THE SCIENTIFIC JOURNAL OF AGRICULTURE (SJA)
Year:2005 | Volume:28 | Issue:1|Papers Count:19

An automatic fruit color sorting system should have high operation accuracy as well as high speed and capacity. In order to improve the accuracy, it is useful to investigate the effect of important parameters on system performance. The objective of this research is thus to determine the effects of fruit and machine parameters on detection and ejection accuracy of an optoelectronic tomato color sorting machine. This system consists of an optic head which is designed to develop a reflection of the fruit. Output of the head is then processed in an electronic control system which generates the appropriate signal for ejection or admittance of the fruit in accordance with its color. This is accomplished by sending the signal to an electrical ejector mechanism that affects the sorting operation. In this research, the effect of three independent variables on detection and ejection accuracy of the system has been evaluated. Independent variables and their levels are: percentage of green tomatoes (at three levels of 30%, 60% and 90%), the fruit size (at two levels of 4-6 and 6-8 cm), shape of tomatoes (spherical and ellipsoidal), and slope of the fruit conveyor system (at three levels of 20, 35 and 50 degrees). Results of performance tests indicated that this system could detect and sort red tomatoes from green, yellow and white ones. The evaluated data from this system show that the effect of color (percentage of green tomatoes among non-red ones), slope of the conveyor system, and tomato size on detection and ejection accuracy and interaction effects of color-size on color detection accuracy of the system were significant (p< 0.05). Based on the results, the highest level of accuracy in color detection for non-red tomatoes is associated with slopes lower than 50° and color-size combination 90% green – 4-6 cm size range. The highest ejection accuracy was achieved at slopes lower than 50°, 4-6cm size range, the highest green percentage (90%), and spherical shape of tomato.

Increasing traction force and efficiency of farm tractors results in more crop productivity and saving of energy consumption. Optimizing these parameters requires detail study of effective condition on performance of traction wheels. In this research development and evaluation of a compelet laboratory system capable of testing and measuring performance parameters of small traction wheels, was envisaged. The aparatus consisted of a soil bin having a dimension length, of 6, 0.3 and 0.3 meters for its lenth, width af depth respectively. The soil bin transverse on a 12 meters length rail by its antifriction wheels having negligible moving resistance. Inside the bin different texture could be processed to a desired condition by using tillage and compacting implement that were fixed on stationary frame and water mister was used to control the humidity of the soil. The driving system consists of an electric motor, a three speed gear box and a traction wheel jointed by suitable levers and free pivots to a stationary frame which provide aparatus movement and exerts different normal loads by using various weights. Data measuring system consisted of two strain gage load cells one located between wheel and stationary frame and measure gross traction effort and the other located between soil bin and adjustable braking system that measures net traction or pull, two D.C.generators were used for measuring the speeds of the wheel and soil bin separately. The out put singnals of the measuring transducers are electrical potential difference which is analog signal and converted to digital signal by a 8 bits and 4 channels data logger. The signals are then transferred to a computer for processing and displaying the quantity of forces, speeds and slippage. A cone penetrometer determines the cone index for every soil condition from surface to 0.15meter dept. During different traction tests, other soil parameters such as texture, structure, water content and machine parameters such as diameter and width of traction wheel , normal load and slippage could be measured. By obtaining these parameters and substituting them in different traction models, calculated traction performance quatities that are comperable to measured quantities in various conditions can he achived. Also traction performance of the small or model traction wheels can he studied and evaluated by changing each of the effective parameters in the tests. The aparatus showed good accurey when some traction performance tests were performed.

Little is known about seed germination responses of Iranian wheat cultivars to salinity stress. In order to evaluate salt tolerance of an array of Iranian common wheat cultivars at germination and early seedling stages, an indoor expriment was conducted using different NaCl salinity levels of 0, 3, 6, 9, 12 and 15 dsm-1 in a 3 replicated RCBD. Among 30 cultivars used in this study, one, i. e. Karchia-66, is known for its resistance to salinity, eight have been reported tolerant by some workers, and the rest are likely to be non- tolerant. The results showed that with an increase in salinity levels different germination idices were significantly affected. Mean comparisons between the cultivars revealed that 15 cultivars of wheat had the highest rates of germiantion stress index, with Karchia-66 being the single most resistant followed by Bistoon, Chamran, Alamoot, Darab 2, Bezostaya, Pitik, Inia 66, Azadi, Bolani, Tajan, Atrak, Niknezhaad, Mexipak and Arvand. Considering this index and the final germination percent, nine cultivars including Karchia-66, Chamran, Bistoon, Alamoot, Bezostaya, Azadi, Atrak, Niknezhaad and Mexipak showed the highest rates of salt tolerance. Based on the three indices of GSI, FBPI and germination rate the two cultivars of Karchia-66 and Chamran are categorized as the cultivars with he highest degree of salt tolerance. A number of cultivars previously reported as salt tolerant did not show a considerable tolerance to salinity stress. Thus, it was concluded that evalution of the cultivar performance based on salinity tolerance at germination stage may not reflect their responses to salinity stress in other stages of the growth.

