جستجوی مقالات مرتبط با کلیدواژه "کارآیی مصرف نور" در نشریات گروه "زراعت"

Growth analysis has a significant perspective on the function of agricultural plants. In the early stages of plant growth, the growth indicators, including the leaf area index, the growth rate of the product decreases, and then due to suitable vegetation, the absorption of light radiation is better, and the accumulation of plant dry matter also increases, and after that Due to aging and yellowing, the leaves are reduced. The amount of light radiation absorbed by the plant varies during the growth period, which depends on the leaf surface index and the arrangement of the leaves of the plant.

The experiment was conducted in the research farm of Khuzestan University of Agricultural Sciences and Natural Resources in 2021-2022. In this research, the effect of three factors of irrigation interruption, cultivars and density was investigated in the form of factorial split with the base design of randomized complete blocks in three replications. The factor (no interruption of irrigation (control), interruption of irrigation at the beginning of flowering until the formation of 50% of the pod and interruption irrigation at the stage of pod formation until harvest the main factor, rapeseed cultivars Hayola 4815 and Aram and plant density per meter square (80, 110 and 140 plants per square meter) were considered as secondary factors.

Irrigation interruption caused a decrease in growth indicators, including the amount of plant dry matter accumulation, leaf surface index, and leaf surface durability. The changes in harvest index and durability of leaf surface and accumulation of dry matter at the beginning of the development of leaves had a slow trend until a little before the appearance of inflorescences, but after that the slope of the mentioned parameters increased. During the experiment, changes in growth parameters including LAI, LAD, RGR, CGR and TDW were evaluated. At the beginning of the plant growth season, the growth rate of the product was low due to the lack of complete vegetation cover and proper light consumption efficiency. In all treatments, with the passage of time, the growth rate of the crop was gradually increasing and it reached the maximum value in the reproductive stages and then went through a decreasing process. The effects of stopping irrigation on dry weight were evident and the accumulation of dry matter was observed during the increasing time. which can be due to the increase in dry weight of stems, leaves and reproductive organs over time. Also The relative growth rate also showed an increasing trend with the increase of the leaf area index at first and then a decreasing trend.

It seems that the second-stage irrigation interruption treatment at a density of 80 plants per square meter and Haiola 4815 variety, by maintaining more green area through more leaf surface durability and lower light consumption in the condition of irrigation interruption at the end of the growing season, was able to achieve a higher RUE100 compared to other treatments. to dedicate The highest seed yield (1572.61 kg per hectare) was obtained from the density of 110 plants per square meter and Hayola variety 4815.

In recent decades, the introduction of high-yielding cultivars under optimal conditions has been the main focus of grain research programs. The identification of wheat cultivars that have acceptable yields on different planting dates has been taken into account.

The present split-plot test was performed with three replications in two cropping years, 2016-2017 and 2017-2018. The main factor included three planting dates (October 20, November 20, and December 20 as early, normal, and delayed planting dates), and the sub-factor included six wheat cultivars (Zare with winter growth habits, Heidari, Pishgam, and Alvand with facultative growth habits, and Sirvan and Pishtaz with spring growth habits). The soil was sampled from a depth of 0 to 30 cm before the experiment, and the physical and chemical traits of the soil were determined. Land preparation steps were performed before the experiment. For this purpose, a land area of 1500 m2 was plowed by a reversible plow and then leveled. Fertilizer application was performed based on the soil experiment results as 100 kg.ha-1 of triple superphosphate, 100 kg.ha-1 of potassium sulfate, and 100 kg.ha-1 of urea before planting. The rest of the urea fertilizer (200 kg.ha-1) was applied at the stage of stem emergence and the beginning of anthesis wheat. Iron, zinc, and manganese fertilizers were also used from their sulfate sources at the rate of 0.2%, which were sprayed in two stages at the beginning of stalking and spiking. Each plot was 5 m long and 2 m wide and consisted of 8 planting rows at a distance of 25 cm. A distance of 50 cm was considered between the two sub-plots and 1 m between the two main plots. The required seed for each experimental plot was determined and distributed based on the density of 400 seeds per m2 based on the weight of 1000 seeds of each cultivar. Irrigation was performed immediately after planting. Agricultural care was applied uniformly, including pest, disease, and weed control. In each subplot, 50 cm from the beginning and end of the rows was considered as the margin. All data were subjected to ANOVA using the GLM procedure of SAS (SAS 9.1) and means were compared by using the Duncan test at 5% probability level.

