• Authors:
    • Sharaiha, R.
    • Adamu, M.
  • Source: World Journal of Agricultural Sciences
  • Volume: 6
  • Issue: 6
  • Year: 2010
  • Summary: Mixed cropping of barley and durum wheat has been the practice of smallholder farmers in some drylands of Ethiopia even though the reasons for this successful cropping system were not well understood. Therefore, four planting densities, five intercrop proportions and three irrigation water levels were studied in a split-split plot arrangement in RCBD with three replications to determine the competition levels and resource use of barley and wheat mixed cropping under different growth stages. Barley was more competitive at early stages, while wheat dominated towards the reproductive stage. Intra- and inter-specific competition was decreased with increasing irrigation water levels but it was increased with increasing planting densities. Intraspecific competition was increased with increasing barley ratio in the cropping systems at all irrigation water levels, planting densities and harvesting stages. Fast growing nature of barley at early growth stages helps the intercropping system in that barley can capture belowground and areal resources faster, while wheat grows slowly and demands less resource at earlier growth stages. At later stages when wheat becomes dominant and resource demanding, early maturity of barley leaves more space for wheat to satisfy its resource demand. Thus niche differentiation index was consistently more than one in all growth stages and irrigation water levels. Therefore, mixed cropping of these two crop species helps combine important characters in a cropping system so as to enhance productivity through complementary resource uses in drylands.
  • Authors:
    • Bedoussac, L.
    • Justes, E.
  • Source: Plant and Soil
  • Volume: 330
  • Issue: 1/2
  • Year: 2010
  • Summary: In a previous paper [Bedoussac L, Justes E ( 2009) Plant Soil, doi: 10.1007/s11104-009-0082-2], we showed that intercropping of durum wheat and winter pea increased the yield and protein concentration of durum wheat when early N availability was less than 120 kg N ha -1. The aim of the present work was to understand these results by analysing intercrop species dynamics for growth, light and N acquisition. A 2-year field experiment was carried out in southwest France with different fertilizer-N levels in order to compare wheat ( Triticum turgidum L.) and pea ( Pisum sativum L.) grown as sole crops and as an intercrop in a row substitutive design. The advantages of intercropping in low N conditions were due mainly to: (1) better light use (up to 10%), thanks to species dynamic complementarity for leaf area index and height; (2) growth complementarity over time (higher growth rate of wheat until pea flowering and then of pea until wheat flowering); and (3) dynamic complementary N acquisition associated with better wheat N status throughout growth. Disadvantages, underlining poorer complementarity within the intercrop stand, were observed with ample available N in early growth. This induced higher cereal growth during winter, which led to increase interspecies competition by reducing pea light absorption and, consequently, its biomass production.
  • Authors:
    • Bedoussac, L.
    • Justes, E.
  • Source: PLANT AND SOIL
  • Volume: 330
  • Issue: 1/2
  • Year: 2010
  • Summary: Grain protein concentration of durum wheat is often too low, particularly in low-N-input systems. The aim of our study was to test whether a durum wheat-winter pea intercrop can improve relative yield and durum wheat grain protein concentration in low-N-input systems. A 2-year field experiment was carried out in SW France with different fertilizer-N levels to compare wheat ( Triticum turgidum L., cv. Nefer) and pea (winter pea, Pisum sativum L., cv. Lucy) grown as sole crops or intercrops in a row-substitutive design. Without N fertilization or when N was applied late (N available until pea flowering less than about 120 kg N ha -1), intercrops were up to 19% more efficient than sole crops for yield and up to 32% for accumulated N, but were less efficient with large fertilizer N applications. Wheat grain protein concentration was significantly higher in intercrops than in sole crops (14% on average) because more N was remobilized into wheat grain due to: (i) fewer ears per square metre in intercrops and (ii) a similar amount of available soil N as in sole crops due to the high pea N 2 fixation rate in intercrops (88% compared to 58% in sole crops).
