جستجوی مقالات مرتبط با کلیدواژه "مازندران" در نشریات گروه "مکانیزاسیون کشاورزی"

Rice with the cultivation area of more than 565 thousand hectares and production amount of 2.45 million tons is the second most important crop after wheat in Iran. Most of cultivated area is also located in Mazandaran and Guilan province. It is clear that reaching to self-sufficiency in rice production is not possible without assessment of current status of rice mechanization. Therefore present study was conducted to determine current status of rice mechanization and propose needed solutions to improve it. Data were gathered by completing questionnaire and by reviewing the literature and field surveying. In view of information obtaeined; degree of mechanization, level of mechanization, capacity of mechanization, economic efficiency of mechanization, field efficiency of machine, potential ability of machine, working hours and days and productivity coefficient of machine were calculated. The results showed that degree of mechanization of primary tillage and secondary tillage was 99.7 and 99.3%, planting operation with transplanter was 22.69% and harvesting operation with mower and combine was 72.8 %. The lowest degree of mechanization of rice production was obtained for mechanical weeding with the value of 8%. The level of mechanization was calculated 2.63 hp/ha. Mean economic efficiency of mechanization and capacity of mechanization of rice was found to be 1.87 ton/ha and 235 hp.hr/ha, respectively.

Abstract In order to determine the best water production function (CWPF) for predicting grain yield of a soybean crop four models were evaluated. The four functions evaluated were Jensen (1968)، Minhas et al (1974) and modified Stewart et al (1977) and modified Bras and Corodova (1981) models. Field experiments were carried out for evaluation of the models. The grain yields simulated by the crop water production function were compared with the field measured data. The grain yields simulated by the crop water production function were compared with the field measured data. The base moisture stress sensitivity indices obtained for the vegetative، flowering and grain filling growth stages of the soybean crop were 0. 23، 0. 82، and 1. 1 respectively for Jenson (1968) and 0. 73، 2. 72 and 3. 4 respectively for Minhos et al (1974) model. The moisture stress sensitivity indices for the vegetative، flowering and grain filling growth stages for the modified Bras and Corodova (1981) model were 0. 25، 0. 73، and 1. 05 respectively and 0. 25، 0. 73 and 1. 05 respectively for modified Stewart et al (1977) model. The indices of the grain filling stage were noticed to be higher than the other growth stages، followed by the flowering stage and then the vegetative، for all models. The trend of the indices therefore implies that the grain filling growth stage was more critical to moisture deficit. Results showed that the models give good estimates of soybean grain yield with modified Bras and Corodova (1981) model performing slightly better than the other three models.

Beetles (Coleoptera) are the largest order of insects, which exist in all agroecosystems and natural ecosystems. Since rice fields include both aquatic and subterranean ecosystems, diverse fauna of beetles are active in rice fields of the world. In regard to the importance of these insects in chain foods of biosphere, fauna of some coleopteran families was surveyed in north rice fields of Iran (including, Mazandaran, Guilan and Golestan provinces) through 2001-2006. In total 69 beetle species of 9 families including, Alleculidae (3 species of one genus), Bruchidae (3 species of 3 genera), Cleridae (3 species of one genus), Curculionidae (15 species of 8 genera), Histeridae (6 species of 5 genera), Nitidulidae (4 species of 4 genera), Silphidae (6 species of 5 genera), Staphylinidae (17 species of 11 genera) and Tenebrionidae (12 species of 11 genera) were collected from rice fields and surrounding grasslands of Northern Iran.

Striped rice stem borer, Chilo suppressalis Walker (Lepidoptera: Pyralidae) is one of the key pests in north of Iran, which damages the rice fields and decreases yield, severely. With attention to the importance of population dynamics of pests in integrated pest management, the population dynamics of immature life stages (egg, larva, pupa) of C. suppressalis were analyzed on three dominant rice varieties including, Fajr, Khazar, and Nemat in Mazandaran. The results indicated that the population density of the pest on the Fajr variety was higher than the two other varieties; therefore Fajr is a susceptible variety to C. suppressalis. Means comparison of population density of immature stages in different dates (23 May until 15 August) indicated that the density was the lowest in early season (May) and then it was gradually increased and reached its highest rate in July and after that, the population density decreased again. With respect to the results of this research, application of controlling agents including, biological or chemical methods at maximum population density of pest and replacement of resistant varieties to the susceptible one (Fajr) are recommendable to the farmers of paddy fields.