نشریه علوم و فناوری بذر ایران
سال ششم شماره 1 (پیاپی 11، بهار و تابستان 1396)

Germination is the first and the most critical stage of plant growth since the early stages of plant growth, such as germination, seedling growth and establishment play in the evolution of plants important role. In order to evaluate the effects of soil depth and texture on germination and survival of Nepeta asterotricha, a factorial experiment in a completely randomized design with 4 replications was implemented in the Yazd University. The germination of seeds in three different soil textures: light, medium and heavy with three different depths (0.5, 1 and 1.5 cm) were studied. The results showed that the time required to achieve 90% of its maximum germination affected by soil texture significantly) P≤0.05). Soil texture also affected other characteristics (P≤0.01). Depth of planting affected the germination percentage, speed germination, seed vigor, and the time required to achieve 50% of its maximum seed germination (P≤0.01). Among the three studied soil textures, sand texture had the highest germination percentage (67.8 %) and the lowest germination percentage observed in silty clay texture (32.2 %). In addition, check out the various features germination in the three-studied depth showed that at a depth of 0.5 cm all germination parameters had the best results. However, at a depth of 1.5 cm parameters had not significant differences. The highest germination percentage related to sand texture and a depth of 0.5 cm (97 %) and the lowest germination percentage related to 1.5 cm deep and silty clay soil texture (23 %).

There is a little information about the effects of temperature and water potential on safflower. In order to study the effects of temperature and water potential on seed germination characteristics of safflower (Carthamus tinctorius L.), an experiment as combined analysis was conducted base on a completely randomized design with 4 replications by 25 seeds in laboratory of seed technology at Yasouj University in 2015. The factors included temperature (5, 10, 15, 20, 25, 30, 35, 40 and 45 oC) and water potential (0, -0.2, -0.4, -0.6, -0.8, -1, -1.2, -1.4 and -1.6 MPa). The percentage and rate of germination, root length, shoot length, ratio of root length to shoot length and seedling vigor index were measured in this experiment. The results of analysis of variance showed that main effects of temperature and water potential and interactions were significant on all indicators of germination at 1% probability level. Also, by decreased water potential, germination percentage and germination rate reduced. At 5 oC and at zero potential germination percentage was 98% while the potential of -1.6 MPa germination percentage dropped to zero. At 35 oC and at zero potential germination percentage was 95% while the using potential of -1.6 MPa germination percentage decreased to 1%.  By increasing the temperature up to 20oC increasing germination percentage and germination rate detected and afterwards reduced.

In this study the identification of chemical and biochemical characteristics of balangu seed oil (Lallemanthia royleana) and their parameters were investigated under accelerated aging conditions at 24 h, 48 h and 72 h at 41°C and 100% RH in a completely randomized design. The results showed that balangu seed oil content was 19.26%.Fatty acid profiles were 90.71% of unsaturated fatty acids (USFA) and 9.29% of saturated fatty acids (SFA), also the linolenic acid (C18:3), oleic acid (C18:1) and palmitic acid (C16:0) were important of PUSFA, MUSFA and SFA oil seeds, respectively.The antioxidants of oil seeds include 427.8 ppm tocopherols and 210 ml.l-1 of polyphenols. The results showed that 15.2% reduction in oil seed under accelerated aging treatment, also this treatments was the cause of increase of SFA compared to USFA. The oxidation and peroxide production peak was between control and 24 h of accelerated aging treatment. Oil resistance (rancimat) in the 72 h of aging treatment was 1.5 times less than to the control. The germination value (GV) was 1.6, 2.5 and 4.5 higher than the accelerated aging treatments, respectively. In general, it is likely that the changes of chemical and biochemical characteristics of seed oil is happened by oxidative enzymes and this condition is quicker in deteriorated balangu seeds

