JOURNAL OF AGRICULTURAL SCIENCE AND SUSTAINABLE PRODUCTION
Year:2005 | Volume:15 | Issue:1|Papers Count:16

Effects of defoliation during the beginning of anthesis stage on oil yield and other components of sunflower was studied at Karkaj Research Station, Faculty of Agriculture, University of Tabriz, in 2000 . Two varieties including Azargol (CMS 19xR46) and Golshid (CMS31xR46) were used in this study. Leaves were removed at the beginning of anthesis (R5) and the treatments consisted of five levels: removal of 1/3 upper leaves, 1/3 middle leaves, 1/3 lower leaves, total leaves and the control(no leaf removal). The trial was conducted as factorial experiment based on a randomized complete block design with three replications. Results of this experiment showed that time of maturity, duration of grain filling, ratio of kernel to whole grain and oil percent were affected by total defoliation but defoliation of 1/3 leaves did not affect these traits. Hollow achene percent, 3 grain yield and oil yield were decreased by removal of total and 1/3 of leaves Defoliation of 1/3 of lower leaves had less effect on these three traits as compared with other leaves. Middle leaves showed more effect than other leaves on grain yield and oil yield in this research.

In order to evaluate wild mustard potential seed production in monoculture and reproductive response of this weed to wheat seed rate and nitrogen fertilizer, an experiment was conducted in 2000-2001 at Agricultural Research Station Ferdowsi-of Mashhad, University, Iran. The experimental design was a factorial split-plot with three replications. The experiment had three factors: Three levels of wheat seed rate (175, 215 and 225 kg/ha), two levels of nitrogen rate at optimum and upper optimum rate of wheat (150, and 225 kg N/ha), and four levels of wild mustard density (0, low, medium, and high). Increasing seeding rates of wheat, from 175 to 215, and 255 kg/ha, reduced wild mustard seed production per plant by 62, 66 and 71%, respectively, compared to its monoculture yield. Increasing in wheat seed rate from 175 to 255 kg/ha, in optimum rate of nitrogen, reduced wild mustard seed production at high density by 40 %, while in upper optimum nitrogen rate, seed production was reduced only 11%. High seed production of wild mustard (21-941 million seed/ha) in the presence of wheat competition indicated that if weed management programs is neglected for one year, soil seed richness would be established for several years.

In this research, potentials of growth and reproduction of Indian meal moth was assessed in an experimental treatments consisting different levels of intraspecific competition (e. g. seven densities of 20, 40, 60, 80, 100, 150 and 200 eggs in each treatment containing equal amounts of pistachio kernels from Badami cultivar) in the laboratory condition at 25±1°C, 60±5% R.H. and a photoperiod of 16:8 h (L:D) during 2002-2003. Then, the effects of population density on the growth, reproduction and mortality of egg, larvae, pupae and adults were assessed. Results indicated that the competition pattern of Indian Meal Moth is Scramble type competition and effects of this type of competition in density-dependent manner caused the asynchrony in completing the life span (mean emerging period of 21 days at highest density and 12 days at lowest ones) and also decrease adults reproduction emerging in that plots (mean of 83.2 eggs at highest density and 165.5 eggs at lowest ones). In addition, competition among larvae of this pest by means of increasing the number of contacts, caused inhibition of feeding and also cannibalism phenomenon in larvae on each other and on eggs and pupae (93.1% total mortality at highest density and 34% at lowest one). Higher levels of population density with acceleration in competition effects led to sever mortality rates in the pest. It was concluded that occurring high-density levels of population of this pest in feeding from pistachio kernels, will more accelerate cannibalism specially on the first instars by feeding on each other and on available eggs, in comparison to the other instars.

The functional response of Lysiphlebus fabarum Marshall to different densities of alfalfa black aphid, Aphis craccivora Koch (Horn.: Aphididae) on two host plants, alfalfa (Medicago sativa L.) and locust tree (Robinia pseudacacia L.) were studied in a growth chamber conditions (55±5 R.H., L:D 14:10 H.) and at temperatures of 20 and 27°e in 2002 in Kerman, Iran. The objectives of the present study were to find the relationship between host densities and number of hosts parasitized by parasitoid and the effect of temperature and host plant on this relation. Functional responses of Lysiphlebusfabarum in both temperatures and host plants, to different aphid densities were fitted to the Holding's type 11 model. Searching efficiency (a') and handling time (Th) on alfalfa and locust tree were 0.0173, 2.6642 and 0.0104, 1.6005, respectively at 200e. They were 0.0109, 3.6187 and 0.0098, 3.1269, respectively at 27°C.

