JOURNAL OF AGRICULTURAL SCIENCE AND TECHNOLOGY (JAST)
Year:2000 | Volume:2 | Issue:3|Papers Count:8

ELISA values (O.D.s) of extracts of separately roots and individual leaves of barley and wheat plants infected by a French BYDV-PAV isolate (PAV-4), were assessed for five different virus incubation periods in controlled conditions (5, 10, 15, 20 and 25 days after inoculation). In most cases, virus contents of individual roots or leaves were not statistically different for barley and wheat. For both plant species, ELISA values peaked sooner in roots than in leaves and in most harvesting dates were higher in roots. The old leaf had a significantly lower virus titre than other leaves. Upper leaves exhibited the highest ELISA values. These results indicate that the upper part of infected plants is the most suitable for virus acquisition by aphids. A scheme for BYDV-PAV spread in young plants is proposed, and compared to the distribution of vectors on the plants.

Toxic effects of malathion and endosulfan to fertile chicken eggs were determined. Injection of 1.25, 2.5, 5.0 and 10.0 mg/egg of malathion into yolk sac of fertile eggs prior to incubation caused mortality of 10.0, 30.0, 83.33 and 93.33% respectively. Similar trend was observed with injection of endosulfan doses. Malathion and endosulfan at 1.25 mg/egg caused no pronounced LD50 increase in mortality as compared to control groups. The LD50 values for these insecticides proved malathion to be more toxic than endosulfan. The hypothesis that the dose response of viable embryo fitted a linear regression line was statistically acceptable. Combination of malathion and endosulfan increased the mortality rate as compared with either one alone. With either compound, an increased dose generally resulted in a decrease in embryonic body weight.

Studies of postmeiotic chromosomes have been impeded by the thick exine of immature pollen grains. Chromosome staining of immature and adult pollen grains through conventional acetocarmine procedure is tedious and often leads to unsatisfactory results. An acetocarmine stain, used in conjugation with Carnoy’s solution as fixative for 72 hrs or until the chlorophyll-containing tissues of spike became colorless, were successfully used to stain chromosome bands and nucleoli of the immature pollen grain in Aegilops cylindrica. Mitosis of immature pollen exhibited several remarkable features, one being the distinguishable haploid chromosome set of immature pollen. Only one of two nucleolus organizer regions of Ae. cylindrica produced nucleolus at the prophase of first pollen mitosis. An acetocarmine-banded karyotype with only minor variations in the acetocarmine-banding pattern was revealed within and between plants of the accession of Ae. cylindrica. Some of banding patterns in the chromosome complement was identical to marker C-bands or accession-specific bands in corresponding genome in Ae. caudata (CC) or Ae. squarrosa (DD). The reliability of the acetocarmine banding for Triticeae chromosome identification is discussed.

Soil affected by salt (NaCl) is a major problem worldwide and in areas with potential agriculture; lands in many countries are not enough to support crop production. The development of salt tolerant cultivars would be enhanced by better understanding of the genetic control of tolerance to salt stress. A new cereal, tritipyrum, a range of amphiploids between Triticum spp. and Thinopyrum spp. offers such a new chance. Those with the 6x construction (2n=6x=42, AABBEbEb) derived from Triticum durum (2n=4x=28, AABB) and Thinopyrum bessarabicum (2n=2x=14, EbEb) are of the potential to become a new high salt tolerant cereal crop. Tritipyrum is prone to problems similar to those exhibited by early triticales, e.g. chromosome instability and low fertility, which in that crop were eventually overcome by breeding. Other problems could be overcome through substitution of Eb genome chromosomes by D genome ones and the feasibility of this have been assessed in the progenies of (6x tritipyrum) x (6x wheat) hybrids with the aid of fluorescent in situ hybridization (FISH). The cytological, morphological and agronomic studies of existing tritipyrum lines, including the effect of vernalization, were carried out, too. A novel multiple- pistil/seed characteristic of one original tritipyrum line has also been investigated and its genetic basis established. The results have shown that, first creation of substituted lines is feasible, and thus it could be a route for the elimination of undesirable traits. Second, improvement should be possible via selection for chromosomally stable lines, with increased fertility and yield. Third, it may also be possible to exploit the perennial habit and multi-tillering traits in a dual-purpose forage/grain crop. Fourth, the multiple-pistil/seed trait may be controlled by two recessive genes. Fifth, there is a high probability of having established the seven possible monosomic additions of Th. bessarabicum to T.durum for the first time.

