جستجوی مقالات مرتبط با کلیدواژه "seed" در نشریات گروه "اکولوژی"

 Albizia julibrissin is one of the ecologically valuable tree species in the Hyrcanian forest at the Norht of Iran that is endangered due to Fusarium wilt disease. Seeds of these trees have low germination because of their hard coat and dormancy. One of the most effective methods to improve the germination characteristics is seed irradiation during pre-sowing processes. Present study was conducted to improve seed germination characteristics.

  Experiment was arranged by completely randomized design in four replications, five treatments and one control. Seeds were radiated with 60 cobalt source emitting gamma rays at the rate of 0.013 Gray/sec and different doses of gamma rays: 15, 25, 50, 100 and 150 Gray (Gy). All of the seeds were sowing in the moist stratification at 25°C.

 Seed germination started simultaneously 28 days after sowing. Results showed that there is significant difference in germination characteristics between treated seeds and control (p˂0.05). The highest value of seed germination was observed in the 15 Gy (86%), the highest seed vigor index was in 15 Gy treated seeds (266.6), the highest germination speed index  were in 15 and 150 Gy (12.17 and 12.32 seed number day-1 respectively) and the highest mean daily germination were in 15, 50, 100 Gy (7.46, 7.32 and 7.34 number/day respectively).

 Increasing seed germination characteristics was observed in seeds that radiated by low dose of gamma radiation. Hence, lower dose (15 Gy) of irradiation treatment can be used to improve the Albizia julibrissin seed germination characteristics.

In this study, 10 promising lines of white bean (Phaseolus vulgaris L.) along with Dorsa and Paak control cultivars were evaluated in a randomized complete blocks design with three replications over two years. During the growing season, the status of the lines was determined in terms of growth type, number of days from planting to flowering and maturity, number of pods per plant, number of seeds per pod, 100-seeds weight, single plant yield and total yield. Results of combined analysis of variance over two yearsfollowed by LSD test showed that grain yields of lines 7, 3 and 6 were 49%, 42% and 41% higher than the control, respectively. Of these three lines, line 3 was superior because of its higher 100-seedsweight. Therefore, this line is suitable for Shahrekord and similar areas. Correlation coefficients of grain yield and its main components were positive and significant. Further experiments to introduce Line 3 as a new cultivar will take place in the coming years. 

 In order to determine the best cold tolerant line of rice, Eight rice genotypes were compared in a randomized complete blocks design with three replicates in Saman town (one of the semi-cold places of Chaharmahal and Bakhtiari province) during 2012-2013. Results of combined analysis of variance showed significant differences among the genotypes for studied traits including; the number of days to the phenological stages (emerging 50% of panicles and 80% of maturity), plant height, the number of fertile and non-fertile tillers per plant, the number of fertile and non-fertile grains per panicle, weight of one thousand seeds and grain yield.  Genotype code 14 (Stevela) with the highest number of fertile tillers per plant and the lowest number of no fertile grains per panicle produced the highest grain yield (6.640 t/ha) and was ranked higher than other genotypes. Three other genotypes (codes 1, 3 and 7) with an average yield of tons per hectare were in a class lower than code 14 but higher than control genotypes. Two control genotypes were Koohrang and local Champa, had an average yield of 4.625 t/ha. 

 Water salinity is one of the most progressive environmental factors limiting the growth and productivity of plants. The objective of this study was to evaluate the effects of salt stress on seed germination and some quantitative trait of tall fescue. For this purpose, a laboratory experiment was conducted at seed laboratory, Islamic Azad University, Isfahan Branch. The traits were radicle and plumule length, fresh and dry weight of radicle and plumule and some properties of seed germination such as germination percent, mean germination time, germination speed, and germination energy and vigor index. Seeds were arranged in petri dishes with 4 replications in completely randomized design with six levels of water salinity including 0, 4, 5, 6, 7 and 8 dSm−1. The results indicated that salinity stress had significant effect on seed germination and physiological characteristics. The results indicated that salinity of irrigation water significantly reduced all studied properties exception of germination time. The values of these properties were continuously decreased with increasing salinity levels. However, time of germination in salinity levels of 4−7 dSm−1 was significantly higher than that distilled water. Seed vigor index was more affecting salinity stress than germination percent.   

