JOURNAL OF AGRICULTURAL SCIENCE AND TECHNOLOGY (JAST)
Year:2000 | Volume:2 | Issue:1|Papers Count:9

This experiment was carried out to study the effect of sodium chloride from drinking water and feed intake on the quality of egs from laying hens. Four hundred and twenty native and white leghorn laying hens ranging from 36 to 43 weeks of age were used. Seven experimental treatments containing different levels of salt supplied by feed and/or drinking water were compared. Increasing salt intake by the addition of NaCI to drinking water or feed intake reduced shell thickness, shell ash and increased, the number of damaged eggs. Shell calcium was not affected hy added salt, however, the addition of salt to the food reduced shell-breaking strength. Breed differences influenced the traits studied, except for shell percentage and shell calcium. Sodium chloride intake from drinking water was more effective in reducing shell quality than salt from food.

Floodwater spreading (FWS) for the artificial recharge of groundwater (ARG), is an easy and economical method of desertification control. An integrated approach to desertification control based on FWS for the ARG was adopted in the Gareh Bygone Plain in southern Iran. Deposition of the suspended load (SL), carried by floodwater into the sedimentation hasins and infiltration ponds, stabilizes the drifting sand and reclaims the eroded rangeland on which the ARG projects are executed. Results of some of the physical and chemical analyses performed on the one to four-year-old sediment samples obtained from the first three sedimentation basins at the Gareh Bygone Plain ARG scheme show that of the 19 factors analyzed, only two changed significantly due to the settlement of the SL in the basins: sand content decreased by 7.9 and 3.8% at the 0-10 and 0-30 cm depth respectively; and the ESP increased by 17.2% at the 0-30 cm depth. Regression equations were developed correlating soil content of organic matter, total N,P, saturation percentage and CEC with silt + clay content. These relationships indicate the geological origin of N and perhaps P and the importance of SL in the fertility status of the drifting sand.

The total nitrogen content of three barley cultivars: Cehada Capa (resistant at 25 °C), Cl 1243 (resistant at 5°C) and Rika 1 (susceptible at all temperatures) to Puccinia hordei 26°C. The results indicate that the total nitrogen content of cv. Cehada Capa leaves was greater than that of Cl 1243 and Rika 1 and that of Cl 1243 was greater than that of Rika 1 when plants were grown at 26°C. When plants were grown at 5°C, the percentage of total nitrogen content of leaves of cv. Cebada Capa was significantly greater than that of Cl 1243 and Rika 1, but no differences were found between Rika 1 and Cl 1243. It was concluded that the total nitrogen content has no role in the temperature sensitivity of barley cultivars. In most cases, especially in susceptible cultivars, the nitrogen content of infected leaves was greater than that of healthy plants when plants were incubated at 26°C, but there were no significant differences between total nitrogen content of infected leaves and that of their healthy control when plants were incubated at 5°C.

A study was carried out to determine whether naturally-occurring weeds and other cultivated plants in tomato growing regions could act as symptomless reservoirs of infection to from weeds and oubergines were used in this investigation. A susceptible tomato cultivar was used for comparison. The plants were artificially inoculated at the five to six leaf stages by root dip method. Only tomato showed wilt symptoms and died three weeks after inoculation. These isolates were identified as F. o. f. sp. lycopersici. Weeds including were colonized to various degrees and determined as symptomless carriers. Therefore, in infested areas, aubergines should not be rotated consecutively with tomatoes and proper measures should be adopted to control the weeds.

Eight wheat varieties some of which were earlier reported to be resistant to arrhennmanes, placing 2-day-old seedlings on the edge of a Pythiumwere inoculated with P. arrhenomanes. Inoculation was performed byP. arrhenomanes culture on corn meal agar dia.) containing glass beads and 1 ml of sterile water, and incubated for 4 days at 25°O Non-inoculated seedlings were exposed to the toxic metabolite(s) from arrhenomanes filtrate of sterile water served as controls. Measurements were taken on root and shoot length, as well as fresh and dry root and shoot weights. There was an indication that it may be possible to use the toxic metabolite(s) in screening for resistance to arrhenomanes. Some differences among them in their reaction to fungal infection or exposure to the toxic metabolite(s).

