THE SCIENTIFIC JOURNAL OF AGRICULTURE (SJA)
Year:2008 | Volume:31 | Issue:1|Papers Count:17

In order to estimate variance components, 8843 test day milk and fat yields records: from first lactation Najdi cattle were used. Data were obtained between years 1989-2005 by Animal Breeding Station of Najdi Cattle located in Shooshtar. Random regression models were studied in respect with different orders of fitting for fixed and random regression. Also, different methods of residual variance in the analysis including assumption of constant residual variance and different assumption about variable residual variance during lactation were assumed. According to the results, the assumption of heterogeneous residual variance during lactation improved characteristics of the statistical model. A suitable model with (3, 3) orders of fit for additive genetic and permanent environmental covariance functions to analyze TD fat and milk yield records were recognized. Minimum of heritability for fat and milk yield was estimated at the beginning of lactation, (0.1, 0.15), respectively. The amount of this parameter increased to mid lactation and almost in the 5thmonth of lactation reached the maximum level (0.34 for milk yield and 0.44 for fat yield), then decreased to the end of lactation. Minimum and maximum of genetic and permanent environmental correlation were estimated between 5 and 270 days of lactation.

Lc50 and Lc90 of the first and second in stars as well as adult Icerya purchasi were determined by using bioassay technique under laboratory conditions of 25±4°C, 75±5% R.H. and 15 h. of L. D. In this research, 9 different concentrations of mineral oil, 10 different concentrations of B. bassiana and 11 different combination of mineral oil and B. bassiana were sprayed on 36 two-year old sweet orange (Thomson navel on Citrus aurantium (rootstock) trees. On average, 50 lcerya purchasi on each tree were tested. Probit analysis has been done using P/Proban LSTATS computer program after preliminary calculations. Based on the laboratory results and our calculations, 100 liters of water provided control of I purchasi nymphs and adults, respectively. Mineral oil at a rate of 500 mi/100 liters of water plus 11.8x1011 conidia/3400 ml of B. bassiana provided control of I purchasi instars equivalent to 2.99x1011 conidia/1300ml of B. bassiana in 100 liters of water with three times treatment every 5 days provided complet control of cottony cushion scales instars. B. bassiana plus mineral oil at a rate of 13.34x1011 conidia/3900ml plus 1 liter/100 liters of water, respectively, equivalent to 5.98x1011 conidia/1800ml of B. bassiana plus 100 liters of water with tree times spray, every 5 days, provided good control of adult cottony cushion scale.

The water resources of the Izeh Plain include groundwater and lake water and the aim of this investigation is to assess available water resources for irrigation of rain-fed lands. Though groundwater resources of the Izeh Plain are relatively significant and the annual abstraction is estimated to be about 6 Mm3, as a result of geological formation heterogeneity, water demands is not met. In order to replenish groundwater, feasibility of artificial recharge was undertaken and only out of five preliminary options, the Takab site was suggested to augment the Izeh aquifer annually about 0.43 Mm3.On the other hand, the Miyangaran Lake water storage is considerable and in the rainy period its area approaches over 40 km2. The investigations have indicated that the present annual inflow into the Lake is roughly 48 Mm3 and by partly allocation of Kohshor ephemeral stream its recharge would exceed 60 Mm3. With the view of considerable storage volume of the lake, it is possible to withdraw annually about 8 Mm3 from the Miangran Lake in rainy period to irrigate approximately 2000 hectares of rain fed-land and prevent water encroachment.

Wheat streak mosaic (WSM), caused by wheat streak mosaic virus (WSMV), is an important disease which causes serious yield losses in the major wheat producing regions of the world. In order to evaluate the amount and changes of some biochemical factors in reaction to WSMV infection, a greenhouse experiment was conducted with seven genotypes. Total protein, free amino acids, tree phenol, peroxidase and proline were measured. To evaluate the effect of two inoculation times on yield and its components another experiment was accomplished with the same genotypes at the Faculty of Agriculture, Shiraz University in 2005. The results indicated that virus infection caused stress on all genotypes. Total protein, free phenol and activity of peroxidase enzyme increased in all infected plants. Free phenol and total protein of tolerant genotypes were higher as compared with the sensitive ones. The amount of peroxidase activity caused by WSMV infection was not significant. Virus infection reduced free amino acid in all genotypes. The changes in the amount of proline did not show a typical trend in tolerant and sensitive genotypes. It appeared that the amount of total protein and total phenol in a genotype could be adapted as a selective factor in preliminary stages of selection for tolerance to the virus. Grain yield and its components showed significant differences in tolerant and sensitive genotypes at various stages of inoculation. Virus infection led to significant reduction in grain yield, and some of the yield components in all genotypes. Inoculation in the first stage (two true leaves) resulted in much more reduction in the grain yield as compared with inoculation in tillering stage. Virus infection had no effect on seed number; however, the reduction in grain yield was mainly via shrived grains in both stages of infection. Based on the tolerance index at two stages of inoculation, genotype 4004 was identified as a tolerant and stable genotype in this study.

