• Authors:
    • Escobar-Gutierrez, A.
    • Louarn, G.
    • Barillot, R.
    • Huynh, P.
    • Combes, D.
  • Source: Annals of Botany
  • Volume: 108
  • Issue: 6
  • Year: 2011
  • Summary: Background and Aims: Most studies dealing with light partitioning in intercropping systems have used statistical models based on the turbid medium approach, thus assuming homogeneous canopies. However, these models could not be directly validated although spatial heterogeneities could arise in such canopies. The aim of the present study was to assess the ability of the turbid medium approach to accurately estimate light partitioning within grass-legume mixed canopies. Methods: Three contrasted mixtures of wheat-pea, tall fescue-alfalfa and tall fescue-clover were sown according to various patterns and densities. Three-dimensional plant mock-ups were derived from magnetic digitizations carried out at different stages of development. The benchmarks for light interception efficiency (LIE) estimates were provided by the combination of a light projective model and plant mock-ups, which also provided the inputs of a turbid medium model (SIRASCA), i.e. leaf area index and inclination. SIRASCA was set to gradually account for vertical heterogeneity of the foliage, i.e. the canopy was described as one, two or ten horizontal layers of leaves. Key Results: Mixtures exhibited various and heterogeneous profiles of foliar distribution, leaf inclination and component species height. Nevertheless, most of the LIE was satisfactorily predicted by SIRASCA. Biased estimations were, however, observed for (1) grass species and (2) tall fescue-alfalfa mixtures grown at high density. Most of the discrepancies were due to vertical heterogeneities and were corrected by increasing the vertical description of canopies although, in practice, this would require time-consuming measurements. Conclusions: The turbid medium analogy could be successfully used in a wide range of canopies. However, a more detailed description of the canopy is required for mixtures exhibiting vertical stratifications and inter-/intra-species foliage overlapping. Architectural models remain a relevant tool for studying light partitioning in intercropping systems that exhibit strong vertical heterogeneities. Moreover, these models offer the possibility to integrate the effects of microclimate variations on plant growth.
  • Authors:
    • Gibson, L. R.
    • Singer, J. W.
    • Blaser, B. C.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 4
  • Year: 2011
  • Summary: Interseeding red clover ( Trifolium pratense L.) or alfalfa ( Medicago sativa L.) into winter cereals in the North Central United States can provide forage and a green manure crop. We hypothesized that winter cereal canopy traits such as leaf area index (LAI) and whole plant dry matter (DM) would influence interseeded legume establishment and productivity, yet the effect of canopy traits on resource competition in intercropping systems is not well understood. This study was conducted from 2005 to 2007 to evaluate the impact of diverse cereal canopy traits on the establishment of frost-seeded legume intercrops. In March, red clover and alfalfa were frost-seeded into three winter wheat ( Triticum aestivum L.) and three triticale (X Triticosecale Wittmack) varieties selected for differences in maximum LAI, plant height, and DM. Across three growing seasons, the cereals produced a range of LAI from 2.1 to 6.2 and whole plant harvest DM of 817 to 2029 g m -2. In the 2 yr with legume data, densities were influenced by cereal 1 yr and DM was affected by cereal both years. Alfalfa and red clover densities were similar, yet DM production was 42% higher in red clover 40 d after grain harvest. The presence of a legume intercrop did not affect grain yield, but reduced weed densities and weed DM 40 d after harvest. Producers implementing this intercrop may select cereal varieties based on grain yield, but must be cautious of varieties known to produce above normal LAI values because of the potential to reduce legume productivity.
  • Authors:
    • Brennan, E. B.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 5
  • Year: 2011
  • Summary: Winter cover crops can add soil organic matter, improve nutrient cycling, and suppress weeds in organic vegetable systems. A 2-yr study was conducted on organic farms in Salinas and Hollister, CA, to evaluate the effect of seeding rate (SR) and planting arrangement on cover crop density, ground cover, and cover crop and weed dry matter (DM) with a mixed cover crop. The mix contained legumes (35% Vicia faba L., bell bean; 15% Vicia dasycarpa Ten., woolypod vetch; 15% Vicia benghalensis L., purple vetch; and 25% Pisum sativum L., pea) and 10% oat (Avena sativa L.) by seed weight. Three SRs (112, 224, and 336 kg ha(-1)) and two planting arrangements (one-way versus grid pattern) were evaluated. Planting arrangement had no effect on the variables measured. When weeds were abundant, weed DM declined linearly with increasing SR from approximately 300 kg ha(-1) at the low SR to <100 kg ha(-1) at the high SR. Increasing SR increased oat and legume DM early in the season, but did not affect final cover crop DM that ranged from 7 to 12 Mg ha(-1). Year affected final cover crop DM production at both sites. The legume DM portion of the total cover crop declined through the season but varied between sites and year, probably due to soil and climatic differences. Higher SRs may be cost effective because weed control is expensive and cover crop seed is a relatively small component of cover cropping costs in this region.
