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  • Author: S.A. Tabatabaei x
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Abstract

Seed aging is the main problem of seed storage. Changes of enzyme activity and reduction of seedling growth are consequence of seed deterioration. An experiment was conducted to evaluate the effects of accelerated aging on germination indexes and enzyme activity of barley seeds. Seeds were incubated in closed plastic boxes for the accelerated aging treatments at 41°C. Three accelerate aging regimes were performed by placing seeds at 41°C and relative humidity (RH) of 90-100 % for 0, 4 and 8 day periods. Our results showed that increasing aging duration resulted higher reduction in germination percentage, germination index, mean time to germination, normal seedling percentage, catalase and ascorbate peroxidase. The highest germination percentage, germination index, normal seedling percentage and enzyme activity were achieved in control conditions (0 day of aging). Under aging conditions, germination percentage, means time to germination, germination index, normal seedling percentage and enzyme activity decrease significantly. Also, our results indicated that seed aging is related to decrease of enzymes and may contribute to low germination efficiency. The general decreases in enzyme activity in the seed lowers the respiratory capacity, which in turn lowers both the energy (ATP) and assimilates supply of the germinating seed, also decrease in antioxidant enzymes is linked to an increased accelerated ageing and decreased germination characteristics. Subsequently, proposed a positive relationship between antioxidant enzyme capacity and the vigour of the seed

ABSTRACT

In order to investigate salinity stress on seed reserve utilization and seedling growth of treated seeds of barley (Hordeum vulgare L.), an experiment was carried out. Factorial experiment was carried out in completely randomized design with three replicates. To create salinity stress, NaCl in osmotic levels at 0 (as control), -4, -8, -12 and -16 bar were used. For seed priming, gibberellin (GA) 50 ppm was used. Our results showed that treatment × drought interaction on these traits: germination percentage, weight of utilized (mobilized) seed, seed reserve utilization efficiency, seedling dry weight and seed reserve depletion percentage were significant. The highest germination percentage, weight of utilized (mobilized) seed, seed reserve utilization efficiency, seedling dry weight and seed reserve depletion percentage were attained from priming by gibberellin at control conditions. Thus, priming increased characteristics as compared to the unprimed. Priming improved seed reserve utilization such as: weight of utilized (mobilized) seed reserve, seed reserve depletion percentage, seed reserve utilization efficiency and seedling growth in barley under salinity stress.

Abstract

Seed germination and seedling growth are critical stages in the life cycle of a plant, especially under adverse abiotic stresses. Seed germination negatively affected by stress conditions. Seed priming techniques have been used to increase germination characteristics and improve germination uniformity in more field crops under stressed conditions. This experimental aimed to evaluate the effect of salinity and halo-priming on seed reserve utilization and seed germination of wheat seeds. For create salinity stress, NaCl in osmotic levels at 0 (as control), -4, -8, - 12 and -16 bar was used. Seeds of were pretreated with halo-priming at 10 °C for 24 h and water at 10 °C for 24 h. Our results showed that treatment×drought interaction on these traits: germination percentage, weight of utilized (mobilized) seed, seed reserve utilization efficiency, seedling dry weight and seed reserve depletion percentage were significant. The highest germination percentage was obtained from halo priming in control conditions. Thus priming improved study traits in wheat under salinity stress. Priming increased germination percentage and seed reserve utilization as compared to the unprimed seeds. The highest germination percentage and seed reserve utilization were as obtained from halo priming in control conditions.

Abstract

Objective of this study was to evaluate the effect of salinity stress on germination characteristics and biochemical changes of sesame seeds. Salinity stress at osmotic potentials of 0 (as control), ⊟3, ⊟6, ⊟9 and ⊟12 bar were adjusted using NaCl before the start of the experiment. Our results showed that, the effect of salinity stress for all traits was significant. By increases of salinity stress, germination percentage, germination, normal seedling percentage, seedling length and dry weight were reduced the ascorbate peroxidase and catalase activity, also proline content were at minimum at control and increased with increase in salinity stress, expressed by the osmotic potential.