Within the framework of study on rust fungi (Uredinales) of Khuzestan, 23 rust species belonging to different genera were identified. Of these, 20 species viz., Aecidium rubellum, Melampsora cf. pulcherrima, Phakopsora zizyphi-vulgaris, Phragmidium bulbosum, Ph. rosae-lacerantis, Puccinia aeluropodis, Pu. calcitrapae, Pu. cancellata, Pu. conclusa, Pu. malvacearum, Pu. pulvinata, Pu. rhagadioli, Pu. scirpi, Tranzschelia discolor, Uromyces anthyllidis, U. glycyrrhizae, U. gypsophilae, U. lineolatus, U. loti and U. rumicis are reported as new members for Khuzestan rust flora. Moreover, several new host species are reported for some identified rusts in Iran. Examination of the type and authentic specimens of Puccinia rhagadioli and Pu. garhadioli revealed that both species are identical and, therefore, Pu. garhadioli is considered as a taxonomic synonym of Pu. rhagadioli.

A distinguished drawback of using flat plate absorber in solar air heater is low value of convective heat transfer coefficient between absorber plate and cooling air which increases top heat loss and decreases thermal efficiency. In this study, a porous absorber solar air heater with slatted sheets and flat glass covers were designed and fabricated. The thermal efficiencies of these two solar air heaters were compared at different cooling air mass flow rates (0.0065 to 0.030 Kg/s.m.2 ) at outdoor conditions. Air mass flow rates were measured by orifice plates, temperatures were measured by T-type thermocouples and solar radiation was recorded by a pyranometer. In this research, the use of porous absorber resulted in increasing convective heat transfer coefficient between flowing air and absorber and decreasing convective and radiative heat losses between absorber and cover systems leading to higher thermal efficiency of the solar air heaters. Results indicate that by increasing the air mass flow rate, the temperature of all points of the two solar air heaters were reduced, thus yielding a higher thermal efficiency. Furthermore, in the air heater with slatted glass sheets cover, the vertically downward air flow reduces convective heat loss from absorber to cover.  Sucking air through the slots recovers part of the short wave radiation absorbed by the glass sheets as well as the long wave emission from the absorber. This process resulted in minimizing the convective and radiative heat losses through the cover. It was shown that, for the range of air mass flow rate studied, the thermal performance of the air heater with slatted glass sheets cover was always higher than the flat glass cover and this superiority improved at higher air mass flow rates. At the highest air mass flow rate, (0.030 Kg/s.m.2 ); the thermal efficiencies of the air heaters with slatted and flat glass covers were 63%,  and 51% respectively at outdoor conditions.

This study was conducted to determine the impact of deficit irrigation on quality and quantity characters and yield of date palm cv. Mozafati in Randomized Complete Blocks design with four replicatis and 4 treatments during 1999 – 2003. In this study, four irrigation levels based on 60, 80, 100, and 120 percent evaporation from class A evaporation Pan were applied in a date palm orchard located in Azizabad region of Bam. In September after harvesting the morphological properties (length, width and weight of date fruit and pit), yield and chemical properties (moisture content, total soluble solids, acidity content and sugar content) of date fruits were measured. The results showed that the effect of trees’s age on yield and other quality was not significant. The statistical analysis of the data indicated that treatments’ effect on yield was significant and on other qualities were not significant. The 80% evaporation treatment led to the maximum yield (15.4 ton/ha) while the 60% evaporation treatment produced the minimum yield (10.4 ton/ha). There was no significant difference between yield of 80, 100, and 120% treatments. Water use efficiency for 80% treatment was 91% more than the other treatments. So, this irrigation treatment can be recommended for date palm irrigation in Bam region.