  • Authors:
    • Ladewig, E.
    • Schulte, M.
    • Schmitz, F.
    • Burcky, K.
    • Buhre, C.
  • Source: Sugar Industry / Zuckerindustrie
  • Volume: 136
  • Issue: 10
  • Year: 2011
  • Summary: Since 1994, data on sugarbeet production in Germany are continuously collected in annual cultivation surveys based on the information from the German sugar factories. Because of the long-term data set, many developments over the last years as well as short-term adaptations could be described. Cereals, particularly winter wheat, are the main pre-crop before sugarbeet (50%), followed by maize. Intercrops have been cultivated on 40% of the sugarbeet area since the beginning of the survey. The use of reduced systems increased in soil cultivation. The soil is covered by intercrops or pre-crop residues on more than 65% of the sugarbeet area. Since 2006, an increase in nitrogen fertilization was observed. Organic fertilizer was applied on 50% of the sugarbeet area. Crop production, from sowing to harvesting is characterized by an increase in technical specialization. The survey is conducted in cooperation with the farmers, or by specialized contractors. The beets are harvested mainly with six-row harvesters and transported increasingly with semi-trailer trucks.
  • Authors:
    • Bandyopadhyay, P.
    • Nath, R.
    • Jena, S.
    • Dutta, S. K.
    • Dutta, A.
    • Chakraborty, P. K.
  • Source: Journal of Crop and Weed
  • Volume: 7
  • Issue: 1
  • Year: 2011
  • Summary: Temperature is an important weather parameter affecting the growth and development of the crop. The growing degree days (GDD) indicate the thermal index required for the onset of phenophases in crop. A two-year (2008-09 and 2009-10) field experiment was conducted at the B.C.K.V Instructional Farm to investigate the effect of GDD on leaf growth rate (LGR), crop growth rate (CGR) and leaf area indices (LAI) of wheat and mustard grown under sole (T 1 and T 2) and intercrop situations, [2 wheat:6 mustard (T 3), 4 wheat:4 mustard (T 4) and 6 wheat:2 mustard (T 5)]. The experiment was laid out in a RBD design with 6 replications having a plot size of 50 m 2. The experimental soil has pH of 6.92, organic carbon 0.63%, total N 0.06%, available P 2O 5 18.47 kg/ha and available K 2O 127.22 kg/ha. The experimental site is under tropical humid climate. From the results, leaf growth rate, crop growth rate and leaf area index were found to be polynomial function of GDD. The results also suggested that the effect of GDD on different growth indices of wheat and mustard were strongly expressed in 4 wheat:4 mustard row ratios which might be adopted in the Gangetic Plains of New Alluvial zone of West Bengal.
  • Authors:
    • Kumari, S. G.
    • Ekzayez, A. M.
    • Ismail, I.
  • Source: Plant Disease
  • Volume: 95
  • Issue: 1
  • Year: 2011
  • Summary: A field survey covering the major cereal-production areas of Syria was conducted during May 2009. A total of 938 wheat and 971 barley samples with typical symptoms of viral infection were collected from 45 wheat and 58 barley fields. Serological tests showed that Wheat dwarf virus (WDV) was detected in 16 wheat (cv. Cham 8) and 5 barley (cv. Arabic abiad) samples collected from Al-Hasskah governorate (eastern region of Syria) and showing dwarfing, yellowing, and reduced heading. The identity of WDV was confirmed by PCR assay. Leafhopper transmission tests indicated that only Psammotettix provincialis was able to transmit Syrian barley WDW isolates from infected barley plants to healthy barley (48 plants became infected of 50 plants inoculated) and oats (45 of 50) under greenhouse conditions. WDV has been reported to infect cereals in other countries in West Asia and North Africa (Turkey, Tunisia and Morocco) and causes economic losses on wheat in many countries in Europe (e.g. Sweden). WDV has been reported to be transmitted in a persistent manner only by leafhoppers ( Psammotettix alienus) to a wide range of cereal and wild grasses. Two strains of WDV are known, one that primarily infects wheat and another that infects barley. This is thought to be the first report of WDV (both strains) infecting wheat and barley crops in Syria and the first report of P. provincialis as a WDV vector worldwide.
