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Agricultural Science and Technology - Volume:8 Issue: 4, Oct 2006

Journal of Agricultural Science and Technology
Volume:8 Issue: 4, Oct 2006

  • تاریخ انتشار: 1385/07/25
  • تعداد عناوین: 9
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  • A. A. Maghsoudi Moud, T. Yamagishi Page 271

    In drought prone environments wheat crop growth and production depends strongly on the water stored in the soil before anthesis and, although some water remains in the soil after harvest, plants experience water deficit. In order to investigate whether water extraction patterns, as a plant feature, have a regulating effect on the amount of water used by them at different soil depths, three wheat cultivars (Asakaze, BR9, BR10) differing in origin and drought resistance in terms of grain yield were grown in pots under gradually downward soil drying conditions. The total water used by cultivars was the same up to the post anthesis stage of growth when plants were harvested. However, Asakaze used more water from emergence to the beginning of the stem elongation period of growth and BR9 used more after that period up to the post anthesis stage. Cultivars showed significant differences in root length at different soil depths. Asakaze was predicted to use more water from topsoil layers compared to BR9 and BR10. On the other hand, BR9 was expected to use more water from deep layers in comparison to Asakaze. These were suggested to be the effect of the higher root density of each cultivar in the top and deep soil layers. It is also suggested that higher root length density in deep soil layers could be targeted as a favorable trait for breeding wheat Cultivars, which are growing under gradually downward soil drying conditions.

  • N. Majnoun Hosseini, H. M. Alizadeh, H. Malek Ahmadi Page 281

    To study the effects of plant density and nitrogen rates on the ability of canola (Regent × Cobra; an inbred variety) to compete with weeds, an experiment was conducted as a factorial complete block design with four replications. The treatments included four levels of plant density at 150, 190, 230, and 270 plants m-2, and four levels of nitrogen (N) fertilizer at 0, 46, 92, and 138 kg ha–1. Results indicated that different levels of plant density and N fertilizer had significant effects on the canola’s leaf area index (LAI) and dry matter accumulation, as well as on the weed’s dry matter at three stages of plant growth (rosette, stem elongation, and 50% flowering). The addition of N fertilizer resulted in increasing plant LAI and decreasing weed dry matter. Densities of 150 and 270 plants m-2, along with 138 kg ha–1 nitrogen showed the highest LAI at the rosette and stem elongation stages. The LAI at different plant growth stages was an important factor in enhancing canola’s competitiveness with weeds. There were significant differences between different plant density and N fertilizer levels for traits such as plant height, pod bearing stem length, biomass and seed yield. An increase in plant density significantly decreased the pod bearing stem length and total pod numbers per plant (i.e. pod numbers in main branches and sub-branches), but increased plant height. The highest seed yield was obtained with 190 plants m-2 along with 138 kg N ha–1. This study revealed that optimum plant density as well as N fertilizer may increase the competitive ability of canola against weeds.

  • R. Asadi, A. A. Talebi, Y. Fathipour, S. Moharramipour, E. Rakhshani Page 293

     The agromyzid leafminers, Liriomyza sativae Blanchard and L. trifolii (Burgess) (Diptera: Agromyzidae) are major pests that attack vegetables in Varamin, Tehran Province. The parasitoids (Hymenoptera: Eulophidae) of these pests were investigated during 2003. The leafminer infested leaves were collected from different host plants, in particular cucumber (Cucumis sativus L.,) and preserved under laboratory conditions until the parasitoids emerged. The vegetable leafminer were parasitized by an expected range of parasitoids. The parasitoid species included Cirrospilus vittatus Walker, Hemiptarsenus zilahisebessi Erdös, Closterocerus formosus Westwood, Diglyphus isaea (Walker), Diglyphus crassinervis Erdös. and Pnigalio sp. nr. pectinicornis. The most common species was D. isaea, followed by C. formosus and D. crassinervis. Although insecticides were applied continuously for control of leafminers, the mean seasonal percentage of parasitism was 51.12%. The morphological characteristics of each species are given in brief.

