نشریه پژوهشهای زراعی ایران
سال دهم شماره 2 (پیاپی 26، تابستان 1391)

In order to evaluate radiation capture and use efficiency and productivity in sole and intercropping of three crops, rapeseed (Brassica napus L.), bean (Phaseolus vulgaris L.) and corn (Zea mays L.), an experiment was conducted in Mashhad region during the growing season of 2007-2008. In this study six treatments including three sole cropping of the crops (rapeseed sown in 22 September 2007, corn and bean in 29 April 2008) and three intercroppig including double cropping (simultaneous sowing of corn and bean in 29 April 2008), two stages-relay intercropping of rapeseed, corn and bean (rapeseed in 22 September 2007, bean and corn in 29 April 2008) and finally tree stages-relay intercropping of rapeseed, corn and bean (rapeseed in 22 September 2007, bean in 8 April 2008 and corn in 29 April 2008) were arranged in complete randomised blocks design with three replications. Based on results, cropping combination affected radiation capture and use efficiency and also radiation productivity, significantly (p≤0.05). In which, among intercropping treatments, double cropping showed the highest capture efficiency (0.54), the highest radiation use efficiency and radiation productivity in terms of seed yield (0.23 and 0.13 g.m-2.Mj-1, respectively) and also the highest radiation productivity in terms of biological yield (0.50 g.m-2.Mj-1) and tree stages-relay intercropping the highest radiation use efficiency in terms of biological yield (0.92 g.m-2.Mj-1). Among sole croppings, bean showed the highest capture efficincy (0.49) and corn the highest use efficiency in terms of biological and seed yield (1.80 and 0.65 g.m-2.Mj-1, respectively) and the highest radiation productivity in terms of biological and seed yield (0.72 and 0.26 g.m-2.Mj-1, respectively) too. In general, double cropping were the best treatment in terms of capture efficincy and corn sole croppig in terms of radiation use efficiency in terms of biological and seed yield and productivity in terms of biological and seed yield. Generally, it seems that such cropping combinations will not be suitable because of shading effect of rapeseed on young seedlings of bean and corn; therefore it is nessesary to adjust more proper planting dates in which growth period of companion crops have less overlapping with growth period of rapseed

Molecular experiment was conducted to confirm resistant to aryloxyphenoxypropionate herbicides in winter wild oat (Avena ludoviciana Duriu.) populations of wheat fields in Khuzestan province, at Faculty of Agriculture of Ferdowsi University, during year of 2006. First, 44 wild oat populations from Ahvaz, Andimeshk, Shush, Shushtar, Ramhormoz, Susangerd, and Dezful cities with a susceptible population were examined in screening experiments. According to these experiments, 37 populations of winter wild oat biotypes selected as suspected resistance populations, and used for molecular experiment to determine resistance mechanism. dCAPS method was carried out in three steps consisting of PCR, enzyme digestion, and gel electrophoresis. Results showed that mutation at position 1781 of ACCase enzyme resulted in resistance in 10 winter wild oat populations from Andimeshk (5), Shush (1), Shushtar (2), and Susangerd (2) to clodinafop propargyl, diclofop methyl, and fenoxaprop p ethyl herbicides. While, in other suspected resistance populations other mechanism such as metabolism is probable. Also, it was concluded that this method is a good technique to detect herbicide resistance and mechanism of herbicide resistance in winter wild oat.

In order to evaluate the effects of beneficial free living bacteria (Azotobacter chroococcum and Azospirillum brasilense) compared to different nitrogen fertilizer levels on yield and yield components of barley (Hordeum vulgare cv Reyhan) a field experiment was conducted at Research Station College of Agriculture, Ferdowsi University of Mashhad in 2007-2008. The experiment was arranged in a randomized complete block design with three replications. Fertilizer treatments were biological fertilizer (combine of Azotobacter and Azospirillum) and six nitrogen fertilizer levels (0, 20, 40, 60, 80 and 100 kg/ha). The plant characteristics were studied in terms of leaf area index, crop growth rate, total dry weight, shoot and root dry matter per plant and seed yield. The results showed that the effect of different nitrogen fertilizer levels imposed a significant effect on all plant characteristics. The difference between biological fertilizers, 60 and 80kg nitrogen fertilizer levels in shoot dry weight were not significant. Additionally, in root dry weight and root/shoot ratio there were significant difference between biological fertilizer and all nitrogen fertilizer levels. There was no significant difference between biological fertilizer, 80 and 100 kg nitrogen fertilizer levels in terms of seed yield. There was no significant difference among biological fertilizer, 40, 60 and 80kg nitrogen fertilizer levels in leaf area index at three finally samples. It seems that, in this experiment biological fertilizer could be provide plant nitrogen requirements the same as 40-80kg nitrogen per hectare.

