Agricultural Sciences and Technology
Year:2002 | Volume:16 | Issue:2|Papers Count:22

Cultivation and herbicide application are general methods of weed control in corn. An integrates of number cultivations and herbicide application methods affecting the efficiency of weed control. Cultivation alone is not effective and herbicide application despite environmental constrains, increases resistance of weeds. In this respect, an experiment was conducted in 1997 at the experimental field of Ramin Agricultural Research and Education Campus of Shahid Chamran University with 8 different combinations of cultivation number (0, 1 and 2 times cultivation) and herbicide application patterns (without herbicide, band applicates and broadcasting) and a weed free control. The experimental design was randomized complete block with 4 replications. The main weeds were Echinochloa Crusgali, Cyperus spp. and Convolvulus arvensis. Herbicides were atrazine, alachlor and 2, 4-D. Results showed that highest weed control was obtained with broadcast and band application of herbicide in corporation with two cultivations. Grain yield with integration treatments had better performance than non integrated methods. First cultivation improved corn yield but second cultivation did not. Band application of herbicides increased yield in contrast with no herbicide application but there were no differences with broadcast application. Among yield components, number of grain per row was affected by treatments. However, integration of band application with two cultivations could control weeds and produced acceptable yield with reduced rates of herbicides.

This experiment was conducted to evaluate various protein sources with animal or vegetative origin and their mixture in broiler diets. The diets were isocaloric and isonitrogenous and similar in their levels of two limited amino acids (methionine and lysine); six diets were formulated with respect to sources of proteins and their combination including: fish meal (diet A), soybean meal (diet B), and sunflower meal (diet E) and soybean meal+sunflower meal (diet F). Each diet was fed to five replicates of fifteen broiler chicks (one-day old). Diet A compared with other diets decreased weight gain, feed intake and feed efficiency (p<0.05). The best results were obtained by chicks fed diets D and E that had a mixture of animal and vegetative protein sources and improved chicks performance (p<0.05). During of this study no significant differences were observed in chicks performances by diets B and C. Chicks fed diet F had maximum feed intake but weight gain was not accordance to feed intakes and therefore, lower feed efficiency.

Field experiments were conducted during the 1999-2000 growing season at the agricultural experimental station of Ferdowsi University of Mashhad. The aim was to investigate the competitive ability of three winter wheat varieties with different levels of wild oat densities and its effects on yield and yield components of the wheat varieties. Wild oat caused 5 to 32 percent yield reduction in wheat, depending on wheat cultivars and wild oat densities. Among wheat varieties, C-73-5 was the most competitive variety and Alamoot was the least competitive variety in different levels of wild oat densities. In each variety, with the increase of wild oat density, the rate of yield reduction was enhanced. While at the highest level of wild oat density, the amount of this reduction in Alamoot and Bezostaia compared with the control treatment was significant. The reduction in Alamoot was due to the significant reduction of the number of produced tillers in each plant during the seasonal growth and wild oat interference. In Bezostaia, the reduction was due to competitive effects and shading of wild oat on this variety during the reproduction period of the plants.

In order to evaluate the effect of rye infestation on some growth characteristics and grain yield of wheat, a field experiment was conducted in 1998 in Rokh Cool season Cereals Research Station of Torbat Haydarieye afflicted to Khorasan Agricultural Research Center. In this experiment, the effect of five levels of rye infestation [0% (control), 10% (25 plants per m2), 20% (50 plants per m2) 30% (75 plants per m2), 40% (100 plants per m2)] on two cultivars of wheat (Alamoot and C-73-5) was studied in a factorial randomized complete block design with four replications. Results showed that by increasing the percent rye infestation wheat height and the number of unfertile tillers increased. Factors such as number of fertile tillers, biological and grain yield decreased with increasing the number of rye plants. Biological yield of Alamoot and C-73-5 at 40% infestation decreased by 21. 9% (2. 29 T/h) and 22. 2% (2.91 T/h), respectively, compare with control. The grain yield of wheat at 40% infestation (100 P/m2) was about 52% of control yield. The presence of 100 plants/m2 (40% infestation) caused a grain yield reduction of 2.5% (3.31 T/h) and 55% (3.23 T/h) in Alamoot and C-73-5, respectively when compared with control. The experiment showed that the presence of 25 rye plants per m2 of wheat field is the threshold limit.

