Showing 62 results for Nitrogen
Masoud Ezzat-Ahmadi, Hamdollah Kazemi, Mohammad Reza Shakiba, Mostafa Valizadeh,
Volume 2, Issue 2 (7-1998)
Abstract
Effect of different times and levels of nitrogen fertilizer application on growth and grain yield of spring wheat cultivar “Ghods” was studied during 1993-1994 growing season at Karkadj, Agricultural Experiment Station, College of Agriculture, University of Tabriz, using a split plot design with three replications. Main plots were assigned to five levels of N fertilizers (0, 40, 80, 120 and 160 kg/ha) and subplots to five times of applications [all of N fertilizer at planting (T0) 1/2 at planting + 1/2 during tillering stage (T1), 1/2 at planting + 1/2 during heading stage (T2), 1/3 at planting + 1/3 during tillering and 1/3 at heading stages (T3) and 1/4 at planting + 1/4 at tillering + 1/4 at stem elongation and 1/4 at heading (T4)]. Results showed that different levels of N applications affected grain yield and biological yield significantly, while the effect of split application and also N levels × times of application interaction on these two traits were non-significant. Growth stages of wheat were not significantly affected by different N Levels and times of application. Dry matter accumulation, leaf area index, and crop growth rate, in response to growing degree days during growing season, increased when higher levels of N fertilizer were applied. Leaf area index and crop growth rate initially increased up to anthesis and then decreased. Crop growth rate decreased to zero level at soft dough stage and then became negative. Variations in relative growth rate and net assimilation rate, in relation to growing degree days, decreased when different levels of N fertilizer were applied at early part of growing season it was maximum while at later growth stages decreased and finally became negative, Times of N application and level × time interaction during growing season did not affect the growth indices significantly.
Abolfazl Faraji, Aghafakhr Mirlohi,
Volume 2, Issue 3 (10-1998)
Abstract
In order to study the effects of rate and time of nitrogen application on vegetative characters, i.e., yield and yield components of rice (Zayandeh-rood variety), an experiment was conducted at Isfahan University of Technology research farm during summer 1996. Four N rates including (60, 90, 120 and 150 KgN/ha) and four splitting form (1- all N applied before transplanting 2- 1/3 N applied before transplanting, 1/3 at the beginning of tillering and 1/3 at the emergence of first panicle in 50% hills 3- 1/2 at the beginning of tillering and 1/2 at the emergence of first panicle in 50% hills 4- 1/3 at the beginning of tillering and 2/3 at the emergence of first panicle in 50% hills) were evaluated in a factorial experiment which was arranged in a randomized complete block design with 3 replications. Plant height, number of tillers per unit area and days to heading and maturity increased with an increase in the rate of fertilizer application. Grain yield and number of panicles per square meter increased when the N rate was raised to 120 Kg N/ha, while application of 150 Kg N/ha resulted in the reduction of grain yield and number of panicles. Nitrogen rate increases did not have any significant effect on number of grains per panicle. The grain weight did not follow any particular trend at different application rates, but harvest index and percentage of filled grains were decreased as the N rate increased. The percentage of nitrogen content of plant was increased as a result of higher N - rate at heading and harvest times. Treatments containing base application of nitrogen resulted in an increase in plant height, number of tillers, plant dry matter, grain yield and number of panicles per square meter, although it caused a reduction in harvest index. The number of grains per panicle and grain weight did not follow any particular trend under the influence of time of application, although plant nitrogen content increased with a delay in time of fertilizer application.
Reza Jamshidian, Mohammad Reza Khajehpour,
Volume 2, Issue 3 (10-1998)
Abstract
Methods of seedbed preparation affect establishment, growth and yield of crops via manipulating physical and chemical properties of soil. These effects on wheat-mungbean double-cropping have not been studied in Isfahan. Therefore, the influences of various seedbed preparation methods on soil physical properties and nutrients content and on establishment of mungbean (experimental line 1-61-16) were studied in a wheat-mungbean double-cropping system during 1996 at the Agricultural Research Station, Isfahan University of Technology. Two residue management treatments (burned and unburned) along with four tillage systems (moldboard plow, disk, khishchee and no-till) were laid out in a strip plot design within a randomized complete block design with four replications. Bulk density and penetrability of soil at various depths were not affected by residue management at emergence. However, at the time of flowering, bulk density at 0-15 cm soil depth was lower and soil penetrability at 3-15 cm depth was higher in unburned treatment due to mineralization. Rate and coefficient of emergence of seeds were lower in unburned residue treatment. Soil bulk density at 0-30 cm depths was lower and penetrability at 3-21 cm depth was higher with moldboard plowing at both emergence and flowering time. In addition, lower soil N, P and K content at 0-15 cm depth at emergence and flowering time was obtained with moldboard plowing. Rate and coefficient of emergence were strongly lower in no-till treatment. Based on these results and considering sustainable agricultural goals, incorporating residue with disk tillage might be advantageous under conditions similar to this experiment.