Freezing stress affected some vital processes of plant, and causing disturbance on the plant growth. In order to study the effect of low temperatures on freezing tolerance of chickpea (Cicer arietinum L.) a factorial experiment with 4 replications carried out using 3 chickpea genotypes (MCC496، MCC763 and MCC798) and 7 freezing temperatures (-4, -6, -8, -10, -12, -14 and -160C). Explants were cultured on MS medium with 2mg. l-1 BAP and 0. 125 mg. l-1 IBA. For acclimation, explants were transfered to 4ºC for 12 days. Then explants were freezed in thermo- gradient freezer. The percentage of survival and injury were determined after 3 weeks. Result showed that the effect of different freezing temperatures were significant on survival and injury percentage (P≤0. 05). By temperature decreasing, survival percentage decreased, wherease injury percentage increased but between 3 genotype differences were not significant. LT50 (injury percentage) in genotypes MCC763 and MCC798 were -15 ºC and in genotype MCC496 was -15/5 ºC. Also, LT50 (survival percentage) in 3 genotypes MCC496, MCC763 and MCC798, were -13, -12 and -12/5 ºC. This study suggests that in vitro screening of chickpea genotypes for cold tolerance is satisfactory and can be replaced by selection in the field, mainly due to its high repeatability.

Soil and water salinity in arid and semi-arid regions, is one of the most important stresses, can severely limit crop production. Black Cumin (Nigella sativa L.) is annual important herbal plant in Rununculaceae Family that sense to salinity. This study was conducted to evaluate the effects of the Priming on seed germination of Black Cumin under saline stress. The experiment was carried out as factorial based on completely randomized design (CRD) with three replications. The experimental factors were salinity stress including: (0, 62.2, 124.2, 186.2 and 248.8 mM) and three levels of priming, seed primed with Kno3 (0.2 %, for the period of 72 hours), GA (500 ppm, during 48 hours) and hydro priming (water distiller, during 24 hours). A saline stress level treated by applies of NaCl, and for priming of distiller water use hydropriming technique. At the first stage, Black Cumin seed was treat and dried at 25°C, then subjected to saline stress treatments for two week at room temperature. The results showed that priming technique had a significant effect (p≤0.01) on seedling parameters. Among pretreatment, The Kno3 had the most positive effect on germination coefficient (GC) and thus GA had the most positive effect on mean germination time (MGT). In order hand, these seeds at the minimum time had the most germination rate. Means comparing showed that the most and least rate of germination was obtained by KNO3 and Hydro priming respectively. So under different level of saline stress, pretreatments of KNO3 and hydro priming had useful effect on radical length, more lateral roots and higher proportion of root to plumule, and the most root and plumule fresh weight was obtain by hydro priming pretreatments. So pretreatment of 500 ppm GA reduced number of abnormal seedlings.The simple correlation coefficients showed that radical length with mean germination time (MGT) had significantly negative coefficient (R2=-0.726**), with abnormal seedlings number had no significant coefficient and with other measured attribes had positive significant correlation. So MGT with measured parameter (except for number of abnormal seedlings and proportion of root to plumule dry weight), had significantly, negative coefficient correlation. Overall, application of seed priming with KNO3 (0.2 %) for the period of 72 hours and GA (500 ppm) during 48 hours suggested for obtain uppermost germination characters.