Temperature is one of the most effective and important environmental agents on seed germination, thus interaction effect of germination with temperature is very important in prediction of germination time and modeling especially. A completely randomized design experiment performed in seed research laboratory of Islamic Azad University, Mahabad Branch with four replications which temperature treatment were 11 levels as: 3, 5, 7, 10, 15, 20, 25, 30, 35, 40 and 45 0C. Three nonlinear regression models as Beta, 5-Parametric Beta and Segmented functions tested. Results revealed that temperature had a significant effects of rate, uniformity and germination percent. The highest uniformity and germination percentage were detected in 15 0C, but the highest value of rate of germination obtained in 20 0C.  Although, there was no significant difference between practiced models in estimation of cardinal temperatures, however, the segmented model which had the less RMSE, CV and the more R2 and correlation coefficients than the others, was a better model and thus, cardinal temperatures including base, optimum and ceiling temperatures were 3.35, 20.84 and 40.94 0C, respectively. Also, the maximum germination rate (rmax ) was  0.010 h-1.

Seed enhancement methods are applied to eliminate or decrease adverse environmental stress effects and increase seed germination rate and vigor of rangeland plants. The coated seed process is from amplifier ways that stick various materials on the outer surface of the seeds that minimize the negative environmental effects and increase the ability of plant establishment. The aim of this study was to assess the effects of seed coating methods on germination of Triticum aesativum, cultivar Sardariin different moisture stress levels and sowing depths. This experiment was conducted with a completely randomized design with four replications. Treatments of covering material was used in four levels including, non coating levels (NC), mineral-based coating (CC), organic- based coating (OC), and hydro gel-based coating (HC). Moisture treatments were used in three levels of moisture soil content. Two planting depth and three seed diameter including M9%, M14% and M21% were used. During the test, speed of germination was evaluated. The results showed that moisture treatments and planting depth at had highly significant effect and there was no significant effect of coating treatments. Also the interaction between type of covering material and soil moisture was not significant for germination speed, but there was significant difference between treatments of seed size in M9% and M21%. Although in the triple interaction, increasing moisture and planting depth enhanced the speed of germination process, but it was not significant statistically. The seedling growth of covered seed developed significantly, so it can be useful in enhancing plant performance.

Harvesting of medicinal plants from their natural habitats, put them in danger, hence their domestication is needed. In this context, knowledge of the properties of these plants, including the cardinal germination temperatures are necessary. In order to determine the cardinal temperatures and the effect of temperature on the percentage and rate of germination in Plantago major ecotypes (Birjand, Ghaen, Torbathydarieh, Mashhad, Kalat and Bojnord) an experiment was conducted based on factorial in a completely randomized design with 9 temperature levels (5, 10, 15, 20, 25, 30, 35, 40 and 45 °C) and four replications in Crop Physiology Laboratory, Ferdowsi University of Mashhad in 2013. To determine the cardinal temperatures Intersected-Lines Model and Five-Parameters Beta Model were used. Results showed that maximum germination percentage was obtained at 30 °C while maximum germination speed achieved at 35 °C in Bojnourd and Birjand ecotypes, respectively. The highest germination percentage was observed in Birjand ecotype at the temperature range of 20 to 35 °C. Based on models fitted depending on the ecotype, cardinal temperatures  (minimum, optimum and maximum) germination were determined (6.3 to 9.8, 1.8 to 5°C) ,(31.1 to 35.9, 28.6 to 35.2°C) and (43.3 to 45.1, 45 to 45.6 °C) of Intersected-lines and Five-Parameters Beta Model, respectively. Diversity in cardinal temperature of plantago major ecotypes could be due to different environmental conditions where they were evolved and adapted

