• Authors:
    • Garcez, F.
    • Bacchi, L.
    • Gavassoni, W.
    • Silva, F.
  • Source: Summa Phytopathologica
  • Volume: 37
  • Issue: 3
  • Year: 2011
  • Summary: The effects of crop residues and their extracts on Sclerotinia sclerotiorum are not well documented. Three experiments were conducted with crop residues and their ethanol and partition extracts. Oat, vetch, bean, pearl millet, corn and wheat were assessed under controlled conditions. Sclerotia covered with oat, vetch, bean and pearl millet residues did not germinate carpogenically. Ethanol extracts of oat and vetch residues were efficient in inhibiting carpogenic germination whereas pearl millet and wheat did not differ from control. All partitioned ethanol extracts inhibited germination. Crop residues negatively affected the number of apothecia per sclerotium.
  • Authors:
    • Pereira, D. C. de
    • Fortes, A. M. T.
    • Spiassi, A.
    • Senem, J.
    • Tomazoni, D.
  • Source: SEMINA-CIENCIAS AGRARIAS
  • Volume: 32
  • Issue: 2
  • Year: 2011
  • Summary: In agricultural crops is common planting the main crop on the remains of straw harvesting the crop earlier due to no-tillage system. The straw remaining in the soil can exert positive or negative influence on the main crop through the release of organic compounds that carry allelopathy on plants of the subsequent growing. This experiment consisted of mixing and blending of different types of turnip ( Brassica rapa L.), oats ( Avena sativa L.), crambe ( Crambe abyssinica Hochst. Ex RE Fries), Safflower ( Carthamus tinctorius L.) and rapeseed ( Brassica napus L. var) in soil and placed in plastic trays where they planted the seeds of maize. The experimental design was completely randomized design with six treatments and three repeticoes. As ratings were: emergence, rate of emergence, shoot length, root length, root dry weight, dry weight of shoots. The cover crops canola and safflower showed a positive effect, as crambe, turnips and oats had a negative effect on initial growth of maize seedlings, are not suitable for cover crop to maize sowing.
  • Authors:
    • Yang, W.
    • Liu, W.
    • Wan, Y.
    • Zhang, J.
    • Xiang, D.
    • Yong, T.
  • Source: Acta Prataculturae Sinica
  • Volume: 20
  • Issue: 6
  • Year: 2011
  • Summary: The aim of this paper was to study the mechanisms of interspecific nitrogen facilitation and transfer in the relay strip intercropping systems of "wheat/maize/soybean" and "wheat/maize/sweet potato". The methods of root barrier and 15N-isotope dilution were used to investigate the nitrogen transfer, nitrogen uptake and residual effect in the two relay strip intercropping systems. Comparing the no barrier with solid barrier, the results showed that in-season 15N uptake and 15N recovery efficiency of wheat increased remarkably, and 15N% abundance left in soil and total N content reduced obviously. In the "wheat/maize/soybean" system, the in-season 15N uptake and 15N recovery efficiency, 15N% abundance left in soil and total N content of maize with no barrier increased by 25.16%, 25.16%, 13.89% and 10.15%. But in the "wheat/maize/sweet potato" system, the value of above indices reduced by 15.98%, 15.99%, 17.37% and 5.19%. For soybean, the in-season 15N uptake and 15N recovery efficiency, 15N% abundance left in soil reduced, the soil total N content increased by 3.03%. For sweet potato, the in-season 15N uptake and 15N recovery efficiency increased, 15N% abundance left in soil and total N content reduced by 0.91% and 4.95%. In the "wheat/maize/soybean" system, the 15N uptake and 15N recovery efficiency of wheat and maize obtained from previous wheat, maize and soybean were higher than that of the "wheat/maize/sweet potato" system. The 15N uptake and 15N recovery efficiency of soybean obtained from previous wheat or maize were lower than that of sweet potato, but that from previous soybean was higher than that from previous sweet potato. The "wheat/maize/soybean" system was more beneficial to increase annual nitrogen uptake, nitrogen residual effect and maintaining soil fertility.
  • Authors:
    • Nagler, P. L.
    • Hunsaker, D. J.
    • Neale, C. M. U.
    • Glenn, E. P.