The artificial recharge of groundwater (ARG), where practicable, is an easy and economical method for desertification control in the arid and semi-arid zones where overpumping has critically lowered the watertable. Although desiltation of floodwaters, which is a prerequisite for the ARG, leads to rehabilitation of the eroded sites that house the sedimentation basins (SBs), the gradual impermeability of these basins and infiltration ponds by migrating phyllosilicates shortens the economic life of such projects. Therefore, characterization of these minerals is necessary if treatments for their removal are to be found. As soil erosion in the watershed that supplies the ARG systems with floodwater deteriorates the land, and threatens the recharge facilities and other hydraulic structures downstream with siltation, identification of the erosion source facilitates prioritization of soil conservation activities. Clay mineralogical analysis has been developed in recent years as a powerful tool in sediment source attribution. However, applicability of such methods to cases in Iran requires regional studies. Sediment samples were collected at 0-10, 10-20, and 20-30 cm increments on two transects in the 1st, 4th and 6th SBs in a Gareh Bygone Plain ARG system. Rock samples were collected on the southern flank of the Bisheh Zard Basin that supplies floodwater to the ARG systems. All samples were characterized by the XRD method. Transmission--electron micrograph (TEM) of one sample was also obtained. Chlorite, mica, smectite, and possibly kaolinite were detected in all samples. The presence of palygorskite was revealed only in a TEM. The non - clay minerals were calcite, dolomite, alkali and plagioclase feldspars, gypsum, halite and quartz. The common origin of these inherited clay minerals precludes their utility in sediment source detection.

To obtain detailed information of sowing density and defoliation intensity under more controlled conditions on herbage production and seed yield, Paraggio medic was grown on raised-beds located outdoors at the Waite Agricultural Research Institute. A split randomized block design was used. Treatments comprised three sowing rates (densities): Low (3 kg/ha), Medium (15 kg/ha) and High (75 kg/ha) (based on pure germinating seed which gave 75, 375 and 1875 seedlings/m2 respectively); four defoliation intensities: Control (undefoliated), Low (6 cm from ground level), Medium (4 cm) and High (2 cm) to simulate different grazing pressures and two defoliation systems of continuous (defoliation from June 1) and deferred (defoliation from June 29). The total combination for experimental blocks was: Main plots, defoliation systems (2) x Sub plots. Sowing densities (3) x Sub-sub plots defoliation intensities (4) x Blocks (4) = 96 micro plots. The continuous defoliation system produced significantly higher (P<0.05) available forage as well as total pasture production (P<0.05) than the deferred. High sowing rate increased (P<0.01) forage availability and total pasture production. Medium and high defoliation intensities significantly (P<0.01) reduced available forage and total pasture production in the deferred defoliation system. Seed production was adversely affected by defoliation intensity.

The environmental scanning electron microscopy (ESEM) is a new development in the field of electron microscopy. In this study ESEM has been used to study the structure of veal semimembranosus muscle. Four treatments, raw (control), conventional heating, domestic and industrial microwave heating, were observed using ESEM. The temperature used in conventional heating was 163 0C. Frequency applied for microwave heating was 2450 MHz with two wattage levels of 700 (domestic microwave) and 12000 (industrial microwave). All samples were heated to 70 0C internal temperature. Occasional cracks across the individual muscle fiber and shrinkage were present in all images of the structure for heated muscle. Erosion at the edges of muscle fibers was clear and increased with continued heating. A gap between perimysium of each muscle bundle was effected with the domestic microwave samples in cross section. This phenomenon was more apparent in industrial microwave heating and the depth of gap between perimysial collagenous fiber is more than that in domestic microwave heating. More damage was observed in the connective tissue network for conventional heating as compared with microwave heating. Denaturation and distortion of connective tissue caused more damage during longer time of conventional heating. Surface damage in structure of semimembranosus was not observed in either conventional heating or the low powered microwave heating. Rapid increase of heat and penetration of the microwaves, at the 12000 wattage level, caused granulation and separation of some parts of the muscle fibers.  

Different layers of acorn (Quercus infectoria), hull, seed coat and seed kernel were analyzed for determination of chemical composition. The results of the preliminary analysis showed that acorn contained more than 65% carbohydrates, 8% lipid and 10% tannin among other constituents. The fatty acid composition of the seed oil was determined using thin layer chromatography and comparing with standards. The results showed the presence of both saturated and unsaturated fatty acids. Saturated fatty acid: are C14:0, C16:0, C18:0, and C20:0. Unsaturated fatty acid: C18: 1 and C18: 2. Total saturated fatty acids represented 20% and unsaturated fatty acids contributed 80% to acorn fat content.