In order to evaluate the allelopatic potential of Eucalyptus camaldulesis aquatic extract on antioxidant enzyme activities, cell membrane damage and α-amylase enzyme activity of S. halapense, thisexperiments was conducted in Islamic Azad University, Shoushtar branch at 2012. The experiment was laid out according to a Completely Randomized Design with five replications and six treatments were various concentration of E. camaldulesis aquatic extract (0, 10, 20, 30, 40, 50 and 60%). The results indicated E. camaldulesis aquatic extract application exhibited gradual rise inhibitory effect on seed germination, seedling fresh weight, antioxidants enzymes activities, and α-amylase enzyme activity. Contrary to the previous traits, elevated malondialdehyde concentration and seedling fatty acid in S. halapense seedlings were detected. The minimum α-amylase enzyme activity (3.1 and 3.5  nmol prot -1 min-2 ), seedling fresh weight (0.1 and 0.8 mg) and seed germination (54% and 42 %) showed in 40% and 50% Eucalyptus camaldulesis aquatic extract.  The highest fatty acid (23.6% and 23.1%) was noted at 40% and 50% Eucalyptus camaldulesis aquatic extract. In conclusion, E. camaldulesis aquatic extract decreased seedling growth, α-amylase enzyme activity and cell membrane stability of S. halapense seedling.

This study was done to evaluate different nonlinear regression models to describe the response of germination rate and to determinate the cardinal temperature of four ecotypes of Cuminum cyminum(Cumin) seeds. This experiment was arranged in the form of three-factor factorial completely randomized design with 4 replications at the Agronomy Laboratory  (Aburaihan College, University of Tehran) in 2011.The seeds were treated with different temperatures (0, 5, 15, 25, 35 and 45 oc) and the germination rate were calculated. The result showed that the temperature had a significant effect on germination rate of all plants. The segmented model was superior compared to other models in ecotypes of cumin since the minimum amount of AICc and maximum value of Adj R2 were related to this model. Base (Tb), optimum (To) and ceiling (Tc) temperatures were predicted with appropriate models. Tb, To, and Tc for Khorasani ecotype were 0, 11.4, 25 °C; for Krmani ecotype were 0, 11.5, 28.9 °C, for Jandaghi ecotype were 3.1, 9.6, 27.1 °C and for Esfahan ecotype 0, 10.1, 35.5 °C, respectively. It was concluded that this model can be used to quantify response of cumin seed germination to temperature and to obtain the proper cardinal temperatures of germination.

Basswood(Tilia begonifolia) and Blacklocust (Robinia pseudoacacia) are two forest trees with seed dormancy due to very hard seed coat. Seeds of two species were collected from Ghorogh nursery in Gorgan province to remove seed coat (breaking seed dormancy) and simplify germniation process and examine the effects of scarification on their germination and viability in 2014.The tetrazolium test was done to measure the seed vitatlity.Then the seed germination rate was tested using hot water (100°C for 1 min. ), H2O2 (1 % for 10 min.), H2SO4 (30 % for 10 min.) and control treatments. The experiment was done in the laboratory of the Faculty of Desert Study (Semnan university). The results of tetrazolium test showed that Tilia begonifolia and Robiniapseudoacacia have 57.25 and 78.30 percent of viability, respectively. The highest rates of seed germination of Tilia begonifolia and Robinia pseudoacacia were observed in H2O2 (%38) and hot water (%66.69) treatments, respectively. As the seeds of Robinia pseudoacacia have higher seed germination than Tilia begonifolia despite of having hard seed coat, it can be concluded that other factors except of hard seed coat can affect seed germination of Tilia begonifolia.  Basswood(Tilia begonifolia) and Blacklocust (Robinia pseudoacacia) are two forest trees with seed dormancy due to very hard seed coat. Seeds of two species were collected from Ghorogh nursery in Gorgan province to remove seed coat (breaking seed dormancy) and simplify germniation process and examine the effects of scarification on their germination and viability in 2014.The tetrazolium test was done to measure the seed vitatlity.Then the seed germination rate was tested using hot water (100°C for 1 min. ), H2O2 (1 % for 10 min.), H2SO4 (30 % for 10 min.) and control treatments. The experiment was done in the laboratory of the Faculty of Desert Study (Semnan university). The results of tetrazolium test showed that Tilia begonifolia and Robiniapseudoacacia have 57.25 and 78.30 percent of viability, respectively. The highest rates of seed germination of Tilia begonifolia and Robinia pseudoacacia were observed in H2O2 (%38) and hot water (%66.69) treatments, respectively. As the seeds of Robinia pseudoacacia have higher seed germination than Tilia begonifolia despite of having hard seed coat, it can be concluded that other factors except of hard seed coat can affect seed germination of Tilia begonifolia.