A. Ronaghi, Y. Parvizi, N. Karimian,
Volume 5, Issue 4 (1-2002)
Abstract
Nitrogen is usually the most limiting nutrient for crop production. Manganese deficiency in some calcareous soils of Iran has been reported. The objective of this study was to evaluate the effect of N and Mn on the growth and chemical composition of spinach (
Spinacia oleracea L.) under greenhouse conditions. The experiment was conducted in a soil from Chitgar series (Fine-loamy, carbonatic, thermic, Calcixerollic Xerochrepts). Treatments consisted of factorial arrangement of five N rates (0, 50, 100, 200 and 400 mg kg
-1 as NH
4NO
3) and three Mn rates (0, 15 and 30 mg kg
-1 as MnSO
4) in a completely randomized design with four replications. Plants were allowed to grow for 60 days and a hand-held SPAD-502 chlorophyll meter was used to evaluate leaf chlorophyll status at harvest.
Results showed that N and Mn application increased shoot dry weight, N and Mn concentrations and total uptake, Mn:Fe ratios and chlorophyll readings, significantly. Nitrogen increased concentrations and total uptake of Zn, Cu and total uptake of Fe in plants, but decreased Fe concentration. Addition of Mn decreased Fe and Zn concentrations in spinach but increased total uptake of Fe and Cu. When maximum dry matter was obtained, the chlorophyll meter reading was about 40. A similar study should be carried out under field conditions before the N and Mn fertilizer recommendations for spinach can be made.
G. Fathi, M. Mojedam, S. A. Siadat, G. Noor Mohammadi,
Volume 5, Issue 4 (1-2002)
Abstract
Effects of different levels of nitrogen fertilizer and cutting time of forage on grain and forage yield of barley (Hordeum vulgare L.) Karoon cultivar was studied during 1995-1996 at Ramin Agricultural Research and Educational Center, University of Shahid Chamran, Ahwas, by using a split plot design in randomized complete block with 4 replications. Main plots were assigned to five levels of N fertilizer (45, 90, 135, 180 and 225 kg N/ha) as urea fertilizer and subplots to three cutting times (no cutting, cutting forage at early stem elongation without removing reproductive meristem and cutting forage in the middle of stem elongation with cut reproductive meristem).
The effects of N rates and cutting time on grain yield were significant. Maximum yield was obtained with 281.6 g/m2 when crop plants received 90 kg N/ha and cutting time at early stem elongation and minimum yield was obtained (158.2 g/m2) with 45 kg N/ha and cutting forage in the middle of stem elongation. Interactive effect of levels of N and cutting time on spike number per m2, grain number in spike and grain weight were significant. Among yield components, spike number and grain weight showed the highest sensitivity to both. Different levels of N increased forage protein concentration and protein yield significantly, but delay in cutting time decreased protein concentration and increased protein yield. Results indicated that high levels of N could not compensate for the delay in cutting time of forage for grain yield. It was concluded that application of 90 kg N/ha and cutting time in early stem elongation was preferable for grain and forage production as compared to other treatments.
Y. Parvizi, A. Rounaghi,
Volume 6, Issue 1 (4-2002)
Abstract
Nitrogen is usually the most limiting nutrient for crop production. Thus, N fertilizer is widely used by farmers. Moreover, Mn deficiency in some calcareous soils of Iran with high pH has been reported. Therefore, the addition of nitrogen and manganese to achieve the optimum yield is necessary. The objective of this study was to evaluate the effect of N and Mn applications on the availability of some soil nutrients under wheat (Triticum aestivum L.), corn (Zea mays L.), and spinach (Spinacia oleracea L.) plants in greenhouse conditions. In a factorial test, five levels of N (0, 50, 100, 200 and 400 mg/kg soil as NH4NO3) and three levels of Mn (0, 15 and 30 mg/kg soil as MnSO4) in a completely randomized design with four replication were applied. Corn, wheat and spinach varieties were sc704 Falat and Spinacea spp., respectively. After eight weeks, total N content and DTPA-extractable Mn, Fe, Zn and Cu of soil were measured.
