نشریه بوم شناسی گیاهان زراعی
سال یازدهم شماره 4 (پیاپی 42، زمستان 1394)

This study was carried out to determine the effect of hormonal priming to improve seed germination and initial growth of safflower seeds under salt stress. The experiment was done using factorial experiment based on completely randomized design in three repetitions in Seed Technology Laboratory of Shahed University. Safflower seeds primed with 3% abscisic acid and 150 and 500 ppm of gibberellic acid then were placed under salinity stress condition of the natural salt of Qom lake (0, 3, 6, 9 and 12 dS.m -1). The germination indicies were measured. Priming seeds with gibberellic and abscisic acid relatively reduced the effect of salinity on seed germination and seedling growth and improved the germination and initial growth in low water potential condition. Gibberllic acid was more effective than abscisic acid. Priming with combination of 500 ppm gibberellic acid and 3% abscisic acid % combination had the greatest effect on germination percent, seedling length and seedling dry matter. Howerer, priming decreased the mean germination time. Priming with 500 ppm gibberellic acid and 3% abscisic acid combination under salinity conditions reduced the negative effects of salinity by increasing the water uptake in the plant, resulted in improvement of germination percentage, seedling length and seedling dry matter and length and weight vigor indecies. On the whole, priming of safflower seeds with combined priming increased the seeds resistance to the drought stress, therefore the seedlings with strong vigor and high germination percentage were produced.

Breeding rice for drought tolerance requires proper evaluation and analysis of genetic diversity in breeding parameters are related to drought tolerance. To identify tolerant index and sensitive rice genotypes to drought stress, an environment was conducted with 59 genotypes of rice in a complete block design with three replications in two flooding and water stress conditions in 2013 growing season in Aliadad Research Farm in Gonbad Kavous, Iran. Data variance analysis showed highly significant differences among genotypes for all studied traits. Significant genetic variation detected between genotypes and the traits evaluated. Analysis of correlation among the performance in terms of flooding and drought and stress tolerance indices showed that the SSI, STI, MP, GMP, HM and YI indices as the best indicators in both flooding and drought stress conditions which could be detect the genotypes by demonstrate robust, high-performance. Cluster analysis was performed using drought tolerance indices, genotypes were divided into three groups. Genotypes with drought tolerance indices were used and they were divided into three groups. Genotype-by IRAT177, IR62761-20, IR60080-42, B6144F-MR-6-0-0, CT13382-8-3-M, UPLRi-7, and IRAT212 were placed in third group and considered as the most drought-sensitive genotypes. According to the indicators of drought tolerance genotypes Caiapo, IR68702-072-1- 4-B and Pegaso considered to have the highest yield in both environmental conditions and a high STI as suggested tolerant genotypes.

Low seed germination and seedling emergence is one of the main problems in saline areas. Seed priming technique has been known as a challenge to improve germination and seedling emergence under different environmental stress conditions. To evaluate the effects of halo-priming on germination indices of wheat under salinity stress, a factorial experiment in a completely randomized design with three replications was conducted in 2015. Treatments consisted of priming with potassium nitrate, potassium chloride, calcium chloride, calcium sulfate 1% and control without priming and salinity levels 0, 50, 100 and 150 mM sodium chloride. Among pretreatments, potassium nitrate and calcium sulfate reduced the effects of salinity stress on germination and other indices. Priming with potassium nitrate had the most effects on germination percentage, dry plumule and seedlings weight. Also, priming with calcium sulfate had the most effect on root fresh weight. Primed wheat seeds had better growth. On the whole, with increasing salinity levels, germination and related parameters decreased and that potassium nitrate and calcium sulfate decreased negative effects of salinity. According to result, priming with potassium nitrate and calcium sulfate is recommended for the improvement of germination and initial growth of wheat seedling under salinity stress.