Seed senescence is one of the major problems in the production of crops. In order to evaluate the effect of accelerated aging on germination and other seed germination components produced from the treated mother plant in three bean cultivars, a factorial experiment was conducted in a randomized complete block design with three replications at the research laboratory of Faculty of Agriculture, Shiraz University. The factors were including pinto bean varieties at 3 levels includes E9, E10, and Khomain, accelerated aging at two levels includes accelerated aging and control, and the third factor was seeds produced from treated mother plant seed in the farm at 7 levels includes: polyethylene glycol (PEG) -5 bar at 6 hours, , potassium chloride (KCl) -20 mM at 6 hours, calcium chloride (CaCl2) - 15 mM at 3 hours, sodium chloride (NaCl) -20 mM at 6 hours, salicylic acid (C7H6O3) 500 mg per liter at 12 hours, distilled water at 12 hours and without pretreatment (Control). The percentage and rate of germination, seedling dry weight, weight and length vigor index and 9th day germination energy were measured. The result showed that the interaction between accelerated aging, pretreatment and variety on germination traits including germination percentage, seedling dry weight, weight and length vigor index and germination energy of the 9th day at 1 % level, interaction between accelerated aging and pretreatment on germination rate at 1 % level and interaction between pretreatment and variety on germination rate and coefficients of allometric at 5 % level were significant. Seed germination traits at accelerated ageing treatment was lower than control. The maximum germination percentage and germination energy of the 9th day was for sodium chloride at 6 hours and E10 variety, maximum seedling dry weight, germination rate and weight and length vigor index in calcium chloride (CaCl2) at 3 hours treatment and E10variety were detected. The result showed that according to the variety and selection of appropriate pretreatment of mother plant, it is possible to improve storage and have seeds with higher power and less deterioration.Seed senescence is one of the major problems in the production of crops. In order to evaluate the effect of accelerated aging on germination and other seed germination components produced from the treated mother plant in three bean cultivars, a factorial experiment was conducted in a randomized complete block design with three replications at the research laboratory of Faculty of Agriculture, Shiraz University. The factors were including pinto bean varieties at 3 levels includes E9, E10, and Khomain, accelerated aging at two levels includes accelerated aging and control, and the third factor was seeds produced from treated mother plant seed in the farm at 7 levels includes: polyethylene glycol (PEG) -5 bar at 6 hours, , potassium chloride (KCl) -20 mM at 6 hours, calcium chloride (CaCl2) - 15 mM at 3 hours, sodium chloride (NaCl) -20 mM at 6 hours, salicylic acid (C7H6O3) 500 mg per liter at 12 hours, distilled water at 12 hours and without pretreatment (Control). The percentage and rate of germination, seedling dry weight, weight and length vigor index and 9th day germination energy were measured. The result showed that the interaction between accelerated aging, pretreatment and variety on germination traits including germination percentage, seedling dry weight, weight and length vigor index and germination energy of the 9th day at 1 % level, interaction between accelerated aging and pretreatment on germination rate at 1 % level and interaction between pretreatment and variety on germination rate and coefficients of allometric at 5 % level were significant. Seed germination traits at accelerated ageing treatment was lower than control. The maximum germination percentage and germination energy of the 9th day was for sodium chloride at 6 hours and E10 variety, maximum seedling dry weight, germination rate and weight and length vigor index in calcium chloride (CaCl2) at 3 hours treatment and E10variety were detected. The result showed that according to the variety and selection of appropriate pretreatment of mother plant, it is possible to improve storage and have seeds with higher power and less deterioration.

