جستجوی مقالات مرتبط با کلیدواژه "زوال بذر" در نشریات گروه "منابع طبیعی"

This study was performed to investigate the effect of pumpkin (Cucurbita pepo L.) seed’s pre-treatment by salicylic acid and ascorbic acid on different aspects of seed germination and biochemical features. A factorial experiment was conducted based on a completely randomized design with three replications. Experimental treatments included two levels of seed maturity (normal seeds and aged seeds) and five levels of priming (control, ascorbic acid 50 and 100 mg/l, and salicylic acid 50 and 100 mg/l). The seed traits were finally measured included the germination percentage, first and second seed vigor index, seedling dry weight, peroxidase and superoxide dismutase activity, electrolyte leakage, soluble protein, and soluble carbohydrate. Based on the results, the seed pre-treatment with 100 mg/l ascorbic acid and salicylic acid could perform the highest germination indices. Moreover, the germination percentage (74%) was improved in aged seeds pre-treated by ascorbic acid and salicylic acid (especially at a concentration of 100 mg/l). Also, the antioxidant enzyme activity was increased while the cell electrolyte leakage was significantly decreased. In total, results indicate, the pre-treatment with salicylic acid and ascorbic acid, not only improved the germination quantity and vigor but also improved the germination quality mainly by the development of carbohydrate and protein content in pumpkin seeds.

This research was carried out to evaluate the storage of wheat seed which produced under different conditions of water deficit and application of chemical nitrogen and biological fertilizers as the first factor was water deficit in milky stage, drought stress at dough stage and without stress (control), and nitrogen fertilizer resources in Urea fertilizer 100%, 75%, 50% and 25% of plant requirement with nitroxin and nitragin. The second factor was storage conditions in 7 and 14% seed moisture within 20 and 4 °C storage, and the third factor was the storage period at 50, 100, 150 and 200 days. The results showed that the content of soluble protein and seed vigor index in seeds that received nitroxin and nitragin fertilizers with 25% urea, by increasing the water deficit, from 1.208 to 0.581 mg/g fresh weight and from 1.945 to 0.376 increased relative to 100% urea, respectively. The amount of catalase activity in seeds with drought stress and biofertilizer was higher and its activity increased at higher storage temperatures. In general, if the irrigation of the maternal plant is discontinued at the seed dough stage and the plant is fed with integrated of chemical and biological fertilizers, then the seed produced had more storage capability.

Glycine max is one of the most important oilseeds plant in all of the word. One of the problems of G. max production is seed deterioration and low germination and vigor during seed storage and before planting time. In order to investigate the effects of seed deterioration on germination and the effects of salicylic acid and ethylene on improvement of deteriorated seed of G. max several experiments were conducted. Accelerated aging test for 0, 6 and 10 days and natural aging test for 6 months were the main effects. After aging conditions, seeds were imbibed with 50 M salicylic acid and 10 M ACC (precursor of ethylene) for 6 hours at 25 °C. Also seeds after natural and accelerated aging test were used without any hormonal treatment as control seed (called dry seed). Germination percentage, electrical conductivity and gene expression of αMY1, βMY1, were investigated on dry seed and under imbibition of water, salicylic acid and ACC for 6, 12 hours using Q-RT-PCR method. Seed germination decreased and electrical conductivity increased with progress of aging. Gene expression varied in different days and different hours. Salicylic acid and ACC had different effects on measured trait. All together aging caused disturbing of seed physiology and salicylic acid and ACC were not able to improve deteriorated soybean seed.

Seed deterioration is an important factor in reducing of physiological seed quality that it increased the severity of damage in adverse environmental conditions. The effects of hydrogen peroxide to improve physiological and antioxidant enzyme activities in aged groundnut seeds under drought stress were studied. A factorial experiment based on completely randomized design with three replications was done. Priming of different concentrations of hydrogen peroxide (0, 50, 100 and 150 µM) under 0, -0.4, -0.6 and -0.8MPa drought stress levels were evaluated. The results showed that seed priming with hydrogen peroxide in different drought levels increased some traits such as germination percentage, germination rate, vigour index, plumule and radicle length, soluble carbohydrates and protein contents and antioxidant enzymes activities (catalase, ascorbate peroxidase and superoxide dismutase). While it decreased mean germination time, electrical conductivity and malondialdehyde content in comparison to nonprime seeds. So seed priming with 50 and 100 µM of hydrogen peroxide in -0.8MPa level increased germination rate, vigor index , soluble carbohydrates and proteins, respectively by 27.89, 93.24, 71.42, 46.12, 27.06, 76.73, 30.26 and 51.04% compared to nonprimed seeds. Also, it increased activity of catalase, superoxide dismutase and ascorbate peroxidase, respectively by 26.37, 8.79, 39.07, 15.43, 5.28 and 21.51% compared to non-primed seeds. Therefore, the use of 50 mM hydrogen peroxide to reduce the negative effects caused by deterioration in drought stress is recommended.