The results showed that delayed planting reduced nutrient uptake and increased the extinction coefficient. Radiation use efficiency on the planting date of December 20 showed a reduction of 27% and 25%, compared to the planting date of October 20 in 2016-2017 and 2017-2018, respectively. Also, on December 20, Sirvan and Pishtaz cultivars with spring growth habits showed lower extinction coefficients and higher photosynthesis rates than winter and facultative cultivars. On October 20 and November 20, the highest grain yield was obtained in cultivars with winter and facultative growth habits. On December 20, the grain yield was higher in cultivars with facultative and spring growth habits than in winter cultivars. Late planting of wheat cultivars with winter growth type, which must receive low temperatures for Vernalization, is very risky. Because delaying planting may lead to a sharp decrease in yield. These negative consequences of the delay in planting may have occurred through disruption of absorption of water, nutrients, and absorption of active photosynthetic radiation. Late cultivation shortens the vegetative growth period and the plant enters the reproductive stage prematurely, and then the plant faces a lack of photosynthetic resources. Also, the grain filling period is faced with drought and heat stress at the end of the season and this final stress causes a sharp decrease in yield.

In general, the delayed planting significantly reduced grain yield, especially in cultivars with winter growth habits. Therefore, it is recommended to use intermediate and spring cultivars for delayed cultivation.

In recent decades, agricultural production systems have already explored many methods to increase the crops yield. Most of these methods involved increasing the efficiency of resources utilization such as nutrients, solar radiation, and atmospheric CO2. Crop growth and yield are considered as a function of photosynthetically active radiation (PAR) that is intercepted by plant as well its utilization efficiency to produce dry matter. Net primary production has often been found to be linearly related to the photosynthetically active radiation (PAR) intercepted by crops. The slopIntroduction In recent decades, agricultural production systems have already explored many methods to increase the crops yield. Most of these methods involved increasing the efficiency of resources utilization such as nutrients, solar radiation, and atmospheric CO2. Crop growth and yield are considered as a function of photosynthetically active radiation (PAR) that is intercepted by plant as well its utilization efficiency to produce dry matter. Net primary production has often been found to be linearly related to the photosynthetically active radiation (PAR) intercepted by crops. The slope of this relationship is light use efficiency (LUE). Several authors have found close correlation between crop growth and yield with the radiation absorption and the LUE. Although, it was previously believed that the LUE is constant during the crop growing season and it is controlled more genetically, but environmental factors and management practices such as change in the sowing date, plant density, cultivars, climate, soil fertility, especially soil available nitrogen due to its specific role in photosynthesis, affect greatly the LUE. Therefore, the objectives of the present study were to evaluate light absorption and use efficiency in different sowing date for chickpea cultivars in Kermanshah regionlight absorption and use efficiency in different sowing date for chickpea cultivars in Kermanshah region climatic.

A split plot experiment was conducted based on Randomized Complete Block Design during 2016-2017 at the research farm of the faculty of agriculture and natural resources of Razi University, Kermanshah, Iran (34°, 19´ N, 47°, 50´ E and altitude 1317 m). The average annual rainfall was 455 mm, and the long-term average of maximum and minimum air temperature was 22.6 and 5.9°C, respectively. Main plots had three sowing dates (February 29, Match 10 and April 6) and sub plots were composed of chickpea cultivars (Bivanij, Adel, Arman and ILC482). The measured indexes were leaf area index (LAI), radiation absorption, total dry matter (TDM), light use efficiency (LUE) and grain yield of chickpea. The LUE was calculated based on g MJ-1 through the slope of linear regression between total dry matter accumulation (g m-2 ) and cumulative absorbed photosynthetically active radiation. Chickpea grain yield was measured at the physiological maturity stage. Results and Discussion The results showed that the maximum LAI of different chickpea cultivars decreased with the delay in sowing date. The greatest LAI (3.8) was related to Arman cultivar with the sowing date of March 1 and the lowest LAI (1.9) was related to ILC482 cultivar with the sowing date of April 6. The light absorption had the similar LAI trend that with the delay in sowing date decreased about 51%. The highest (15.9 MJ m-2 ) and the lowest (13.4 MJ m-2 ) light absorption were observed for Arman cultivar with the sowing date of March 1 and ILC482 cultivar with the sowing date of April 6, respectively. Combined analysis of variance of the results indicated that the effects of sowing date and cultivars were significant on TDM and grain yield, but the interactions of sowing date and cultivars were not significant for TDM and grain yield. The results indicated that the delay in sowing date led to reduce in the grain yield (45%) and TDM (33.5%). The highest (158 g m-2 ) and the lowest (102 g m-2 ) grain yield were related to Bivanij and Arman cultivars, respectively. The grain yield of Bivanij cultivar was higher (35%) compared to other cultivars. The highest LUE (1.6 g MJ-1 ) was observed for Adel cultivar with the sowing date of March 1 and the lowest LUE (0.7 g MJ-1 ) was related to Arman cultivar with the sowing date of April 6. Late sowing dates of March 11 and April 6 reduced LUE compared to early sowing date of February 29 about 4.2% and 2.7% in Bivanij cultivar, 9.4% and 27.3% in Adel cultivar, 43.4% and 40.3% in Arman cultivar and 19.1% and 16.8% in ILC482 cultivar, respectively.

