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  • Author: O. Ansari x
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Abstract

Seed priming techniques have been used to increase germination, improve germination uniformity and seedling establishment under stressed conditions. Seed priming was used in rye mountain (Secale montanum) to increase seed germination and tolerance on stress exposure (Cold stress). Rye seeds were treated with water (Hydro priming) and polyetelyn glycol 6000 (Osmo priming). The effect of priming was assessed on germination characteristics under cold stress (at 3°C) for 7 days. Analyze of variance for hydro priming showed that temperature × time of priming interaction was significantly (P < 0.01) for all traits under cold stress and for osmo priming showed that Concentration of PEG × Temperature × Time of priming interaction was significantly (P < 0.01) for all traits under cold stress except seedling dry weight (SDW). For hydro priming the highest germination percentage (GP) was attained from hydro priming at 15±1°C for 16 h (70%), whereas the highest normal seedling percentage (NSP) (22.5%), germination index (GI) (8.57), seedling vigor index (SVI) (38.9) and seedling length (SL) (1.7 cm) were in the hydro priming at 10±1°C for 16 h. For osmo priming the highest germination percentage (GP) (80 and 80.5%), normal seedling percentage (NSP) (48 and 45%), seedling vigor index (SVI) (101.26 and 85.25) and seedling length (SL) (2.11 and 1.89 cm) observed in the osmo priming with concentrations of -9 and -15 bar PEG at 15±1°C for 24 h.

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

Safflower (Carthamus tinctorius) is a highly branched, herbaceous, thistle-like annual plant. It is commercially cultivated for vegetable oil extracted from the seeds, which is cultivated under arid environments. 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). Safflower seeds were germinated in various polyethylene glycol (PEG 600) solutions to obtain water potentials of 0, -0.2, -0.4, -0.6, and -0.8 Mpa. Results indicated that germination of safflower cultivars decreased significantly with reduction of osmotic potential. The highest germination percentage for Sina (93.06 and 94.02%), Faraman (93.52 and 95.33%), Talaei (94.98 and 93.98%) and Kouseh (93.58 and 95.55%) cultivars were attained from distilled water (0 MPa) and -0.2 MPa, respectively. The hydrotime constant (θH) for Sina, Faraman, Talaei and Kouseh cultivars were 0.93, 0.84, 0.78 and 0.72 MPa d, and the water potential (Ψb(50)) for Sina, Faraman, Talaei and Kouseh cultivars were -0.56, -0.67, -0.64 and -0.77 MPa, respectively. Cumulative germination of safflower seed was higher in Kouseh cultivar, than in Sina, Faraman and Talaei cultivars. Results showed that, hydrotime model is suited to predicting seed germination of safflower seeds. In addition, the information gathered with this work allows us to build mathematical models to predict germination of safflower cultivars in the field under various environments.

Seed Reserve Utilization and Seedling Growth of Treated Seeds of Mountain Rye (Secale Montanum) as Affected by Drought Stress

The environmental stress such as, drought are serious obstacles for field crops in further areas of the world, especially in arid and semiarid regions. In order to investigate drought stress on seed reserve utilization and seedling growth of treated seeds of mountain rye (Secale montanum), an experiment was carried out. Factorial experiment was carried out in completely randomized design with three replications. The first factor was the seed treatments (unpriming, hydropriming and osmopriming) and the second factor was drought stress. To create drought stress, polyetylenglycol 6000 (PEG 6000) in osmotic levels at 0 (as control), -0.4, -0.8, - 1.2 and -1.6 MPa were used. The results indicated that for these traits: germination percentage (GP), timson index (TI), energy of germination (EG), weight of utilized (mobilized) seed (WMSR), seed reserve utilization efficiency (SRUE), seedling dry weight (SLDW), and seed reserve depletion percentage (SRDP), was a significant treatment x drought interaction. Thus hydropriming and osmopriming improvement study traits in Secale montanum under drought stress. While in higher osmotic pressure the highest seed reserve utilization were obtained from osmopriming.

