• Authors:
    • listed as anonymous
  • Source: Egyptian Journal of Plant Breeding
  • Volume: 11
  • Issue: 1
  • Year: 2007
  • Summary: These proceedings contain 30 papers on the various aspects of plant breeding including heterosis, combining ability and inheritance studies, characterization of cultivars, performance evaluation and genetic improvement of field crops (including wheat, cotton, soyabean, maize, rice, barley, rape, sorghum and faba bean) and horticultural crops (e.g. mango, tomato, pepper and grape).
  • Authors:
    • Anderson, R. L.
    • Beck, D. L.
  • Source: Weed Technology
  • Volume: 21
  • Issue: 1
  • Year: 2007
  • Summary: Producers in the Great Plains are exploring alternative crop rotations with the goal of reducing the use of fallow. In 1990, a study was established with no-till practices to compare 8 rotations comprising various combinations of winter wheat (W), spring wheat (SW), maize (C), chickpea (CP), dry pea (Pea), soyabean (SB), or fallow (F). After 12 years, we characterized weed communities by recording seedling emergence in each rotation. Downy brome ( Bromus tectorum), cheat ( Bromus secalinus), redroot pigweed ( Amaranthus retroflexus), and green foxtail ( Setaria viridis) were the most common weeds observed. Weed community density was highest for W-CP, being 13-fold greater than with Pea-W-C-SB. Downy brome and cheat were rarely observed in rotations where winter wheat was grown only once every 3 or 4 years; in contrast, density of the brome species was 75-fold greater in W-CP. Warm-season weeds were also affected by rotation design; density of redroot pigweed and green foxtail was 6-fold greater in W-C-CP compared with Pea-W-C-SB or W-F. One rotation design that was especially favourable for low weed density was arranging crops in a cycle of 4, with 2 cool-season crops followed by 2 warm-season crops.
  • Authors:
    • Duarte, G.
    • Diaz-Zorita, M.
    • Barraco, M.
  • Source: Wheat Production in Stressed Environments Developments in Plant Breeding
  • Volume: 12
  • Year: 2007
  • Summary: Wheat ( Triticum aestivum L.) grain yields under no-till production systems have been shown to be reduced in the presence of maize ( Zea mays L.) residues. It has been suggested that sowing a greater density of wheat seeds or removing maize residues from the planting rows contributes to avoid this problem. However, the causal factors and the mechanism that produce reductions in wheat yields are no clearly defined. Our objective was to determine the effects of different volumes of maize or soybean [ Glycine max (L.) Merrill] residues on no-tillage wheat establishment and production under field conditions on a Typic Hapludoll from the Pampas region of Argentina. The study was performed during the 2002, the 2003 and the 2004 growing seasons. Two treatments [residue volume (0, 4, 8 and 16 Mg ha -1) and crop residue (maize and soybean)] were imposed after sowing wheat at low and high plant densities, (301 and 396 seed ha -1, respectively). The previous crop was sunflower ( Helianthus annus L.) and the residues were applied on the soil surface immediately after planting and fertilizing with 125 kg ha -1 of Nitrogen. Independently of the quality of the residues and the sowing density, wheat plants m -2, spikes m -2 and grain yields ha -1 decreased when residue volume increased. In general, lower soil temperatures values and variability were observed when increasing the volume of residues. The presence of large amounts of maize or soybean residues causes the reduction in no-tillage wheat productivity (plant stand and numbers of spikes). However, only maize residues causes significant reductions in grain yields, independently of the seeding rate. The absence of significant differences in soil temperature measurements between residues allows us to think that the effects on surface soil temperature are not the main factor explaining the reduction in wheat grain yields in the presence of maize residues. Increasing the seeding rate can contribute to ameliorate the grain yield reduction in the presence of maize residues but further research is required for explaining the reasons for the behavior of the crop.
  • Authors:
    • Vigil, M. F.
    • Nielsen, D. C.
    • Mikha, M.
    • Benjamin, J. G.
    • Calderon, F.
    • Henry, W. B.
  • Source: Soil Science Society of America Journal
  • Volume: 71
  • Issue: 4
  • Year: 2007
  • Summary: No-till cropping systems in the semiarid West have the potential to improve soil physical properties by increasing cropping intensity and crop diversity. An investigation at Akron, Colorado, USA, compared soil conditions in winter wheat ( Triticum aestivum)-summer fallow (WF) plots with soil conditions in wheat-maize ( Zea mays)-fallow (WCF), wheat-maize-sunflower ( Helianthus annuus)-fallow (WCSF), wheat-maize-millet ( Panicum miliaceum) (WCM), and a perennial grass/legume mix. The study began in 1990. Bulk density, pore size distribution, and saturated hydraulic conductivity were measured 7, 11, and 15 years after inception. Bulk density in the grass plots decreased from 1.39 to 1.25 Mg m -3 in 15 years. Bulk density in the annually cropped plots decreased from 1.38 to 1.30 Mg m -3 during the same time period. The pore size distribution became more uniform among the cropped treatments 15 years after the start of the experiment. Saturated hydraulic conductivity increased in the grass plots from 27 to 98 mm h -1 in 15 years. Saturated hydraulic conductivity in the annually cropped plots increased from approximately 14 to approximately 35 mm h -1 during the same period. The results show that improving soil physical properties by cropping system alone may take many years. Perennial vegetation may be more effective than annually cropped systems at improving soil physical conditions because of less surface compaction from planting operations and the apparent ability of perennial root systems to create a more stable, continuous pore network.