In general, the results of this study show that the delay in sowing date, which is unavoidable under some climatic conditions by the farmer, lead to reduce in measured traits such as grain yield and LUE of chickpea. However, it seems that late sowing could help with the selection of suitable chickpea cultivars that could offset the yield loss due to unsuitable environmental condition such as drought stress by end of the growing season.e of this relationship is light use efficiency (LUE). Several authors have found close correlation between crop growth and yield with the radiation absorption and the LUE. Although, it was previously believed that the LUE is constant during the crop growing season and it is controlled more genetically, but environmental factors and management practices such as change in the sowing date, plant density, cultivars, climate, soil fertility, especially soil available nitrogen due to its specific role in photosynthesis, affect greatly the LUE. Therefore, the objectives of the present study were to evaluate light absorption and use efficiency in different sowing date for chickpea cultivars in Kermanshah regionlight absorption and use efficiency in different sowing date for chickpea cultivars in Kermanshah region climatic. Material and MethodsA split plot experiment was conducted based on Randomized Complete Block Design during 2016-2017 at the research farm of the faculty of agriculture and natural resources of Razi University, Kermanshah, Iran (34°, 19´ N, 47°, 50´ E and altitude 1317 m). The average annual rainfall was 455 mm, and the long-term average of maximum and minimum air temperature was 22.6 and 5.9°C, respectively. Main plots had three sowing dates (February 29, Match 10 and April 6) and sub plots were composed of chickpea cultivars (Bivanij, Adel, Arman and ILC482). The measured indexes were leaf area index (LAI), radiation absorption, total dry matter (TDM), light use efficiency (LUE) and grain yield of chickpea. The LUE was calculated based on g MJ-1 through the slope of linear regression between total dry matter accumulation (g m-2) and cumulative absorbed photosynthetically active radiation. Chickpea grain yield was measured at the physiological maturity stage. 

The results showed that the maximum LAI of different chickpea cultivars decreased with the delay in sowing date. The greatest LAI (3.8) was related to Arman cultivar with the sowing date of March 1 and the lowest LAI (1.9) was related to ILC482 cultivar with the sowing date of April 6. The light absorption had the similar LAI trend that with the delay in sowing date decreased about 51%. The highest (15.9 MJ m-2) and the lowest (13.4 MJ m-2) light absorption were observed for Arman cultivar with the sowing date of March 1 and ILC482 cultivar with the sowing date of April 6, respectively. Combined analysis of variance of the results indicated that the effects of sowing date and cultivars were significant on TDM and grain yield, but the interactions of sowing date and cultivars were not significant for TDM and grain yield. The results indicated that the delay in sowing date led to reduce in the grain yield (45%) and TDM (33.5%). The highest (158 g m-2) and the lowest (102 g m-2) grain yield were related to Bivanij and Arman cultivars, respectively. The grain yield of Bivanij cultivar was higher (35%) compared to other cultivars. The highest LUE (1.6 g MJ-1) was observed for Adel cultivar with the sowing date of March 1 and the lowest LUE (0.7 g MJ-1) was related to Arman cultivar with the sowing date of April 6. Late sowing dates of March 11 and April 6 reduced LUE compared to early sowing date of February 29 about 4.2% and 2.7% in Bivanij cultivar, 9.4% and 27.3% in Adel cultivar, 43.4% and 40.3% in Arman cultivar and 19.1% and 16.8% in ILC482 cultivar, respectively. ConclusionIn general, the results of this study show that the delay in sowing date, which is unavoidable under some climatic conditions by the farmer, lead to reduce in measured traits such as grain yield and LUE of chickpea. However, it seems that late sowing could help with the selection of suitable chickpea cultivars that could offset the yield loss due to unsuitable environmental condition such as drought stress by end of the growing season.