ABSTRACT

Seed priming with gibberellin (GA) enhances seed germination performance; but the quality of primed seeds in aging condition often reduces more than non-primed seeds. An experiment was conducted to evaluate the effect(s) of heat shock treatments on germination characteristics and enzyme activity of primed mountain rye (Secale montanum) seeds with gibberellin under accelerated aging. Heat shock treatments, can substantially decrease the speed of quality reduction of mountain rye (Secale montanum) primed seeds. In primed seeds with gibberellin, which has non-aged, the highest germination percentage (GP) and normal seedling percentage (NSP) was attained from heat shock treatment at 35°C for 3 h, also after 3 days aging, it was attained from heat shock treatment at 35°C for 3 h. After 3 days of aging the highest germination index (GI) was attained from unprimed seeds, but no significant difference with heat shock treatment at 35°C for 3 h. The minimum means time germination (MTG) was in heat shock treatment at 30°C for 3 h in non-aged seeds. After 3 days of aging, heat shock treatment reduce MTG as compared to the primed seeds. Heat shock treatment at 35°C for 3 h increased seed vigor index (SVI) as compared to the unprimed and primed seed in non-aged seeds and after 3 days aging. Seedling length (SL) increases with heat shock treatment at 30°C for 4 h in non-aged seeds as compared to the primed and unprimed seeds, but after 3 days of aging heat shock treatment except at 35°C for 3 h and 40°C for 4 h reduced SL as compared to the primed and unprimed seeds. Also, heat shock treatments increase some antioxidant enzymes [Catalase (CAT), Ascorbat peroxidase (APX)].

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

This experiment was carried out in the form of factorial split in the model random complete block design in three replicates. In this design three kinds of durum wheat including Yavarous, Karkheh, Seimareh were planted in the main plots and three levels of 40, 80 and 120 kg net nitrogen in hectare which it had been provided from source of urea and three levels of bio fertilizer including Azotobacter spp. and Azospirillum spp. and without using bio fertilizer (control) as factorial were cultivated in secondary plots. Before cultivation, amount of seeds which it must be mixed with together Azospirillum spp. and Azotobacter spp. bacteria’s, it was mixed together water and sugar with 2% density of wet and in proportion of 2 kg in 100 kg seeds were mixed with seeds. The irrigation of blocks was separately done for preventing from mixture of bacteria. This research will have a new asped for/in order to effect of biological fertilizers in replacement with/to fertilizers and it hasn't demonstrate its comparison on durum wheat in the region by now. Finally, with interpretation of results obtained from this research defined that positive effect of biological fertilizers on growth that before they have verified about plants, also, they are true about grains such as wheat. So, considering the obtained results from this research, it is seemed that application of suitable biological fertilizers can be effective in increase of function, improvement of growing traits of wheat and decrease nitrogen fertilizer.

Abstract

The objective of this study was to isolate and characterize bacterial strains associated with the gut of the hybrid Carniolan honey bee, Apis mellifera carnica, and to determine their in vitro and in vivo potential against Ascosphaera apis, the causal organism of chalkbrood disease, with the purpose of exploring feasible biological control. Six bacterial strains were isolated from healthy worker honey bees by culture-dependent methods. Six fungal strains (A3, A4, A7, A8, A9, and A15) of A. apis were isolated from larvae suffering from chalkbrood disease on Yeast-Glucose-Starch agar (YGPSA) medium. All bacteria were identified by a combination of morphology, Gram stain, and 16S rRNA sequence analysis, and fungal strains were identified by morphology and 5.8S rRNA. In vitro and in vivo inhibition assays were carried out to determine the ability of bacterial isolates to inhibit A. apis, the causal agent of chalkbrood disease. The analysis of 16S rRNA sequences revealed that four bacterial strains (B2, B4, B10, and B100) belong to Bacillus subtilis species, and two strains (P1 and P5) belong to Pseudomonas fluorescence. Significant differences in antagonistic activity of all bacterial strains were observed. B. subtilis isolate B2 showed the highest antagonistic activity, as measured by the inhibition zone against A. apis, followed by the P1 strain of P. fluorescence. SEM analysis also supports the antagonistic activity of these bacteria against A. apis. This study provides a theoretical basis for biological control of honey bee chalkbrood disease.