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Agricultural Science and Technology - Volume:9 Issue: 2, Apr 2007

Journal of Agricultural Science and Technology
Volume:9 Issue: 2, Apr 2007

  • تاریخ انتشار: 1386/04/11
  • تعداد عناوین: 9
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  • K. Zarafshani, Gh. H. Zamani, M. J. Gorgievski, Duijvesteijn, M. A. Goodarzi Page 1

    This survey-study carried out among 360 randomly selected farmers living in drought-prone areas of Fars Province, Iran, set out to investigate the perceptions and psychological coping strategies of farmers when facing drought. Results showed that farmers perceived drought as a threat to all of their resources (material, conditions, personal, social and energies) and used emotion-focused and reactive problem-focused coping strategies rather than problem-focused strategies that require planning and being innovative to counteract its psychological consequences. Using structural equations modeling (SEM), relationships between perceived resource loss and the way farmers cope with drought were tested. Problem-focused coping was predicted by a greater loss of objects (e.g., yield, work utilities, land) and personal resources (e.g. motivation, patience and self-efficacy), but a smaller loss of energies (e.g. time and money). Predictors of emotion-focused coping were a greater loss of objects and energies, but smaller losses of condition and personal resources. The implications for educational interventions are discussed.

  • Y. Filizadeh, A. Rezazadeh, Z. Younessi Page 2

    Crop rotation is one of the essential practices in sustainable agricultural systems, because of its effects on soil fertility and other benefits including a reduction in weed competition. A field experiment was conducted at Chaparsar Rice Research Station, Tonekabon, Iran, from 2002 to 2003 to assess the influence of crop rotation, time of planting, and tillage depth on rice (Oryza sativa L.) yield and density and the biomass of three important paddy weeds. Treatments included the crop rotations of continuous rice and rice-soybean-rice, in combinations with planting times and no tillage, minimum tillage, and chisel plowing. Crop rotation had a significant effect on the growth of barnyardgrass (Echinochloa crus-galli), arrowhead (Sagittaria sagittifolia), and water plantain (Alisma plantago-aquatica) weeds. Continuous rice planting produced the highest density of barnyardgrass, arrowhead, and water plantain weeds, compared with a rice–soybean-rice rotation. Weed biomass and weed densities were lower in the rice-soybean-rice rotation than in continuous rice. There were a 62.5 and 80% reductions in the weed density and weed biomass respectively, in the rice-soybean-rice rotation compared with continuous rice planting. Fewer barnyardgrass, arrowhead and water plantain growth were observed in no-tillage treatments than in minimum tillage and chisel. Therefore, rice yield in rotation treatments increased by 17 and 21% in 2002 and 2003, respectively, compared to continuous rice planting.

  • K. Poustini, F. Mabood, D. L. Smith Page 3

    The objective of this research work was to study the effect of Rhizobium leguminosarum pre-induced with genistein (G) and methyl jasmonate (MJ) on nodulation, nitrogen fixation and early growth of the common bean (Phaseolus vulgaris L.). Four day-old seedlings were transferred to pots, containing sterilized sand and turface (2:1 v:v) mixture and, receiving Hoagland’s nutrient solution, without nitrogen. The plants were grown in a growth chamber using a randomized complete block design with six replications. The rhizobia were cultured in TY medium and incubated with G, and/or MJ. The incubated rhizobia were used after 24 hours to inoculate the bean seedlings. The results showed that both G and MJ enhanced the nodule number, nitrogen content per plant, and plant dry matter. Genistein and MJ, when applied together to cultures, showed synergistic effects on all the characters studied. The results of this study indicated that MJ alone, or in combination with G, can be used to promote bean nodulation, nitrogen fixation and early plant growth.