This experiment was done in seed and plant certification and registration institute laboratory in 2015. The treatments were corn seed produced in Karaj and Moghan , seed storing condition in two controlled and Free weather conditions stores also Disinfection and non- Disinfection. The experiment was conducted as factorial based on completely randomized design in three replications. Germination percent of Karaj seeds before accelerated aging test was 92 percent and after 144 hours aging, it reduced 3 percent in controlled storage and it dropped 6 percent in Moghan conditions storage. While similar condition led to a decrease of 18 and 28 percent in Moghan seeds produced. When seeds were stored in controlled storage, indicated 17 percent higher protein content compared to storage in Moghan conditions. Catalase activity of Karaj seeds was higher than Moghan seeds (14%). Seed treatment had significant effect on peroxidase and MDA content, as peroxidase activity in treated seeds was 11 percent higher and MDA content was 8 percent lower than untreated seeds. Karaj seeds in controlled storage had the highest peroxidase activity and the lowest MDA content. So production seed conditions in Moghan was more critical in terms of temperature and humidity than Karaj so the biochemical properties of seeds have been affected. So that Moghan seeds had less storability after storing. On the other hand, seeds in Moghan store subjected to more critical temperature and humidity than controlled condition so more deteriorated.

In order to study effects of seed priming with Gibberellin (GA), Ascorbic acid (AsA) and Salicylic acid (SA) on mitigation of seed deterioration damage and improvement of seed and seedling qualities of three sunflower cultivars (Farrokh, Barzegar and Shamshiri), a pot experiment was done in 2016. This research was carried out as a factorial experiment based on RCBD with three replications. Seeds were exposed to accelerated aging then primed. Priming treatments were included: control, hydropriming, GA (50 and 75 ppm), AsA (100 and 150 ppm), SA (138 and 207 ppm), GA 50 ppm + AsA 100ppm, GA50 ppm + SA 138 ppm, AsA 100ppm + SA 138ppm, and GA 50ppm + AsA 100ppm + SA 138 ppm. Barzegar cultivar had better seedling emergence percentage and rate than the Shamshiri and Farrokh. Seedling emergence was improved by priming treatments; however, suitable treatments were different for the cultivars. Maximum seedling emergence percentage was obtained in Barzegar by GA 50ppm + SA 138ppm; however in Shamshiri and Farrokh by hydropriming. Priming improved seedling emergence rate of the three cultivars, but the response to priming was cultivar specific. Priming decreased seedling malondialdehyde (MDA) significantly in three cultivars. The lowest MDA content was obtained in Barzegar cultivar primed by AsA + SA.

In order to investigate the effect of sodium nitroprusside (NO donor) on improvement of aged pumpkin seeds under drought stress, a factorial experiment was carried out based on completely randomized design with three replications in Bu-Ali Sina University, Hamedan, Iran. Seed priming with different concentrations of sodium nitroprusside including 0 (hydropriming), 25, 50 and 75 µM in drought stress levels (0, -0.2, -0.46 and -0.6 MPa) was performed. Germination percentage, germination rate, seed vigor, seedling length, soluble carbohydrates, soluble proteins, memberane electrical conductivity, malondialdehyde content and antioxidant enzymes activity (catalase, ascorbate peroxidase and superoxide dismutase) were evaluated. The results showed that seed priming with different concentrations of sodium nitroprusside mitigated significant decrease of germination parameters of aged seeds under drought stress. At -0.6 MPa, seed priming with 75 µM of sodium nitroprusside increased germination rate, vigor index , soluble carbohydrates and proteins 25, 214.1, 90.8, 117.1%, as well as the activity of catalase, superoxide dismutase and ascorbate peroxidase increased by 34, 14.5, 41.4% in comparison to control, respectively. Therefore, seed priming with sodium nitroprusside specialy with 75 µM is suggested for aged pumpkin seeds by decreasing oxidative stress due to drought stress.