The results indicated that N and Mn applications increased Mn-extractable of soil in three cultures but didn’t affect the soil total N. Nitrogen application in corn increased available Fe in soil. Mn application decreased extractable Zn and Cu of soil in wheat and soil extractable Cu in corn.
H. Ghadiri, M. Majidian,
Volume 7, Issue 2 (7-2003)
Abstract
In order to investigate the effects of different nitrogen fertilizer levels and water stress during milky and dough stages on grain yield, yield components and water use efficiency of corn hybrid SC 704 (late maturing, non prolific and dent type), a field study was conducted. The factorial design of the study comprised of a randomized complete block with four replications. Four levels of nitrogen fertilizer (0, 92, 184 and 276 kg/ha nitrogen) along with three levels of irrigation (water stress imposed at milky stage, dough stage and a season-long optimum irrigation) were used as treatments.
Results showed that water stress during milky and dough stages significantly decreased grain yield and thousand kernel weight. Also, effect of nitrogen fertilizer on grain yield, kernel number per ear, kernel weight per ear and thousand kernel weight was significant. Maximum grain yield was produced with 276 kg/ha nitrogen, although no significant differences were found among 92, 184 and 276 kg/ha nitrogen levels. Regarding water use efficiency during water stress, maximum efficiency was observed at milky stage but, as water stress declined with optimum irrigation, water use efficiency decreased.
A. Mojiri, A. Arzani,
Volume 7, Issue 2 (7-2003)
Abstract
In order to study the effects of different levels of nitrogen fertilizer and plant density on grain yield and its components in sunflower, an experiment was conducted using 'Record' cultivar at the Research Farm of College of Agriculture, Isfahan University of Technology in 1996. Four levels of nitrogen (0, 75, 150 and 225 kg/ha) and four plant densities (65000, 75000, 85000 and 95000 plants/ha) were used in a split plot arranged in a randomized complete block design with three replications. Developmental stages, plant height, stem diameter, head diameter, number of head per m2, grain yield, biological yield, harvest index, 1000-grain weight, number of grains per head, grain oil percentage, oil yield and grain protein content were measured.
The results indicated that N fertilizer caused an extension of the growth period and means of days to physiological maturity. It also increased plant height, stem diameter and head diameter. While increasing plant density had an incremental effect on plant height, it negatively affected stem diameter and head diameter. N fertilizer up to 150 kg/ha increased the grain yield and biological yield, whereas higher levels of N fertilizer decreased both. Plant density of 85000 plants per hectare was observed as a suitable plant density, whereas the higher plant density had a negative effect on grain yield. N fertilizer via increasing the number of grains per head, and plant density via increasing the number of heads per unit area and also decreasing the number of grains per head influenced the grain yield. One-thousand grain weight was not affected by neither N fertilizer nor plant density. Considering the superiority of 150 kg/ha of N fertilizer and plant density of 85000 plants/ha for grain yield and oil yield, it appears that they could be recommended for producing desirable yield in the regions similar to the study region.
D. Hashemabadi, A. Kashi,
Volume 8, Issue 2 (7-2004)
Abstract
The effects of 4 different levels of nitrogen (0,120,150, and 180 kg nitrogen per hectare) and one level of poultry manure (10 tons per hectare) on the quantitative and qualitative characteristics of an autumn grown cultivar of cucumber [Cucumis sativus, cv.'super dominos] were studied in DarrehShahr, Ilam. The experiment was conducted in a completely randomized block design with 3 replications.
The results showed that treatments affected yield, number of nods and plant fresh weight and the highest yield was 41/287 ton/ha in the plots receiving poultry manure. Also 180 kg of pure nitrogen increased yield compared to control. Effect of treatments on fruit length, diameter, and fruit dry matter was different. Plant length, number of nodes, and plant fresh weight showed a positive and significant correlation with plant yield.