For determination of percent parasitism of the aphid, Thelaxis suberi (Del Guercio) (Thelaxidae) parasitized by Adialytus thelaxis Stary (Aphidiidae), samples were taken from oak trees at four times in Abbas Abad, Behshahr, Mazandaran province, Iran during 1998-99. Sampls were taken randomly from cutted apical shoots having 10 centimeter length. Mummified aphids were counted carefully in the laboratory. Alive aphids were dissected under a stereomicroscope and parasitoid larvae were counted. Percentage of parasitied unmummified aphids (arcsine transformation) was plotted against percentage of mummified aphids (Mp) and the linear regression model of Nmˆ = - 0.82Mp + 57.3 was obtained. By incorporating estimated percentage of unmummified parasitism (Nmˆ) in model (2): Tp=Mp+ Nmˆ total percentage of parasitism (Tp) was estimated.Therefore, by means of these models it is not necessary to dissect aphids to determine percent parasitism. Total parasitism (Tp) could be estimated through determining merely the percent parasitism of mummified aphids.

In order to study the growth rate, yield and yield components of four wheat cultivars under rainted conditions and two irrigation regimes (I-at planting time and ear emergence, 2-planting time, ear emergence and grain filling), a factorial experiment on the basis of randomized complete blocks design with three replicates was conducted in Dryland Agriculture Research Institute at Maragheh during growing season of 1997-98. In this experiment wheat cultivars of Sabalan/1-27-56-4, Anza/3/Pi/Nor//Hys/4/sefid, 4493-P.1533-Bez and Sabalan were used. Several traits such as crop growth rate, relative growth rate, dry matter accumulation Per unit area, number of ears per unit area, number of grains per ear, 1000 grain weight, biological yield, grain yield, harvest index and productivity degree were determined. The results showed that drought stress led to the reduction of dry matter production, crop growth rate and relative growth. rate. There were no significant differences between wheat cultivars, regarding green cover percentages, crop growth rate and relative growth rate. All traits (except grains per ear and harvest index) were affected by water deficit. However, irrigationx variety interaction was not significant for any trait. Considering traits studied in this research, no significant differences were found between two and three times of irrigation. Green cover percentage, plant height, crop growth rate, biological yield and productivity degree were significantly correlated with grain yield. Among these traits, mean green cover had the highest positive correlation with grain yield. Since this index could be determined easily and rapidly, it can be recommended as a suitable index for evaluating field performance of different crops.

Radiation is a meteorological variable that governs many hydrological and phonological processes, but its measurements are not made routinely. To overcome this problem, continuous hydrological models that include evapotranspiration, snowmelt (using solar radiation data) and plant growth modules have applied different strategies to generate daily radiation data. In this paper, artificial neural networks (ANNs) and temperature-based (TB) approaches for estimation of solar radiation was used and compared. These two approaches were assessed by the records of Tehran-Mehrabad, Shiraz, Zahedan and Ammameh Stations. Results revealed better performance of ANNs than TB. However, the TB method because of its capability to generalize results and to be easily linked with hydrological models appears to be a good candidate to be applied in the catchments where the climatological data are limited.

In order to evaluate infiltration rates, cumulative infiltrations and to determine coefficients of infiltration models (Green-Ampt, Philip, Kostiakov, modified Kostiakov and Horton) using various infiltrometers (flooding and sprinkling), an investigation was carried out at the Agricultural Research Center of East Azarbaidjan (Khosrovshahr) in 1998. The experimental design was factorial with randomized complete blocks and four replications. The first factor was assigned to four different methods of infiltration measurement (rainfall simulator with two intensities of 200, 100 mm/h, double rings and raindrop simulator). The second factor was two conditions of soil surface (tilled and untilled) and the third factor included 5-minute measuring periods. The results indicated that infiltration rate from double rings in tilled soil was 2-3 times higher than those from the other methods both in tilled an untilled conditions. There was a significant difference at 5% level of probability between the means of cumulative infiltrations of the three methods: the highest figure was occurred in double rings in the tilled soil and under untilled conditions it was less than other two infiltrometers. Means of infiltration rates in all three infiltrometers at the first 5-minute period was about twice more than the other 5-minute intervals. Infiltration rates and cumulative infiltrations of rainfall simulator with 200 mm/h intensity was more than 100 mm/h intensity.Infiltration rates and cumulative infiltration in both intensities were significantly less than raindrop simulator infiltrometer. Among the various infiltration models, Kostiakov model showed best fitness to the experimental data.