Wild almond (Amygdalus scoparia) is one of the most important species that provides a variety of ecological functions in the Zagros forest ecosystem. In this study, we investigated the effects of some seed treatments on the survival and growth of Amygdalus scoparia after seed planting at different aspects and elevations under natural conditions. The seed pretreatments consisted in soaking them in water at cold (10 °C) and warm (80 °C) temperatures for 24 hours. The impact of these pretreatments was evaluated on the survival rate (%), height and diameter growth of newly emerged seedlings. Based on Duncan’s test, the height of seedlings established on the north-facing aspect was significantly higher than the other aspects, while the lowest seedling height was observed in the south-facing aspect. The height of seedlings established on east- and west-facing aspects had intermediate values and were statistically similar. The tallest seedlings were observed when seeds were buried at a depth of 2 cm and seedling height tended to decrease with increasing burial depth. Seedlings established on the north-facing aspect at both elevation levels (1200 and 1800 m) were significantly taller than those found on the south-facing aspect. Overall, the use of cold water as a seed pre-treatment in conjunction with a north-facing seedling at a burial depth of 2 cm maximize the survival and the development of Amygdalus scoparia seedlings.

Vermiwash contains enzymes, macro and micronutrients that could stimulate the growth and yield of crops. It can be prepared by different ways. In the present study, vermiwash was produced from the earthworm, Eisenia foetida, under field condition and also in the laboratory under cold and heat stress methods. These washes were used in different ratios for seed germination of mung, Vigna radiate. The results showed that the vermiwash produced by cold stress diluted at the ratio of 1:5 showed 100 % germination of mung seed followed by 1:5 ratio vermiwash produced naturally that resulted 95 % of seed germination. Undiluted vermiwash produced naturally and by cold stress showed 90 % of germination of mung seed than the undiluted vermiwash produced by heat stress. Cold stress produced vermiwash diluted with 1:5 ratio showed a vigour index of 1650 followed by naturally produced 1:5 ratio diluted vermiwash which showed a vigour index of 1092. However, the undiluted naturally produced vermiwash showed the lowest vigour index of 450.

The sunflower oilseed and confectionaries types (Helianthus annuus L.) are definitely different in nutritional responses. This study attempted to evaluate differences in the expression levels of phosphorus and zinc arising from different fertilization treatments. The field experiment was conducted out at Agricultural Research Centre, in Islamic Azad University Arak, Iran, during 2011. Experiment was laid in split plot in randomized complete block design with 3 replications. Phosphorus treatments were in main plots and zinc in sub plots. Phosphorus levels were including 350, 175, 175 kg/ha triple super phosphate plus 100 g/ha phosphorus solublizing bacteria (PSB) and PSB alone and zinc levels were 0, 25 kg/ha soil application zinc sulphate, 25 kg/ha soil application of zinc sulphate plus 10% soluble zinc foliar application and soluble zinc foliar application alone. The results of roots quality in two sunflowers types showed P concentration in confectionary sunflower roots in all zinc levels was significantly higher. Use of 175 kg/ha triple super phosphate plus phosphorus solubilising bacteria (P < /font>3( or utilization of pure PSB (P < /font>4) in test plots was one of the main cause to increase phosphorus concentration in sunflower roots in check plots for zinc (Z1). Leaf phosphorus content was sharply higher in confectionary sunflower when fertilized with phosphorus and zinc mixture. High P application (P < sub>1) was the main cause for slow reduction in leaf zinc concentration for oilseed from 40 to 20 mg/kg. However, PSB and chemical phosphate use (P < sub>3) and PSB alone (P < sub>4) caused the leaf zinc content to increase significantly by foliar zinc application (Z4). Furthermore, the most zinc accumulation was detected in confectionary sunflower seeds by 55 mg/kg in PSB and chemical phosphate use treatment plus foliar soluble zinc application (P < sub>3Z4).

Hoary alyssum (Berteroa incana L.) is a rangeland weed of British Colombia, Canada and a prolific seed producer. Knowledge of spatial and temporal dynamics of seed banks and factors affecting them is essential to understand the persistence strategy of this weed. Little information on distribution of B. incana seeds dormancy and modification of germination behavior by climatic factors is available. The hoary alyssum seed dormancy and temperature influence on seed germination were investigated. Effects of temperature on seed germination and dry heat on seed viability were studied in Petri dish assays. B. incana seeds showed that 25-30°C were the optimal temperatures for germination; germination did not occur at 40°C and above, exposure to dry heat (80 or 90°C) for 8 hr significantly reduced seed germination at 25°C. While 1 to 3 d of anaerobiosis delayed seed germination (by ~1 d) upon their subsequent incubation in Petri dishes at 25°C, it did not induce dormancy. A 5-d anaerobiosis reduced seed germination by 24-47 %.

