مجله علمی کشاورزی
سال:1377 | دوره:21 | شماره:1 |تعداد مقالات:8

Rural youth are the major clientele for agricultural extension programs. Rural youth can be a very effective force in rural and agricultural development. In most countries youth organization with specific philosophy and objectives have been established to promote development programs. Since there are cultural, social, and economical differences among the countries, one cannot copy the others, philosophy and aims in setting up an organization. For this reason a research project was conducted to develop a program based on the perceptions of extension agents and supervisors in Khuzestan Province. The aim of this paper is to present the philosophy and objectives of youth club organizations in Iran as perceived by extension officers and agents of Khuzestan province. The results show that the most important philosophy for a youth organization is to change the youth behaviours in cognitive, attitude, and psychomotor domains to develop their ability for protecting and effective utilization of agricultural, industrial, services and natural resources. The most important objective for the organization was perceived teaching agriculture, and home-economics to rural youths as the future farmers for the country.

The effects of the intake diversion angle on sediment entry to the lateral intake located on a 90o river bend has been studied. The purpose of this study was to determine the best location and the best diversion angle for minimum sediment entry and maximum water diversion. To reach such goals a 90o hydraulic model of a river bend was constructed in the hydraulic laboratory. The first series of tests conducted showed that the best location for lateral intake in such a bend is at 60o. At this location, water was diverted with five different diversion angle 15o, 45o, 60o, 75o and 90o. The sediment were consist of fine particles (D75 = 0.22mm), was mixed with flow by a sediment feeder upstream of the bend in a constant rate. The weight of sediment passed through the bend and entered the intake was trapped, dried and weighted. From the analysis of data obtained in this study it was concluded that the best diversion angle is 60o.

Aflatoxins are mycotoxins generally produced by Aspergillus species. These toxins contaminate many foods and feeds. Epidemies due to these toxins have occasionally killed many domestic animals. 100 samples of chiken liver, collected from poultry producers around the city of Ahwaz, were analysed to determine aflatoxins B1 and M1 both qualitatively by TLC and quantitatively by HPLC. Samples were extracted with dichloromethane, and a column of silica gel was used to remove fats and other impurities. Aflatoxins were eluted by dichloromethane: aceton (4:1). Solvents were evaporated and the residue was dissolved in known volume of dichloromethane for further experiments. Preliminary treatment of samples by T.L.C showed that 43% of them contained aflatoxins. Aflatoxins then were separated and quantified by HPLC. Results on HPLC showed that the highest levels of aflatoxins B1 and M1 were 0.71 and 1.1 ?g/100 grams of samples respectively. On the other hand, the minimum amount of aflatoxins B1 and M1 which were detected by TLC were 0.11 and 0.14 ?g/100 grams of samples as judged by HPLC. According to the previous reports these levels of aflatoxins B1 and M1 are considered as safe, but it should be noted that the production of aflatoxins may be accelerated by improper production and handing of feeds.

The developmental period of Orius minutus (L.) and Stethorus punctillum wies by feeding on the red spider mite, Panonychus ulmi Koch, were studied under the laboratory conditions, of 23-28?C and 50±5% RH. The developmental period of the first, second, third, fourth and the fifth instars and nymph were: 2.6±0.2, 2±0.3, 1.9±0.1, 2±0.2, 2±0.3 respectively. The adults lived 5.8±0.3 days. The average number of eggs laid by and adult female was 41.14±0.9. On an average each predatory bug (O.minutus) at first, second, third, fourth and fifth in star nymphs and adults fed 10.3±1, 39.8±3.7, 39.9±3.4, 53.6±2.4, 69.9±8.9 and 158.5±5.6 mites respectively. The life cycle of S. punctillum temperature of 22-28?C and 50±5% RH for egg, first, second, third and fourth instare, larvae, prepupa, pupa and adult were: 1.9±0.2, 2.1±0.3, 1.3±0.3, 1.9±0.2, 2.4±0.2, 2.5±0.2, 7.3±0.6 days respectively. The average number of eggs laid per female was 80.25±6.10. Feeding rate of different life stages of S. punctillum from the red spider mite for first, second, third and fourth instares and adult insect were: 6.8±0.7, 23.5±2.4, 37.3±4.5, 92.9±4.6 and 211±5.2 mites respectively.

Number of fertile tillers per unit area is one of the most important components which determine grain yield. Since grain yield of main stem obviously higher than that of tillers and because tillers are depended on main stem assimilates during early stage of growth, it has been suggested that the role of tillers in grain yield is negligible. When aborted unfertile tillers may translocate their assimilate into main stem and therefore, some believe that the presence of certain number of tillers may ensure an acceptable yield. However, suitable number of tillers depend on environmental as agronomic conditions. An experiment was conducted in 1375 (1996) in Ahwaz to evaluate the optimum number of tillers in bread wheat (cultivar kauz-s). The experimental design was a split plot and replicated four times. Main plots consisted of 3 sowing rates of 100, 300, and 500 seeds m-2. Subplots were allocated to 4 tiller removal; a) no tiller removal (control), b) removing all tillers, c) and d) removing all except 2 and 1 tiller, respectively. Tillers were carefully removed by hand upon emergence. In control treatment, tillering started 28 days after planting (DAP) and reached to their maximum number in all densities 56 days after planting and declined then after. Contribution of first, second, and third tillers in final dry matter were different in all treatments. In general, the contribution declined as plant densities and / or number of tillers per plant increased. Number of seeds per main spike as well as first and second tillers and also number of tillers per plant. Seed weight was the only yield component that was not affected by the different treatments. The results of this experiment revealed that high tillering cultivars may show higher yields only if they produce limited number of tillers and in a limits time period. In other word, tillering may not compensate lower plant numbers per unit area when seeding rate is low.