The potato Colorado beetle, Leptinotarsa decemlineata Say., is one of the most important pests of potato in the world. This pest especially in larval stage causes serious damages by foliar injury. The effect of Confidor (Imidacloprid) in two recommended dosages, Custom BC-3, Novodor and Phuzalone on the Colorado potato beetle larvae was determined 1 through 15 days after pesticide application during 2000-2001 in Ardabil. Custom BC-3 and Novodor were the commercial products of Bacillus thuringiensis subsp. tenebrionis. Fozalon was selected because it is used as a conventional insecticide in potato fields in Ardabil. Sun-Shepard method was used to determine the effects of the insecticides. For this purpose the number of survival larvae 1 day before and 1, 2, 5, 10 and 15 days after insecticides application were counted. After analysis of variance, Duncans multiple rang test for mean comparison of the treatment was done. Results showed that in both years and in most of the day-intervals after spraying, Confidor (Imidacloprid) and Fuzalon were more effective than the others.

Cucurbits are widely grown in East Azarbaijan. Since cucumber mosaic cucumovirus (CMV) infects cucurbits worldwide, infection of cucurbits by CMV in East Azarbaijan was surveyed. The plants showing suspected symptoms were collected and subjected to enzyme-linked immunosorbent assay (ELISA) with CMV- and or CMV subgroup 1- specific antibodies. Then, total RNA was extracted from each sample by a quick and simple phenol and chloroform extraction protocol. The total RNAs were subjected to an RT-PCR assay with a primer pair specific to coat protein coding region of the virus. An expected approximately 870 bp DNA fragment was amplified from many samples. These results showed a high incidence of the virus in cucurbits of Azarbaijan and revealed that CMV subgroup I isolates were involved in the infection.

Insecticidal effect of certain weeds of Guilan flora in Iran, like Artemisia annua L. and Sumbucus ebulis L. on the first and third instar larvae, pupa and adults of elm leaf beetle were investigated under laboratory condition. The plants were dried in the shade and extracted in distilled water. The oil phase was separated with diethyl ether and ultimately the ether was evaporated in a rotary evaporator. Diluting the concentrates in acetone, resulted in desired concentrations of 1, 5, and 10 percent. Each concentration considered as a treatment with three replicates using 10 individuals. In order to make comparisons two controls were used, one with acetone and another without any treatment. Mortality rates were calculated and corrected based on Abbot's formula. The data were subjected to statistical analysis (SAS) at %5 probability level. The results were indicative of the maximum effect of 10% concentration of both plant species and therefore were no difference between the larval, pupal and adult stages treated, nor between the two plant extracts in the above concentrations. The first larval instar was highy susceptible and therefore showed 100% mortality in all of the concentrations applied. The adult insect also exhibited 100% mortality in all the treatments except in 1% Sumbucus ebulus. The least mortality (3.3±2.7 and 10±4.7 percent) was observed with 1 and 5% cncentrations of Sumbucus. The Artemisia annua extract with average 91.31% mortality showed a higher rate compared to 77.11% caused by Sumbucus extract.

To study the effects of deficit irrigation on seed yield and seed oil content of two sunflower cultivars, an experiment was conducted in Zanjan Agricultural Research Station in 1999-2000. It was carried out in a split plot design with three replications. The experimental factors were sunflower cultivars (Golshid and Armavirsky) and time and frequency of irrigation which were assigned to main and sub plots, respectively. Irrigation treatments were: E1= without watering, E2=watering at flowering stage, E3=watering at bud formation and flowering stages, E4= watering at bud formation, flowering and seed filling stages, E5= watering at bud formation and seed filling stages and E6= watering at 90 mm cummulative evaporation from class A pan. After sowing, all treatments were irrigated to stimulate seed germination and the amount of water used for each treatment was measured during growing season. After harvest, seed yield, one thousand seed weight, protein and oil contents of seed were measured and economic output of deficit irrigation was calculated. The results showed that the main effect of irrigation and interaction of irrigation and cultivar on seed yield were significant at 1 and 5% probability levels, respectively.Comparison of average yield between treatments showed that the highest seed yield (3870 kg/ha) was obtained from full irrigation (E6).Treatments E4 and E3 producing 2690 and 2610 kg/ha seed yield, were placed in the second and the third orders, respectively. Calculation of economic output of treatments showed that watering at bud formation and flowering (E3) increased economic return, which was significant at 5% level. Based on the results obtained, E3 decreased the net benefit by 33%, when compared with E6 (Complete Irrigation). However, if the saved water be used to irrigate more land (1.6 hectare) the net benefit will be 75% more than that of complete or full irrigation. The results of this study show that when there is a shortage of water, irrigation at bud formation and flowering stages will give a suitable yield.