There are different methods for harvesting of maize seed production fields. In order to detect the most effective methods of maize seed harvesting method, in addition to seed quality analysis, partial budgeting technique was studied and the results were analyzed using preferred investment method. According to the results, maize seed harvesting by picker-husker auto-harvester, PTO connected picker and harvesting by hand are most profitable methods, respectively. Since in the studied region (Moghan) well trained workers are available and investing for purchasing picker-husker auto-harvester is costly for great part of maize seed producers, so currently harvesting by workers, is most economic and profitable harvest method. In technical part of the survey which harvesting by hand and air drying the cobs was compared with conventional harvesting seed maize in Iran (direct harvest by combine harvester), all of physical and physiological quality characters, storability and percentage of above 6 mm seeds in harvesting by hand and air drying the cobs was significantly higher than conventional method.

In this research, cleaning, drying and grading of corn seed were investigated in Ardabil provinces (Mogan zone). Beside investigation of corn seed drying and processing machineries, some items such as moisture changes of corn seeds, broken and cracked seeds studied during process steps in four seed process factories. Although the most seed breaking belong to the large and round seeds, the most cracked seeds observed in round seeds. Cracked seeds had increasing trend and direct relationship with moisture. Numbers and revolution speed of bucket elevators had direct effect on seeds physical damages. It may increase seed cracking more than 30 percent. In totality about 15 percent of seeds go out of process line as broken seeds. Besides 30 percent of seeds cracked during process. Endosperm damages increased risk of planting and cusses to lack or poor germination.

In order to study of the effects ofnano-zinc oxide andseed inoculation with plant growth promoting rhizobacteria on phosphatase activity, zinc and protein content and related traits to grain growth of Triticale, a factorial experiment was conducted based on a randomized complete block design with three replications in research greenhouse of faculty of Agriculture Sciences, University of Mohaghegh Ardabili in 2013. Factors were seed inoculation with plant growth promoting rhizobacteria in four levels (without inoculation as control, seed inoculation with Azotobacter chrocoococum strain 5, Azosprillium lipoferum strain OF and Psedomunas putida strain 9) and foliar application of nano-zinc oxide at five levels (0 as control,0.25, 0.5, 0.75 and 1 g.lit-1). Means comparisons showed that maximum of phosphatase activity (1.35 nmol.min-1, zinc (31.4 mg.kg-1 and protein (134.2 g.kg-1) content, rate (0.10017 g.day-1) and grain filling period (40.74 days)were obtained at application of  1 g.lit-1 Nano-Zinc oxide and seed inoculation with Azosprillium and minimum of them (0.46 nmol.min-1, 23.1 mg.kg-1  ,108.6 g.kg-1, 0.0012 g.day-1 and 24.12 days respectively) were recorded at no application of nano-zinc oxide and without of seed inoculation with PGPR. Therefore, it seems that in order to improve seed quality, increasing of grain filling period, zinc and protein content, it can be suggested that be applied 1 g.lit-1 Nano-Zinc oxide ×seed inoculation with Azosprillium.