  • Source: Hydrological Processes
  • Volume: 25
  • Issue: 26
  • Year: 2011
  • Summary: Crop coefficients were developed to determine crop water needs based on the evapotranspiration (ET) of a reference crop under a given set of meteorological conditions. Starting in the 1980s, crop coefficients developed through lysimeter studies or set by expert opinion began to be supplemented by remotely sensed vegetation indices (VI) that measured the actual status of the crop on a field-by-field basis. VIs measure the density of green foliage based on the reflectance of visible and near infrared (NIR) light from the canopy, and are highly correlated with plant physiological processes that depend on light absorption by a canopy such as ET and photosynthesis. Reflectance-based crop coefficients have now been developed for numerous individual crops, including corn, wheat, alfalfa, cotton, potato, sugar beet, vegetables, grapes and orchard crops. Other research has shown that VIs can be used to predict ET over fields of mixed crops, allowing them to be used to monitor ET over entire irrigation districts. VI-based crop coefficients can help reduce agricultural water use by matching irrigation rates to the actual water needs of a crop as it grows instead of to a modeled crop growing under optimal conditions. Recently, the concept has been applied to natural ecosystems at the local, regional and continental scales of measurement, using time-series satellite data from the MODIS sensors on the Terra satellite. VIs or other visible-NIR band algorithms are combined with meteorological data to predict ET in numerous biome types, from deserts, to arctic tundra, to tropical rainforests. These methods often closely match ET measured on the ground at the global FluxNet array of eddy covariance moisture and carbon flux towers. The primary advantage of VI methods for estimating ET is that transpiration is closely related to radiation absorbed by the plant canopy, which is closely related to VIs. The primary disadvantage is that they cannot capture stress effects or soil evaporation. Copyright (C) 2011 John Wiley & Sons, Ltd.
  • Authors:
    • Efent'ev, A. N.
    • Grigorov, M. S.
  • Issue: 4
  • Year: 2011
  • Summary: Maize cultivation has a great potential in Russia with the current area under crop of 2.5 million ha and the prospective grain yield of 2.38 t/ha by 2015. The main reason for unstable yield of maize grain in Russia is water shortage in arid climate conditions of steppe zone. An author gives an overview of maize cultivation techniques in arid areas including fertilization, different irrigation methods, irrigation norms and regimes, irrigation machinery, as well as maize cultivars suitable for dry climate conditions. Effects of irrigation rate and fertilization on productivity of maize hybrid Povolzhskii 20 SV were studied in the production enterprise "Lider" of the Volgograd region in 2010. The maximal grain yield of 6.65 t/ha was achieved by applying irrigation rate of 3600 m 3/ha and 220:100:60 kg of NPK/ha.
  • Authors:
    • Gutierrez-Martin, C.
    • Gomez Gomez, C. M.
  • Source: Spanish Journal of Agricultural Research
  • Volume: 9
  • Issue: 4
  • Year: 2011
  • Summary: This paper develops a general preference model to explain farmers' decisions. Contrary to better known and most commonly used simulation models, the one presented in this paper allows to calibrate, simulate and explain farmers' decisions without assuming linear preferences (as in many multi criteria decision models) or unobservable implicit cost functions (as in positive mathematical programming models). The model is calibrated for crop decisions in the Genii Cabra irrigated area in the Guadalquivir valley (South Spain) as the resulting empirical model is used to study how farmers react by adjusting these decisions when efficiency in the use of water is improved under different scenarios regarding water use rights. The main conclusion of the paper is that the potential water savings from enhancing irrigation technique (636 m(3) ha(-1)) are overcome by increasing water demand due to higher per drop water productivity when sunflower is replaced by maize. For that reason water price increases and/or reduction of water use rights is a necessary condition to convert water savings through improved efficiency into lower water use and better conserved water sources.
  • Authors:
    • Zaidi, J. H.
    • Matiullah
    • Husaini, S. N.
    • Arif, M.
  • Source: Journal of Radioanalytical and Nuclear Chemistry
  • Volume: 290
  • Issue: 3
  • Year: 2011
  • Summary: Due to the inadequate water sources, usually sewerage water and industrial effluents are being use for irrigation of the agricultural land around the industrial areas in Pakistan wherein crops and vegetables are cultivated. As untreated effluents contain heavy elements, toxic metals and organic pollutants that may find its way through food chain to general public and may cause health hazards. It is, therefore, mandatory to assess the toxic metals in such crops and vegetables. In this regard, samples of corn, millet, cabbage, spinach and potato were collected within the vicinity of industrial areas of the Faisalabad and Gujranwala regions. The food samples were analyzed using neutron activation analysis (NAA) technique. The highest concentration values of Arsenic (1.90.1 g/g) and Cobalt (0.850.01 g/g) were found in cabbage whereas Manganese (91.60.2 g/g), Antimony (0.150.03 g/g) and Selenium (1.10.1 g/g) were observed in spinach and Chromium (9.631.3 g/g) was found in millet crop. The observed concentrations of all the toxic and heavy metals in crops and vegetables are higher than those reported in the literature.
  • Authors:
    • Grant, C.
    • Cai, D.
    • Wu, X.
    • Sun, Y.
    • Feng, Z.
    • Zhang, D.
    • Zhang, X.
    • Zhao, Q.
    • Meng, C.
    • Dai, K.
    • Yang, Y.
    • Wang, X.
