JOURNAL OF RESEARCH IN AGRICULTURAL SCIENCE
Year:2010 | Volume:6 | Issue:2 (11)|Papers Count:9

Pedotransfer function (PTF) is a new technique for predication of the soil physical properties (SPP). Generally, SPP such as dry density, porosity, void ratio, soil hydraulic conductivity are estimated by a semi-empirical equation. The objective of this research was developing some PTF for estimation of SPP in bank of the Yangtze River, in Nanjing city, Jiangsu province, China. The SPP that has been considered in this research were: wet density (rw), dry density (rd), void ratio (e), liquid limit (LL) and plastic limit (LP). All soil analysis carried out by the soil geotechnical analysis standard method. 650 series of data were used for calibration and more than 100 series data for verification. The result shows that most of SPP in the study area can be significantly estimated by wet density (rw). For instant rd=1.474+1.531 × rw and L1=142.766- 54.898 × rw. Base on the results a computer program has been developed to estimate the SPP.

Alternaria brown spot is a serious disease of fruit and foliage of citrus. This disease caused by Alternaria alternate and causes serious economical losses on susceptible cultivars in Iran. In this research, susceptibility of seven citrus cultivars including Fortune, Orlando tangelo, Mineola tangelo, Page, Clementine, Sour orange and Sweet orange (Thomson) fruits to A. alternata was investigated. The result revealed that the Fortune, Orlando tangelo, Mineola tangelo, Page and Thomson fruits are highly susceptible and showed severe symptoms of brown spot, especially in “unwounded” fruits. In contrast, Clementine and Sour orange are resistant to this pathogen, and A. alternata could not grow on unwounded fruits. However, weak symptoms were observed in Clementine and Sour orange when cuticle was broken and flavedo or flavedo + albedo was removed.

In this research the susceptibility of the first three larval instars ofOcneria terebinthina (Lep.: Lymanteridae) toBacillus thuringiensis var. kurstaki was investigated. The eggs of the insect were collected from orchards where located around Rafsanjan. Different larval instars groups were separated by measuring the head capsule width and then used in all bioassays. In bioassays, LC50 values of Bt on the first, second and third instars larval groups were determined. The data was analyzed by log-probit transformation using the MSTATC software. LC50 values for each group of larvae were estimated by using treated pistachio offshoot. The LC50 values of Bt on the first, second and third instars of larvae were 276.91, 1494.53 and 2817.34 ppm, respectively. The first larval instar was the most susceptible to Bt. According to collected data in this research and the selective nature of Bt, we can conclude that this microbial compound can be used for reasonable control of O. terebinthina.

European elm scale [Gossyparia spuria (Modeer)] is one of the most important pests of elm trees in Isfahan province (Behdad, 1987). In this study, intensity of infestation of elm trees in various regions of Isfahan city was studied. Samples were collected biweekly from Ulmus carpinifolia and Ulmus carpinifolia var. umbraculifera which are the most common trees in the Isfahan landscape. In five geographical zones of the city (North, South, East, West and Center), percentage of infestation and intensity of infestation was determined.85.6% of U. carpinifolia and 72.6% of U. carpinifolia var. umbraculifera were infested. Low infestation intensity, [mean number of 0.6-2 female scales on 16 branches (each 30 cm long)] and medium infestation intensity (mean number of 2-20 female scales on 16 branches) were observed on U. carpinifolia and U. carpinifolia var. umbraculifera, respectively. Results showed that infestation of elm trees in humid microclimates in the city center and adjacent to the Zayandehrood river is much more pronounced than in other parts of the city.

Apple is one of the oldest trees in the world which is widely cultivated because of it’s highly compatibility with various climatic conditions. In this study, we applied phenological statistics of agricultural meteorology of Golmakan to anticipate different phonologic phases of apple using intelligent neural network. At first the matrix of input data which is consisting of climatic parameters such as minimum temperature, maximum temperature, the mean of daily temperature, absolute minimum temperature, and absolute maximum temperature has been established. The range of temperature changes, growing days and timed chilling unit (in silver tip phase) had been prepared for different phenological stages during 1999-2005; then the matrix of out coming data which, in fact, were the occurrence dates of different phenological stages of apple was prepared and the modeling of different phenological stages was performed by using neural network. In this study the accuracy of model was examined by using RMSE index and by contrasting real and anticipation dates during 2 years. For this purpose observed climatic and phenological data was also used in similar Figure at out of investigating zone. It’s also specified we could anticipate phenological stages of apple with acceptable accuracy using climatic parameters.

In order to study the effects of nitrogen and sulphur on yield and oil content of canola (Brassica napus L. cv. RGS003), this experiment was conducted in 2007-09 at Safiabad Agricultural Research Center of Dezful, Iran. The experimental design was a complete randomized block with factorial arrangement of treatments with three replications. Factors included two levels of nitrogen: 180 and 240 kg N ha-1 as Urea and four levels of sulphur: control (S0), 200 kg S ha-1 as sulphur powder inoculated with Thiobacillus.sp (S1), 100 kg S ha-1 as ammonium sulphate (S2) and 100 kg S ha-1 as gypsum (S3). The results showed that nitrogen had no effect on seed and oil yield, while sulphur affected these traits significantly. Interaction of nitrogen and sulphur was not significant on seed and oil yield. The highest seed and oil yield (2182 kg ha-1 and 675 kg ha-1, respectively) were obtained with application of 180 kg ha-1 N and 100 kg S ha-1 as ammonium sulphate.

The Artemisia sieberi Besser plant belongs to the Asteraceae family which disperses in dry lands. This species is resistance to drought and plays an important role on preserving the soil in dry regions. The aim of this study was to investigate the effect of drought stress on the Artemisia sieberi Besser germination behavior. To evaluate the drought treatment effect on the Artemisia sieberi Besser plant germination, the seeds were pre-chilled for 9 days at zero to 5oC for its dormancy duration to remove its dormancy. Moisture stress test was carried out with 0, -0.2, -0.4 and -0.6 MPa treatments using PEG solutions in petri dishes under a random plot. The results of this experiments showed that the water potential has a very significant different on the rate and percentage of germination, plumule length and allometry ratios, and is significant on one percent level, in a way that rate and percentage of germination is decreased through the water potential decrease, But radicle length is significantly less sensitive on drought stress in comparison with other features. As through stress increasing, the radicle length would be increased till -0.6 MPa and then in would be decreased.

This research was conducted to study the effects of nitrogen application rates, and plant densities on, nitrogen agronomic efficiency, nitrogen use efficiency and nitrogen recovery fraction of grain corn (hybrid SC.604) in 2007 in experimental field of Agricultural college, of Urmia University, Iran. Three nitrogen rates consisting of 100, 200 and 300 kg N ha-1 were chosen as main plots, and three plant densities consisting of 75, 85 and 95 thousands plant ha-1 as sub plots. The results showed that the effect of plant density and nitrogen on grain, biological and protein yield and harvest index was significant. The increase of nitrogen application rate caused significant increase in grain, biological and protein yield and harvest index. The response of grain and protein yield and harvest index to increase in plant density was negative. The results showed that nitrogen agronomic efficiency was higher in plant density of 95 thousand plants with application of 100 kg N ha-1 and Nitrogen use efficiency and nitrogen recovery fraction was higher in 75 thousand plants ha-1 with application of 100 kg N.