In order to study the germination characteristics of dodder (Cuscuta campestris) under drought and salinity stress conditions, two laboratory's experiment were conducted. Experiments were conducted in completely randomized design with 4 replications. The treatments, for salinity and drought stress were six potential levels (0,-3, -6, -9, -12 and -15 bar) of NaCl and five potential levels (0, -3, -6, -9 and -12 bar) of PEG 6000 respectively. Results showed that increasing drought and salinity stress significantly germination rate and germination percentage, plumule and radicle length, plumule of Dodder and its radicle fresh weight decreased. However ratio of radicle to plumule and root to shoot were increased (P≤0.01). It seems that among the characters, plumule length is more sensitive to drought and salinity stresses. In addition, germination of dodder was tolernt to drought stress more than salinity stresses.

In order to investigate the effects of different levels of nitrogen and phosphorous fertilizers on flower yield, yield components and some quality components of German chamomile, a factorial experiment based on a randomized complete block design with four replications was carried out in the Medicinal Plant Research Farm of Shirvan College of Agriculture during growing season of 2007-2008. Nitrogen had three levels (0, 100, 200 kg/ha urea) and phosphorous also had three levels including 0, 30, 60 kg.ha-1 triple super phosphate. The results showed that application of nitrogen and phosphorous fertilizers imposed a significant effects (p < 0.01) on plant height, number of branches per plant, number of flower per plant and flower yield. Plants treated with 200 kgha-1 urea had the highest flower yield (1423 kg.ha). Among phosphorous levels, plant treated with 60 kgha-1 triple super phosphate produced the highest flower yield (1309 kgha-1). Fertilizers had no effect the percentage of chamazulene. However, plant treated with 200 kgha-1 urea and 60 kgha-1 triple super phosphate fertilizers produced the highest essential oil and chamazulene per square meter due to higher flower yield.

In order to evaluate the effect of nitrogen absorption and use efficiency in relay intercropping for winter wheat and maize, a field experiment was conducted during 2008-2009 at the Agricultural Research Station of Ferdowsi University of Mashhad, Iran. A randomized block design with three replications was used. Treatments included four combinations of relay intercropping of wheat and maize (three rows of wheat + one row of maize (3:1), three rows of wheat + two rows of maize (3:2), four rows of wheat + two rows of maize (4:2) and six rows of wheat + two rows of maize (6:2)) and their monoculture. Results indicated that the effect of relay intercropping on the absorbed nitrogen, nitrogen relative absorption, nitrogen absorption and use efficiency of maize and wheat was significant (p≤0.05). The highest and the lowest nitrogen absorption efficiency of wheat and maize were observed in three rows of wheat + two rows of maize (33.70 and 36.50 kg tissue N content kg-1 soil N) and monoculture (14.73 and 19.37 kg tissue N content kg-1 soil N), respectively. Range of nitrogen relative absorption of intercropped wheat and maize were 1.47-1.08 and 0.41-0.54, respectively. Nitrogen use efficiency of wheat and maize were 88.62 and 147.33 kg seed N content kg-1 tissue N content, respectively. In general, relay intercropping of winter wheat with maize increased nitrogen absorption and use efficiency.

Seed germination is a crucial stage in the plant life cycle and salt tolerance during germination stage is vital for the establishment of plants in saline soils. In order to evaluation of sesame (Sesamum indicum) landraces germination to salinity stress at different temperature, an experiment was conducted at Ferdowsi University of Mashhad, Collage of Agriculture during 2009. Experimental type was complete randomized design in factorial arrangement with 4 replications. Factors included salinity at 7 levels (0, -2, -3, -4, -6, -8, -10 and -12 bar), temperature at 3 levels (15°c, 20°c, 25°c) and 3 sesame landraces (Sabzevar, Kalat and Oltan). Results showed that germination parameters (germination percentage, germination rate, root length, shoot length, dry weight of roots and dry weight of shoots) in all landraces were significantly (p≤0.01) affected by salinity and temperature. Increasing salinity reduced all above parameters in sesame cultivars, so that highest tolerated dose of salt was obtained in 25°c and increasing of temperature reduced effects of salinity. The highest germination percent was observed in salinity between 0 to -4 bar at 25°c. Sabzevar and Oltan landraces exhibited the highest and the lowest indicators at different temperatures respectively. According to these results, it seems that in saline condition and temperature variation, Sabzevar is the appropriate sesame landraces for optimal seedling establishment.