Introduction Wheat breeders have been constantly working to develop new varieties with improved productivity and yield and resistance to pests and diseases. These varieties are being released frequently and are replaced existing ones over and released on basis of their performance under open conditions. Intercropping has been widely applied to reduce soil erosion and water loss, restoring ecological balance, improving radiation and nutrient use efficiency, raising land equivalent rate and increasing economic benefits. The objective of the present work was to determine the effect of row intercropping of old and newwheat cultivars and canola as additive series on the yield, yield components, radiation use efficiency and land equivalent ratio under climatic conditions of Mashhad. Materials and Methods This experiment was conducted as factorial layout based on a randomized complete block design with three replications at the Agricultural Research Ftation of Ferdowsi University of Mashhad, Iran during two growing season of 2014-2015 and 2015-2016. The first and the second factors were wheat varieties (the old: Roshan and Tabasi and the new: Parsi and Sirvan) and intercropping ratios of wheat and canola in additive series (0:100, 25:100, 50:100, 75:100, 100:100 and 100:0), respectively. Investigated traits were seed, biological and straw yield of wheat and number of pods per plant, number of seeds per plant, 1000-seed weight, seed, biological and straw yield of canola, radiation use efficiency based on seed yield and total dry matter land equivalent ratio. For analysis of variance SAS 9.1 was used. All the means were compared according to least significant test (p≤0.05) Results and discussion Results showed that the highest wheat yield and yield components, except for 1000-seed weight, were obtained for under monoculture and by increasing the proportion of canola to 75%, significant decrease was observed in seed yield and biological yield of wheat. There was a significant increase in seed yield of new wheat varieties compared to Tabasi as an old variety while the biological yield was not affected by the variety. As compared to other wheat variety, in the presence of the new variety Sirvan, seed and biological yield and radiation use efficiency of canola were significantly increased. However, between different wheat varieties there was no significant difference in radiation use efficiency. The maximum land equivalent ratio (1.41) was calculated with 25% canola+100% wheat. Conclusion Results revealed that yield of wheat and canola were significantly affected by intercropping ratio and wheat varieties in which yield of both crops due to competition was reduced. However due to different criteria of these species associated with better use of water, radiation and nutrient resources when they are intercropped, land use efficiency was increased. New varieties of wheat seems to preform better when intercropped with canola. However, there was no significant differences in radiation use efficiency and land equivalent ratio between the old and the new wheat varieties. Acknowledgement This research (32693) was funded by Vice Chancellor for Research of Ferdowsi University of Mashhad, which is hereby acknowledged.

Canola (Brassica napus L.) is one of the most important oil crops in the world. It has placed in third rank after soybean and palm and has the fastest of growth rate among oil seed in recent decades too. Canola yield was 1592 and 1567 kg.ha-1 in Iran and the world in 2003, respectively, however it has increased to 2125 and 2043 kg.ha-1 in Iran and the world in 2014, respectively. Crop physiologist should investigate the important physiological parameters which in the past have increased yield and can help to increase the quality and quantity of crop yield in the future. Therefore, the current study was carried out to evaluate the physiological traits associated with canola (Brassica napus L.) genotypes yield improvement. Experiment was conducted as randomized complete block design with four replications at Higher Education Complex of Shirvan during growing seasons 2014-2015 and 2015-2016. Treatments were included 20 cultivars and lines of rapeseed. The record of phonological stages was done based on Sylvester-Bradley (1984)’s method. Before the plants showed elongation. Aboveground biomass and leaf area index (LAI) were measured from destructive sampling and it has been continuing at intervals of 6 to 10 d until physiological maturity. The ratio intercepted photosynthetic active radiation (PAR) was obtained by measuring of radiation at the top and bottom of the canopy with a Ceptometer (ACCUPAR model LP-80). Light was measured just before each destructive sampling between the hours of 12 to 14 on clear days. To calculate the daily cumulative solar active radiation we used RLY- calc program (Soltani, 2011). In order to investigation of growth indices, we have divided the varieties to three group based on cluster analysis and is select a variety as group representative. The groups are included high yield (Bilbao), medium yield (Karaje 3) and low yield (Sarigol). Results indicated that there were significant differences among studied varieties in terms of phenological traits. So that Sarigol, Talayee, Shirali, Zafar and Zarfam were achieved earlier than others to physiological maturity. Positive and significant correlation of flowering duration with yield and the number of pod plant-1 has showed its importance in determination of yield. Positive and significant correlation among flowering duration with yield (r=0.66**) and the number of pod per plant (r=0.88**) showed its importance in determination of yield. Also, the most important of stage at making yield was affected by environmental conditions such as temperature, radiation and rainfall. LAI for Bilbao was higher than Sarigol and Karaje 3. Also, Sarigol was achieved maximum LAI earlier than two other varieties. There was strong correlation between yield and maximum dry matter accumulation (r=0.81**). The synchronization of maximum LAI with more solar radiation was much more important to achieve maximum yield. In the first year of experiment, crop growth rate (CGR) and relative growth rate (RGR) were higher than second. There was more solar radiation in first year that it was increased growth indices. The average extinction coefficient of light (KPAR) is estimated 0.70 and 0.72 in the first and second year of experiment respectively. In the first year of experiment, KPAR was varied between 0.65 (Shirali) to 0.76 (Modena and GKH-2005). In the second year, the highest and lowest extinction coefficient was belonged to the varieties Zafar (0.80) and Karaje 3 (0.63) respectively. The average of radiation use efficiency (RUE) is estimated between 3.8 and 3.6g MJ .m-2 in the first and second year respectively. Reducing light use efficiency in the second year can be probably because of obvious difference of weather between two years especially decreased of radiation. In other words, more scattered radiation in the second year than first year can be a major reason for this difference. In general, grain yield in the first was more than the second year of the experiment. The average yield of cultivars in the first and second year was 453.8 g.m-2 and 401.8 g.m-2 respectively. The highest yield in the first year belonged for Bilbao, Kodiak, SW102, GKH-305 and Traviata with the mean 495.5 g.m-2 and the lowest yield related to Zarfam, Sarigol, Talaei, Shiraly and Modena with the average amount of 370.5 g.m-2. The highest yield in the second year belonged to Bilbao, GKH-305, Slm046, L72, SW102, Kodiak and Traviata with the average amount of 450.3 g.m-2 and the lowest yield belonged to cultivars Talayeh, Opera, Karaj 3, Okapi, Modena, GKH-2005 and Karaj 1 with an average yield of 349.7 g.m-2. In general, cultivars with a higher LAI, as well as whose their maximum LAI coincided with higher radiation input had higher yield. It can be concluded the importance of the synchronization maximum leaf area index with more solar radiation. For canola if the maximum LAI is less than four can say that growth and yield will be limited due to lack of leaf area because LAI about four is sufficient to obtain about 90 % of solar radiation. Therefore in spite of second year, in the first year LAI was not limiting factor to achieve maximum biomass. Since maximum LAI of canola occurs in flowering stage, so higher leaf area index at this time was caused the cultivars use more solar radiation. In addition to maximum LAI, the coincidence maximum LAI with higher radiation input was important factor to achieve a higher yield as a result more dry matter accumulation.