  • Authors:
    • Hoffmann, A. A.
    • Penfold, C. M.
    • Sharley, D. J.
    • Thomson, L. J.
    • Danne, A.
  • Source: Environmental Entomology
  • Volume: 39
  • Issue: 3
  • Year: 2010
  • Summary: Indigenous cover crops have the potential to promote an increase in natural enemies providing fortuitous control of pest species and other ecosystem services. We test this idea in a vineyard in south eastern Australia, where reduced water availability because of drought coupled with increased temperatures has generated interest in sustainable alternatives to the exotic perennial cover crops commonly planted. Three endemic perennial cover crops, comprising the grasses Austrodanthonia richardsonii and Chloris truncata and a mix of two saltbushes ( Atriplex semibaccata and Atriplex suberecta) were established as cover crops and compared with introduced oats ( Avena sativa). Abundance of a range of predators and parasitoids was higher in vines with native cover crops compared with the oat control. In addition, predation levels of sentinel eggs of a common vineyard pest, light brown apple moth ( Epiphyas postvittana), were increased in the native cover crops. However, the native cover crops also increased the abundance of some potential pest species. Native plants therefore have potential to increase abundance of beneficial invertebrates that assist in pest control, but need to be used carefully to ensure that they do not increase local pest problems.
  • Authors:
    • Eskandari, H.
    • Ghanbari, A.
  • Source: Notulae Scientia Biologicae
  • Volume: 2
  • Issue: 4
  • Year: 2010
  • Summary: An experiment was conducted in University of London, Kent, UK during the year 2003. The aim of experiment was to investigate the effects of planting pattern on performance of wheat and bean intercrops. A complete randomized block design with four replications was employed to compare the treatments. Treatments included wheat sole crop (W), Bean sole crop (B), within row intercropping (M 1), row intercropping (M 2) and mix cropping (M 3). The density of intercropping was according to replacement design (one wheat replaced by three bean plants). The results showed that total dry matter achieved by intercrops was significantly higher than those achieved by either wheat or bean sole crop. Regarding to weed control, intercrops were more effective than sole crops, especially bean sole crop. Crops performance in terms dry weight, height and percentage of leaf, stem pod and ear was affected by cropping systems depending on crop species, where wheat showed more changes compared to bean. Grain yield, harvest index and thousand grain weights of wheat were decreased in intercropping while bean had reduction only in grain yield.
  • Authors:
    • Eskandari, H.
    • Ghanbari, A.
  • Source: Notulae Scientia Biologicae
  • Volume: 2
  • Issue: 3
  • Year: 2010
  • Summary: Wheat ( Triticum aestivum) and bean ( Vicia faba L.) sole crops and their mixture in three planting pattern (M 1: alternate-row intercrop, M 2: within-row intercrop, M 3: mixed intercrop) were used to investigate the amount of resource consumption in terms of PAR interception and nutrient uptake. The experiment was carried out as randomized complete block design with four replications. The results showed that intercropping systems had a significant effect on environmental resources consumption, where intercropping systems had more nutrient uptake and light interception compared to sole crops, suggesting the complementarity effect of intercropping components in resources consumption. The ability of wheat and bean was different in intercropping systems in absorbing nutrients because of their differences in root morphology and cation exchange capacity.
  • 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:
    • 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:
    • Dube, R.
    • Dhyani, S.
    • Ratan, S.
    • Sharma, A.
