THE SCIENTIFIC JOURNAL OF AGRICULTURE (SJA)
Year:2008 | Volume:30 | Issue:4-B|Papers Count:15

Complications in hydrological systems, lack and insufficient data cause difficulties in hydrological forecasting. Systematic approach is common for hydrological surveys. Such analyses lead to better estimation of water balance components. Extending rainfall-runoff relationships from gauged watershed to un-gauged ones are viewed in this category. A case study is done in this research for two neighboring watersheds of Nahrain and Korit located in Tabas city, Yazd province. Nahrain has some hydrological and meteorological stations while Korit is an un-gauged watershed. Based on topographic and geological features, the two watersheds are hydrologically similar. Therefore, the process of rainfall runoff is considered the same for the two watersheds. After constructing rainfall time series for the two watersheds, runoff coefficient for Nahrain was used for Korit. Rainfall runoff relationships at monthly and annual scales surveyed, yet there were no acceptable results. We analyzed the effect of monthly and annual rainfall for the previous year in a multi-variable model to predict the Nahrain runoff. Runoff coefficients determined by these models were compared and one with the greatest R2 was determined. This shows the effect of rainfall history on watershed yield. Five commonly used empirical models for annual runoff predications were examined. We found Justin equation and that of Irrigation Department of Utrapradish of Indian more convenient for the region.

Investigation of the behavior of density current released down a sloping surface in a tank of freshwater is reported herein. The influence of slope on the behavior of density currents, head velocity and body entrainment are experimentally investigated. The experiments were carried out in a tilting flume with different sediments to reasonably obtain a wide range of results. Based on the dimension analysis, dimensionless parameters were determined. Observations and measurements revealed a variety of phenomena depending strongly on the Richardson Number and the angle of incline. Also the non-dimensional head velocity and non-dimensional sediment fall velocity were being considered. A power type equation was found between head velocity and Buoyancy flux. Based on the present study and previous investigations of other researchers, regression equations of water entrainment were determined as functions of Richardson number and bed slope.

Pulvinaria aurantii (Cock.) is the most important pest in Mazandaran province with major chemicalcontrol being used against it in citrus orchards every year. Spray oil is the best pesticide for IPM purposes. Efficacy of two mineral oil, Cipron@and Medium oil@, with different physical character, in 1% (V/V) was evaluated for control of P. aurantii (Cock.) in 2002 and 2003. Result showed that population of 1st and 2nd instars and 3rd instar and female adults of P. aurantii was significantlysuppressed by Cipron@as well as 1St and 2nd instars and 3rd instar and female adults of P. aurantii by Medium oil@. Result of comparison between predatory mites population in mineral oil treatment and chemical pesticide treatments, such as Abamectin and Dursban, indicated that although predatory mites, such as Phytoseiidae, Anystidae and Trombididae in all treatment do not have significant difference after treatment, predatory mite population in mineral oil treatments are significantly more than chemical pesticides treatments after 1 month. This phenomenon may be the result of permanent toxical residue and replant effects of mineral oils. Mineral oils can be used for control of both P. aurantii and Phyllocopteruta oleivora (Ashmed), the most important pests in Mazandaran province.

Agriculture development appears mostly bounded by factors of water resources. Such a performance requires an optimized regime, a thrifty consumption and cautious habits to avoid resources wasting. So, an irregular and interrupted paying water charges causes the reliable organizations to be ineffective. These organizations usually are incapable of financing the variable costs of up keeping the public establishments, which in turn set irretrievable destructions in this sector. This research has been done to assessing and ranking the effective factors of the water charges in Dez irrigation network based on farmers' opinion. The results reveal that among the key effective factors in determining the rate of water charges yield-production, price production (guarantee or fixed), cultural and political aspects and optimal cropping pattern respectively, show more effectively.

To investigate the effects of plant density, suitable harvest time and preservative solutions on the vase life of gladiolus, a research was conducted on the cut flower of gladiolus c.v. Chloe. This experiment was done based on the complete randomized block design as factorial with 3 plant density (80, 100, 120 plants/m2) and two different times (morning and afternoon) determine the best preservative solutions, flower pots in S1= 8- Hydroxyquinolin (300 ppm) + sucrose (4%) + Acid citric (1000 ppm) , S2= silver nitrate (300 ppm) + sucrose (4%) + Acid citric(100ppm). Were Considered Some of qualitative characteristics (flower stem diameter, spike length, floret diameter, number of open floretsts, number of wilted florets and vase life of cut flowers) were studied. Results indicated that with reduction of plant density (80 plants/m2) floret diameter, spike length and number of open floretsts increased and number of wilted florets reduced ( P = 1%). Also, the results indicated that there was a significant difference between two harvest times, morning and afternoon (P = 1%). In morning harvest floret diameter, number of open florets and vase life of cut flowers increased and the number of wilted florets decreased. Also, the vase life of gladiolus increased in 8- Hydroxyquinolin (300 ppm) + sucrose (4%) + Acid citric (1000ppm) treatment.

In the Guelph permeameter method (GP), soil's saturated hydraulic conductivity (Kfs) and matric flux potential (Æm) above the water table are determined by Richard's two head analysis. In this method, a high percentage of Kfs and Æm values may be negative. In this study, in order to evaluate the single and two head analysis of GP, some holes were augered in loam soil and in each of them the Q values in constant head of 0.05, 0.07, 0.10, 0.12, 0.15, 0.18 and 0.20 meter were read. Also, in order to improve the single head analysis, based on the experiment result, some values of a* (sorptive number) were recommended. Results showed that the computed values of Ks with this recommended a*, in the constant head of H2, are close to Kfs in ratio of H2/H1>2 and their correlation increased with the increase in H2/H1 ratio.