In order to study the effects of drought stress on yield and yield components of safflower genotypes, a split plot based on randomized complete block design with four replications was performed at the Research Field, Islamic Azad University, Arak, Iran during summer of 2009. Irrigation treatments included three levels of 100, 75 and 50% crop water requirement and four levels of safflower genotypes included Esfahan native, Esfahan-14, PI-537598 and IL-111. The results showed that drought stress, reduced grain yield and seed oil of safflower. So by decreasing irrigation from 100% crop water requirement to 75 and 50% crop requirement reduced seed yield from 1198 Kg ha-1 to 1081 and 936 Kg ha-1, respectively. The highest seed yield was observed for Esfahan native with 1402 Kg ha-1. Interaction effects indicated that the maximum seed yield and seed oil were achieved in 100% crop water requirement and Esfahan native with 1583 Kg ha-1 and 38%, respectively. The highest seed yield and seed oil were obtained for Esfahan native under without and with stress. So, it concluded that this genotype of safflower could be produce acceptable amount of seed yield and oil content under water deficiency.

Tomato as a highly nutritious vegetable crop is widely grown in the world. Hybrid seed is preferably used for tomato production. Identification of superior hybrid combination is one of the most important steps in the hybrid breeding programs. Breeding of high yielding hybrids is expensive and involves testing large numbers of hybrid combinations in multi-environment trials. Successful prediction of heterosis from the genetic similarity of their parents based on molecular markers has been reported in several crops and can be very helpful in hybrid breeding. The present study was carried out to evaluate genetic divergent among tomato lines and to assess the relationship between genetic distance and heterosis among them. Thirty genotypes were examined for DNA polymorphism, using amplified fragment length polymorphisms (AFLPs). A total of 165 polymorphic variants were generated and genetic distances ranged from 0.04 to 0.23. Our result indicated that AFLP markers were successful in identification of polymorphism and genetic distances among tomato lines, but correlation of genetic distance based on AFLPs with mid-parent heterosis of yield, fruit weight, fruit number and fruit durability time was low and not useful for predicting heterosis in tomato genotypes.

In order to investigation of response of durum wheat genotypes to terminal drought stress, this experiment was conducted in Neishabour Agricultural Research Station during two growing seasons of 2004-2005 and 2005-2006. Seventeen advanced durum wheat genotypes, two bread wheat cultivars and one durum wheat cultivar (i.e. 20 genotypes and cultivars) were evaluated in two separate experiments (normal and limited irrigation) based on a randomized complete block design with four replications. Combined ANOVA of grain yield data revealed that there were significant differences among genotypes for grain yield of Durum Wheat (P)

To investigate the effects of micronutrient such as Fe, Zn and Complete Micronutrient Fertilizer as foliar application and using in the soil on some physiological indices of corn an experiment as a randomized complete block design with 4 replication and 10 treatments was conducted. Treatments including, control (C), foliar application of complete micronutrient in Stem elongation stage (M1), foliar application of complete micronutrient fertilizer in Stem elongation stage + ear appearance stage (M2), foliar application of Zn in Stem elongation stage (Z1), foliar application of Zn in Stem elongation stage + ear appearance stage (Z2), foliar application of Fe in Stem elongation stage (F1), foliar application of Fe in Stem elongation stage + ear appearance stage (F2), soil use of complete micronutrient fertilizer (Ms), soil use of Fe (Fs) and soil use of Zn (Zs). Analysis of variance showed that effects of different fertilizer treatments on seed yield, biological yield, number of rows in cob, number of grain in row and cob length traits were significant (p≤0.01). Also impacts of applied treatments on harvest index, cob diameter, 1000 grain weight and cob weight in 5% probability level were significant. Mean comparison of treatments showed that in all studied traits, foliar application of complete micronutrient fertilizer in Stem elongation stage + ear appearance stage (M2) and control (C) treatments had a highest and lowest effects respectively.