To evaluate the effect of sulfuric acid (75%) on breaking the dormancy of the seeds of goosefoot (Chenopodium album L.) and red-root amaranth (Amaranthus retroflexus L.) as potato weeds, an experiment was conducted in Seed Technology Laboratory, Department of Agronomy, University of Mohaghegh-e-Ardabili, Ardabil, Iran in 2010 based on a Randomized Complete Design with three replications. The treatments included pretreatment of the seeds of both species with sulfuric acid (75%) for 0, 7, 14, 25 and 45 minutes. The results showed that with the increase in the duration of treatment with sulfuric acid (75%), the germination percentage of amaranth seeds increased from 2% to 78.5% and its germination rate increased from 0.8 to 4.4 but radicle length and weight decreased from 32 to 7.4 cm and from 0.00054g to 0.00001 g, respectively. There was no significant difference among the treatments of pretreatment with sulfuric acid for 7, 14 and 25 minutes. The highest and lowest germination rates were observed in 45-minute pretreatment with sulfuric acid and control, respectively. With respect to goosefoot seeds, no germination and seedling growth was observed after treated with sulfuric acid (75%).

An important factor in determining water demand and optimum water management at different growth stages of sugar beet seed-bearing plants is crop coefficient (Kc). The crop coefficient (the ratio of sugar beet seed-bearing plant evapotranspiration (ETc) to grass evapotranspiration (ET0)) was calculated at different growth stages. The study was carried out by 6 lysimeters located in research station of Karaj Soil and Water Research Institute, Meshkinabad, Karaj in 2006. Two lysimeters where grass had been cultivated, were used for determining ET0. To determine ETc of sugar beet seed-bearing plants, vernalized roots of sugar beet (200-250 g) were planted in four lysimeters. About 2000 and 1000 m2 were planted by the same crop around the lysimeters of sugar beet seed-bearing plants and grass, respectively. The moisture contents of all lysimeters were measured during the growth period and also after harvest at the depth of 0-60 cm. To compensate soil moisture deficit, the irrigation was carried out after depletion of 40% of available moisture. In addition, precipitation, daily temperature, relative humidity, wind speed, sunny hours and evaporation from Class A pan was measured in a meteorological station located around the grass lysimeters during the growing period. The measured crop factors included root number, total biomass weight, shoot dry weight, root dry weight, flowering stem weight, seed total weight, seed size, standard seed weight, 1000-seed weight, vigor, germination rate and seed viability. ET0 was calculated by evaporation pan and applying pan coefficient (Kp) of Karaj and also by Penman & Mantis method and was compared with the data of grass lysimeter. ETc, ET0 as well as Kc were estimated at different growth stages. The results showed that there was great conformity between two methods of ET0 calculation, i.e. by software CROPWAT and measurement. But at the beginning of the study, the ET0 calculated by grass lysimeters was lower than that calculated by meteorological data. However, over the time, the latter was affected by climatic parameters of temperature and sunny hours and increased with a stronger gradient than the former. This period was from the 50th day on. The results indicated that crop evapotranspiration decreased at the initial stage because of undeveloped shoots and at final stage and at the end of growth period because of shoot yellowing and loss of green area and the need for the decrease in seed moisture during maturation. At the second stage, the crop absorbed greater amount of water and as a result, its evapotranspiration increased because of the fast growth of sugar beet seed-bearing plants and the proliferation of aerial organs. At the third stage, since on one hand the leaf area of sugar beet seed-bearing plants was at its peak and on the other hand, the other organs were green, the evapotranspiration of the crop was in its peak. At initial stages of the growth, ET0 was greater than ETc of sugar beet seed-bearing plants; however, the gradient of these two curves became almost constant over the time and ETc started to sharply decrease from the beginning of the final stage (i.e. about 90th day). The Kc of sugar beet seed-bearing plants at initial, development, middle and final stages was 0.29, 0.89, 1.12 and 0.66, respectively. Sugar beet seed-bearing plants consumed 35.13, 141.93, 273.59 and 65.49 mm water at initial, development, middle and final stages, respectively. Their peak water consumption was at middle stage with a rate of 7.82 mm/day.

To evaluate the effects of water deficit stress and Selenium application on maize yield and yield components, a field study was carried out in 2008 as a split-split plot design based on randomized complete block. In this study, irrigation treatments included irrigation cutoff at full flowering stage and irrigation up to the end of growth period as main plots, studied cultivars included SC700 and SC613 as sub-plots, and Selenium treatment from sodium selenite source (spraying at full silking stage) constituted sub-sub-plot. The results showed that there were significant differences between irrigation treatments and cultivars as well as Selenium levels at probability level of 99%. Means comparison of cultivars showed 46% decrease in yield under stress condition. Selenium application increased yield under water deficit stress. It also increased thousand-grain weight and grain number/ear. Thousand-grain weight and grain number/ear were affected by water stress and Selenium application. SC700 had the highest thousand-grain weight and yield. The highest leaf area index was observed at grain filling stage both in control and drought stress treatments. Selenium application decreased leaf area index, so that SC700 had the lowest leaf area.