Summary

Root-knot nematodes are major pests of legume fields in Iran. This research evaluated the effect of Rhizobium leguminosarum bv. phaseoli and Pseudomonas fluorescens CHA0 (stand alone and combination treatment) on galling and reproduction of root-knot nematode, Meloidogyne javanica, in legum (chickpea, bean, lentil, pea) seedling rhizosphere, and the growth properties of the host plants. The legumes seeds were sown in 1kg sterilized sandy loam soil. Inocula were 5 J2/g of soil, in the case of the nematode, while considering the bacteria 1×107 cfu/kg soil. A treatment of nematicide (cadusafos) was performed, as a commonly used nematicide in Iran, at 2g/kg soil. Two months after inoculation, the following parameters were recorded: the number of knots, egg masses and reproduction factor of the nematode, bacterial nodules per root, and growth properties of seedlings in the treatments (control, nematode, nematode+nematicide, and nematode+rhizobacteria). The greatest bacterial effect on the control of the nematode was observed in the rhizosphere of the bean treatments. Inoculation with Rhizobium in the soil decreased the galling on the legumes’ roots, and the combined inoculation with Pseudomonas and Rhizobium resulted in a higher decrease of the galling.

Abstract

Seed germination is a complex biological process that is influenced by different environmental physical factors including temperature, water potential, salinity, pH and light, as well as intrinsic genetic factors. In such environments, the water needed for germination is available for only a short time, and consequently, successful crop establishment depends not only on rapid and uniform germination of the seedlot, but also on its ability to germinate under low water availability. All of these attributes can be analyzed through the hydrotime model (HT). Millet (Panicum miliaceum L.) is cultivated in arid and semi-arid regions of Iran. Therefore, in this study, using the hydrotime modeling approach, germination response of millet to priming (water and gibberellin 50 ppm at 15°C for 24 h) and water potential (0, -0.3, -0.6, -0.9, and -1.2 Mpa) was studied. Hydrotime (HT) model were fitted to cumulative germination of seeds and recorded in germination tests carried out at different water potentials (0, -0.3, -0.6, -0.9 and -1.2 MPa) and priming treatments (control, hydropriming and hormone priming). Results showed that, germination of millet decreased significantly with reduction of osmotic potential. Results indicated that the hydro-time constant (θH) for control, hydro-priming and hormone priming were 0.89, 0.79 and 0.67 MPa d, the water potential (Ψb(50)) for control, hydropriming and hormone priming were -0.89, -0.94 and -1.11 MPa, respectively. Results indicated that the use of hydrotime model in germination prediction could be useful to provide more accurate estimates for the timing of sowing and management of millet.

Abstract

Seed priming is one of the methods that can be taken to counteract the adverse effects of abiotic stress, also Seed priming treatments have been used to reduce the damage of aging and invigorate their performance in many crops. Objective of this study was to evaluation the effect of gibberellin on germination characteristics and antioxidant enzymes of safflower seeds after aging. Experimental design was a factorial one with complete randomized design with three replications. The first factor was priming by gibberellin (0 and 50 ppm) and non-primed seeds (control) and the secondary factor was combinations of four levels of aging (0, 1, 3 and 5 days of aging, at 43°C). The results showed that the priming and aging effects on germination percentage, germination index, normal seedling percentage, seedling length, vigor index, catalase and ascorbate peroxidase were significant, but on mean time to germination not significant. Results showed that, the highest germination characteristics such as; germination percentage, germination index, normal seedling percentage, seedling length, vigor index, catalase and ascorbate peroxidase were attained from priming by gibberellins, under non aged conditions. Also, our results indicated that seed aging is related to decrease of enzymes activity and may contribute to low seed germination efficiency, also priming increases enzyme activity and increases enzyme activity with priming treatment may contribute to improve germination characteristics. The general decreases in enzyme activity in the seed lowers the respiratory capacity, which in turn lowers both the energy (ATP) and assimilates supply of the germinating seed.

Abstract

Maximum germination percentage achieves immediately after harvesting and gradually decreases with storage time. Aging is one of the key factors in plant yield loss especially in vegetables. Seed aging is the main problem of seed storage. Application of accelerated aging treatment is used to assess seed vigor and quality. Seed priming enhances seed germination performance after aging. An experiment was conduct in order to investigate the activity of catalase and ascorbate peroxidase during accelerated aging and repair during priming treatment of sorghum seeds. In order to improve germination characteristics in aged seeds with seed priming. Our result showed that seed priming treatments significantly (p≤ 0.01) affected, germination percentage, germination index and means time to germination after aging (0, 3 and 6 days). Increasing aging duration resulted higher reduction in germination characteristics. Priming with gibberelic acid (GA), salicylic acid (SA) and ascorbic acid (ASC) increased germination characteristics of seed aged. The highest germination percentage, germination index, normal seedling percentage and enzyme activity were achieved in control conditions (0 day of aging). Antioxidant activity of aged seeds increased after seed priming.