  • Authors:
    • Mentreddy, R. S.
    • Cebert, E.
    • Kumar, S.
    • Bishnoi, U. R.
  • Source: World Journal of Agricultural Sciences
  • Volume: 3
  • Issue: 3
  • Year: 2007
  • Summary: In the southeastern USA, winter rape in addition to winter wheat can become another commercial crop with benefits such as breaking of disease and insect cycles caused by continuous wheat cropping. Information on agronomic production practices and comparative profitability of rape and wheat for the southeastern USA is lacking. Therefore, from 1998 to 2005, a series of field experiments were conducted on rape to determine the optimum planting date, seeding, nitrogen and sulfur rates, rotation suitability with summer crops and comparative economic value to winter wheat. Results from three planting dates, three seeding rates and four nitrogen rates experiments showed that rape planted in early October produced significantly higher seed yield (3204 kg/ha) than from mid to late October 10-15 (2362 and 2058 kg/ha) plantings. The seeding rate of 6.0 kg/ha and 180 kg N/ha gave the highest (3779 kg/ha) seed yield. Rape response to sulfur application was significant and highest seed yield (3259 kg/ha) was obtained with 30 kg S/ha along with 228 kg N/ha. As a rotation crop after soyabean and maize, rape gave significantly higher yields of 3129 and 2938 kg/ha, respectively, than when planted after cotton (2521 kg/ha) or grain sorghum (2650 kg/ha). Both winter rape and wheat produced similar yields of 2.6 and 2.9 t/ha, respectively. As grain crop, canola with its higher price fetched $220/ha compared to $109/ha from wheat, however, this profitability is almost equal when income from wheat straw was added to that from grain.
  • Authors:
    • Sharma, R. K.
    • Sharma, S. K.
    • Jain, P. M.
    • Laddha, K. C.
  • Source: Indian Journal of Dryland Agricultural Research and Development
  • Volume: 21
  • Issue: 2
  • Year: 2006
  • Summary: A field experiment was conducted in Bhilwara, Rajasthan, India, during 1998 to 2004 to study the effect of compost, green leaf manure (subabul ( Leucaena leucocephala) loppings) and chemical fertilizer alone or in combination with organic residues on yield of maize and black gram cultivated in rotation in two blocks as well as in strip and change in soil properties under dryland conditions. Results revealed that application of 15 kg N through compost with 10 kg N through chemical fertilizer (urea) gave the highest yield of maize and subsequent yield in black gram in blocks as well in strips. The treatments where compost and green leaf of subabul were applied for supply of nitrogen along with chemical fertilizers were found at par in a maize block system. Organic carbon and available phosphorus content of the soil increased by the continuous application of compost and fresh green leaf of subabul and there was an indication of lowering of pH as well as electrical conductivity. The bulk density of soil decreased under treatments where compost and green leaf of subabul were used. Maximum infiltration rate of soil was observed with the application of green leaf of subabul along with 10 or 20 kg N through inorganic fertilizer in both block and strip systems.
  • Authors:
    • Bali, S. V.
    • Singh, B.
    • Lehria, S. K.
  • Source: Short Rotation Forestry for Industrial and Rural Development
  • Year: 2006
  • Summary: A field experiment was conducted at Rakh Dhiansar during Kharif 1995 and 1996 and Rabi 1995-96 and 1996-97 under dryland conditions of Jammu (J&K). The results based on growth, yield attributes and yield revealed that application of 15 t ha -1 of subabul leaves as basal+25% N recorded maize (var. Local) yield of 45.22 q ha -1, which was significantly higher than the recommended dose of fertilizers and it was at par with 15 t ha -1 of subabul leaves as basal only, yielding 45.06 q ha -1. The residual effect of green leaf manuring on wheat (var. PBW-175) revealed that growth, reproductive and yield attributing characters were also influenced positively. By using this material, 50-75% N can be saved by the small and marginal farmers of the dryland region.
  • Authors:
    • Nielsen, D. C.
    • Vigil, M. F.
    • Benjamin, J. G.