A. Jafari Malekabadi, M. Afyuni, S. F. Mousavi, A. Khosravi,
Volume 8, Issue 3 (10-2004)
Abstract
In recent decades, the use of nitrogen fertilizers has increased irrespective of their effects on soil properties, agricultural products and, particularly, on environmental pollution. Nitrate easily leaches from soils into groundwater. The objective of this study was to determine temporal and spatial nitrate concentrations in groundwater in agricultural, industrial and urban regions in some parts of Isfahan Province. Water samples were collected monthly from 75 agricultural, industrial, and urban wells of Isfahan, Najaf-abad, Shahreza, Natanz and Kashan during January-May 2001. The results indicated that NO3-N concentrations in most of the regions studied were higher than the standard level (10 mg/l) and nitrate pollution must be reckoned among the most serious problems of sustainable agriculture and exploitation of groundwater resources. Average NO3-N concentration in different wells ranged from 1.03 to 50.78 mg/l (4.64 to 228.5 mg/l as nitrate). The average NO3-N concentration in groundwater of Najaf-abad, Shahreza, Isfahan and Natanz-Kashan was 17.56, 14.6, 16.04, and 8.24 mg/l and 95.5, 100, 84 and 33.3 % of total wells in these regions had nitrate concentrations above the standard level, respectively. Maximum NO3-N concentration was detected in the agricultural region south of Najaf-abad (64.6 mg/l). Nitrate pollution in most of the sampling areas was mainly linked to agricultural activities. The average NO3-N concentration in groundwater of all agricultural, industrial, and urban regions, except for urban regions of Natanz and Kashan, were above the standard level. Generally, nitrate concentration level in groundwater increased with time and was maximum in March and April.
J. Pourreza, M.a. Edriss, H. Khosravinia, A. Aghaee,
Volume 8, Issue 3 (10-2004)
Abstract
In a completely randomized design, the effects of six different additive compounds including limestone, hydrochloric acid, zeolite, aluminum sulfate, pad ammoniac, and fatty acids on nitrogen, pH, temperature, moisture, water soluble phosphorus, and microbial count of litter of broiler chicken were investigated. Each compound was added at a level of one kg/m2 of litter. Six–hundred-and-sixteen (616) day- old broiler chickens (both sexes) were divided into 28 groups, 22 chicks per group. Four replications were allocated to each treatment from 1 to 56 days. All groups were fed with the same diet. Litter moisture was not affected by the treatment. Experimental treatments significantly (p<0.05) influenced the litter pH on day 21. The lowest pH was obtained with aluminum sulfate and the highest pH was obtained with limestone. At the end of the experimental period, all treatments had nearly the same pH levels. Litter temperature was not affected by the treatments . Experimental treatments had a significant (p<0.05) effect on litter nitrogen and bacterial count. Correlation between litter pH and nitrogen was significant and negative (r = -0.95, p<0.05). Effect of treatments on soluble P was significant and the lowest soluble P belonged to aluminum sulfate and pad ammoniac. Correlation between soluble P and pH was positive (r = 0.48, p<0.05). The results showed that some chemical compounds can be used to reduce litter pH, nitrogen, and soluble P and their effectiveness diminishes as chicks grow older.
M. Babashahi, Gh. Ghorbani, H. R. Rahmani,
Volume 8, Issue 3 (10-2004)
Abstract
The purpose of this study was to evaluate nutritional status in Isfahan dairy herds and the relationship between milk urea nitrogen (MUN) and fertility in the first postpartum insemination. Blood and milk samples were collected from 170 and 290 Holstein cows from 9 dairy herds, respectively. Feed samples were also collected to quantify the relationship between MUN and protein and energy content of the ration. When simple linear regression was used, a close relationship was found to exist between blood and milk urea nitrogen. Regression equations indicated crude protein percentage and protein to energy ratio in the diet only explained 7 and 10 percent of milk urea nitrogen variations, respectively. The low correlation coefficient is probably due to incorrect nutritional management and variation in diet composition in different feeding days. Logistic regression was used to determine the relationship between MUN and fertility. A negative curvilinear relationship existed between MUN and rate of pregnancy at first insemination. Since cows with MUN concentrations of 16.5 to 19 mg/dl had a better chance for pregnancy than those having either below or above these values, it seems likely that pregnancy chances for those cows having this range of MUN concentration are 1.94 and 1.63 times more than cows with less than 14 mg/dl and between 14 - 16 mg/dl, respectively.
The results of this study indicated that although MUN is a useful tool for nutritional management of dairy cows, it is not suitable for monitoring reproductive performance.