Plant density is one of the important factors influencing the amount of light reaching to plants. An experiment was carried out at agricultural research farm of Azad university of Dezfol (Sanjer region) in 2013 and 2014. The experiment design was factorial in a randomized complete block with three replications. Plant densities of (4.5, 5.5, 6.5 and 7.5 plant/m2). Two sunflower cultivars of Shahroodi and Domsefid were cultivated. The results showed that the effect of plant density was significant on leaf area index (LAI), Radiation use efficiency (RUE), Grain yield, extinction coefficient (K) and light interception (LI). The highest LAI and RUE were 4.24 and 1.92(MJ/M2/S) for Shahroodi cultivar, respectively. The highest K and LI in Domsefid cultivar were 0.137 and 43.4% respectively. The increase in plant density of both cultivars resulted in increasing the RUE. The highest grain yield for Domsefid cultivar (6.5 plant/m2) was 5249.9 kg/ha. The highest grain yield for Domsefid cultivar (6.5 plant/m2) was 5249.9 kg/ha. The highest grain yield for Domsefid cultivar (6.5 plant/m2) was 5249.9 kg/ha.

Intercropping plays an important role in agriculture because of beneficial interactions. Intercropping of legumes and cereals is an old practice in tropical agriculture dating back to ancient civilization. Cereals and other plant intercrops could substantially increase forage quantity and quality and decrease the requirement for protein supplements. Intercropping of cereals and other plants is important for development of sustainable food production systems. This may be due to some of the potential benefits of intercropping systems such as high productivity and profitability, improvement of soil fertility, efficient use of resources, reducing damage caused by pests, diseases and weeds and improvement of forage quality The main advantage of intercropping is more efficient utilization of the available resources and the increased productivity compared to sole crops of the mixture. Therefore, this experiment was conducted to evaluate agronomic characteristics of wheat and Land Equivalent Ratio (LER) under relay intercropping with sugar beet.
In order to evaluate radiation use efficiency (RUE), yield and dry matter accumulation in winter wheat relay intercropping and sugar beet, a field experiment was conducted at Agricultural Research Station of Ferdowsi University of Mashhad, Iran, during 2012 growing season, using a completely randomized block with four replications. The experimental treatments included four treatments intercropping ratios of rows: 3: 1, 3: 2, 4: 2, 6: 2 (beet and wheat) with monocropping beet and monocropping wheat (sole crops), comprised the experimental factors.
The results of this experiment showed that the effects of intercropping were significant for many study traits. Also, the results showed that during the growing season, leaf area index, radiation crossing the canopy, radiation use efficiency, the amount of dry matter production and yield per unit area were affected by intercropping. The highest yield of wheat was observed in the intercropping treatments 4: 2 (1942 g.m-2) and the highest dry matter of beet sugar was obtained in monoculture (2063 g.m-²). Highest radiation use efficiency of wheat and sugar beet) was observed in treatment 4: 2 (65.1 and 38.2), respectively.
In general, results showed that maize-peanut intercropping could be profitable due to use of the available resources. It can be concluded that intercropping was more efficient than sole cropping especially this is the way to make better use of resources and increase efficiency compared with sequential planting species.