  • A. A. Pourmirza Page 305
    In laboratory experiments the toxicity of acetone was investigated against four species of stored-product insects. In empty-space trials, estimates of the lethal concentrations of acetone (LC, 72-h exposure) for 50% mortality against adults of the lesser grain borer, Rhizopertha dominica (F.), red flour beetle, Tribolium castaneum (Herbst), rice weevil, Sitophilus oryzae (L.) and eggs of the angoumois grain moth, Sitotroga cerealella (L.) were 33.64, 41.05, 43.90 and 46.11 μl/liter, respectively. At the LC95 level, the order of sensitivity was rated to be: R. dominica adults > S. oryzae adults > T. castaneum adults > S. cerealella eggs. Penetration tests revealed that acetone vapour could penetrate into the wheat mass and kill concealed insects in interkernel spaces. Comparison of LC50 values between empty-space tests and penetration experiments (after 72-h exposure) indicated that the increase in penetration toxicity was 8.52- and 8.09- fold for R. dominica and T. castaneum, respectively. A similar trend was observed at the LC95 level. In the hidden infestation trial, the acetone vapour destroyed all the developmental stages of S. oryzae concealed inside the wheat kernels and resulted in a complete control with a concentration of 320 μl/liter for 8 weeks after the exposure. Based on the data collected in this study, acetone should be considered as a potential compound for empty space fumigations. However, due to its sorption characteristics and the application of high doses, acetone may have only limited use as a fumigant under practical conditions.
  • Gh. Rafiee Che Roos Saad Page 313

     The effects of natural zeolite as a bed medium in increasing lettuce and red tilapia growth as well as improvement of water quality parameters in an aquaponic system were investigated. An experiment with a completely randomized design was run with two treatments in triplicates, 1) an aquaponic system without use of zeolite as a control group and 2) use of a small cotton bag, containing 10 g zeolite as a bed medium for planting a lettuce seedling. In each experimental unit, 42 seedlings of lettuce were introduced. The individual weight of fish and lettuce yield in treatment 2 was significantly higher (P< 0.05) than treatment 1 at the end of experiment. The initial mean individual weight of red tilapia juveniles was 6.23 ± 0.06 g and increased to 32.50 ± 2.00 and 37.50 ± 2.20 in treatments 1 and 2, respectively by the end of experiment. The yield of lettuce was higher in treatment 2 (1507 ± 445.00 g/unit) compared to the control (275 ± 83 g/unit). The concentration of total ammonia-N in the water was significantly lower (P< 0.05) in treatment 2 compared to treatment 1 at the end of experiment. The concentration of phosphorous and potassium in the fish rearing tanks was significantly lower (P< 0.05) in treatment 2. These results indicated that the use of zeolite, as a bed medium to plant lettuce seedlings in a recirculating aquaponic system could increase the growth of lettuce seedlings as well as improving water quality parameters.

  • M. H. Azizi, S. M. Sayeddin, S. H. Payghambardoost Page 323

    The effect of flour extraction rate on flour composition, dough rheological characteristics and the quality of Iranian flat breads (lavash, taftoon and barbari) and their staling rate was investigated. Flours with different extraction rates (70, 75, 80, 83, 86, 88, 90 and 93) were subjected to different tests. Resultes indicated that, by increasing the extraction rate, the amount of protein, fat, fiber, ash, wet gluten, water absorption and the color of the flours all increased but the moisture content, sedimentation value and falling number decreased. Rheological studies of doughs by farinograph showed a reduction in dough stability, whereas the dough mixing tolerance index increased along with the extraction rate. By using an extensigraph it was shown that dough resistance, extensibility and the area under extensigram curves were decreased by increasing the extraction rate. A study of the effects of flours with different extraction rates on bread quality, showed that the overall quality of breads is generally affected by the flour extraction rate. Sensory analysis of breads in respect to overall quality and staling indicated that the desirable rates of extraction for lavash, taftoon and barbari, breads are 88, 90 and 88 respectively.