This study was conducted for evaluating of 45 F1 hybrids derived from direct diallel crosses 10 superior selected early maturity inbred lines of grain corn. The hybrids planted in the α- Lattice design with 3 replications at Thorough Agricultural Research Station of Mashad on 1994. Analysis of variance showed highly significant differences between F1 hybrids for all traits (p≤ 0.01). Effects of general combining ability (GCA) was highly significant for all of traits showing the role of additive gene effects on controlling of these traits. Also, the specific combining ability (SCA) was highly significant for all traits except 1000 kernel weight, showing both additive and non- additive gene effects. For grain yield K1369/4 and S61 parental inbred lines had the highest combining ability for increasing-and decreasing of grain yield, respectively. The hybrid TV A 629 * K 1249/3 had the highest SCA for grain yield among all hybrids.

In this study, microwave technology in saffron drying has been investigated. To carry out this research, fresh saffron from Khorasan province were treated with microwave in six different powers. Also one sample was dried by traditional method as a reference. Comparison between microwave assisted drying with traditional method was studied by measurement of color, aroma and flavour intensity, and also total microbial counts, yeast and mold contamination according to standard methods. The results showed that microwave dried samples had significant difference with samples dried in traditional method. Thus, by using microwave energy drying efficiency could be improved and so microbial contamination of saffron samples would be decreased.

To study the effects of irrigation regimes and plant densities on yield and agronomic characteristics of Isabgol (Plantago ovata), a field experiment was conducted at Research Station, College of Agriculture, Ferdowsi University of Mashhad, during the years 2000 and 2001. A split plot design based on randomized complete block design with three replications was used. The treatments comprised four irrigation regimes, 7, 14, 21 and 28 interval days allocated in the main plots and four plant densities, 8, 10, 14 and 20 in the first year and 20, 60, 100 and 140 plant/m2 in the second year allocated in sub plots. The characteristics that were studied consist of spike length, plant height, number of spikes per plant, number of seeds per spike, 1000 grains weight and grain yield. Results showed that the irrigation regimes in each of 2 years had significant effects on plant height, number of spikes per plant and grain yield. The seven irrigation interval days had the highest grain yield. Plant density had no significant effects on spike length, plant height and 1000 grains weight in 2 years. The effect of plant density on number of grains per spike was significant only in the first year of study. In the first year, plant density had no significant effect on number of spikes per plant, but in the second year with increasing in the densities, the number of spikes decreased. The lowest number of spikes was shown in the highest density (140 plants/m2). With increasing plant density grain yield were increased significantly in both years. The highest grain yield was obtained at the highest density (140 plants/m2).

Using the flexible production functions, the economic value of irrigation water in Saveh region was estimated. The results of the study show that the average economic (shadow) price of one cubic meter of irrigation water at the farm gate used in wheat production is 215 Rials, in cotton production is 386 Rials, in Cucumbers production is 342 Rials, and in pomegranate production is 265 Rials. A comparison of estimated and the current price of water shows that the economic value of irrigation water is much higher than what is currently received by the local water authorities. Under these circumstances, an inappropriate use of water and the lack of incentives in investing in water saving technology are expected.

In order to investigate the effect of nitrate (KN03) on growth and biological nitrogen fixation (BNF) in subterranean clover (Trifolium substratum var Goss), an experiment was conducted using a completely randomized design with 3 replications, the treatments were 0, 1,2.5 and 5 mM KN03 in Hogland solution with sand culture. Results showed that with increasing nitrate nodulation and nodule growth severely decrease. Nodule growth was more sensitive than nodulation. Nitrate treatment resulted in greater leaf area per plant. The highest plant dry weight was obtained in 2.5 mM KN03. Ratio of root/shoot decreased with rising nitrate level. The highest total nitrogen percentage was obtained in 2.5 mM KN03. The increasing total nitrogen content was as a result of nitrate ion accumulation (not BNF).