  • S. Khodabandeh Page 4
    The ultrastructure of the cells, Na+, K+-ATPase activity and immunolocalization were examined in the barnchial chamber of Libellula lydia (Drury, 1773) larvae. Na+,K+-ATPase activity and localization were performed through biochemical techniques and immunofluorescence light microscopy using a mouse monoclonal antibody IgGα5, respectively. The branchial chamber possesses six pair gills lamellae that extend into the rectal lumen. A thickened epithelial layer and a modified fat body cells layer are present at the base of the each gill lamella. Epithelial cells covered by a thin cuticle and they possess apical microvilli and baso-lateral membrane infoldings associated with mitochondria. The cytoplasm of the modified fat body cells is filled with mitochondria, glycogen and a few lipid droplets. The Na+,K+-ATPase activity was significantly higher (15.36 µM Pi mg-1 protein h-1) in the branchial chamber. Na+,K+-ATPase immunofluorescence staining was observed in the epithelial layer cells of the basal pads of the rectal gill lamellae, with a consistently high immunoreactivity. These findings show that the epithelial cells present cytological features of the ionocytes, a high activity and concentration of Na+,K+-ATPase, confirming their participation in osmoregulation through active ion exchanges.
  • H. Samizadeh, B. Yazdisamadi, M.R. Behamta, A. Taleii, G. R. Stringham Page 5

    Pod length is one of the effective components on canola yield selection on the basis ofwhich can increase not only the seed yield but also the oil yield. Molecular markers associatedwith long pod loci were identified in a doubled haploid population derived from across between the canola lines ‘Quantum’ (long pod) and bulked segregant analysis. A molecular marker linkage map of 37 loci for this populationwas used to identify quantitative trait loci (QTL) controlling pod length of whichtwo markers in two unlinked loci were selected by using an interval mapping model whichexplained 22% of phenotypic variation for pod length in this population. Selection formarkers at two loci for increasing pod length resulted in a group of doubled haploid lineswith an average 112 mm pod length that increased 15% of whole population mean. Thisshows that using these markers in the breeding program will enhance the breeding of longpod canola varieties.× ‘China A’ (short pod) using RAPD

  • S. Hosseini Gh. H. Mosahebi M. Kohi, Habibi S. M. Okhovvat Page 6
    Zucchini yellow mosaic virus (ZYMV) is a potyvirus with a worldwide distribution. This virus causes serious economic losses in Iran in many cucurbits. During 2002-2003, samples were collected from squash fields in Tehran Province. Five isolates (Z1, Z2, Z3, Z4 and Z5) were inoculated on 27 species of Cucurbitaceae, Chenopodiaceae, Amaranthaceae,Solanacae, Leguminosae and Ranunculaceae. Chenopodium quinoa and C. amaranticolor showed chlorotic local lesions. Gomphrena globosa developed necrotic local lesions. Systemic symptoms were produced in the members of Cucurbitaceae and Ranunculus sardous. Z2, Z4 and Z5 caused mosaic symptoms on Phaseolus vulgaris cv. Red Kidney and P. vulgaris cv. Khorram but Z1 and Z3 caused chlorotic local lesions.Virus was purified from Cucurbita pepo. Virus particles in immunoelectron microscopy were filamentous flexuous. The molecular weights of coat protein using SDS-PAGE and western blotting were estimated at 32 kDa. Reverse transcription polymerase chain reaction (RT-PCR) was performed using one primer pairs designed by Desbiez et al. An approximately 458 bp fragment was amplified with a specific primer.
  • A. Elahinia J. P. Tewari Page 7
    Confocal laser scanning microscopy (CLSM) is a revolutionary advance in the field of light microscopy which, in recent years, has been used on interaction studies between host and pathogen. This study carried out on the flag leaves of the susceptible spring wheat cultivar (Triticum aestivum L.) known as Thatcher and its near isogenic line with the Yr-18 adult-plant resistance gene to stripe rust fungus (Puccinia striiformis f. sp. tritici), by confocal laser scanning microscopy. A suspension of fresh urediniospores of stripe rust, isolate SR99-UA (race, 70E 128) in a light mineral oil (Soltrol, 170) was sprayed on the flag leaves in vitro, then four segments were sampled at 2, 4, 8, 12 and 18 days after inoculation. These segments were further divided into 1-2 cm. For detailed observation, two fluorescent dyes Acridin orange and X-Rodamin-1, known to be nucleic acid and calcium binding probes, were used, respectively. CLSM made it possible to visualize host/pathogen interaction in serial without sectioning at a three dimensional level from adaxial to aboxial leaves. According to the results, no difference in pre-penetration behavior of the fungus in the two genotypes was observed. During the early stages of penetration, host cell necrosis was occasionally seen only on the resistant genotype. Few dead cells were observed on the susceptible host 12-18 days after inoculation. However, by this time, the resistant host had a markedly high number of dead cells; there were numerous necrotic areas or pustules resembling hypersensitive response. In the infected areas and around the pustules of the resistant host a remarkable red color was observed by the presence of a thick fluorescence rich calcium layer. The intensity of calcium fluorescence in the non-infected areas of both genotypes and in the infected areas of the susceptible host were nearly the same, indicating calcium mobilization as part of the defensive response in resistant near isogenic lines containing the gene Yr-18. This result indicated that calcium mobilization at the point of challenge by the pathogen played an important role in the near isogenic resistance line of Thatcher in the wheat stripe rust pathosystem. This is the first report on calcium mobilization in a cereal rust pathosystem as a part of the resistance response.
  • Sh. Mahmoodi, A. Heidari, M. H. Masihabadi, G. Stoops Page 8