  • Source: Agronomy Journal
  • Volume: 98
  • Issue: 4
  • Year: 2006
  • Summary: Forages, with greater water use efficiency (WUE) than grain and seed crops, could be used to diversify reduced and no-till dryland cropping systems from the traditional wheat ( Triticum aestivum L.)-fallow system in the semiarid central Great Plains. However, farmers need a simple tool to evaluate forage productivity under widely varying precipitation conditions. The objectives of this study were to (i) quantify the relationship between crop water use and dry matter (DM) yield for corn ( Zea mays L.), foxtail millet ( Setaria italica L. Beauv.), and winter triticale ( X Triticosecale Wittmack); and (ii) determine the range and distribution of expected DM yields for these three crops in the central Great Plains based on historical precipitation records. The three crops were grown in a dryland no-till corn-millet-triticale sequence from 1998 through 2004 at Akron, CO. Dry matter production was linearly correlated with water use for all three crops, with regression slopes ranging from 24.2 (corn) to 33.0 kg ha -1 mm -1 (millet). Water use efficiency varied widely from year to year (0-32.2 kg ha -1 mm -1) for the three crops, as influenced by growing season precipitation and time of year in which the crops were grown. Millet and triticale produced similar amounts of DM for a given water use, while corn produced less. Precipitation use efficiency for the millet-triticale-corn forage system was 8.7 kg ha -1 mm -1, suggesting this as an efficient forage system for the region.
  • Authors:
    • Klocke, N. L.
    • Schneekloth, J. P.
    • Davison, D. R.
    • Payero, J. O.
  • Source: Irrigation Science
  • Volume: 24
  • Issue: 4
  • Year: 2006
  • Summary: Many farmers in West Central Nebraska have limited irrigation water supplies, and need to produce crops with less water. This study evaluated the impact of four water management strategies on grain yield of surface-irrigated corn ( Zea mays L.) at North Platte, Nebraska. Treatments included: (1) no irrigation (DRYLAND), (2) one irrigation prior to tassel formation (EARLY), (3) one irrigation during the silk stage (LATE), and (4) irrigation following farmer's practices (FARMER). The study included three wet years (1992, 1993, and 1996) and 2 years with average annual rainfall for the area (1994 and 1995). Significant yield differences among treatments, and a yield response to irrigation, were only observed during the 2 years with average rainfall. During all years, the FARMER treatment was over-irrigated and resulted in considerable water losses by runoff and deep percolation. Grain yield response to irrigation during the three wet years was insignificant among the treatments, but significant during the dry years. The results of this study suggest that inducing stress is not a good strategy for increasing crop water productivity (yield per unit ET d) for corn and point out the need to minimize irrigation water losses and improve irrigation scheduling.
  • Authors:
    • Payero, J. O.
    • Melvin, S. R.
    • Irmak, S.
    • Tarkalson, D.
  • Source: Agricultural Water Management
  • Volume: 84
  • Issue: 1-2
  • Year: 2006
  • Summary: Irrigation water supplies are decreasing in many areas of the US Great Plains, which is requiring many farmers to consider deficit-irrigating corn ( Zea mays L.) or growing crops like winter wheat ( Triticum aestivum L.) that require less water, but that are less profitable. The objectives of this study were to: (1) quantify the yield response of corn to deficit irrigation, and (2) determine which of several seasonal water variables correlated best to corn yield in a semiarid climate. Eight (T1-T8) and nine (T1-T9) deficit-irrigated treatments (including dryland), were compared in 2003 and 2004 in North Platte, Nebraska. The actual seasonal crop evapotranspiration (ET d) (calculated with procedures in FAO-56) for the different treatments was 37-79% in 2003 and 63-91% in 2004 compared with the seasonal crop evapotranspiration when water is not limited (ET w). Quantitative relationships between grain yield and several seasonal water variables were developed. Water variables included, irrigation ( I), total water ( Wall), rain+irrigation ( WR+I ), evaporation ( E), crop evapotranspiration (ET d), crop transpiration ( Td), and the ratios of ET d and Td to evapotranspiration and transpiration when water is not limited (ET w and Tw). Both years, yield increased linearly with seasonal irrigation, but the relationship varied from year to year. Combining data from both years, ET d had the best correlation to grain yield (yield=0.028ET d-5.04, R2=0.95), and the water variables could be ranked from higher to lower R2 when related to grain yield as: ET d ( R2=0.95) > Td ( R2=0.93) > ET d/ET w ( R2=0.90) = Td/ Tw ( R2=0.90) > Wall ( R2=0.89) > E ( R2=0.75) > WR+I ( R2=0.65) > I ( R2=0.06). Crop water productivity (CWP) (yield per unit ET d) linearly increased with ET d/ET w ( R2=0.75), which suggests that trying to increase CWP by deficit-irrigating corn is not a good strategy under the conditions of this study.