A field experiment was conducted in Khorasan agricultural research center in order to investigate the effect of municipal compost and its fortification with chemical fertilizers on growth and yield of sugar beet (Beta vulgaris). A complete randomized block design with four replications were used. Treatments consisted of: Control (without fertilizer); Chemical fertilizers; Animal manure and Compost used separately and in combination with fertilizers and manure. Significant difference (at 5% level) were found for parameters like extractable and total sugar yield, percent of extractable and total sugar, and harmful nitrogen concentration in plant tissues between treatments. Application of compost, animal manure and chemical fertilizer, increased root and sugar yield compared with control. Using 40 Mgh-l compost along with 50% chemical fertilizer had a higher yield than chemical fertilizer alone, however, their difference was not significant. Thus, it appears that 50 percent of needed fertilizer may be replaced by compost. Adding 40 Mg animal manure per hectare alone, partly increased root yield. When this treatment was fortified with two times of urea dressing, maximum root yield, was obtained whereas its fortification with a mixture of chemical fertilizers and 50% of recommended amount put the root yield on topl.

The effects of salinity on yield and yield components of eight wheat (Triticum aestivulII) cultivars Ghods, Falat, Roshan, Cross Roshan, Cross Arvand, Mahdavi and Akberabady were studied at Amirabad Experimemal Field in Birjand during 1999-2001. The water sources for irrigation contained three electrical conductivity 1.1 (check), 5.3 and 10.37 (dS/m). The trial was conducted in split plot experiment of randomized complete block design with four replications per treatment. The salinity treatments were applied after 2 to 3 leaf stage. The irrigation time was determined according to the soil moisture curve using gypsum blocks in check plots up to 30 centimeter soil depth in order to irrigate the plots when half of the available water left the soil. The water requirement for each plot, calculated by volumetric method. The electrical conductivity of irrigation water was measured for each irrigation and the variation of soil salinity was determined by electrical conductivity of saturated soil extract within the depth of 0-30 centimeter before each irrigation. The results indicated that salinity had pronounce effect on grain yield, biological yield, harvest index, number of tillers, number of spike, and number of seeds per spike. The number of plants per unit area was not affected by salinity. All of the above parameters decreased with increasing salinity. On the other hand, the percentage of seed protein increased with increasing salinity. Among cultivars, Akbarabady had the highest grain yield, biological yield, harvest index and yield components, but its seed protein which was the lowest. However, this cultivar, along with Roshan, Cross Roshan, Ghods and Mahdavi were in the same group, Cross Arvand, Hearmand and Falat were in one group and they had the lowest grian yield, biological yield and yield components. In this group Falat showed the minimum performance, especially regarding to the grain yield and biological yield. In this experiment, number of spikes, and number of seed per spike were the most important yield components under salinity conditions. In conclusion Akbarabady is a salt tolerant cultivar, Roshan, Cross Roshan and Ghods are semi salt tolerant, and Cross Arvand, Mahdavi, Hearmand and Falat are sensitive cultivars to salinity.

Antioxidative activity of Saliva leriifolia leaves and its potential for application as a natural antioxidant was investigated. Comparison of extraction efficiency and antioxidative activities using different organic solvent extracts (i.e. methanol, ethanol, acetone, chloroform and hexan) indicated that the methanolic extract had the highest antioxidative effect on sunflower oil. The effect of three levels of methanolic extract (0.10, 0.15, 0.20% WN) on oxidative stability of sunflower oil in light and in dark (60°C) were compared with butylated hydroxytoluene (BHT) (0.02% WN) and α-tocopherol (0.04% WN). For all treatments, peroixde and thiobarbitoric acid tests were conducted during two months with 10-day intervals. The results were analysed as a factorial experiment in a completely randomized design with three replicates. All the three levels of methanolic extracts showed that antioxidative activity was increased significantly (P<0.05) with increasing in concentrations. However, antioxidative activity of methanolic extract was significantly lower than BHT and α-tocopherol (P<0.05) even at its highest concentration. Change of sunflower oil oxidation during time in the presence of different levels of methanolic extract was similar to that of BHT and α -tocopherol. Furthermore, control of oxidative rancidity with the methanolic extract, BHT and α-tocopherol, was higher in dark than in light. The results of taste panel on two products containing 0.2% of methanolic extract (the highest concentration) which were prepared at two temperatures (low and high) showed that, there was no negative effect on sensory properties.