Biology and life table of Anthocoris minki pistaciae, Wag. a predator of common pistachio psylla Agonoscena pistaciae Bur. & Laut. was studied under laboratory conditions at five temperatures of 15, 20, 25, 30 and 33oC, 65±5%relative humidity and photoperiod of 14:10 (L:D) on common pistachio psylla nymphs. Life table parameters and developmental periods of all stages from egg to adult were determined using Excel and jackknife. Developmental periods from egg to adult were 46.83, 20.11, 15.00, 18.40 and 15.38 days respectively. Temperature thresholds (t) and the thermal constant (DD) using linear regression were 9.33oC and 235 degree days, respectively. The mean adult longevity of females were 118.50, 75.83, 48.65, 46.80 and 27.13 days at the experimental temperatures of 15, 20, 25, 30 and 33oC respectively. Mean numbers of eggs at the same conditions were 63.08, 95.06, 73.95, 55.93 and 31.75 per female. The intrinsic rates of increase (rm) were also 0.035, 0.062, 0.11, 0.049 and 0.01 and doubling time (DT) were 19.66, 11.26, 6.23, 14.14 and 52.32 days respectively for the mentioned temperatures. The highest finite rate of increase (l) was 0.118 at 25oC and mean generation time (T) at 33oC were the lowest (17.78 days) with the highest at 15oC (63.46). In conclusion, the most  appropriate temperature for rearing was found to be 25oC. The results of this research were a suitable criterion for assessing the efficiency of this bug in controlling the host.

During growing season of 2005, Potato tubers showing black scurf symptom were collected 1Tommajor growing areas in Khuzestan (Anjilack, Aghili, Sarbisheh, Jareah, Shoush, Shoushtar and Shams Abad). Collectively 130 isolates of Rhizoctonia were recovered by transferring sclerotia to the PDA plates. Morphological characteristics, nuclear number per cell of the young hyphae, anastomosis group, temperature requirement and pathogenicity of the isolates were studied. Nuclear staining with Sa1Tanin0 revealed that all isolates were multinucleate. Anastomosis groups of the isolates were determined using glass slide, covered with water agar. Results indicated that 122 isolates were AG-3; 3 were AG-4; 3 were AG-5 and 2 were unknown. The effect of temperature on the activity of isolates was determined. Optimum temperature for the growth was 25oC. Effect of different temperatures on sclerotia production by the isolates was investigated. All the isolates belonging to the AG-3 produced the highest level of sclerotia at 25oC. Diversity in the pathogenecity of the isolates was assessed on potato seedlings in petri plates. To do so, germinated potato seeds were placed at the periphery of growing colony of isolates in water agar plates. Disease severity was assessed based on a scale of 0-5 according to the lesion size on the seedling roots after 15 days of incubation. Pathogenecity of the AG-3 isolates was the highest compared to the other isolates. In addition to the Petri plates, diversity in pathogenicity was studied under greenhouse condition. Eighty days after inoculation, there was significant difference in the treatments. Data analysis, according to Duncan's test, showed that control plants had the highest level of growth compared to the other treatments. There was no significant difference among the isolates in stem canker production, but there were significant difference between isolates in causing root rot. In general, AG-3 isolates had higher pathogenecity than the other two AGs and are considered as the principal cause of black scurf.

The effect of seed tubes under different tillage levels and ground speed on wheat seed distribution were studied by performing laboratory and field tests in 2005-2006, at Ramin Agricultural and Natural Resources University. A strip split block design was employed and two tillage levels, rough (plough only) and smooth (Plough+disc+leveler), two ground speed rates (4.5 and 9 km/hr), and five seed tube levels (2 and 3 pieces telescopic, spiral, springy and simple hose) were evaluated using four replicates. The results showed that with all of the tubes rough tillage increased longitudinal seed distribution and ground speed at 9 km/hr enhanced this parameter. Analyses of data showed that the effect of different levels of seed tube on this character had significant difference (p<0.01). Spiral and 3- piece telescopic tube with 86.75 and 48.87 percentage means had max and min. longitudinal seed distribution respectively. Only significant difference was seen by interaction effect between ground speed and tube treatment on longitudinal seed distribution (p<0.01)and 2- piece telescopic tube with 9 and 4.5 ground speed treatment had maxand min. mean longitudinal seed distribution respectively. Similar testes were also performed under laboratory conditions, using Grease belt. The effect of interaction between speed and seed tube was different in laboratory and field test based on the effect of tillage factor on field test. The results of comparison between laboratory and field tests by means of seed detection sensor showed that if using low' speed and seed tubes inner level was smooth or this tubes was springy instead of flexible, distribution of seeds by them was down.

A complete randomized block design experiment with five treatments (o, control, 1, 2, 3 and 4 yellow sticky cards in each date palm tree) and five replications was conducted to evaluate the effect of different densites of yellow sticky traps on population of Ommatissus lybicus Deberg. At the end of this experiment, the number of O.lybicus eggs in 25 lealets was recorded. The results of this esperiment were then compared with the results of chemical control. The analysis of variance indicated significant differences in oviposition rate among the five different treatments. Females deposited a significantly greater number of eggs on control (zero traps) than on any other number of traps tested (p<0.05). A Duncan's test indicated that there was no difference among the number of eggs deposited in 1, 2, 3, and 4 traps treatments. A t-test analysis indicated no significant difference between the number of eggs deposited in one trap and chemical control treatments. So, installation of one yellow sticky trap in the canopy of date palm tree is recommended. Leafhopper population were aggregated in date palm tree as indicated with tailors power law; b values of 1.65,1.74 and 1.34 were found for eggs nymphs and adults, respectively.