In order to investigate the effect of magneto priming on seed germination of sesame seed under water stress conditions, a factorial experiment based on a completely randomized design with three replications was carried out in 2014 in Ferdowsi University of Mashhad. Dry seeds of sesame exposed to magnetic fields (control (no priming), 25 mT[1] for 10 minutes and 75 mT for 60 minutes) bulky, then they treated by Polyethylene glycol 6000 (PEG6000) with different potentials (control (distilled water), -2, -4, -6 and -8 bar). Finally, germination traits such as germination percentage, germination rate, plumule and radicle length, dry weight of plumule and radicle and seedling length and seedling weight vigour indices were measured. The results showed that magneto priming led to increment of germination rate, radicle and plumule length, radicle dry weight and seedling length and seedling weight vigour indices, especially in high levels of water stress compared with control treatment. Radicle length of magneto primed sesame seeds with 75 mT (for 60 minutes) in -8 bar was 16.6% and radicle dry weight of magneto primed seeds with 25 mT (for 10 minutes) at the same level of water stress, was 64.4% more than control (no priming). In addition in -8 bar potential, due to priming with 75 and 25 mT intensities of magnetic fields, seedling length and weight vigour indices enhanced 38% and 22.6%, respectively, in comparison to control treatment. [1] mili Tesla

The aim of this researchwas to investigate the possibility of using image processing to determine the quality of seed germination after applying dynamic loads. For this purpose, mechanical damage at four levels (0.0404, 0.0808, 0.1212 and 0.1617) on three cultivars of chickpea seed (Azad, Hashem and ILC) were investigated. The study was conducted based on a completely randomized factorial design. The results showed that the ILC had the lowest electrical conductivity (12.02), the highest germination rate (10.31), the highest seedling growth (18.69), the most vigor (84.2), the maximum radicle length (13.29), radicle dry weight (0.574), hypocotyle dry weight (0.271) and the highest seedling dry weight (0.844) among other cultivars. Mean comparison of energy treatment showed that with inceasing energy level, germination quality and vigor were reduced. Then, length and area of radicle were evaluated using image processing. Based on statistical analysis, there was no significant difference between image processing and manual measurments. This shows the potential of replacement of time-consuming manual with image processing method for examination of seedling parameters

The experiment was conducted to examine the effects of nano-particle silicon dioxide to improve germination of deteriorated soybean seeds (Williams). The experiment was done as factorial in a completely randomized design with three replications in 2015 in Seed Technology Laboratory in the University of Shahed. The first factor involves different levels of accelerated aging including control and accelerated aging for 24 and 48 hours at 41 ° C in high humidity conditions and different concentrations of nano-silica as the second factor including zero (control), 40 and 60 ppm, respectively. The traits such as germination percentage, germination rate, the average duration of germination, the number of normal seedlings, seedling fresh weight, root to shoot ratio, relative water content of root, seedling length and chlorophyll content were measured. The results showed that the effect of nano-silica pre-treated soybean seed germination was significant on all traits. But the interaction of nano-silica priming and the deteriorated seeds of soybean was significant only in some germination characteristics. Pre-treatment of 60 ppm nano-particle silica increased 20% of deteriorated seeds germination rate and reduced the average time of germination. Pre-treatment of 40 ppm increased about 7-10% of the number of normal seedlings, and also treatment of silica nanoparticles improved seed germination with compensate amount of chlorophyll in deteriorated seeds.

In order to investigate the effects of seed deterioration on the activity of antioxidant enzymes and lipid peroxidation in pumpkin seedlings a factorial experiment conducted based on completely randomized design with three replications. Treatments were three deterioration levels (control, 5 and 10 days deterioration at 45◦C and 95-100% relative humidity) and three germination temperatures (15, 25 and 35°C). Results showed that activity of superoxide dismutase and catalase were the highest at 5 days aging and 25°C, and activity of peroxidase was the highest at non-aging and 25°C. Also, the highest amount of Malondialdehyde (7.1 mmol gr-1FW) observed in the seeds with 10 days deterioration and 15°C. The highest respiration index (0.018 mg) achieved in 5 days deterioration and 35°C and the lowest value (0.009 mg) was related to 10 days deterioration and 35°C. It seems that reduction in seed vigor under deterioration and high temperatures causes to oxidative stress and lipid peroxidation and leads to increase in the activity of antioxidant enzymes in order to face the related damages. Considering results obtained from germination and antioxidant enzymes activity the best temperature for germination of aged seeds of pumpkin was 15◦C.