A high correlation existes between crop growth and the rate of radiation intercepted. The efficiency of radiation interception and absorption is dependent on leaf area index, light extinction coefficient and radiation use efficiency.To study extinction coefficient and radiation use efficiency in different cultivars of Safflower under different levels of N fertilizer, an experiment was carried out in the research field at the University of Valiasr in Rafsanjan during 2013-2014.
Experiment was arranged in a split plot design in complete randomized block design with four replication. Experiment factors inciuding N fertilizer were a main factor in 5 levels (control, 50, 100, 150 and 200 kg per hectare) and cultivar in 4 levels (Local Esfahan, goldashat, sofe and naeen). In addition to measuring the radiation above and under the canopy, the plots were sampled 8 times during growing season and leaf area index, total dry matter and finally light extinction coefficient and radiation use efficiency were measured.
The results showed that light extinction coefficient was not affected by N fertilizer but comparisom of extinction coefficient in difference cultivars showed that Goldasht cultivar have significant difference with Landrace of Isfahan and Soffah. and RUE obtained for endemic cultivars of Isfahan, Goldasht, Naien and Soffah were 0.46, 0.54, 0.48 and 0.46 respectively. Radiation use efficiency was influenced by N fertilizer; in this case, at fertilizer level of 150 kg, there was a significant difference among endemic cultivars of Isfahan, Goldasht, Soffah with control. At 200 kg level, Naien cultivar had a significant difference with control for RUE. There was no significant difference in obtained RUE in different cultivars and amount of RUE obtained for endemic cultivars of Isfahan, Goldasht, Naien and Soffah were 4.45, 4.19, 4.62 and 4.35 g / MJ, respectively. In addition, at fertilizer level of 100 kg /h, maximum leaf area index of all cultivars had a significant difference with control level.
In this experimental study with increasing the level of N fertilizer, maximum leaf area index also increased significantjy. Increasing the leaf area index caused radiation use efficiency be affected by N and generally in the highest level of radiation use efficiency obtained in N level 100 to 150 kg per hecter. It seemed that among the above cultivars, the most suitable one for radiation use efficiency was Naien cultivar.

In order to investigate the effects of different levels of nitrogen rate on extinction coefficient and radiation use efficiency of genotypes wheat cultivars، an experiment was conducted on Araghi Mahalleh (Gorogan) research farm during 2009. The experiment was carried out using randomize complete block with four replications. Nitrogen rates were arranged in four levels (0، 90، 180، 270 kg ha-1) and wheat cultivars included; Tajan، Falat and N81-18. The result showed that nitrogen rate and cultivar do not effect on the extinction coefficient، but they effect on radiation use efficiency. In such a way that maximum amount of radiation use efficiency is for N81-18 cultivar on nitrogen rate of 90 kg ha-1. As increase in fertilization level، leaf area index and dry material increased too. But this increase was grater in fertilization level of 90 kg ha-1 compared with 180 kg ha-1.

Water and nitrogen are among the most important limiting factors controlling yield in crops. With due attention to importance this subject, in wheat a split plot experiment was carried out in the field, using randomized complete block design with three replications under different irrigation and nitrogen levels during the cropping season of 2009-10 in Shirvan region. The experimental treatments consisted of four levels of irrigation, I1= optimum irrigation (field capacity, FC), I2= Irrigation at 80% FC, I3= Irrigation at 60% FC and I4= without irrigation which were assign to main-plots, and four levels of nitrogen fertilizers, namely, N1= 0, N2= 100, N3= 175 and N4= 250 kg N/ha to sub-plots. The results of experiment showed that the highest amount of seed yield, biological yield, leaf area index during different growth stages, radiation use efficiency and nitrogen content in whole wheat and seed obtained from treatment of optimum irrigation (I1) and applications of highest nitrogen fertilizer level (N4), but there wasn’t significant different between this treatment with treatment of optimum irrigation and consumption of 175 kg N/ha (I1N3). The lowest values were obtained from treatment of no irrigation and nitrogen (I4N1). For nitrogen use efficiency there was two different conditions. In the first condition, nitrogen use efficiency increased under optimum irrigation (I1) and irrigation at 80% FC (I2) with increasing nitrogen level from N1 to N4. In the second condition, nitrogen use efficiency decreased under irrigation of 60% FC (I3) and without irrigation (I4) with increasing nitrogen level from N1 to N4. Generally, it can be concluded that to obtain the highest yield in region, optimum irrigation is necessary. To obtain highest nitrogen fertilizer consumption and seed yield 250 kg N/ha would be required however there wasn’t significant difference between 250 an 175 kg N/ha applications.

In order to evaluate radiation absorption and use efficiency in row intercropping for wheat and canola, a field experiment was conducted based on a randomized block design with three replications at Agricultural Research Station of Ferdowsi University of Mashhad during two growing seasons of 2008-2009 and 2009-2010. Treatments included four combinations of row intercropping of wheat and canola (one row of wheat + one row of canola (1:1), two rows of wheat + two rows of canola (2:2), three rows of wheat + three rows of canola (3:3) and four rows of wheat + four rows of canola (4:4)) and their monoculture. Results indicated that the effect of row intercropping was significant on radiation use efficiency of wheat and canola. The highest radiation use efficiency based on biological yield of wheat and canola were observed in monoculture (with 1.6 and 1.04 g.MJ-1) and three rows wheat+ three rows canola (with 1.4 and 0.57 g.MJ-1), respectively. The maximum radiation use efficiency based on economical yield of wheat and canola were obtained in monoculture (with 0.52 and 0.3 g.MJ-1) and three rows wheat+ three rows canola (0.49 and 0.23 g.MJ-1), respectively. The range of land equivalent ratio for radiation absorption efficiency in different row intercroppings of wheat and canola was 1.31-1.61. In general, row intercropping of wheat with canola increased radiation use efficiency and combination of three rows of wheat + three rows of canola was the most promising one.