Effective screening techniques for drought resistance would be beneficial in wheat (Triticum aestivum L.) breeding programs. Two drought resistance criteria. consisting of relative water content (RWC) and stomatal resistance were evaluated in field and greenhouse to investigate drought resistance in five wheat cultivars reputed to differ in drought resistance: Alvand and B. C. Roshan (resistance), Zarrin and C-73-5 (moderate and Navid (susceptible). In both experiments, R WC decreased with progressing in phonological stages. There was a significant difference in RWC among cultivars (except at stem elongation stage in the field) but drought resistant genotypes has not superiority to susceptible ones. In greenhouse a significant linear relationship was obtained between RWC and yield reduction ratio as determined by Yr=1-(Ys/Yp)(Ys and Yp=yield under stress and non-stess conditions, respectively). In stress conditions, stomatal resistance in the greenhouse was higher than in the field. Stomatal resistance and yield reduction ratio in greenhouse showed a significant correlation. It seems that there is a relationship between RWC and stomatal resistance and these criteria were recognized as beneficial drought resistance indicator but the time of drought stress is an important factor in this subject.

The main purpose of the present study is to investigate the effects of inputs in production of irrigated wheat and barley. To do this the Shephard’s Lemma, translog cost function and translog multiproduct cost function along with seemingly unrelated regression iterative are used in order to estimate the demand function for water, chemical fertilizer, labor and agricultural machinery. Data were obtained from 210 questionnaires, filled by farmers producing wheat and barley in Zayanderoud watershed during 2000-2001. The results showed that the translog cost function efficiently modeled the data. Moreover, the water as an major input can be considered as a complement for labor and substitution input for machinery. The value of elasticity of demand water is more than unit, therefore, it indicates demand water is elastic.

Calorie content of ice cream can be decreased by substitution of it's two main energy sources, fat and sugar. However, reducing sugar and fat content of ice cream may affect its physico-chemical characteristics and subsequently the quality of ice cream. The main objective of this research was to find the optimal replacement ratio of fat and sugar in low calorie ice cream, keeping the quality at acceptable level. Fat and sugar of a reference ice cream with 8% fat and 15% sucrose were replaced with starch gel and glucose syrup in three separate trials. In the first and second trials, glucose syrup and starch gel were replaced separately at the ratios of 0, 25, 50, 75 and 100% for sucrose and fat. In the third trial, simultaneous replacement of fat and sucrose was carried out at the same ratio of the first two trials. Two levels of stabilizer (0.2 and 0.3%) were used. In all trials, overrun, whipping rate, melting resistance, vicosity, density, pH, total solids and calorie content were determined and the results were analysed as a factorial experiment in completely randomized design with 3 replicates. Sensory properties of samples (taste, aroma, texture and total acceptance) were judged by 10 panelists. Glucose had no effect on physicochemical characteristics regardless the ratio of replacement. Therefore, its effects on sensory properties was only studied in the third trial. However, replacement of fat by starch gel at ratios higher than 50% resulted in a significant increase of viscosity (P<0.05) and a considerable decrease in overrun, total solids, melting resistance and whipping rate. Taste and total acceptance scores were significantly lower than reference ice cream at fat replacement ratios higher than 50%. The results of this research showed that starch gel at the ratios of 50% could be an appropriate cheap substitute for fat with a considerable reduction of calorie while maintaining physico-chemical and sensory properties of ice cream.

Seven tobacco cultivars of Burley type (Burley 21, Burley CDL 28, Burley Banket, Burley Resistance, Burley 14, Burley 26 and Burley TN 86) were intercrossed in the year 2000 in a half-diallel design and F1s plus parents were transplanted in the year 2001 in Tobacco Research Center in Rasht, with 3 replications and their resistance to Peronospora tabacina A. and Meloidogyne incognita were investigated by COREST A standard methods. The diallel analysis of results showed sufficient fitness with additive - dominance model introducing by Hayman and Griffing. Since in formation of resistance of cultivars to nematodes the over dominance effect of genes were seen, in genetic control of blue mould resistance were partial dominance effect of genes involved. The diallel analysis of results showed significant GCA and SCA additive and no additive-dominance-effects of genes) by genetic control of resistance to nematodes, but for resistance of cultivars to blue mould were only GCA (additive effects of genes) significant. The estimated narrow sense heritability (18-29%) for resistance to nematodes and 46-52% for resistance to blue mould give a moderate chance for selecting of resistance lines to nematodes and a good chance for selecting resistance lines to blue mould. The cultivars Burley Banket and Burley TN 86 were favorite parents for transferring of resistance to nematodes to their progenies. The cultivar Burley CDL 28 were also with his lowest infection to blue mould and significant and negative GCA the favorable parent for transferring blue mould resistance to their progenies. As progenies with a negative and significant SCA for resistance to nematodes are hybrids (B. 21 x B.CDL 28), (B. CDL 28 x B. 26) and (B. CDL 28 x B.TN 28) favorites. Also the cross progenies of Burley CDL 28 with other cultivars showed lowest infection to blue mould.