The main goal of seed storage is to maintain its quality from harvesting to sowing time. Among all factors, storage temperature and seed moisture content are the most important factors affecting seed longevity. This experiment was conducted at University of Tehran, Department of Agronomy and Plant Breeding during 1394 to determine the Ellis and Roberts deterioration model of Satureja hortensis seeds and introduce constants of viability equation. Seed viability and initial moisture content was measured and after that seeds were adjusted to 5, 7, 9, 11 and 13% moisture content and sealed hermetically in Nano packets. Storage temperatures were 10, 15, 20 and 25˚C. The interval of sampling depended on the storage conditions. Seed viability constants were estimated to predict seed longevity in this species and relationship between sigma and moisture content and temperatures was determined. After probit analysis, survival curves were depicted in each condition. Results showed that seeds with 5% moisture content stored at 10°C had the highest germination percentage, but seeds which were stored at 13% moisture content and 20 and 25°C had the highest deterioration rate. Estimates of KE, CW, CH and CQ were 4.31, 1.83, 0.031 and 0.0004, respectively. Also, the results showed that seed longevity decrease with increased seed moisture and temperature.

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 effect of cytokinin on improvement of aged groundnut seeds under drought stress, a factorial experiment was done based on completely randomized design with three replications. Seed priming with different concentrations of cytokinin including 0 (hydropriming), 50, 100 and 150 ppm in drought stress levels (0, -0.4, -0.6 and -0.8 MPa) was performed. Germination percentage, mean germination time, germination rate, seed vigor, seedling length, soluble carbohydrates, soluble proteins, memberane electrical conductivity, malondialdehyde content and antioxidant enzymes activity (catalase, ascorbate peroxidase and superoxide dismutase) were evaluated. The results showed that seed priming with different concentrations of cytokinin alleviated significant decrease of germination and seedling parameters of aged seeds under drought stress. At -0.8 MPa, seed priming with 100 ppm of cytokinin increased germination percentage, vigor index , soluble carbohydrates and proteins 0.65, 1.73, 1.09, 1.05, and in 150 ppm of cytokinin 1.37, 4.51, 2.5, 2.85 fold, as well as the activity of catalase, superoxide dismutase and ascorbate peroxidase increased by 15.92, 13.35, 33.17 and 25.47, 17.96, 45.19% in comparison to control, respectively. Therefore, cytokinin pre-treatment specialy with 150 ppm is effective in germination and seedling indices of aged groundnut seeds by decreasing oxidative stress due to drought stress.

Storage conditions, especially high moisture storage and high temperature environments, greatly affect the quality of oil seeds. In order to investigate the effect of temperature, seed moisture content and storage time on the deterioration of flax seed oil a factorial experiment was conducted based on a completely randomized design with four replications in the seed lab of Yasouj University. The factors included the temperature at four levels (15, 25, 35 and 45 °C), moisture content in 5 levels (initial moisture content, 5, 9, 13 and 17%) and six storage times (30, 60, 90, 120, 150 and 180 days). The results showed that germination and  normal seedlings percentage, germination rate and vigor index reduced with increasing moisture content and during storage at each temperature level and with a combination of high temperature and moisture content this reduction was more severe. The lowest level of deterioration was in 5 °C with 5% moisture content that after 180 days storage, viability was reduced from 93 to 90 percent. Over time and with increasing moisture content, electrical conductivity also increased, and this increase was greater at high temperatures and seed lots with high electrical conductivity had low viability

During seed storage, some seeds traits might change and seed vigor may decrease in bad storage situation, to determine the effect of some hormones in different concentrations, the study was conducted in biotechnology laboratory of Agriculture University of Tehran in 2012. In this study, seeds aging were tested for 0, 2 and 4 days and after they were primed with distilled water, salicylic acid, IAA and kinetin. Traits measured included germination percent, germination rate, shoot length, root length, seedling dry matter and vigor. The results showed that hydro priming improved many characteristics in fresh seeds but it's not very useful for seeds under ageing conditions. For rising seed vigor in these cases, it's better to use hormones, especially salicylic acid which is called tolerant hormone. Using IAA because of broadleaf control property, it doesn’t seem logically. The best treatment in this study was salicylic acid in low concentration