Drought is the most important limiting factor for plant growth and crop production. In this study, resistance of 2 olive cultivars including Mahali Baghmalek and Zard to the drought was investigated by using different irrigation treatment (I1: watering when 0-3% of the plants available water was used. I2: watering when 33-66 % of the plants available water was used. I3: watering when 66-100 % of the plants available water was used), three potassium levels (0, 50 and 100g potassium sulphate for each plant at planting time in pot). The experiment was carried out in a completely randomized design with factorial arrangements with four replications. Measured parameters included crop water potential, leaf relative water content and accumulation N, P and K elements in leaf and root. The results showed that crop water potential in cv. Mahali Baghmalek was lower than cv. Zard, but its relative water content was higher. In both cultivars, water potential and relative water content were reduced with decreasing of irrigation. The best RWC and water potential was related to I3 water treatment As well as N, P and K elements in leaf were lower in I3 treatment. Use of potassium led to the increase of the relative water content and decrease of the plant water potential. The best RWC and the lowest water potential were related to K1 potassium treatment (100 g potassium sulphate). Potassium fertilization led to increasing potassium of the root and leaves in each cultivar, but did not show significant effect on N and P in the leaf and root.

Accuracy of estimations made by conventional soil maps is low because they do not take in account the spatial variability of soil properties. In this study, a new idea in order to improve the quality and accuracy of predictions of a conventional soil map is introduced. To do this, a detailed soil map of Farrokhshahr area located in Chaharmahal and Bakhtiari province was combined with kriging maps of seven soil surface properties including percentage of CaCO3, clay, silt, sand, gravel, organic matter and the thickness of A horizon. The results showed a considerable bias in the predictions made with the conventional soil map in comparison with kriging and combined methods. According to mean square error (MSE) index, soil map predictions were also less accurate than the two other predictors. Mean absolute error (MAE) index indicated that predictions of the combined procedure were mostly unbiased and accurate although some bias and accuracy differences found with two other predictors, particularly kriging, for some soil properties were not very large. In situations where soil spatial variability lies somewhere between abrupt and gradual changes and also lack of alternative methods, the weighted linear combination of kriging-soil map procedure can be used as a valuable tool for improving the quality of conventional soil maps.

Sitobion avenae (Rodani), Schizaphis graminum (Fabticius) and Diuraphis noxia (Mordviko) are the most important aphids in wheat rain fed fields of Broujerd. In this research, seasonal population dynamics and selection of sampling methods as well as sample universe of these species were investigated during 2003-2005. Sampling was done twice a week and during three months by using X, U and zig-zag shaped movement in the fields. In each occasion, 100 plants were selected randomly in each field and adults as well as nymphs of each species were recorded. Result showed that there were two population peaks of S avenae and one for S graminum and D. noxia. S graminum which appeared 5-7 days earlier than the two species in the agronomic conditions. Relative variation (RV) and relative net precision (RNP) were compared to determine the best sampling methods. Comparison of three methods of sampling indicate that X- shaped movement was more precise that U and zig-zag shaped methods of movement. Results of regression stablishment between the number of aphids on target organs and the whole number of aphids per occasion showed that in pre heading periods for Savenae the leaves but for Sgraminum and D.noxia the flag leaves were suitable sample universe. In post wheat, ear was an appropriate place to take samples from the plant.

To investigate the effect of environmental temperature upon quantitative and qualitative traits of hen eggs, an experiment was conducted on 1632 fresh collected eggs. The hen eggs were randomized collected in a manner of 50 eggs each 10 days. Traits such as: egg weight, yolk weight, white weight and shell weight, white and yolk height, shell thickness and resistance, yolk index were estimated. The results have shown that the environmental temperature had a significant effect on all the studied traits so that the highest egg, yolk, white and shell weight, yolk height, shell thickness and resistance, form and yolk index were obtained in the temperature less than 25 °C (P<0.01), While the white height was the only trait which was decreased in the environmental temperature less than 25°C (P<0.05).

In order to investigate the effects of boron application on seedling growth and yield of different genotypes of canola to boron application, an experiment was conducted in 2005-2006 at Ramin Agricultural and Natural Resources University, Kouzestan province, Iran. The pots were arranged in a randomized complete block as a split-plot design with two B rates (0 and 10mgH2B03/kg Soil) and six genotypes of canola (Hyola 401, Hyola 407, PF, PF 7045/1095, RGS and Option). All treatments were replicated three times. The results showed that the boron application increased the number of seeds per pod, 1000 grain weight, seed yield and biological yield significantly but increased the number of pods per unit area non-significantly.Between different genotypes of canola there was no difference in seed and biological yield, but HI, number of pods per unit area and 1000 grain weight varied significantly between different genotypes of canola. Between different genotypes of canola, root dry weight, shoot dry weight and root/shoot ratio in seedling growth stage varied significantly, but no difference in leaf boron content in early flowering stage was observed. With boron application, root dry weight, shoot dry weight and root/shoot ratio in seedling growth stage increased significantly. Cultivars RGS and Option with boron application showed lower seed yield significantly which indicates canola genetic variation in response to boron application.

To determine plant bioclimatology over Karoon basin, 52 climatic parameters were selected from climatology and synoptic stations of the study area. These variables affect plants growth directly. Point data were changed to regional data using geostatistical methods. Then important factors with variation more than 1 were determined using factor analysis method. Factor scores were used as inputs in cluster analysis and maps of plant bioclimatic zones were prepared. Results indicated that 5 factors involved 94.26 percent of the variation. These factors were thermal temperature, precipitation, precipitation of spring, wind and relative humidity which represent 43.8, 26.96, 13.3, 5.15 and 5.1 percent of variation, respectively. Method of hierarchical cluster showed that Karoon basin with an area of 4275400 ha has 9 plant bioclimatic zones with different capability.