  • Authors:
    • Eskandari, H.
  • Source: African Journal of Biotechnology
  • Volume: 10
  • Issue: 77
  • Year: 2011
  • 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 photosynthetically active radiation (PAR) interception, water and nutrient uptake. The experiment was carried out as randomized complete block design with four replications. The results show that intercropping systems had a significant effect on environmental resources consumption, where intercropping systems had more light interception and water, and nutrient uptake 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. Regarding weed suppressions, intercrops were more effective than wheat sole crops, which were related to lower availability of environmental resources for weeds in intercropping systems.
  • Authors:
    • Emeran, A. A.
    • Shtaya, M. J. Y.
    • Fernandez-Aparicio, M.
    • Allagui, M. B.
    • Kharrat, M.
    • Rubiales, D.
  • Source: Crop Protection
  • Volume: 30
  • Issue: 8
  • Year: 2011
  • Summary: Chocolate spot incited by Botrytis fabae is a serious faba bean disease of worldwide distribution. The increasing interest in sustainable tools for disease control, together with the lack of sufficient levels of genetic resistance triggered our interest in the use of intercropping as a tool for the management of this disease. The effect of intercropping on chocolate spot severity was studied in field experiments performed in Egypt, the Palestinian Territories, Spain and Tunisia, in which a susceptible faba bean cultivar was grown as a monocrop or with two mixed species intercrops of either barley, oat, triticale, wheat, pea or common vetch, or with three mixed species intercrops of wheat and berseem clover. Chocolate spot was significantly reduced when faba bean was intercropped with cereals, but not when intercropped with legumes. Suppressive effects can be ascribed to a combination of host biomass reduction, altered microclimate and physical barriers to spore dispersal.
  • Authors:
    • Cavariani, C.
    • Gazola, E.
  • Source: BIOSCIENCE JOURNAL
  • Volume: 27
  • Issue: 5
  • Year: 2011
  • Summary: The objective of this research was to evaluate crop yield and some characteristics and yield components of transgenic soybean cultivars sown after different winter cover crops in the first year under no tillage system. The experimental design was the completely randomized block with split plots and four replications. The main plots consisted of five winter cover crops, white oat ( Avena sativa L.), forage turnip ( Raphanus sativus L.), barley ( Hordeum vulgare L.), wheat ( Triticum aestivum L.) and ground pea ( Pisum sativum L.) and an area under fallow (spontaneous vegetation). The subplots consisted of six soybean cultivars (BRS 243 RR, BRS 245 RR, BRS 247 RR, BRS 255 RR, BRS 256 RR and BRS 244 RR). Variance analysis for agronomic characteristics showed that soybean yield components were influenced by the interaction between winter crop and soybean cultivar. Thus, final population, number of nodes and pods per plant, nodes dry matter per plant, number of grains per pod and grain yield were affected significantly. When soybean nodulation was evaluated, the treatment with the area under fallow showed lower values. There was difference among winter crops for BRS 243 RR grain yield, white oat showed the highest values.
  • Authors:
    • Sawargaonkar, G. L.
    • Gadade, G. D.
    • Shinde, V. S.
    • Gokhale, D. N.
    • Zade, K. K.
  • Source: Journal of Cotton Research and Development
  • Volume: 25
  • Issue: 2
  • Year: 2011
  • Summary: Field studies were carried out at Department of Agronomy, Marathwada Agricultural University, Parbhani during, 2007 to 2010 to explore the suitability of different soil moisture conservation and integrated nutrient management (INM) techniques in relation to yield and economics of Bt cotton under rainfed conditions. The results revealed that opening of furrow in alternate row recorded significantly highest seed cotton yield (2758, 2214 and 1452 kg/ha) as compared to cotton+straw mulching (2421, 2003 and 1233 kg/ha) and intercropping of cotton with soybean (2036, 1626 and 1106 kg/ha) treatments during the three year of experimentation respectively. However, intercropping of cotton+soybean recorded significantly highest seed cotton equivalent yield and thereby net returns and B:C ratio over wheat straw mulch and opening of furrow in alternate row. As regards to integrated nutrient management (INM) 100 per cent calculated RDF (100:50:30 N, P 2O 5 and K 2O kg/ha)+micronutrients (zinc, iron and boron) based on soil test recorded significantly highest seed cotton yield as compared to all other INM treatments. However, application of RDF with soil testing (75 per cent N, P 2O 5 and K 2O kg/ha through inorganic+25 per cent N, P 2O 5 and K 2O kg/ha through vermicompost) was next best treatment which recorded significantly highest seed cotton yield over rest of the treatments.