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Search Results: 1 - 10 of 50636 matches for " Y. Emam "
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Effect of Defoliation and Drought Stress on Yield Components and Chlorophyll Content of Wheat
E. Bijanzadeh,Y. Emam
Pakistan Journal of Biological Sciences , 2010,
Abstract: In order to examine the effects of source restriction and drought stress on yield components, flag leaf chlorophyll content and Relative Water Content (RWC) of wheat cultivars, a greenhouse experiment was carried out at Shiraz University, Shiraz, Iran, during 2009-2010. The wheat cultivars including Shiraz, Bahar, Pishtaz, Sistan and Yavaros were sown in 5 kg plastic pots. The source manipulation treatments including control (C), defoliation of all leaves (D1), defoliation of all leaves except the flag leaf (D2) and defoliation of all leaves except the flag leaf and penultimate leaf (D3), were imposed at anthesis. Results showed that source restriction decreased number of grain per spike significantly in Shiraz cultivar under drought stress condition. Maximum 100-grain weight was observed in C treatment of Yavaros and Shiraz under well-watered condition. Among the defoliation treatments under drought stress condition, D2 in Pishtaz and D1 in Shiraz had the highest (3.66 g) and lowest (2.71 g) 100 grain weight, respectively. In all cultivars drought stress decreased main shoot yield significantly but in Pishtaz and Sistan decreasing rate was less than the other cultivars. RWC in Shiraz decreased sharply from 92.1% in well-watered to 66.7% (27.5% reduction) under drought stress at 10 DAA. After anthesis, Pishtaz and Sistan maintained higher content of flag leaf chlorophyll (from 49.4 to 56.8 SPAD unit) under drought stress condition. Generally, selection and culture of cultivars that had small responses to defoliation might be a useful strategy in yield improvement of wheat in areas where the water availability is low.
Effect of Source-Sink Manipulation on Yield Components and Photosynthetic Characteristic of Wheat Cultivars (Triticum aestivum and T. durum L.)
E. Bijanzadeh,Y. Emam
Journal of Applied Sciences , 2010,
Abstract: To investigate the effect of source-sink manipulation on photosynthetic characteristics and yield components of wheat cultivars, a research was carried out in the greenhouse at the College of Agriculture, Shiraz University, Shiraz, Iran, during 2008-2009 growing season. Five wheat cultivars including Shiraz, Bahar, Pishtaz, Sistan (as bread wheat) and Yavaros (as durum wheat) were grown in 5 kg plastic pots. The source-sink manipulation treatments including defoliation of all leaves, defoliation of all leaves except the flag leaf, removal of 25% of spikelets and removal of 50% of spikelets were applied at anthesis. Results showed that number of grains per spike was significantly decreased by defoliation treatment in Shiraz, Bahar and Yavaros cultivars, so that in Shiraz and Bahar cultivars, source restriction reduced the number of grains per spike by 18.97 and 11.07%, respectively. In Shiraz cultivar, defoliation of all leaves decreased main stem grain yield by 40.75%, which demonstrated that Shiraz was very sensitive to source restriction. The little response of main shoot grain yield to defoliation in Pishtaz cultivar indicates high mobilization of photoassimilate from other parts of the crop to the grains. Under sink restriction conditions, wheat cultivars (except Pishtaz) had potential to increase their 100-grain weight; moreover, Pishtaz yield appeared to be more sink rather than source-limited. Removal of all leaves except the flag leaf at 8 and 18 DAA, in Pishtaz and Yavaros cultivars, had no significant effect on net photosynthesis rate (Pn) and in all cultivars except Pishtaz, sink restriction significantly decreased Pn rate. Further research, is recommended for improving our understanding on source-sink relationship in Iranian wheat cultivars.
Physiological and Morphological Responses of Two Barley Cultivars to Salinity Stress in Relation to Grain Yield
M. R. Tadayon,Y. Emam
Journal of Science and Technology of Agriculture and Natural Resources , 2007,
Abstract: In order to study the physiological responses of two barley cultivars to salinity stress, a 4-replicate CRD greenhouse experiment was conducted during at the College of Agriculture, Shiraz University, Iran2003-2004. The treatments consisted of two barley cultivars: Afzal and Reyhan and five salinity levels: 0, 4, 8, 12 and 14 dS/m. Seedling emergence, number of tillers and leaves per plant, leaf area and dry matter decreased with increasing salinity levels. The reductions were lower in Afzal (salt tolerant) than Reyhan (salt sensitive). A lower Na+ and higher K+Na+ in Afzal compared to Reyhan were observed under high level of salinity. The results of the present experiment also showed that the tolerance to salinity was associated with a greater stomatal conductivity, as well as transpiration and photosynthesis rate. Sub-stomatal CO2 concentration in both cultivars decreased with an increase in salinity, with the exception of 12dS/m, where it led to an increase in sub-stomatal CO2 concentration. Leaf temperature increased with an increase in salinity level in both cultivars, whereas a more pronounced decrease for number of fertile tillers, ears per plant, kernels per ear, thousand grain weight and harvest index was observed in Reyhan compared to Afzal .Since a higher tolerance to salinity in Afzal was apparently associated with a lower concentration of Na+ and a higher K+/Na+ ratio of the shoots, this trait could probably be used for yield improvement of barley cultivars under saline conditions.
