JWSS - Journal of Water and Soil Science

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In 1998 and 1999, adult population density of pistachio psylla and its sex ratio were determined weekly in two orchards with yellow sticky board traps and limb jarring. Also egg and nymphal population was determined on the leaves. By studying the seasonal population fluctuaions, the efficiencies of the two methods were compared. Meanwhile, using yellow sticky boards, diurnal activity of adults was investigated. Adult pistachio psylla became active during flower and leaf bud opening. Adult capture with both methods showed a high correlation with egg and unwinged nymphal density counts, with at least five peaks (maximum six). Two peaks occurred during spring and densities were much lower in comparison with those of later generations. First adult capture was observed on yellow traps. Yellow traps were found to be a better method than the limb jarring method for the study of seasonal population from adult captures. Sex ratio was equal through out the growing season and during the warmer or cooler months of the year. However, more males were attracted to traps and more females were captured with limb jarring early in the season. Peak activites during day occurred through 9-16 p. m.

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Color sticky board traps are used in pest management for capture of adult insect, to estimate and predict population densities in later stages. Yellow sticky board traps showed high attraction for pistachio psylla. It is important to study these relationships for the right placement of traps. For each of three repetition in one year, four pistachio trees were selected randomly in one orchard. Eight traps were located on two heights and four cardinal directions of each tree (32 traps in each repetition). After one week the adult psylla captured were counted. One and two weeks 1ater, eggs and nymph densities were counted on five leaves in one of the eight positions of each tree on four other randomly selected trees (total 160 leaves each time). Data were subjected to analysis of variance. Coefficient of variation was determined between adults captured in each position and eggs and nymph density counts. There were significant differences for adult capture and egg density among directions, and in most cases significant correlations were observed between adults captured on each position and total egg and nymph density count on trees. It was concluded that for egg and nymphal density estimation, we can place traps on either of two heights and four directions except on lower east part, but preferably on either height in south direction of the trees . Also suggestions for egg and nymph sampling are given in the text.

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To determine the effects of spawning frequency and density of incubating eggs on the survival rates of eggs and larvae in rainbow trout, five different groups of broodstocks with varying spawning frequencies were stripped. After fertilization, the percentage of survival at different stages of development, from eying, hatching to free swimming fry stages and also growth rates of larvae were determined. Moreover, the effects of incubating egg density (4000, 7000, 10000 per tray) on the different developmental stages of egg through free swimming larvae for each group of broodstock was studied. The study was carried out in a completely randomized design as a 5*5*3 factorial arrangement with three replicates. The results indicated that survival and growth rates are significantly correlated with spawning frequency (P<0.05) so that, survival and growth rates from fertilization to free swimming fry in broodstocks at their third and fourth spawning period were significantly different from the results obtained for broods in the first, second and fifth or higher spawning periods (P<0.05). Although the holding densities had no significant effects on the growth rate of larvae from different broodstocks, the survival rates from fertilization to free swimming stage was affected by incubating density so that the significantly lower value was recorded for density of 4000 per tray (P<0.05). In general, the results indicate that eggs obtained from broodstocks at their third and fourth spawning years have a better performance than those obtained from younger and older spawners. Also, the low holding density of eggs could decrease the performance of the fertilized eggs during incubating period.

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High attraction is reported for yellow sticky traps to capture pistachio psylla. In pest management, it is important to forecast from the adult population density the density of other developmental stages in order to gain an estimate of the density in damaging stages. In 1998 and 1999, yellow sticky boards with 10150.15 cm were installed in two pistachio orchards in Borkhar district of Isfahan and egg and nymphal densities were simultaneously counted on leaves. Collected data were used to determine regression relationships between two weeks’ average egg density, first and second nymphal instar densities and the sum of egg and first and second instar nymphal densities, one week after the average adult capture in two previous weeks. A low correlation was found between egg count and adult capture, but higher coefficients were obtained between other stages. It was possible to estimate first and second instar nymphal populations from the following equations:

 For high adult densities (X):

Y= 58.6+0.4762X-(7*10^-5)X²                                    R²=0.82                             commercial orchard

 Y= 27.68+0.5092X-(5*10^-5)X²                       R²=0.86                              abandoned orchard

and for low adult densities (X)

Y= 1.7162X-17.454                                     R²=0.97                              commercial orchard

 Y= 1.1117X-4.9841                                    R2=0.90                              abandoned orchard

The application of this method is recommended for the management of pistachio psylla.