    • Jia, S.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 90
  • Issue: 3
  • Year: 2011
  • Summary: A field micro-plot experiment for winter wheat was conducted in an irrigated winter wheat ( Triticum aestivum)-summer maize ( Zea mays L.) rotation system in Mazhuang, Xinji of Hebei province in the North China Plain, using the 15N isotope method to determine the effects of N application (rates and timing), and irrigation frequency on urea- 15N fate, residual-N and N recovery efficiency (NRE) of wheat. The experiment was conducted under two irrigation treatments (I2 and I3, representing for two and three irrigations, respectively), at three N rates (150, 210, and 270, kg ha -1), divided between two 15N-labeled applications of basal- 15N (90 kg ha -1) and topdress- 15N (60, 120, and 180, kg N ha -1, respectively). The total N uptake by wheat (ranging from 186 to 238 kg ha -1) and the fertilizer-derived N (Ndff, about 34-55%) were measured. The Ndff from labeled basal- 15N and from labeled topdress- 15N were about 15-22% and 16-40%, respectively. The NRE (measured either as recovery in grain or as the total N recovery in the plant) was higher with I3 (39-41 or 47-49%) than with I2 (35-40 or 42-47%), showing maximum NRE in grain of about 40% both at N210 with I2 and at N150 with I3 treatment. The NRE by the first wheat crop (in grain or the total N recovery in plant) was higher with labeled topdress- 15N (39-48 or 45-56%) as compared to that with labeled basal- 15N (30-37 or 36-45%), while the unaccounted N losses were lower with labeled basal- 15N (14-22%) relative to labeled topdress- 15N (14-35%). Higher residual N in soils was found with labeled basal- 15N (41-51%), as compared to labeled topdress- 15N (18-35%). Residual N in the 0- to 150-cm soil depth ranged from 26 to 44% while the unaccounted N losses ranged from 14 to 30%. Recovery of residual N by the 2nd and 3rd crops in the rotation was 5-10% in the maize crop and a further 1.7-3.5% in the subsequent wheat crop. The accumulated N recovery and the unaccounted N losses in continuous wheat-maize-wheat rotations derived from labeled topdress- 15N were 54-64% and 16-37%, respectively while they were 47-53% and 16-28%, respectively from labeled basal- 15N. This study also suggested that an N rate of 210 kg ha -1 (with a ratio of basal-N to topdress-N of 1:1.3) with two irrigation applications could optimize wheat grain yields and NRE, under the water limited conditions in North China Plain.
  • Authors:
    • Behzad, M.
    • Naseri, A. A.
    • Karimi, G. H.
    • Meskarbashi, M.
  • Source: RESEARCH ON CROPS
  • Volume: 12
  • Issue: 3
  • Year: 2011
  • Summary: A lysimeter experiment was conducted to study the shallow groundwater contribution in supplying maize water requirement. Twenty-four lysimeters, each consisting of a 1.2 m deep, 0.8 m diameter polyethylene pipe, were installed. Summer maize was planted in the lysimeters. The depth of groundwater table in the lysimeters was set to 0.6 m using Marriotte bottles. Three groundwater salinity levels (2.5, 5 and 7.5 dS/m) with two irrigation levels (at rates of 0.7 and 1 times of evaporation from pan class A at the before irrigation period) which replenished soil water on a weekly basis were used in the experiment. Factorial experiment in a randomized complete block design with three replications was established. In an individual treatment, maize was planted with full irrigation and No Ground Water (NGW) as the control treatment, replicated three times. The results indicated that groundwater contribution per cent at full irrigation level for each three salinity treatments (above mentioned) was 5.28, 4.61 and 3.76, and at deficit irrigation level was 25, 22.09 and 19.71, respectively. All differences were significant at the 0.05 Duncan's multiple ranges test. At deficit irrigation level, the grain yield reduction compared to control treatment was 23.57, 28.17 and 30.16% for three salinity treatments, respectively, and the dry matter reduction was also 37.50, 38.96 and 39.20%. At full irrigation level, the grain yield reduction was 19.42, 25.48 and 21.90% and the dry matter reduction was also 28.08, 33.60 and 25.78%. At full irrigation mode, the groundwater contribution decreased when the groundwater salinity increased and may be less evaporation from the soil surface causing less salt rising in the root zone and more relative yield.
  • Authors:
    • Kugbei, S.
  • Source: Journal of Crop Improvement
  • Volume: 25
  • Issue: 3
  • Year: 2011
  • Summary: Production figures in 2008 showed that new private seed enterprises in Afghanistan produced and sold about 12,000 tons of certified wheat seed, which accounted for 95% of the total certified seed produced in the country. At a retail price of about US$1,200 per ton, the enterprises earned an average margin of 20%. When interviewed, the farmers ranked high yield as by far the most important characteristic they sought in improved varieties. Besides yield, the next important attributes were earliness, disease resistance, grain color, and bread making quality. Estimates of on-farm productivity showed that use of improved wheat varieties alone could contribute up to 33% incremental yield under irrigated conditions, whereas the use of quality seed could enhance yield further by 28%. These estimates were obtained under recommended fertilizer rates, in the absence of which yield levels would have declined substantially. Apart from wheat, other major crops the farmers grew varied by regions but in broad terms included rice, vegetables, maize, potato, cotton, barley, watermelon, and alfalfa.