This study was conducted to explore the effects of drought stress and different levels of potassium sulfate on yield and yield attributes of grain sorghum at Agriculture and Natural Resources Research Station of Sistan during year of 2009. Treatments were arranged in a split-plot lay out based on a randomized complete block design with three levels of drought stress as main plot (irrigation at 70%, 50%, and 30% field capacity) and five levels of potassium sulfate as sub plot (0, 100, 150, 200 and 250 kg ha-1) in three replications. Drought stress by reducing the yield components, especially the number of panicle per plant and one-hundred grain weight reduced grain yield. Maximum yield (3499 kg ha-1) and biological yield (14464 kg ha-1) was obtained at 70% FC. Grain and biological yields for the plants irrigated at 70% FC were 58.5% and 27.4% greater, respectively, than the yields of the plants irrigated at 30% FC. Potassium sulfate at the highest rate increased grain and biological yield by 28% and 22%, compared to control respectively, Through improving growth conditions. Interaction effect between drought stress and potassium sulfate on all studied traits was significant and optimum soil K levels protect plants from drought. These observations indicate that adequate K nutrition can improve drought resistance of sorghum.

Research on crop response to deficit irrigation is important to reduce agriculture water use in areas where water is limited resource. Using drought resistant landraces with irrigation scheduling based on phenological stages in semi-arid and arid regions may provide an opportunity to optimize irrigation efficiency and water savings in these regions. In order to evaluate of yield and yield components of black cumin under different plant density and limited irrigation condition an experiment was conducted in Research Farm of Islamic Azad University of Damghan during growing season of 2007-2008. The experimental treatments were arranged in split plots based on a complete randomized block design with three replications. The limited irrigation (based on phenological stages) treatments were included: cutting irrigation at blooming (folded flowers), cutting irrigation at flowering stage, cutting irrigation at seed formation and normal weekly irrigation (control) were allocated to the main plots and different plant density: 100, 150, 200 and 250 plant per square meter (m2) were allocated to sub plots. The results showed that the effect of limited irrigation, plant density and their interaction on plant height, number of follicle, follicle weight, number of seed, 1000 seed weight, seed yield, biological yield and harvest index Black Cumin. The highest yield and yield components was obtained in normal irrigation (control) and 200 plant density and the lowest yield were obtained when irrigation cut at the blooming stage and 250 plant density. There was a significant correlation between seed yield and number (r=0.90), 1000 seed weight (r=0.95) and biological yield (r=0.97). Optimum plant density of black cumin was decreased under limited irrigation treatments. Under normal (control) and limited irrigation, optimum plant density was 200 and 150 plant per (m2) respectively.

In order to evaluation the effect of planting date on development stages and some characteristics of spring safflower varieties, an experiment was conducted as split plot based on randomized complete block design with six replications at the Kabotar Abbad Research Station, Isfahan during two growing seasons of 2006-2007 and 2007-2008. Three safflower varieties such as Arak, Sofea and Goldasht cultivated at eight planting dates (including 6th March, 20th March, 4th April, 19th April, 5th May, 6th June and 23th June). The results showed that development stages of safflower were longer that it increased vegetative and reproductive growth at the first year of experiment. The highest yield of safflower was observed in the first planting time. By delaying from the first to the 7th planting time decreased photosynthetic areas and seed yield due to enhancing in development. These varieties of safflower were different about some of development. Goldasht and Sofea were the earliest and latest varieties, respectively. The effect of variety was not significant on seed yield of safflower. The maximum oil content and 1000-seed weight were observed in Sofea and Goldasht, respectively. Goldasht had the minimum plant height.

In order to survey the influence of metribuzin herbicide on physiological indices and yield of wheat, an experiment was conducted at experimental field of Plant Pest and Disease Research Institute, Karaj, Iran during 2007. Treatments were in factorial arrangement laid out in four randomized complete blocks. The factors investigated were three plant densities: 400, 500 and 600 plant.m-2 and metribuzin doses: 0, 0.2, 0.4, 0.6 and 0.8 kg.ha-1. The result showed that the highest physiological indices and grain yield were obsevered in densities of 500 plant.m-2 and in applications of 0.6 and 0.8 kg. ha-1. Higher rates could be provided an acceptable level of weed control. Plant density could provide good control on weed and could be decrease using herbicide too by decreasing of available light for weed. This strategy can reduce the peresure of selection in resistant weeds population.