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Oval fertilization and survival rates at incubation stage form the most important issues of concern in rainbow trout hatcheries in Iran. Hatchery managers tend to use the best method in fertilizing the ova in order to obtain the highest survival rates. A survey of common fertilization methods may help to determine the best one. In this study, the ova from two groups of 3-5 year-old and younger than 3 years broodstocks were fertilized employing dry and semi-dry methods in normal water and dry and semi-dry methods in fertilization solution. The experiment was carried out in a completely randomized design as a 422 factorial arrangement and with two replicates. The analysis of final results indicates that the highest survival rates of eggs and larvae were obtained in semi-dry fertilization. These rates significantly increased when fertilization solution was used (P<0.05). Moreover, the survival rates of eggs and larvae of 3-5 year-old broodstocks were higher than those of younger than 3 years. On the other hand, type and methods of fertilization showed no significant differences with degree-day (sum of heat) at developmental stage but the age of broodstocks made significant differences with degree-day from fertilization to the first hatching stage (P<0.05).

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  Planting patterns through growth indices affect yield formation. To evaluate these effects on safflower, Koseh local variety of Isfahan, a field experiment was conducted in summer, 2004 at the Agricultural Research Station, Isfahan University of Technology. The experiment was performed using a randomized complete block design with a split plot layout and four replications. Main plots consisted of three row distances (20 and 30 cm flat and 45 cm on bed), and sub-plots included two planting densities (40 and 50 plant m^-2). The experiment was planted on June 25. The results showed that p lant canopy closed sooner, leaf area duration (LAD) increased and plant dry matter weight, leaf area index (LAI) and crop growth rate (CGR) were higher up to the middle of seed development as row distance decreased. In addition, the highest relative growth rate (RGR) and net assimilation rate (NAR) were obtained in 20 cm row distance. The highest (3039 kg ha^-1) and lowest (1930 kg ha^-1) seed yields were obtained with 20 and 40 cm row distances, respectively. Plant density did not affect the rate of canopy closure, CGR, RGR, NAR and seed yield. But, maximum plant dry weight, higher LAI and lower LAD values were obtained with 50 plants m^-2. The results obtained in this experiment indicate that 20 cm row distance with 50 plants m^-2 might be appropriate for summer planting of safflower, a local variety of Isfahan, under similar conditions.

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Regarding the public concerns about serious health risks from pesticide, the occurrences of 105 pesticide residues including Organochlorine, Organophosphorus, Organonitrogen, Dicarboximides, Strobilurin, Triazine, Pyrethroids were assessed using a descriptive method in 25 fresh and greenhouse vegetable samples (fresh carrot, greenhouse tomato and cucumber). Ethyl acetate was used for extraction of pesticides from samples and the extract was cleaned up by Envicarb Solid Phase Extraction column chromatography. Pesticide residues were identified and quantified using gas chromatography ion trap mass spectrometry detector. The mean recoveries and limit of detection of the pesticides in samples were respectively 61.67-117% and the reproducibility of relative standard deviation values for the pesticides was 3.49-14.55%. Our data demonstrated that 80% of the total analyzed samples contained detectable residues including trifluralin, permethrin, chlorpyrifos, fenvalerate, fenpropathrin and iprodione, which were below the accepted maximum residue limits (MRL_S) adopted by FAO/WHO Codex Commision Alimentarius.

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