In order to evaluate the effects of plant density on morphological characteristics and yield of cotton, this experiment was conducted by using a factorial design, based on randomized complete block, with two varieties (Varamin and B-557), five plant densities (5, 10, 15, 20 and 25 plants per square meter) and four replicates in the Cotton Research Center of Varamin during 2000 growing season.With the exception of plant height, internode length and dry weight of single boil, B-557, was surperior in other characters, as compared with cultivar Varamin. Although there was not significant differences between varieties with regard to number of vegetative branches per plant, per unit area and yield, it is better to use higher plant population of B-557 which has close growth, because in this condition the growth of these varieties will not be limited as compared with Varamin which has open growth. Increasing plant density, decreased height of plants. The significant effect of plant population on the number of nodes and its nonsignificant effect on internode length suggest that reduction in the number of nodes per plant influenced plant height.Although higher plant densies reduced number of vegetative and reproductive branches per plant, number of bolls per heactare1dry weight of single boil, dry weight of bolls per plant and dry weight of single plant, yield, per hectares due to higher plant number per unit area, was increased. In spite of nonsignificant differences between 15, 20 and 25 plant populations, highest yield gain was obtained when 25 plants per m2 were used. Number of bolls per plant and per m2, dry weight of bolls per plant, dry weight of single plant and dry weight of plants per m2 were inf1uenced by variety and plant density interaction.

In order to -evaluate the environmental effects and estimate the genetic parameters for mean of birth weight, average daily weight gain, from 3-6 months, weight of 3 months old, average weight gain of 6-9 and 12 month old in Moghani sheep, data of 1831 lambs, 83 rams and 555 ewes were recorded in the flock of Jafar Abad sheep breeding station in Moghan from 1992 to 1997. Data were subjected to analysis which consisted of fixed effects of parturition number, year of birth, sex and lamb birth type. Random effects in the model were sire and animal effects. Year of birth had significant effects (P<0.001) on all growth traits, with greatest effect on yearling weight. Except of yearling weight and daily weight gain of 3-6 months old, parturition number had significant effect (P<0.001) on animal performance traits. Birth type had also significant influence (P<0.001) on all studied characters, but this relationship was not observed in daily weight gain of 3-6 months. All studied traits were statistically affected by sex (P<0.001) and mean of observation were higher in male lambs as compared to females. Heritabilities of traits were estimated by sire model with Henderson method III and animal model using REML method (DF- REML algoritm). Using the first method of analysis, estimated heritability for birth weight, weaning weight, 6-9 and 12 month weight and daily weight gain of 3-6 and 6-9 months of ages were: 0.097±0.041, O.068±0.042, 0.078±0.046, 0.089±0.065, 0.079±0.099 and 0.074±0.041, 0.071±0.044, respectively. However, for the above mentioned traits, using DF-REML method, estimates of 0.112±0.061, 0.084±0.045, 0.099±0.047, 0.101±0.052, 0.085±0.079 and 0.093±0.089, 0.083±0.053 were abtained. Genotypic, phenotypic and environmental correlations were estimated by sire multiple trait model. Estimated genetic correlations between daily weight gain from birth up to 3 and 6 month of ages were 0.827 and 0.766, respectively. However, the genetic correlation between birth weight and 3-6 months old were 0.636, 0.453, respectively.

To study the effects of water deficit on physiological indices and indentification of drought resistant cultivars of rapeseed among common cultivars in Eastern-Azarbijan, an expriment was carried out at Research Station of Factually of Agriculture, University of Tabriz, Tabriz, Iran. Genetic material was constituted of Global, Puma, Regent, Eureka and PF 7045.91 from napus species, Sonja and Parkland from rapa species and two hybrids, Hyola308 and Hyola 401. The experiment was conducted using a splite-plot design arranged in RCBD with 8 replications. Irrigation treatments with two level control and water deficit, were considered as main factor and cultivars as sub factors. Water deficit treatment was created by with holding irrigation at 50% flowering. Four weeks after induction of stress, physiological characteristics, including leaf water potential, specific leaf weight, and relative water content along with plant height, shoot dry weight, number and length of silique were measured. Mean of all traits, studied except specific leaf weight, were decreased under water deficit condition. Among the cultivars, studied global, had potentially higher number of silique, leaf water potential and shoot dry weight under both normal and water deficit condition, Thus, not only this genotype can directly be grown under water deficit condition but also can be used as one of the parent in developing mapping populations for identification of quantitative trait loci (QTL) for traits contributing in drought resistance.