pea-wheat ( Pisum sativum L.- Triticum aestivum L.) intercrops in 2007 and 2008 at two locations in France. Whatever the stage of application, N fertilizer tended to increase wheat growth and to decrease pea growth. N fertilization (applied once at different dates from tillering to the end of stem elongation) delayed the decrease in the contribution of wheat to total biomass and maintained the competitive ability of wheat over pea for longer than in unfertilized intercrops. N acquisition dynamics and N sharing between the two species were modified by N fertilization and its timing. Crop conditions at the time of N application (growth and phenology of each species, and their proportions in the intercrop biomass) greatly influenced intercrop response to N fertilization. Partitioning between species of soil and fertilizer N was correlated with the proportion of wheat in the total intercrop biomass observed at the date of N application. Short-term inhibition of nitrates on SNF was shown during the few days after N application, whatever its date. SNF recovery after N applications was observed only until pea flowering, but was prematurely stopped by N fertilization after this stage. The effect of N fertilization on the amount of fixed N 2 at harvest was correlated with pea biomass. N fertilization affects N 2 fixation mainly by affecting crop growth rather than %Ndfa in pea-wheat intercrops. In conclusion, N fertilization could be used as a tool to enhance the contribution of wheat in the intercrop biomass but may reduce the amount of fixed N 2 in the intercrop by decreasing pea biomass.
  • Authors:
    • Zavalin, A.
    • Pasynkova, E.
  • Source: Russian Agricultural Sciences
  • Volume: 36
  • Issue: 1
  • Year: 2010
  • Summary: It is shown that a comparative evaluation of the biological efficiency and intensity of competitive relations in cereal (spring wheat) and pulse (spring vetch) mixed crops is the most complete and accurate in yield of the main product (grain, dry matter) and biological yield (grain+straw+chaff, dry matter).
  • Authors:
    • Lemarchand, E.
    • Rouault, F.
    • Jumel, S.
    • Schoeny, A.
    • Tivoli, B.
  • Source: European Journal of Plant Pathology
  • Volume: 126
  • Issue: 3
  • Year: 2010
  • Summary: Field experiments were conducted in western France for two consecutive years to investigate the effect of pea-cereal intercropping on ascochyta blight, a major constraint of field pea production world-wide. Disease pressure was variable in the experiments. Intercropping had almost no effect on disease development on stipules regardless of disease pressure. In contrast, disease severity on pods and stems was substantially reduced in the pea-cereal intercrop compared to the pea monocrop when the epidemic was moderate to severe. Therefore, a pea-cereal intercrop could potentially limit direct yield loss and reduce the quantity of primary inoculum available for subsequent pea crops. Disease reduction was partially explained by a modification of the microclimate within the intercrop canopy, in particular, a reduction in leaf wetness duration during and after flowering. The effect of intercropping on splash dispersal of conidia was investigated under controlled conditions using a rainfall simulator. Total dispersal was reduced by 39 to 78% in pea-wheat canopies compared to pea canopies. These reductions were explained by a reduction in host plant density and a barrier or relay effect of the non-host plants.
  • Authors:
    • Guiducci, M.
    • Tosti, G.
  • Source: European Journal of Agronomy
  • Volume: 33
  • Issue: 3
  • Year: 2010
  • Summary: Intercropping cereals and grain legumes is a common practice because of the advantages in N use, in pest and volunteer plant smothering, but when the grains need to be separated, there are several technical difficulties. These problems may be overcome by adopting a particular form of intercropping (termed "temporary intercropping") where the coexistence of the crops is limited to a portion of their life cycles. In a cereal-legume temporary row-intercropping, the legume component is ploughed into the soil before cereal shooting; thus the legume is used with a mere fertility purpose in order to improve N availability for the cereal component. The presence of such a positive effect, already confirmed in permanent intercropping, needs to be verified in temporary intercropping systems. In an organic farming system, a field experiment was carried out in two consecutive years (2005 and 2006) to evaluate the technical feasibility of a temporary intercropping between three varieties of durum wheat ( Triticum durum Desf.) and faba bean ( Vicia faba L. var. minor Beck.) and to test the effects on interspecific competition for light, N availability, cereal grain yield and quality. The species were temporarily intercropped following an additive design, and there was no fertilisation or crop protection. The N incorporated into the soil by the faba bean biomass was rather stable across years. The competitive effect of the legume reduced the biomass accumulation of the intercropped wheat, but the cereal N status was considerably improved. After the faba bean incorporation into the soil, the marked asymmetry of the temporary intercropped wheat (i.e. large inter-row space coupled with high plant density in the row) affected the radiation balance, nevertheless the yield was positively affected and the wheat grain protein content was increased to an excellent (from 12.0 to 13.9% in 2005) or a good (from 10.2 to 11.5% in 2006) level. Temporary intercropping was shown to be excellent method to improve the quality of organic durum wheat in the Mediterranean environmental conditions.