Roughly B-invex Multi-Objective Programming Problems  [PDF]
Tarek Emam
Open Journal of Optimization (OJOp) , 2012, DOI: 10.4236/ojop.2012.11001
Abstract: In this paper, we shall be interested in characterization of efficient solutions for special classes of problems. These classes consider roughly B-invexity of involved functions. Sufficient and necessary conditions for a feasible solution to be an efficient or properly efficient solution are obtained.
Physiological Characteristics and Grain Yield of Winter Wheat in Response to Planting Density and Sowing Date
F. Momtazi,Y. Emam,N. A. Karimian
Journal of Science and Technology of Agriculture and Natural Resources , 2005,
Abstract: The physiological characteristics of winter wheat(cv. Shiraz) were evaluated in a 2-yrs field study by using a spilit plot design with four replications, at the experimental farm of Shiraz University, College of Agriculture located at Badjgah. Main plots consisted of three sowing dates (November 6th, December 6th and January 5th) and four planting densities (150, 250, 350 and 450 plants/m2) were assigned as sub plots. The results indicated that delay in sowing was associated with a significant reduction in the grain yield. So that the grain yield in sowing date of January 5th was significantly less than it in sowing dates of November 6th and December 6th. Moreover with delay in sowing date the developmental rate of wheat was enhanced and plants reached maturity more rapidly. The trend of the leaf area index changes and the dry weight of the plants were under the effect of experimental treatments, leaf area index was found to be greater at the higher densities and early planting date. Number of stems per m2 were decreased with delay in the sowing date, although at the higher densities, the number of stems per m2 was greater, despite severe tiller death observed at these densities. The study of trend of dry weight changes during the season indicated that biomass was greater at higher densities and earlier sowings, which resulted in earlier ground cover and higher amount of radiation interception. In conclusion, the results of the present investigation revealed that to achieve a reasonable grain yield, the 6th of December and 250 plants per m2 were the best sowing date and planting density for wheat (cv. Shiraz) under similar agro climatic conditions with the present investigation.
Effect of Supplemental Irrigation and Amount of Available Water on Yield, Yield Components and Physiological Characteristics of Two Rainfed Wheat Cultivars
M.R. Tadayon,Y. Emam
Journal of Science and Technology of Agriculture and Natural Resources , 2008,
Abstract: Photosynthesis and wheat grain yield responses to supplemental irrigation with different amount of applied water under dryland conditions were investigated. Therefore, a two-year field experiment was conducted research farm of College of Agriculture, Shiraz University during 2004-2005. Five levels of irrigation including dryland conditions, irrigation at stem elongation, booting, flowering and grain filling were main plots and two wheat cultivars: Agosta and Fin-15 were subplots, and three rates of nitrogen including zero, 40 and 80 kgha-1 were sub sub-plots. The results showed that in both years, photosynthetic rate, stomatal conductance, substomatal CO2 concentration and transpiration rate, were significantly higher under irrigation at stem elongation stage compared to other supplemental irrigation treatments. In all of the four supplemental irrigation treatments, photosynthetic rate, stomatal conductance, substomatal CO2 concentration and transpiration rate decreased with decreasing the amount of applied water to each plot. In both years, the highest grain yield was obtained from supplemental irrigation at stem elongation stage, and the lowest yield was harvested at dryland conditions. The highest photosynthetic parameters, yield and yield components were obtained from interaction of supplemental irrigation at stem elongation stage × Fin-15 and 80 kg N ha-1 in both years. The supplemental irrigation in 2004 and 2005 increased the grain yield 200 and 221 percent, respectively, compared to dryland conditions. Thus, supplemental irrigation at sensitive stem elongation stage could affect significantly wheat grain yield of rainfed wheat cultivars and provision of adequate water for a supplemental irrigation at the appropriate growth stage could double the grain yield of rainfed wheat.