The percentage of urediniospore germination of two isolates of yellow rust striiformis f. sp. tritici) |Race 41E 139 (4)], was studied at various temperatues between 5-20°C on agar and the adaxial surface of detached leaves on a layer of benzimidazole agar. Four replicates for five temperature treatments were arranged as a preliminary investigation to find the most appropriate temperature for the subsequent comparison of spore germination on the host material under investigation. Mean percentage values were analyzed separately and the levels of urediniospore germination at different temperatures were compared using analysis of variance and Student- Newman-Keuls techniques. Spore germination of both isolates was high over the temperature range 5-10°C, but dropped significantly at 15-20°C. At the cooler temperatures 5°, 7.5° and 10°C, isolate WYR 69/10 consistently germinated at a higher level than isolate WYR 79/4, whereas at 20°C, the latter isolate gave the highest figures. This observation indicates that both isolates germinated most effectively at 10°C on agar and detached leaves.

The ovipositiomil behavior and success of encyrtid endoparasitoid of mealybugs, affinis oviposition starting from the searching for the host to the post-oviposition activities were described. Once encountered, the mealybug host was examined and probed by the ovipositor of the parasitoid. Oviposition success was influenced by the defense activity of the host. parasitism than important role in increasing the efficacy of subsequent oviposition.

There is undoubtedly general agreement that the efficiency of educational investments should he maximized through the managerial process as far as possible. Agricultural extension is one of the crucial tasks in developing agricultural societies calling for considerable consumption of intellectual investment. The management of agricultural extension projects (AEPs) however, needs careful planning in utilizing this investment specially in terms of meeting the right clientele. This paper reports on the use of a statistical device which can be applied for planning the social modeling of agricultural extension programs. This statistical device, the so-called Dichotomous Distribution of the Extension Clientele (DDEC) was designed and used by the author to determine the social modeling of agricultural extension projects in Iran and the degree to which the extension projects have been successful in reaching their target clientele. The procedure consisted of four major criteria: farmers, educational needs, participation in AEP: access to utilities needed for adoption and utilization of the innovation (advice given by the extension agents). As a result of using this method and interviewing 912 farmers thought 57 randomly selected AEPs, it was found that 66 percent of the projects in 1988 and 60 percent in 1989 were thoroughly efficient, and 16 percent in 1988 and 12 percent in 1989 were efficient. Four projects in each year were found to have a very low efficiency rate while one project in 1988 and four projects in 1989 were inefficient in terms of their social modeling. This procedur has been applied to study the social modeling along with the efficiency of the extension projects dealing with the biological control of rice stenborer in eastern part of Mazandaran province where rice is the dominant cash crop. Acording to this result obtained from the recent research projects, it was shown that the less differences among the number of trained farmers and the target groups the more efficient were the extension project In addition, there was statistically significant difference among those of target groups and none target groups in term of applying the extension boicontrol guidlines in rice production practices. The related extension projects were also efficient (r=0.73) in term of their social modelings.

Electrical conductivity (EC) has been evaluated as a possible method for measuring viability and seedling vigour in wheat and other crops. A study was conducted using dormant, stock, naturally-aged (5 years) and artificially-aged (10 and 15 days) wheat seeds (Triticum aestivum cv. Omid) to evaluate the effect of different seed lots on electrical conductivity. All seed lots were subjected to the following tests: standard germination; speed of germination; germination rate; time to reach 50% germination; electrical conductivity and seedling growth rates. C.K.I), experimental design was used. Solute leakage from imbibed wheat seeds increased with treated or accelerated aging in a linear manner in the range over which vigour was depressed. Significant differences were observed among selected seed lots in most of the parameters of seed quality.