In order to determine the effect of different irrigation intervals on some morphophysiological traits of basil (Ocimum basilicum L.), an experiment was conducted as factorial based on randomized complete block design with three replications under greenhouse conditions during 2010. Treatments included five irrigation intervals with 4, 8, 12, 16 and 20 days intervals and two ecotypes of basil (green and purple). The results showed that by increasing irrigation interval plant height, spike number, spike weight and shoot dry weight between irrigation intervals decreased. Purple basil was more tolerant than basil green ecotype to drought stress. Interaction between irrigation intervals and ecotypes showed that the best treatment related to four days irrigation interval and purple basil ecotype. The effect of irrigation intervals on root area, root diameter mean, total length, root volume and dry weight of root was significant. In all irrigation intervals, purple basil had better performance compared to green ecotype. The results showed that by increasing in irrigation interval decreased root surface area, but increased total root length. It was concluded that increasing irrigation interval up to 12 days decreased shoot and root surface areas. Increasing irrigation interval decreased chlorophyll- a, b and increased prolin amino acid content of basil leaf.

In order to study the realationship between genetic diversity and different characteristics associated with grain yield in barley, 28 genotypes of barley cultivars contain seven cultivars and 21 hybrids were evaluated in Randomized Complete Block (RCB) design with three replications. Cultivars were Valfajr, Makuei, Kavir, Rayhan, Gorgan, Nusrat and Nimroz. This study was carried out in research field of Islamic Azad University – Karaj Branch during 2009 – 2010. Thirteen traits including grain yield, biological yield, harvest index, 100 seed weight, stem diameter, plant height, spike length, days to heading, spike weight, awn length, peduncle length, seed length and seed diameter were studied. Results identified that the correlation coefficients between grain yield and biological yield, weight spike, awn length, seed length and peduncle length were positive and significant. Path analysis revealed that biological yield have the most direct and positive effect on grain yield. Spike weight indirect effect via biological yield on grain yield was positive. Factor analysis showed that four factors explained 70.68 percent of the total variance. The first, second and third factor called yield, morphological characteristics and seed characteristics respectively. Cluster analysis according WARD method grouping the genotypes into three main groups.

In order to investigate effect of deficit irrigation on phenological stages and yield of soybean cultivars, an experiment was conducted as split plots based on randomized complete block design with three replications at Agricultural Research Farm, University of Guilan in 2009. Main factor was included four irrigation levels based on potential moisture 30-35 (I1), 50-55 (I2), 70-75 (I3) centibar soil using tensiometer and without irrigation (I4) and sub plot factor was included seven soybean cultivars 033, 032, Sahar (belong to group maturity 4), L.17, Zan, Clark and Madari (belong to group maturity 3). To determine thermal requirement growth degree day system was used. Thermal units required by daily weather statistics for planting to flowering, planting to poding, planting to seeding, planting to maturity, seed filling period and reproductive period, were determined. At harvest time, the following data were recorded: Plant height, no. of seeds per plant, weight of seeds per plant, plant dry weight, seed and biological yields. Planting to poding period and planting to seeding period increased with reduction in water available and water deficit delayed appearance of pods. Water deficit decreased the yield components, significantly. Cultivar had significant effect on the yield components and all of phenological stages. The highest seed yield produced from 033 cultivar. In general, the results showed that water deficit is capable by delays in the occurrence of phenological stages in time and decreasing yield components, reduce yield of soybean. The lowest time for appearance of pods and the highest yield was belonged to I1. According to results, it seems that application of irrigation based on I1, can improve growth and yield of soybean in Rasht region.