M. Sharifi, M. Hajabbasi, M. Kalbasi, M. Mobli,
Volume 9, Issue 1 (4-2005)
Abstract
Potato (Solanum tuberosum L.) has relatively weak root system and requires high nitrogen fertilizer which is costly and may pose environmental pollution. This study was conducted to compare root morphological characteristics and nitrogen uptake of some potato cultivars growing in Iran. A greenhouse experiment using a completely randomized design with 3 replications and 8 potato cultivars including: Arinda, Agria, Premiere, Diamant, Concord, Marfona, Marodana and Nevita was conducted at Isfahan University of Technology, Isfahan. Virus-free seed tubers were planted and grown up to flowering stage. The plants were then harvested and their root length (RL), root average diameter (RAD) and root surface area (RSA) were determined using a Delta-T Scan image analysis system and Windias software. Root length density (RLD), root length and shoot weight ratio (R/S) were also calculated. Dry mater production and nitrogen accumulation (total nitrogen uptake) (PNA) were also determined. Soil inorganic nitrogen was measured before planting and after harvest. All measured parameters, except RAD, were significantly (p<0.05) affected by cultivar. Large differences observed between cultivars for all traits indicated genetic diversity among the studied potato cultivars. The highest and the lowest values of RL, RLD, RSA, R/S, RDW and PNA were found in Marfona and Nevita respectively. Based on cluster analysis, cultivars were divided into four different groups. Under the condition of this study, Marfona was superior whereas Arinda, Nevita, Marodana and Agria were inferior. Due to the high differences in root morphological characteristics and nitrogen uptake among potato cultivars, plant breeders may produce cultivars with larger root volumes and high nitrogen uptake.
J. Mohammadi, H. Khademi, M. Nael,
Volume 9, Issue 3 (10-2005)
Abstract
In order to achieve a sustainable management of land resources and to improve land quality, quantitative assessment of effective factors and soil quality indicators are required. The aim of this study was to evaluate variability of selected soil quality attributes in central Zagros affected by such factors as region, land use and management practices. Twelve sites were selected in three provinces including Chahar Mahal va Backtiari (Sabzku, Broujen), Isfahan (Semirum), and Kohkeloyeh va Boyerahmad (Yasodje). Different management practices were considered such as: protected pasture, intensive grazing, controlled grazing, dryland farming, irrigated wheat cultivation, legume-farming practice, protected forest, and degraded forest. Systematic sampling with taking 50 samples of surface soil in each site was carried out. The results of univariate and multivariate analysis revealed that all factors significantly influenced the spatial variability of selected soil quality attributes namely phosphatase activity, microbial respiration, soil organic matter, and total nitrogen. The results obtained from discriminant analysis indicated that all selected soil quality parameters could significantly be used as soil quality indicators in order to recognize and discriminate sustainable agricultural and forestry ecosystems and/or optimal management practices.
M. Sepehri, N. Saleh Rastin, H. Asadi Rahmani, H. Alikhani,
Volume 10, Issue 1 (4-2006)
Abstract
Heavy metals have deleterious the effects on nodulation and N2 fixation of Rhizobium- Legume symbiosis, due to their inhibitory effects on the growth and activity of both symbionts. This research has been undertaken to evaluate the effect of Cd tolerance of native rhizobial strains on diminution of the Cd detrimental effects on Sinorhizobium meliloti-alfalfa symbiosis. For this purpose, a greenhouse experiment was conducted based on Randomized Complete Block Design. The treatments in this experiment included: plants inoculation with 6 bacterial strains (sensitive, partially tolerant and tolerant to Cd), 5 levels of Cadmium (0, 2, 5, 10, 20 mg/kg soil) and non-inoculated control. In different levels of Cd, the effects of bacterial inoculation on root nodule number and total amount of nitrogen in plant shoot were compared. The results indicated that soil pollution by Cd even at 2 mg/kg had significant effect on symbiotic properties of rhizobial strains, and according to Cd tolerance of various strains, the mentioned effect was different. Decreasing effect of Cd concentration on root nodules and nitrogen concentration in plants that were inoculated with sensitive strains in comparison with plants inoculated with tolerant strains was 68.31% and 40.8%, respectively. In this research, R95m was introduced as the best strain because of its ability for nodulation and nitrogen fixation.