In this investigation the effects of fruit harvesting time of Local Mandarin (Citrus reticulata Blanco) fruit on weight, diameter, peel thickness, dry matter, total extract and hesperidin flavonoid content in the total extract are studied. The statistical design used was a split plot arrangement randomized completely conducted in the Citrus Research Organization located in Tonecabon (Kotra), the north of Iran. On the basis of the results, harvesting time of the fruit had significant effect on the above-mentioned parameters. Fruit diameter variation was proportional to the fruit weight and was quite rapid. Fruit peel thickness at the first step of growth increased with fruit development and then decreased. Percentage of dry matter at the first harvest increased and then decreased. The total extract was significantly affected by the fruit harvest time. The highest total extract (10.8 g/100g DW) was obtained from the fruits were harvested 65 days after a full bloom. Results also show that the highest hesperidin content (18.12% of total extract) found in the fruit was harvested 45 days after full bloom and with 7.5 mm of fruit diameter.

Sewage sludge is rich in organic matter that can improve soil fertility as well as soil physical properties. The objective of this study was to determine residual and cumulative sludge application on soil physical properties. Four rates (0, 25, 50, and 100 t ha-1) of sewage sludge were applied to a clay loam soil (fine Loamy, Mixed, Thermic, Halargid). To determine cumulative and residual effect on soil physical properties, in the second year, each plot (15x3) m) was divided into two sub-plots (3x3 and 3x9 m) and sewage sludge was added to the larger portion at the same rates as before. Bulk density, infiltration rate, aggregate stability, and organic matter content were measured 100 and 210 days after the sludge applications.  Application of sewage sludge in the second year significantly increased infiltration, hydraulic conductivity and decreased bulk density. Residual sludge had similar effects, but as the time passed and organic matter decomposed, the soil physical properties approached the values in the control plots. The results indicate that the effect and duration of sludge application depended on the sludge rate and time of sludge application.

In order to ermine the critical period of weed control of Colorado bean (Phaseolus vulgaris L., Talash cultivar) in Lordegan region, an experiment was conducted in 2001 and 2002. The experiment was arranged in Rndomized Cmplete Block design with 4 replications. Treatments included weed free and weed-infested period with ten days interval after bean emergence. First group of treatments consisted of weed control from bean emergence to 10, 20, 30, 40 and 50 days after emergence. In the second group of treatments, weeds were allowed to interfere from emergence time to the aforementioned stages of bean growth. Meanwhile, two additional treatments were arranged in control plots as weed free (full season control) and weed-infested (full season competition) respectively. Gompertz and Logistic equations were used to determine the critical period of weed free and weed-infested period, respectively. Results showed that bean yield loss increased with increasing duration of weed interference, and decreased with increasing duration of weed control. Critical period of weed interference in Colorado bean with 5% accepted yield loss occurred between 24 days to 38 days after bean emergence (2 weeks period). This period was the same with the V3 and before R1 (flowering stage) respectively. Due to higher impact of weeds, critical period in the second year was longer than the first year, in such a way that it occurred between 18 and 44 days after bean emergence (a 26- day- period). Pod number per plant was correlated more with bean yield than other yield components. This character was severely reduced by increasing duration of weed interference after bean emergence.

To determine the suitable pollinator for olive, cv. ‘Dezful’ among Manzanilla, Sevilana, Kalaman, local Gorgan 2 and local Gorgan 3 cultivars, this study was accomplished in Safiabad Agricultural Research Center for 2 years. The experimental design was Randomized Complete Blocks with four replications. Cross pollinations were carried out on four ‘Dezful’ cv. trees having the same situation and, the fruit set was measured at stone hardening period. The results showed that the kind of pollen affected ‘Dezful’ cultivar fruit set and cross pollination could increase fruit set significantly (p<0.01). Comparison of fruit set means in different treatments showed that 21.49 and 31.23 percent of ‘Dezful’ pistils pollinated by pollens of ‘local Gorgan 2’ and ‘local Grgan 3’ cultivars in first and second examined years were fertilized respectivily, while only 7.78 and 9.02 percent of self pollinated ‘Dezful’ pistils were fertilized, therefore, apparently self incompatibility exists in ‘Dezful’ olive. Analysis of combined two years showed that the annual effect on fruit set in ‘Dezful’ was not significant. The effect of pollination on oil content of fruit was not significant in different treatments, varying between 51.3 and 54 percent in dry matter. Study of flowers in ‘Dezful’ cultivar showed that the ratio of perfect and imperfect flowers from year to year was not the same and about 20 –34 percent of flowers were perfect. Fruit set of all flowers with open pollination was 3.04 – 3.4 percent.  