    Soils of the arid–semiarid Karaj Basin in north-central Iran have formed on alluvium-colluvium derived from mixed calcareous-gypsiferous marls of Miocene and basic igneous rocks of Holocene age. In order to characterize and classify the soils and to determine the soil-landscape relationship in the area, sixteen pedons located on different physiographic positions have been described, sampled and analysed. According to field descriptions these soils all show evidences of carbonate accumulation to be classified as Calcids or Cambids. However, soils with well developed argillic and calcic horizons have been observed on apparently younger colluvial fans, whereas the less developed soils with calcic and cambic horizons occur on older upper alluvial plains. Due to the calcareous gravelly soil parent materials, clay films are mainly masked by carbonates and their identification in the field is mostly impossible. Also due to the adherence of these clay films to coarse gravels and their separation from the fine earth materials through sieving, they may not sometimes appear on the particle size distribution analysis. Yet under the microscope the soils show enough indicators to be characterized as argillic horizon and to classify the soils properly according to Soil Taxonomy as Argids instead of Calcids. Also, these findings point out the relatively older ages of these physiographic surfaces now they are covered by younger colluvial materials.

  • J. Asghari J. P. Tewari Page 9
    The allelopathic potential of the foliage tissues of eight barley cultivars was investigated using seedlings bioassays of Indian brown mustard (Brassica juncea) and green foxtail (Setaria viridis) as typical broadleaf and grass weeds of the croplands. The correlations of allelochemical compounds with seed germination of weeds were determined. The barley cultivars used were Jackson, Bronco, CDC Dolly, B1602, Harrington, UNA80, Stander, and TR251. Three dilutions of the extracts of each barley cultivar (20, 10 and 5 g/L) plus deionized distilled water, as a control, were assayed on the target weeds. The effects of barley cultivars and extract concentrations on seed germination and radicle and shoot lengths of the target weed seeds were highly significant (P<0.001). By increasing the concentration of the allelopathic extracts, the percent germination, radicle and shoot lengths of both target plants seedlings decreased. Seed germination and seedling growth of B. juncea were more sensitive than those of S. viridis. Relative to the germination inhibition of target weed seeds in comparison to the untreated control, the selected barley cultivars were categorized as being highly allelopathic, moderately allelopathic and of low allelopathic potential. Among the phenolic compounds detected, the cumulative effect of four small-quantity-compounds (vanillic, chlorogenic, p-coumaric, and ferulic acids) on average weed germination was very high (R2 = 0.83), with B. juncea it was high (R2 = 0.70) and with S. viridis it was very low (R2 = 0.15). The two high concentration phenolic compounds of protocatechuic and p-hydroxybenzoic acid, when accumulated with the small-quantity phenolic compounds of barley cultivars, reduced the weed seeds germination correlation to r=- 0.11.