Dry matter production and partitioning of redroot pigweed (Amaranthus retroflexus) in pure and mixed stand with corn (Zea mays) was studied in an experiment conducted in 2001 in a field experiment at Ferdowsi University of Mashhad. A spilt plot arrangement with 3 replications was applied, main plots were planting dates (21 May, 6 June) and subplots were pure stand of corn at two densities (9.5 and 7.1 plant per m2) and pure and mixed stand of pigweed at two densities of corn. Results showed a close correlation between the transmission of photo synthetically active radiation (PAR) and leaf area index. Biomass production was linearly related to cumulative intercepted PAR. Total dry matter of pigweed reduced as radiation decreased along with increasing corn density. At both planting dates total dry matter of pigweed in pure stand was 2.5 fold pigweed dry matter in mixed stand. Results showed that when the level of competitive stress increased, pigweed allocated relatively more biomass to main stem than to branches.

Relative competitive ability of3 soybean cultivars (Willims, Clarck and Hobit) and redroot pigweed were assessed during entire growing season by using replacement series experiments .Decreasing the proportion of plant density resulted in increasing relative yield (RY) of soybean cultivars. Competition within species was higher than competition among" species. Relative yield of redroot pigweed was less than soybean cultivars due to higher inter- specific competition rather than intra- specific competition. Relative yield total more than 1 indicates niche differentiation between soybean and redroot pigweed. Also relative crowding coefficients (RCC) for soybean cultivars higher than unit, indicates higher inter specific competitive cultivars than potential redroot pigweed. Aggressivity (A) index in soybean cultivars were higher than redroot pigweed. However, in Hobit aggressivity was less than other cultivars.

In this study income fluctuations of Iranian pistachio producers and its causes were investigated. The results show that this instability is high and risky. Thus farmers cannot forecast and eliminate income variability. The results, also, show that both pistachio price and yield variations have impacts on income fluctuations. In other words, if the income variability should be approached zero, both price and yield volatility should be reduced. Thus a portfolio of crop insurance and exchange market for pistachio is necessary. But the success of these tools in Iran should be investigated more.

Drought tolerance levels in some wheat cultivars received the uniform cold region wheat yield trial (URWYT-C) across the country were studied using a strip-plot based on randomized complete block design with 3 replications for 2 years (1998-2000) in Torogh Agricultural Research Station Mashhad, Iran. The main plots (Horizontal factor) were assigned to 3 levels of irrigation: 10-day irrigation (A 1), 20-day irrigation (A2) and 30-day irrigation (A3) intervals. The sub-plots (Vertical factor) were assigned to 20 lines or cultivars of winter and facultative bread wheats set up for URWYT cold Regions (C-75: 120). The amount of seed and inorganic fertilizers applied as recommended in region. During the growth stages, major agronomic, morphological and physiological traits were recorded. Irrigation requirement was supplied by using a drop irrigation system. Irrigation, treatments were carried out on the basis of the difference between soil moisture before irrigation and its water content at field capacity. Based on the results of combined years analysis, the effect of irrigation levels on grain yield, biological yield, number of spike per m2, harvest index and 1000 kernel weight, were significant (P<0.05). With increasing water stress (long period between two irrigation) these parameters were decreased. There was a significant difference among cultivars for number of kemel per spike, harvest index, peduncle length, plant height, days to heading and maturity. In A2 treatment, water use efficiency (or water productivity) was higher than other two treatments. In Al treatment, grain yield, biological yield and number of spike per m2 ofC-75-6, C-75-10 and C-75-16 lines were higher than the others. In A2 and A3 treatments (slight and severe water stress, respectively), grain yield, number of spike per m2, harvest index and water productivity of C- 7 5-14 and C-75-9 lines were high. Moreover, they had good flexibility in normal and stress conditions (slow stressing).The studied lines had an acceptable drought tolerance index and were moderately early mature.