  • Source: Indian Journal of Agronomy
  • Volume: 55
  • Issue: 4
  • Year: 2010
  • Summary: A field experiment was conducted at Selakui, Dehradun from 2001 to 2004 to study the effect of tillage, viz. conventional tillage (CT) and minimum tillage (MT); and weed-control practices, viz. chemical and mechanical weeding along with legume mulching, viz. in situ grown sunnhemp ( Crotalaria juncea L) and subabul [ Leucaena leucocephala (Lam.) de Wit] on soil moisture conservation, crop productivity and soil health in maize ( Zea mays L)-wheat ( Triticum aestivum L. emend Fiori & Paol.) cropping system. CT gave higher grain yield of maize (+0.11 to 0.17 t/ha), but wheat performed equally well under CT (2.48 t/ha) and MT conditions (2.36 t/ha). Chemical weeding with herbicides (alachlor in maize and isoproturon in wheat) resulted in 7.8 and 9.9% higher yield of maize and wheat, respectively over mechanical weeding. Beneficial effect of live mulching with sunnhemp or Leucaena was similar (12.3-14.7%), while their combined application increased the maize yield by 19.1% over no mulching. Further, enhanced soil moisture conservation due to mulching at maize harvest led to greater productivity of wheat by 16.1% with sunnhemp or Leucaena, and 27.0% with sunnhemp+ Leucaena. Nitrogen uptake of maize and wheat increased significantly with chemical weeding and legume mulching, but tillage practices made no effect on wheat while in maize it was lower under MT. Wheat gave 4-5 times more net returns than maize, and the net B:C ratio of the system was >1.0 with chemical weeding and legume mulching. Tillage and weed-control practices made no effect on organic C and total N status of soil but legume mulching improved these parameters and reduced bulk density associated with increased infiltration rate. It was concluded that CT along with legume mulching in maize and MT in wheat, and chemical weeding of both the crops was beneficial for improving moisture and nutrient conservation, and achieving higher productivity and profitability of maize-wheat cropping system under Doon valley conditions.
  • Authors:
    • Dube, R.
    • Dhyani, S.
    • Singh, R.
    • Sharma, A.
  • Source: NUTRIENT CYCLING IN AGROECOSYSTEMS
  • Volume: 87
  • Issue: 2
  • Year: 2010
  • Summary: Mulching with vegetative materials is a highly beneficial and widely-investigated agro-technique in rainfed areas but the adoption of this practice has been constrained due to non-availability of mulch biomass locally. Live mulching with fast-growing annual green manure legumes like sunnhemp ( Crotalaria juncea) or prunings of Leucaena leucocephala grown as hedge rows can be done for moisture conservation as well as nutrient cycling in the maize-wheat cropping system, which is predominantly followed in the high rainfall sub-mountainous region of north-western India. A field experiment was conducted at Selakui, Dehradun during 2000-2004 to study the effect of legume mulching, viz. in situ grown sunnhemp and Leucaena prunings, along with varying N levels, viz. 0, 30, 60 and 90 kg N ha -1 (to maize), and 0, 40 and 80 kg N ha -1 (to wheat) on productivity, soil moisture conservation and soil physico-chemical properties. Intercropped sunnhemp added 0.75-1.45 t dry matter and 21.6-41.3 kg N ha -1 at 30-35 days, while Leucaena twigs added 1.89-4.15 t dry matter and 75.2-161.3 kg N ha -1 at 60-65 days of maize growth. Live mulching with sunnhemp or Leucaena biomass improved soil moisture content at maize harvest (+1.15-1.57%) and crop productivity by 6.8-8.8% over no mulching. Combined use of both the mulching materials was more effective in improving the soil moisture content (+2.08-2.29%) and grain yield (15.1%) over their single application. Response of maize to N fertilizer application was significant up to 90 kg N ha -1, and it was relatively more pronounced under the mulching treatments. Residual effect of mulching on wheat showed an increase in yield of 10.2% with sunnhemp or Leucaena, and 27.9% with sunnhemp+ Leucaena. There was an improvement in organic C and total N status of soil, and a decrease in bulk density associated with an increase in infiltration rate due to mulching at the end of 4 cropping cycles. It was concluded that legume mulching is a highly beneficial practice for enhanced moisture and nutrient conservation, leading to increased productivity and soil health of maize-wheat cropping system under Doon valley conditions of north-western India.