To achieve optimal yield and high production in wheat، need to adapt the plant''s vegetative and reproductive growth stages to environmental conditions and increase use efficiency of production factors by desirable density. in order to study the effect of plant density on Extinction Coefficient and Radiation Use in Modern and old Wheat (Triticum aestivum L.) genotypes، an experiment was conducted on the agricultural research farm located in Gorgan city using three density levels (150، 262 and 375 plant per meter square) and three Wheat- genotypes (Falat، Tajan، N-81-18) during 2007-2008. The experiment was conducted with factorial arrangement based on randomized complete block design، with 4 replications. Results showed that the highest amount of LAI and DM was obtained in N-81-18 line and 375 plant in meter square، also plant density and genotype was not effect on the Extinction Coefficient، but just plant density effects on Radiation Use Efficiency. in such a way that the highest amount of Radiation Use Efficiency is for N-81-18 line in 375 plant in meter square.

Intercropping may be helpful manner to increase interception and utilization. The aim of this study was to compare radiation use efficiency and radiation interception in intercropping with sole cropping. An experiment was conducted at the Agricultural Research Station، Ferdowsi University of Mashhad in the growing season of the year 2008. The experimental treatments were: 1- sole crop of bean 2- sole crop of sweet basil 3- strip intercropping of bean and sweet basil (four row bean and two row sweet basil) 4- strip intercropping of bean and sweet basil (two row sweet basil and four row bean) 5- row intercropping of bean and sweet basil. For this purpose a Complete Randomized Block design with 3 replications was used. For analysis crop radiation capture and utilization، three indices are often used: the fraction of radiation intercepted (F)، harvest index (HI) and radiation use efficiency (RUE). Results showed that the intercrop F was higher than the sole crop F and there was no difference HI among treatments. RUE of sweet basil in intercrop treatments was increased compared to sole crop and highest RUE of sweet basil obtained in row intercropping (3. 2g/Mj)، RUE of bean decreased in intercrop treatments and highest RUE of bean obtained in sole crop bean (2. 03g/Mg). Light extinction coefficient of bean was obtained 0. 55 and sweet basil 0. 47. The highest Leaf area index (LAI) in bean was obtained in sole crop (4. 3) and the highest LAI in sweet basil was in strip inter cropping with 4 row sweet basil.

In many parts of the country farmers are faced with the problem of synchrony between sowing date of spring crops and the grain filling period of winter cereals. Competition for limited resources, mainly water results in delayed sowing in spring. In this research relay intercropping of winter/spring species was studied as an alternative practice for conventional double cropping system. Four intercrop treatments with ratios of 3:1, 3:2, 4:2 and 6:2 (wheat:corn) together with sole crop of each species was evaluated in a randomized complete block experiment with 3 replications. Corn seeds were sown in pre-established rows within wheat strips 32 days before harvesting wheat. During the growth period leaf area index, fraction of transmitted radiation and dry matter production was measured in two-weekly intervals and grain yield of species at harvest. Absorbed radiation during the season, radiation use efficiency of species, harvest index and land equivalent ratio were calculated based on the collected data. The results indicated that in all sowing ratios absorbed radiation by the intercrop canopy was significantly higher than sole crops. However, radiation use efficiency of species was not differed between treatments. As indicated by land equivalent ratio, relay intercropping treatments had yield advantage of 27 to 31% over sole crops which was mainly due to increased light absorption by the intercrop canopies. While the number of wheat rows had no drastic effects on the yield, the best results was obtained from 3:2 (wheat:corn) intercrop. It was concluded that relay intercropping of winter cereals with spring crops results in better utilization of resources and increased yield compared to double crop of the same species.