This study was conducted to investigate genetic and phenotypic relationship between different agronomic traits and yield components in safflower (Carthamus tinctorius L.). In this study, 66 selected lines from different Iranian landraces of Azarbaijan, Khorasan, Kordestan, Markazi (Arak), Isfahan along with 13 foreign genotypes and local populations of Koose and Arak-2811 were evaluated in a simple lattice design. The correlation coefficient revealed that the number of seeds per head and the number of heads per plant had the highest positive, phenotypic and genetic correlation with both of seed yield and seed yield per plant. Also, there was a high positive genetic and phenotypic correlation between the seed yield per plant and seed yield (kg/ha). Based on the regression analysis, the number of seeds per head and the number of heads per plant were recognized as the most important components of seed yield per plant and were accounted for 75% of its variation. Path analysis showed that the number of heads per plant had the most positive and direct effect and a high negative and indirect effect through seed weight on both seed yield and seed yield per plant. Despite high positive and direct effect of seed weight on seed yield, the correlation between this trait and seed yield was negative. It was most probably because of a high negative correlation between seed weight and the number of heads per plant. The oil content which was determined for 20 superior lines in terms of seed yield, and also for the local population of Koose, showed that there was no significant correlation between oil content and the other traits, except for the number of seed per head (rg =0.53*).

During growing seasons of 2001-2002 this study was conducted to investigate and determine the Fusarium spp. associated with foot and root of faba bean in Khuzestan. Samples were collected from infected plants from different fields in different regions of Khuzestan including Ahwaz, Hamidie, Behbahan, Aghili, Shooshtar, Dezful, Sefiabad, Shoosh and Andimeshk. Eighty four isolates of the Fusarium species were isolated and purified by single spore or hyphal tip methods. Based on morphology, the isolates were identified as: F. oxysporum (27 isolates, 32.14%), F. solani (23 isolates, 27.38%), F. moniliforme (18 isolates, 21.42%), F. proliferatum (8 isolates, 9.52%), F. semitectum (4 isolates, 4.76%), and F. equiseti (4 isolates, 4.76%). This is the first report on these species from vicia faba from Iran. Besides, Faba bean is reported to be a Matrix nova for F.proliferatum, F.semitectum and F. equiseti. In pathogenicity tests, seedlings were inoculated using different methods including dipping roots in a spore suspension with 106CFU/ml, adding spore suspension to the soil around the roots, and using inoculated wheat grains (with the fungal isolates) in the soil around the seedling roots. Results indicated that all the isolates were pathogenic to the broad bean plants. In all pathogenicity methods mentioned above, F. solani had the most virulent.

Sugarcane (Saccharum officinarum L.) fields and rotational crops have been cultivated without potassium fertilization for 42 and more than 100 years, respectively. Sugarcane fields receive approximately 30 000 m3 ha-1 (or 300 cm) irrigation water while the latter receive 10 000 m3 ha-1 annually. As a result of long duration of cultivation as well as the amount of irrigation water consumed some alteration in physico-chemical properties of these soils might have happened annually as compared to physico-chemical properties of uncultivated fields. The objective of this research was to evaluate physico-chemical properties of soil with emphasis on changes in different forms of soil potassium. In cultivated fields both gypsum and calcium carbonate were reduced in surface soil as a result of leaching. The K uptake along with its leaching resulted in alteration of illite clay fraction to form expanding clay mineral in surface soils of cultivated fields. The above result was supported by XRD studies. This alteration was supported by changes in physico-chemical properties with special reference to increased fixed K and CEC. Fixed K in soils under rotation cropping system did not show any different trend as compared to soils of uncultivated fields. Nevertheless, it decreased in sugarcane cultivated.