The Effect of Drought Stress and Cycocel on Barley Yield (Cv. Valfajr)
S. Sharif,M. Saffari,Y. Emam
Journal of Science and Technology of Agriculture and Natural Resources , 2007,
Abstract: Many experiments have been carried out to alleviate the negative effect of drought stress and to obtain suitable growth under water deficient condition. Application of plant growth regulators (especially growth retardants) is one of the proposed methods. In a greenhouse experiment using a completely randomized block design with 4 replications at Kerman University Agricultural Department, the effect of 4 drought levels 25, 45, 65, 85 percent of field capacity and 3 different concentrations of chlormequat chloride 0, 1500, and 3000 mg/liter on some factors of winter barley cultivar Valfajr was investigated. Results indicated that increasing the cycocel concentration from 0 to 3000 milligram per liter leads to significant decrease in plant height. Relative water content affected by growth retardants was increased. Numbers of tillers and root and shoot dry weight, were also decreased because of applying cycocel in dry condition. The result also indicated that the root/shoot dry weight ratio, grain number per ear and ear number in dry condition without stress would increase using cycocel treatment.
Nitrogen and Boron Interactional Effect on Growth and Shoot Nitrogen and Boron Content in Rice
H. Koohkan,M. Maftoun,Y. Emam
Journal of Science and Technology of Agriculture and Natural Resources , 2008,
Abstract: Nitrogen (N) is usually low in the majority of agricultural and non agricultural soils in Iran, mainly due to the lack of adequate soil organic matter (OM). On the other hand, boron (B) toxicity is becoming more widespread in arid and semi arid regions of this country, where soils or irrigation waters contain relatively high B content. Results of the research indicate that addition of certain plant nutrients such as N may reduce the harmful effect of high B levels. Therefore, the present experiment was undertaken to evaluate the interactive effect of N and B on the growth and chemical composition of rice in a calcareous soil. Treatments consisted of six B rates ( 0, 2.5, 5, 10, 20 and 40 mg kg-1 as boric acid) and four levels of N ( 0, 75, 150 and 300 mg kg-1 as urea) arranged in a factorial manner in a completely randomized design with three replicates. Application of B decreased shoot dry matter. At low B levels, N application alleviated the toxic effect of B. Moreover, the addition of B increased B and N concentrations in the rice shoot. The N concentration increased and B accumulation decreased with increasing N rates. There was a general trend of increase in shoot N and chlorophyll concentrations with increasing chlorophyll meter reading. Chlorophyll concentration decreased with increasing B levels. N fertilization increased chlorophyll content and somewhat reduced the adverse effects of high B rates on this plant parameter. The results reported herein show that in soils with high B levels, N application may alleviate the suppressing effects of B toxicity and increase rice growth possibly due to a decrease in B absorption by the plant
Response of lettuce to Cd-enriched water and irrigation frequencies
A Azizian, S Amin, M Maftoun, Y Emam, M Noshadi
African Journal of Environmental Science and Technology , 2011,
Abstract: This pot experiment was an attempt to investigate a broad response of lettuce to different cadmium (Cd) levels of irrigation water (0, 5, 10 and 20 mg l-1) under different irrigation intervals (1, 2 and 4 days). The results showed that increased level of soil Cd through irrigation eventually decreased the yield of lettuce in all cases; however, in some cases yield was increased with lower doses of Cd application. No injury symptoms were observed other than plant height and yield reduction. Shoot dry weight proved to be the most sensitive parameters to the cadmium, especially under water stress conditions. The results also showed that the concentrations of nutrient elements in lettuce shoot were suppressed by water stress. The presence of cadmium in irrigation water did not significantly affect the absorption of nutrient elements by plants except for Fe. Shoot Cd concentration and its uptake decreased with increasing irrigation frequencies and the reverse trend occurred with increasing Cd levels of irrigation water. However, the values were higher than recommended guideline in all conditions. Also, shoot Cd content showed a significant positive correlation with the final accumulated Cd concentration of soil and was expressed by a plateau model under the dry irrigation regime and linear models at other irrigation intervals. Overall, shoot Cd concentration was predicted by using a simple linear regression model regardless of evapotranspiration and transpiration rate of plant.
Exogenous application of salicylic acid and chlormequat chloride alleviates negative effects of drought stress in wheat
H. Pirasteh Anosheh,Y. Emam,M. Ashraf,M. R. Foolad
Advanced Studies in Biology , 2012,
Abstract:
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