  • E. Pourjam, W. Bert Page 331

    Several soil samples were taken from western parts of Iran. One of the samples collected from the rhizosphere of nectarine trees (Prunus persica L.) in Moghan, Ardabil Province, contained Aprutides guidettii. The species Subanguina picridis was recovered from leaf gall of Serratula latifolia Boiss (Asteraceae) in the vicinity of Mashhad, Khorasan Province. Although this species showed remarkable differences from the original description, it was considered to be S. picrides considering the high level of variability described in the literature. Both species are described in detail and documented with drawings. Additional morphological data are illustrated by means of SEM. Subanguina picridis is described here for the first time from Iran.

  • A. Samadi Page 343
    Application of phosphorus (P) fertilizers as solid or liquid fertilizers to soils leads to reactions of orthophosphate ions with various soil components which remove P from the solution phase and convert it to less soluble phosphates. This study was aimed at determining soil properties that affect the rate of phosphate retention in 28 contrasting calcareous soils from different geographical regions (14 soils from Western Azarbaijan in Iran (WAI) and 14 soils from Western Australia in Australia (WAA). The results showed that the mean apparent recoveries of applied available P (Olsen P-based recovery) after 160 d of incubation at field capacity was found to be 7% for the soils of WAI and 25% for the soils of WAA. A study of correlation coefficients showed that, for the soils of WAA, there was a negative relationship between the recovery of applied P and the clay content (r = -0.59, P≤ 0.05), whereas there was a positive relationship between the recovery of P and the active CaCO3 (ACCE) content (r = 0.64, P ≤ 0.01). For the soils of WAI, there was a negative correlation between the Olsen P-based recovery and the clay content (r = -0.61, P ≤ 0.01). The decline in extractable P with time was best fitted to a second order kinetic equation. The kinetic rate constant (k) ranged from 0.092 to 0.55 mg kg-1d-1 for the soils of WAI and from 0.31 to 0.92 mg kg-1d-1 for the soils of WAA. The kinetic rate constant (k) increased with increasing the ratio of the clay content to ACCE for all soils of WAI. A regression analysis study showed that the ratio of clay/ACCE was the major factor governing P retention.
  • H. Rahmani, K. Kamali, A. Saboori, J. Nowzari Page 351

    This research explains the morphometric characteristics of Varroa destructor Anderson and Trueman in Tehran Province. 180 adult female mites were collected from three different colonies of Apis mellifera L. in three apiaries during September 2003 to May 2004. These colonies were divided according to three altitudes-less than 1000m, 1000- 1500m and more than 1500m above the sea level. The morphological characteristics of mite samples were examined using light microscopy. Measurements of mite specimens including body lengths, widths, mean size of leg segments and chelicerae were obtained from 180 females. Data were analyzed using the SAS package. The results revealed that: with 95% confidence intervals, body lengths were 1152.6-1218.9 (for less than 1000m altitude), 1163.2-1220.7 (for 1000-1500m altitude) and 1167.1-1228.3 (for grater than 1500m altitude). Also, body widths for those apiaries with 95% confidence intervals were: 1709.8-1818.2, 1712.1-1819.5 and 1720.4-1820.6, respectively. Mean body lengths were 1197.2, 1199.2 and 1200.1 and mean body widths were 1775.6, 1781.7 and 1789.9, respectively. No significant differences were observed between the size of leg segments and chelicerae among specimens studied. Comparison between measurements of body lengths and widths of specimens which were collected from Firozkoh (above 1500m altitude), Karaj(1000-1500m altitude) and apiaries in Varamin (less than 1000m altitude) in Tehran Province revealed that there was no significant difference between the three colonies. These specimens were also differ from V. jacobsoni. The results showed that our specimens were V. destructor not V. jacobsoni. Moreover, the Tehran Province specimens are similar to V. destructor in that they are less spherical than V. jacobsoni