This experiment was carried out to evaluate the vase life and quality of rose cut flowers cv. Ilona using chemical solution in 2000-2001 in Dezful region. For this reason factorial experiment was conducted in a compeletely rando   mized design. Silver thiosulfate in 5 different stages 0,100, 200, 300 and 400 mg/lit and 8-hydroxy chinolin citrate in 3 different stages 0,100 and 200 mg/lit, with 4 replications in 2 temperature treatments include 25°C with and without percooling period at 4°C for 24 hours. Flower stems after harvest were placed in vases containing 500 ml of various solutions and vase life and opening of flower were determined. Results showed that the effects of Silver thiosulfate on vase life and flower opening was significant (P>0.01). The Effect of 8-hydroxy chinolin citrate on vase life was significant while on flower opening was not. Comparison of different treatments at 25° C without percooling showed that concentrations of 200mg/lit Silver thiosulfate and 8-hydroxy chinolin citrate were extended the longevity of cut roses by to 4.75 days and at 25°C with percooling, concentrations of 400 mg/lit silver thiosulfate and 200 mg/lit 8-hydroxy chinolin citrate were extended the longevity of cut roses by to 4.5 days. Results of the first and second experiment years showed that with aging mother plants in second year in comparison to the first year, vase life of cut roses decreased significantly.

In order to evaluate the effect of crop rotation on weed community, a three–year field study was conducted with 4 crops including wheat, canola, fodder corn and sorghum in a research farm of agricultural faculty of Mashhad. The statistical design was arandomized complete block with rotation factor in four levels and three replications. Weeds study was laid out on two periods, first before crop canopy closure and second before crop harvesting. The effect of rotation was investigated on the last crop. The results indicate that both rotation and previous crop have significant effect on weed dry matter and density. Weed dominant species and weed flora were also affected by rotation. All parameters in the first period were higher than the second period. In most cases boardleaf weed dry matter and density were higher than narrowleaf weed. Second and third rotations had the highest dry matter and weed density respectively. Previous crop, especially canola, was as volunteer crop on the next plant but only in the first period. This research emphasizes the effect of crop rotation on unstability of weeds communities. Crop and sequential cropping system have an influence on both periods, but the effect of corn was higher in the second period.

The effect of six constant temperatures (15, 20, 25, 30, 35 and 40 ) on biological parameters (immature develo) pmental time, females longevity, oviposition rate, pre-oviposition, oviposition, post-oviposition periods and the mean number of egg per female per day) and also demographic parameters (net reproductive rate, mean generation time, intrinsic rate of increase and finite rate of increase) of Tetranychus turkestani Ugarov & Nikolski were studied under laboratory controlled conditions: 55±10 % RH and  16L:8D. The upper and lower thermal threshold were estimated 13.4 and 41.6°C respectively. The highest and lowest juvenile development time were recorded 4.33 and 30.35 days at 35 and 15°C respectively. According to maximum intrinsic rate of increase (0.379), minimum mortality percent and also highest egg production per female (73.8) at 35, it can be concluded that this was the optimum temperature for population development of T. turkestani. Increase in mortality rate at 40 indicates the proximity of the upper thermal threshold. No significant trend was found in daily fecundity rate between 6 temperatures. The total number of eggs laid per female was significantly different between the studied temperatures. The use of Logan et al. (1976) model allowed the description of temperatures influence the population growth. The values of Logan et al. model parameters, estimated by least–squares regression techniques, were p1 = 0.102, p2 = 0.106 and p3 = 5.47. According to our results, the temperature ranges within which T. turkestani can develop, from 13.4°C to more than 40.00°C is very broad. Althogether, this phytophagus mite has a high potential for population growth with regard to the temperature ranges and the high rates of increase were obtained from 0.089 to 0.379 between 15 and 35°C Further investigations concerning the influence of other biotic and abiotic factors on the biology of T. turkestani should be conducted to characterize the main factors responsible for changes in its population dynamics.

In order to study the effect of different crop sequences on weed community diversity, a field experiment was conducted in the educational field of Ramin (Molasani) Agricultural Faculty in the subcounty of Ahvaz. The experimental design was RCB with crop sequence factor in 5 levels and 3 replications. The results show that weed communities are affected by crop sequence factor. Therefore, weed dry weight and density changes depend on crop type and crop temporal arrangement. Both previous and present crops had the main role on the determination of the quantity of weed dry weight and density. Broadleaf weeds were the most dominatied form of weed communities and this group increased by an increase in broadleaf crops. At least, this research has shown that mono cropping system has had a lower weed than some sequence cropping systems. Margalef’s species richness index (DMG) was the best criteria for the comparison of weed diversity among cropping sequences.