Efficient use of radiation for medicinal plants production، might increase flower yield، essential oils and extract yield. A split plot design. was used in a two years (2005 and 2006) field study in Torogh region (36،10° N،59. 33° E and 1300 m altitude) of Mashhad، Iran، to observe the effects of different nitrogen application and plants densities on flower dry matter production، essential oils، and radiation use efficiency in a multi-harvested Marigold (Calendula officinalis). The levels of nitrogen fertilizer were 0، 50، 100 and 150 kg ha-1 and levels of density were 20، 40، 60 and 80 plant m-2. The combined analysis results revealed significant effects of nitrogen and density levels on flower dry matter production، essential oils، and radiation use efficiency of Marigold. The highest dry flower production obtained by 150 kg ha-1 N and 80 plant m-2 plant population (102. 86 g m-2). The higher flower dry matter production caused more essential oils and extract production in high nitrogen and density levels. The amount of essential oils and extract per 100g flower dry matter decreased during the flower harvesting period. The higher amount of essential oil and extract obtained at early flowering season. The essential oil and extract ranged from 0. 22 to 0. 12 (ml. per 100g flower dry matter) and 2. 74 to 2. 13 (g per 100g flower dry matter) respectively. Increase of both nitrogen and density caused higher radiation use efficiency. The most radiation use efficiency obtained at 150 kg ha-1 nitrogen and 80 Plant m-2desity treatments. In 150 kg ha-1 nitrogen treatment، increase of density levels from 20 plant m-2 to 80 Plant m-2 caused increase in radiation use efficiency from 1. 41 g MJ-1 to 1. 44 g MJ-1 respectively.

In order to study of yield, yield component, plant height, total dry matter and radiation use efficiency with 13 spring varieties of rapeseed, an experiment was carried out in 2007 growing season at Agriculture and Natural Resources Research Station of Torogh,Mashhad. These cultivars were from three rapeseed species belonged to Brassica napus, Brassica rapa and Brassica juncea. Experimental design was Randomized Complete Block with 4 replication. Result showed that a significant difference was existed among cultivars for yield, yield component, plant height and total dry matter. With exception of number of pod, Hyolla Hybrids had more yield components than other cultivars. Meanwhile cultivars of B.napus had more yield components than cultivars of B.rapa. Hyolla 330 with average of 1475 Kg.ha-1, BP18 with average of 1277Kg.ha-1 and Hyolla 401 with average of 1274 Kg.ha-1 had the most yields in this experiment respectively. we concluded that cultivars of B.napus had more yield than varieties of B.rapa. Cultivars in this trial presented considerable difference regarding radiation use efficiency. The value of radiation use efficiency under this investigation ranged from 0.4487±0.201 DM. MJ-1 to 1.8355±0.07 DM. MJ-1. Hyolla 330 with average of 1.8355+0.07 DM. MJ-1 and Zarfam with average of 1.32+0.725 DM. MJ-1 had the most radiation use efficiency. At this experimental condition, generally cultivars of B.nupus had greater slope of dry matter expansion in unit of cumulative received radiation than both B.rapa and B.juncea cultivars.

Field experiment was carried out during 2008 growing season at the research farm of University of Tehran, Karaj, Iran, to evaluate the interference effects of redroot pigweed (Amaranthus retroflexus L.) on light interception and RUE of four Sesame cultivars. Experimental design was a randomized complete block with three replications per treatment. The first factor was the sesame cultivars including, Otlan (Multiculum), Varamin 2822, Naz Uniculm and Karaj 1 (Uniculm cultivars). The second was the redroot pigweed density at five levels: 0, 2, 4, 8, and 16 plant m2. The results indicated that leaf area distribution in the canopy has a triangular function and the height, in which maximum leaf area redroot pigweed was observed, was not the same among treatments. Light interception by sesame cultivars under redroot pigweed interference decreased by 12, 47, 32, and 42 percent for Oltan, Varamin 2822, Naz Uniculum and Karaj 1, respectively, compared to control. Redroot pigweed interference reduced RUE by 18.6, 35, 27.7, and 21.7 percent for Oltan, Varamin 2822, Naz Uniculum and Karaj1 respectively, compared to control. The highest RUE was observed in Oltan cultivar.

To evaluate the genetic improvement in yield of wheat (Triticum aestivum) bred between 1956 and 1995, a field experiment was carried out in Arak, Iran, during the 2001-2002 growing season. Six wheat cultivars, from different years of release (Omid 1956, Bezostaya 1969, Azadi 1979, Ghods 1989, Alamot 1995 and Alvand 1995) were sown with and without competition from wild oat (Aven fatua). The results showed a trend to increasing yield at later release dates with a rate of 2.2 % yr-1 and 3.8% yr-1 under weed free and weedy conditions, respectively. The greater yield increase obtained in weedy conditions indicates an improvement in the potential competitive abilities of new cultivars. Harvest Index (HI) and biomass were highest in new cultivars. Increased HI could explain 74% of the gain in yield, whereas, the remaining 26% of yield improvement was attributed to increases in biomass. There were no differences betweencultivars in extinction coefficients (K) and Radiation Use Efficiency (RUE). However, RUE was reduced significantly in weedy conditions. RUE increased with the year of release by 0.77% yr-1 and 0.14% yr-1 under weed free and weedy conditions, respectively. Average RUE values of of 1.3 g MJ-1 (in terms of absorbed photosynthetically active radiation, APAR) and M. Beheshtian-Mesgaran et al. 33 0.83 g MJ-1 were estimated in weed free and weedy conditions, respectively. Leaf area index (LAI) was the only component that decreased as year of release increased.