R. Taherkhani, M. Shivazad, M. Zaghari, A. Zare Shahne,
Volume 10, Issue 1 (4-2006)
Abstract
A chick bioassay with chemically defined amino acid (AA) diets was conducted to compare four different AA profiles: the NRC 1994, Feedstuff 2002, Rhone Poulenc Animal Nutrition 1993(RPAN) and Illinois Ideal Chick Protein (IICP) AA profiles. This battery study involved male and female chicks during 7 to 21 days of age. Indispensable AA were rationed to lysine according to requirement ratios presented in the four profiles. Digestible lysine set at 1.07 and 0.98 % of diet for male and female respectively. This experiment was carried out in a completely randomized block design using 2 5 factorial arrangement with for replicate per each diets were kept isonitrogenous (2.6 % N ) by varying levels of L-glutamic acid. All diets were checked to have at least 0.3 % proline and 0.6 % glycine. Diets for all profiles contained 3200 kcal ME/kg and a positive control diet were used according to NRC 1994 recommendations. Chicks fed a common corn-soybean meal diet for 160 h and were raised in the floor pen. Then chicks weighted individually and allocated to battery pens so that most uniformity between pens occurs. Four battery pens of five chicks were fed one of four different profiles or positive control diet in both male & female. Weight gain and feed efficiency measured for each pen at day 21. Results indicate an improved weight gain and feed efficiency in male rather than female (p<0.5). Chicks fed positive control diet weighted more (p<0.5). Between semi purified diets chicks fed diets formulated with NRC AA ideal ratios had significantly (P<0.5) better weight gain and gain: feed in both sexes relative to IICP and RPAN, but not to Feedstuff. RPAN had worst weight gain and feed: gain in females. Results of this experiment indicated that new ideal ratio of theronine (relative to lysine) in IICP for starter period may be under-estimated.
A. Azizian, A. R. Sepaskhah, A.r. Tavakoli, M. Zibaee,
Volume 10, Issue 4 (1-2007)
Abstract
Irrigation water Scarcity is the major limiting factor for crop production in irrigated farming. Therefore, optimal use of water is influenced by seasonal rainfall especially where the water price is high. Nitrogen also plays a key role in plant nutrition. In this study, wheat grain yield production as a function of applied water (irrigation plus seasonal rainfall) and nitrogen fertilizer (applied plus soil residual nitrogen) using existing data of a field experiment, were used. This function was obtained based on the data from the Maraghah Agricultural Experiment station. Based on this production function, maximum attainable yield can be 8.12 t/ha obtained by the consumption of 1.56 m of water (irrigation plus rainfall) and 193 kg/ha of nitrogen. An economic analysis based on the Iso-Quant curve was conducted to optimize the application rates of production inputs (water and nitrogen). When land is limited, the optimum water and nitrogen use will be based on maximizing net returns from land unit area. The optimal levels of these inputs were determined on the basis of farmer ability for paying the costs of water and nitrogen. Furthermore, optimum amounts of water and nitrogen were determined for different levels of wheat yield. The results indicated that despite low price of irrigation water and nitrogen fertilizer, at present market value, optimum values of water were more variable than those of nitrogen, for its high effective role in wheat production. The results also indicated that when there is no limitation of the source and use of water and nitrogen, and farmers are also able to pay their costs, application of 1.47 m of water (irrigation plus rainfall) and 190 kg/ha of nitrogen (applied plus soil residual) will produce maximum profit per hectare, reaching Rls 12,207,506. When water is limited, optimum levels of water and nitrogen will be based on the maximizing profit per unit of water. In this analysis, the use of 0.556 m of water (irrigation plus rainfall) and 190 kg/ha of nitrogen (applied plus soil residual) resulted in maximum net income per unit of applied water (irrigation plus rainfall) amounting to Rls/m3 1203. This amount of water use, which is 64.4 % lower than its amount under maximum yield condition, resulted in 181 % increase of cultivated area. Graphic expansion path on the isolines of yield showed more dependence of wheat production on water than nitrogen. Therefore, the optimum amounts of nitrogen in the three mentioned conditions are close to each other due to its subsidized price and lower effect on wheat production relative to water.