Study on the biotic potential and sex ratio of parasitoids is one of the fundamental researches in biological control programs. Trichogramma spp. are the most important and powerful egg parasitoids of striped stem borer (Chilo suppressalis Walker; Lepidoptera: Pyralidae) in Mazandaran, Northern Iran. Therefore, a research was conducted in order to study the sex ratio and biotic potential of Trichogramma spp. In natural condition of central Mazandaran. In the studies of sex ratio, the efii;ct of three varieties including, Fajr, Khazar and Nemat, and the effect of three different climates including, (Low-, Middle- and High- altitudes) were evaluated. To evaluate the biotic potential, the effect of two factors including the mentioned climates and varieties were studied on the parasitoid. The results indicated that the rice variety had significant effect on the sex ratio of the parasitoids, as the number of female offspring was higher in Nemat than Khazar and Fajr. Clutch size of host (c. suppressalis) was effective on sex ratio of Trichogramma spp., as the produced males in small egg masses were higher than the females (1.27 male to 1 female), but more female progenies were reared from big clutch size (1 male to 1.39 female). Of the two factors including climates and rice varieties, the climates had the effective role on the biotic potential of Trichogramma spp. but the varieties had no significant effect. In relation to the climate, the percentage produced progenies was higher in the Low- and High-altitudes that the Mid-altitudes.

The dominant species of Grape leafhoppers in Esfahan vineyards is Arboridia kermanshah Delabola and the most abundant natural enemy of the pest is the egg parasitoid, Anagrus atomus L. In order to compare parasitism based on recruitment (the real) and common method (the actual), the phenology of the parasitoid and its host was studied at two research stations located in the West of Esfahan, the central region of Iran, during 1997-98. In this phenology, we considered numbers of host's eggs as the vulnerable part of life cycle and numbers of parasitized eggs entering into the system. Three distinct parts with different rates of the host and parasitoid numbers entering into the system were observed. The most synchronization between the two components of the system occurred during the second part. During the first part, the rate of host numbers entering the system was higher than the parasitoid numbers, whereas during the third part, the rate of parasitoid numbers exceeded the host numbers. Therefore, the second part was used to calculate the percentage of parasitism. The mean maximum percentage of parasitism for two years was calculated 33.2 and 52.02 for recruitment and common methods respectively.

Soil salinity is a great problem in south Khouzestan province. This study was conducted in years 2005-2007 in Shawoor Agricultural Research Station on a silty-clay soil with salinity 8 dsm-1, in randomized complete block design with split plot method, three replications and six planting methods as broadcasting seeder + disk harrow (P1), broadcasting seeder + disk harrow + corrugate (P2), band seeding (P3) band seeding + corrugate (P4),double row at Farrow extremes (P5) and triple row at farrow extremes (P6), in main plots and four Hyola 401 seed rates as 6, 9, 12 and IS kg/ha in sub-plots respectively. The results showed significant difference between planting methods. The change of P1 to P5 planting methods caused plant per square meter, pods per plants, seed per pods increasing from 69.8. to 81.3, 55.8 to 74.3, 16.3 to 21.8 and increasing seed yield from 991.9 to 1967. 6 kg/ha. As the seed rate increased from 6 to 15, kg/ha, the number of plants per square meter increased ITom66.7 to 90.4 plants per mz, but there was no significant difference on pods per plants. There was no negative relationship between yield components, as seed rate increased the seed per pods decreased, and there was no significant difference in thousands seed weights, and seed yield increased from 1299.4 to 1599.4 in 6 and 12 kg/ha seed rates treatments. Finally, the highest seed yield 2134.3 was produced in double row at farrow extremes (P5) and 12 kg/ha seed rate which might be recommended in saline soils.

One of the oilseed rape problems is pre-harvest and harvesting grain losses due to uneven maturation of the pods. This experiment was conducted in order to evaluate the losses of different harvesting methods. A split plot experiment based on randomized complete block design with three replications was used. The main plots concerning harvesting methods were as: windrowing in 35% grain moisture content (M.C.) and harvesting in 10% grain M.C., two stage harvesting in 15% and 10% grain M.C., harvesting in 15% grain M.C. and harvesting in 10% grain M.C. subplots concerning rapeseed varieties were: hyola 308, hyola 401 and R.G.S. 003. Grain losses rate was significant in both main plot and sub- plot and their interactive effects. The least and highest losses rate was in windrawing treatment (3.8%) and harvesting in 20% grain M.C. (23.2%), respectively. In harvesting in 20% grain M.C. treatment, the most losses were behind the combine in unthreshed pods form. The least and highest rate of losses were observed in R.G.S. 003 (11.8%) and Hyola 401 (10.37%), respectively