Cultivation of high efficacy crops in resource utilization, especially with higher water and radiation use efficiencies is one of the important strategies to achieve the goals of sustainable agriculture. Align with these guidelines and in order to estimate light extinction coefficient and radiation use efficiency of sesame a split plot arrangement of two factors based on randomized complete block design with three replications was conducted in 2009-10 growing season. Cultivation and no cultivation of Lathyrus sp. and Persian clover (Trifolium resopinatum) as cover crop in autumn assigned to the main plots. The sub plot factor consisted of three different types of biofertilizers plus control, including 1-nitroxin (containing of Azotobacter sp. &Azospirillum sp.), 2- biophosphor PSB (containing of phosphate solubilizing bacteria,Bacillus sp. &Pseudomonas sp.)), 3- biosulfur SSB (containing of Thiobacillus ssp.) and 4- control (no fertilizer). The results showed that application of biofertilizers resulted to 15 days shorter period to achieve maximum leaf area index compared to control and as a result, the maximum fraction of absorbed radiation and consequentlysesame dry matter produced at the sixtieth day after emergence, 15 day sooner than control. Sesame dry matter production after cover crops cultivation was 19 percent higher than no cover crop cultivation treatment. Although, light extinction coefficient in control (no biofertilizer) was higher than biofertilizer treatments (0. 78 vs. 0. 69), but radiation use efficiency (RUE) in biosulfurand nitroxin was higher compared to control (1. 31, 1. 24 and 1. 09respectively) which resulted to highest biological and seed yield and harvest index. Sesame radiation use efficiency in plots with cover crop was 0. 18 higher than plots with no cover crop. In this research, the total mean sesame RUE estimated of 1. 19 gMJ-1 (R2=0. 95). In general, these results indicated that application of nitroxin and biosulfur combined with cover crops cultivation enhanced utilization of radiated and absorbed radiation by sesame canopy and consequently improved yield.

Iran is located in arid and semi-arid areas and has limited water resources that yield reduction due to low irrigation in these areas can be inhibited by programming and wise facilities usage. Supplemental irrigation is an approach that can lead to satisfactory and sustainable yield in dryland. The effects of supplemental irrigation on growth and yield of rainfed wheat (Var. Azar2) were investigated in at Dryland Research Station of Shirvan, during growing season of 2008-2009. Four sensitive stages of wheat to drought stress are A) germination, B) tillering, C) flowering, and D) seed set. Single or combined irrigation patterns in these four stages created 16 combinations. That it carried out based on randomized complete block design with 4 replications. These treatments included single irrigation in each stage (A, B, C, and D), two times irrigation (AB, AC, AD, BC, BD and CD), three times irrigation (ABC, ACD, ABD and BCD), four times irrigation (ABCD) and control (No irrigation). The results showed that supplemental irrigation had no significant effect on plant height, but its effect was significant on spike length, tillers and fertile tillers number, seed number per spike, 1000-seed weight, grain yield, harvest index and dry weight of wheat. The highest yield was obtained from 2 times irrigation in flowering and seed set stages (CD with 2009.2 kg/ha) which had no significant difference with 2 times irrigation in tillering and flowering stages. The lowest yield was obtained from no irrigation treatment (NO with 1045.2 kg/ha). The highest seed number per spike was obtained from BC and highest 1000-seed weight from AD. According to the result of this study, it could be concluded that supplemental irrigation in dryland wheat had significant effect on yield and can increase dryland wheat yield. So, it seems that enough water in flowering stage can increase the yield to a satisfactory level.

In order to evaluate terminal drought tolerance in different Canola cultivars based on drought tolerance indices, an experiment was conducted based on randomized complete block design (RCBD) with three replications at experimental field of Seed and Plant Improvement Institute (SPII), Karaj in 2008-09. Results using stress tolerance index (STI), geometric mean productivity (GMP) and mean productivity (MP) indices revealed Zarfam, Talaye and GKH305, were as cultivars with highest yield in both optimum irrigation and terminal drought conditions. High and positive correlation between STI, GMP and MP indices with yield in optimum and drought conditions indicated that they were as the best indices for introduction and characterization of drought tolerant canola cultivars. Biplot graph showed that MP, GMP and STI indices had high correlation coefficient with each other, and tolerant genotypes were located near tolerance indices. Also results of three dimensional scatter plot indicated that cultivars Zarfam, GKH 305 and Tassilo were recognized as tolerant genotypes to drought stress, and cultivars ES Astrid, GK Helena, Modena and Okapi were identified as sensitive genotypes.