H. R. Ali Abbasi, M. Esfahani, B. Rabiei, M. Kavousi,
Volume 10, Issue 4 (1-2007)
Abstract
Effect of nitrogen (N) fertilizer levels and its split applications on yield and yield components of rice (Oryza sativa L.) Cv. Khazar was investigated in a completely randomized block design with 3 replications in a paddy light soil at Guilan province, Iran, 2003. In this experiment, six treatments including: T1-control (no N fertilizer) T2- 40 kg/ha N (at transplanting time) T3- 80 kg/ha N (at transplanting, and tillering times) T4- 80 kg/ha N (at transplanting, tillering, and panicle initiation times) T5- 120 kg/ha N (at transplanting, and tillering times) and T6- 120 kg/ha N (at transplanting, tillering, and panicle initiation times) were compared. Results showed that the highest fertile tiller number was obtained in the fifth and sixth treatments with double and triple split applications of 120 kg/h N (236 and 248 m-2). The highest fertile filled spikelets percentage (84.8%), 1000-grain weight (26.1 g) and grain yield (4.83 t/ha) belonged to the sixth treatment, but grain yield and 1000-grain weight were not significantly differerent in the fourth and sixth treatments with three fertilizing times. This finding may have resulted from the third topdressing application of nitrogen fertilizer in panicle initiation and higher leaf area (44.8 and 45.5 Cm2), leaf greenness (39.4 and 39.9) and leaf nitrogen concentration (31.2 and 33.6 g/kg) during grain filling in the fourth and sixth treatments. Regression analysis also showed that flag leaf greenness (SPAD values at 5 days after flowering) and flag leaf area accounted for about 75% and 78% changes in yield, respectively. In conclusion, triple split application of 80 kgN/ha could be suggested for rice Cv. Khazar in these regions since the yield would be the same as the application of 120Kg/ha N.
A. Bahrani, Z.tahmasebi Sarvestani,
Volume 11, Issue 40 (7-2007)
Abstract
Understanding the nitrogen remobilization by plant, in order to obtain cultivars with higher quality, has specific importance in plant physiology. In this experiment, a bread and a durum wheat cultivar, were treated with different rates and times of nitrogen application, by using split factorial on the basis of randomized complete block design with three replications at Shiraz region during 2001-2002. Main plots consisted of two levels of cultivars ( Falat and Yavaros) and sub plots included nitrogen (40, 80 and 160 (kg ha-1) and times of nitrogen application (T1= all N fertilizer at planting , T2= 1/2 at planting + 1/2 during stem elongation and T3= 1/3 at planting + 1/3 during stem elongation + 1/3 at heading stage). The results showed that there was a significant difference between cultivars in flag leaf nitrogen content at maturity stage, N remobilization and its efficiency from flag leaf to grains and also grain protein percentage. Durum wheat was more efficient in nitrogen remobilization and therefore, had a higher grain protein percentage. Increase in rates and times of nitrogen application had significant effect on most of the measured traits. There were significant interactions between cultivars, rates and times of N application, indicating that durum wheat was more efficient in N remobilization from flag leaf to the grain. It appeared that N remobilization efficiency was the important factor affecting the grain protein percentage. Also increases in yield are associated with corresponding decreases in wheat protein.
M. Heidari, H. Nadeyan, A.m. Bakhshandeh, Kh. Alemisaeid, G. Fathi,
Volume 11, Issue 40 (7-2007)
Abstract
The influence of Nitrogen (N) rates on mineral nutrient uptake in stem and seeds, proline and carbohydrate in flag leaves of Wheat (Triticum aestivum L . Var Chamran) under saline conditions was studied in a field experiment in 2003 and 2004. The experiment was conducted using a split plot design with three replications. The treatments comprised five levels of salinity: 1.5, 5, 10, 15 and 20 ds/m in main plot and three nitrogen levels: 50 , 100 and 150 kg N/ha in sub plot. Salinity treatments were applied in a clay–loam soil by water with NaCl and CaCl2 (5:1 by wt ). The results showed, the nutrient uptake was influenced by both salinity and N treatments. With the Exception of magnesium in seed, salinity increased nitrogen, calcium and magnesium concentrations in seed and stem in both years. By increasing salinity levels, the concentration of potassium in stem and seed decreased and Sodium concentration increased. In the stem the concentration of Sodium in the 20 ds/m was about 17 and 22 times more in the first and second year, respectively. In these experiments, by increasing salinity and nitrogen treatments, proline concentration in flag leaves increased in the two stages (flowering and milky stages) in both years. Salinity had similar effect on carbohydrate accumulation in both stages, but nitrogen treatment had two different effects on carohydrate concentration. In flowering stage, by increasing nitrogen application, carohydrate concentration increased but in milky stage decreased.