  • Authors:
    • Zekaite, V.
  • Source: Vagos
  • Issue: 88
  • Year: 2010
  • Summary: Field experiments, designed to study weed incidence in Poaceae and Fabaceae monocrops and their mixtures as influenced by an organic cropping system, were carried out during 2007-2009 at the Experimental station of the Lithuanian Research Centre for Agriculture and Forest in Perloja on a Hapli-Albic Luvisol. Short-lived weeds prevailed in the crops. They accounted for 93-95% of the total weeds. The highest counts of weeds were recorded at the beginning of the growing season when the conditions for their emergence were the most conducive ones. In 2007 and 2009 the weather conditions during cereal tillering stage were wet and warm, which created optimal conditions for weed emergence and the weed count per m -2 was 257-264. In the third ten-day period of April 2008, re-current night frosts inhibited cereal and weed emergence, which resulted in 43.6-51.7% lower emergence. With increasing crop competitive power (milk maturity stage), weed emergence tended to decline and was by 17.9-9.8% lower compared with the weed count at tillering stage. Weed air dry weight decreased proportionally, however, only at crop hard maturity stage, with the reduction in crop competitive power, weed air dry weight increased by 31.6%. Due to the weather conditions, weed air dry weight in the wet year 2007 was by 35-55% higher than that in 2008 and 2009. Lupines, oats and wheat and its mixture with peas performed best in suppressing weeds. A strong linear correlation was established between weed number and precipitation and weigh (r=0.901, r=0.758); between plant density and precipitation amount (r=0.745).
  • 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:
    • Muller, C.
    • Amor, T.
  • Source: Agricultural Journal
  • Volume: 5
  • Issue: 2
  • Year: 2010
  • Summary: In this study, we estimate agricultural technology for Tunisian peasants, accounting for the crop choice of perasants and distinguishing inputs for individual crops such as: vegetable farming cereal and fruit-trees. The study employed the use of cross-section data from distinguishable irrigated crops survey conducted on a sample of 218 farmers frome 11 regions in Tunisia. The data were collected with the aid of structured questionnaire and were later analysed. The Cobb Douglass production frontier model is employed in order to analyse data collected. Among the irrigated crop farmers, the significant variables were: farmuar manuar fertiliser quantity, labor, mecanic traction and among of irrigated water applied. The estimated sigma square (sigma 2) and gamma (gamma) are widely significants for all irrigated crops and revealed that >85% of the variation in the Tunisian irrigated output among farmers in the study area are due to the differences in their efficiencies. Howerver, we find that predicted technical efficiency widely varies across farms and crops from an average of 54.7% for vegetable farming up to 80.6% for fruit-trees. The study also revealed the existing on inefficiency effects among the farmers as: education, farmer's age, irrigation techniques, lack of education, property of land.
  • Authors:
    • Prasad, V.
    • Staggenborg, S.
    • Assefa, Y.
  • Source: Crop Management
  • Issue: November
  • Year: 2010
  • Summary: Because sorghum is a drought-tolerant crop, it is often preferred by producers in cases of expected water stress. The objectives of this review were to summarize the water requirements, effect of water stress, and hybrid variation in drought tolerance of grain sorghum, and to suggest possible solutions that could help narrow the gap between potential and actual dryland sorghum yield. We reviewed more than 70 reports in peer-reviewed journals, extension publications, books, and websites. Grain sorghum tolerates and avoids drought more than many other cereal crops, but the drought response of sorghum does not come without a yield loss. Water stress at the vegetative stage alone can reduce yield more than 36%, and water stress at the reproductive stage can reduce yield more than 55%. Eighty percent of sorghum production in the world is under dryland conditions. We deduced that by focusing on techniques that can improve water availability in sorghum growing season alone, we can double the current dryland sorghum yield with the existing genetic potential. Results of this review suggest the existence of genotypic variation in drought tolerance among sorghum hybrids due to possible physiological differences or vice versa. We concluded by presenting possible management options to reduce the effects of water stress in dryland conditions and suggesting possible areas of research.