High temperature during seed set and seed filling can reduce yield and seed quality. In order to evaluate the effect of high temperature during planting date and also plant density on soybean seed quality, an experiment was conducted at two locations, namely, Seed and Plant Certification and Registration Institute in Karaj and Agricultural and Natural Resource Center of Moghan, in 2013. The studied factors were included planting date (5th of May, 5th of June and 5th of July), plant density (300, 400 and 500 thousand plant/ha) and soybean varieties (Williams and L17) were sown in the rate of 40 plants per m-2 at 5th May, 5th June and 5th July. The experiment was conducted as a factorial based on a randomized complete block design (RCBD) with three replications. The results of standard germination test showed that in Moghan area, the highest normal seedling percentage (92.1%) was obtained at fifth of June and in Karaj area, it (96.2%) was gained at fifth of July. In addition, it was noticed that cv. L17 in Moghan and cv. Williams in Karaj had the highest normal seedling percentage. The results of accelerated aging test was cleared that the normal seedling percentage in karaj was more than Moghan area and it showed that the quality of seed that were produced in Karaj was better than Moghan area. There was no significant difference between areas in 300 and 400 thousand of plant/ha and in these both density, the result of Karaj was better than Moghan area, but there was significant difference between normal seedling percentage after accelerated aging test in Karaj (77.6%) and Moghan (58%) in 500 thousand plant/ha. The highest seedling vigor index (11.75) was obtained in 400 thousand plants/ha at fifth of July in Karaj area and the lowest rate of it (5.41) was observed in 300 thousand plants/ha at fifth of June in Karaj area.

Because of the importance of the role of maternal environment during seed development on germination of produced seed and seedling establishment an experiment in a randomized complete block design base as a factorial was conducted to evaluate effects of drought stress (0.0, -0.2, -0.4, -0.8 and -1 MPa) on germination and seedling growth characteristics of wild oat seed production under different irrigation regime (100,80 and 60 percentage of water requirement of wheat from stem elongation stage to the end of growth season) in Shahrood Agriculture research center. According to the results, maternal irrigation regime, drought stress and interaction effects between them had significant effect on germination and seedling characteristics of wild oat. The results showed that germination characteristics were decreased significantly with decrease of water potential to -1 MPa. The highest rate and percentage of germination and radicle length in this water potential was related to irrigation regime of 60% water requirement and the least of plumule dry weight was related to irrigation regime of 60 and 80% water requirement. Length and dry weight of plumule decreased more than those of radicle under drought stress conditions and showed greater sensitivity to reduced water potential. Lower dry weight and green area was observed in seedling that germinated at water potential more than -0.4 MPa. The results showed that drought stress during the seed formation caused significant changes in response of wild oat germination under stress condition.

In order to study the effects of planting date on quantitative and qualitative characteristics of different clover seed varieties, this research was conducted in a field during cropping year of 2012. The research facilities of Seed and Plant Improvement Institute of Karaj use at this study. This research in split plots including the major factor of planting date on 3 cultivation levels (conventional planting date 11 September and delayed planting date including 5 September and 20 October) and the sub-factor clover genotypes at 10 cultivation levels (Persian clover 7 cultivar, Berseem clover (production in Karaj). red clover, a variety called Nasim and Locki clover, a variety called Alborz 1). This research was conducted in a randomized complete block design (RBCD) with four replications. The results showed that the effect of planting date for traits such as grain yield, harvest index and seed quality traits is significant at one percent level. The results seed quality traits showed that the first planting date (11 September) with 86.4 germination percentage and 38.3 germination rate is the best treatment. Comparing the varieties showed that the Persian clover cultivars number 1 with 92.2% germination and 43.8-rate germination is the highest rate. Comparing the mean of varieties showed that the Crimson clover Alborz number 1 seed with 35 grams weight and the harvest index of 4.5 best among the studied varieties