Allelopathic potential of aqueous extracts of wheat and rapeseed on rice, maize, sunflower, common amaranth and cockspur grass was studied. Plants foliage were dried at 60 °C, grounded and used for plant extractions preparation in concentrations of 1, 2.5, 5.0, 7.5, and 10% w/v ratios. Experiment was carried as completely randomized block design with three replications. The aqueous extracts caused significant inhibitory effect on germination, radicle and hypocotyl elongation in receptor plants. The inhibitory effect of wheat and rapeseed aqueous extracts was proportional and higher concentrations 5-10% had the strong inhibitory effect whereas stimulatory effect was observed in some cases of lower concentrations of 1-2.5%. Also, inhibitory effects were much pronounced in radicle elongation rather than hypocotyl growth. Also, inhibitory of canola was greater than wheat on germination indices. Negative allelopathic effects on common amaranth growth were greater than on cockspur grass. On the whole, wheat and canola residues had allelopathic potential on studied plants. Therefore, it is giving them this advantage in mixed cropping and crop rotation to control weeds and possibly fighting with plant pathogens. Hence, these plants can be a good candidate to study and produce bio-herbicides and pesticides as one of the important goals of sustainable agriculture.

To study the effect of biofertilizers including mycorrhiza, azotobacter and azospirillum bacteria on vegetative traits of basil plant, an experiment was conducted at research field of Karaj Azad University based on randomized complete block design with four replications. Eight treatments include: no inoculation as control, inoculation with mycorrhiza, inoculation with azotobacter, inoculation with azospirillum, inoculation with mycorrhiza azotobacter, inoculation with mycorrhiza azospirillum, inoculation with azotobacter azospirillum, and inoculation with mycorrhiza azotobacter azospirillum. Shoot amd root dry and fresh weight, inflorescence and plant height of sweet basil significantly increased by incubation with biofertilizers. Shoot dry weight was significantly higher in integrative inculation in camparison with control, but there were no significant differences among individual incubation of biofertilizers with control. Root dry and fresh weight were significantly higher in azotobacter and azospirillum in comparison with mycorrhiza; however, there was not a noticeable increase in integrative inoculation of biofertilizers. Inflorescence length and plant height were siginificantly higher in treated plants in camparison with control. In contrast, leaf width, leaf length and essential oil content of basil were not affected by biofertilizers. Thus, integrative application of azotobacter and azospirillum as seed incubation to increase the biomass and essential oil yield of basil is recommended.

ABSTRACT The current study was conducted to evaluate the effects of the nitrogen on borage seed germination under saline stress. The experiment was in a factorial based on completely randomized design with three replications. The experimental factors were salinity stress including 0, 3, 6, 9 and 12 ds.m-1 and five ratio of nitrogen source nutrition, NO3-:NH4 (100:0, 75:25, 50:50, 25:75 and 0:100). The effect of salinity and also effect of salinity and nitrogen source on growth and physiological traits including dry weight, proline content, nitrogen and nitrate reductase activity was investigated. Increasing salinity levels caused a significant decrease of seed germination and seedling dry weight. Nitrogen nutrition with ratio 50% of ammonium with increasing proline in high salinity conditions, to moderate the negative effects of stress, in contrast, by increasing the amount of ammonium than nitrate, nitrate reductase activity and total seedling growth decreased and salinity showed more negative effects, so that the seedling growth of 75 and 100% ammonium was stopped. Amount of nitrogen in terms of more nitrate than ammonium negative correlation with salinity, and conversely by increasing the amount of ammonium than nitrate showed a positive relationship. Applications of nitrogen source with NO3- by rate of more 50% is suggesting for obtaining uppermost germination indices.

ABSTRACT Low germination and wheat seedling emergence problems are the most important difficulties under rainfed condition.Better and enough application of nitrogen in parent plants nutrition can play important role in production of seeds with high quality and vigor. The current research was conducted to evaluation the effects of different nitrogen rates in wheat cv. Azar2 parent plants on germination, seed vigor and seedling establishment. Laboratory tests were conducted as completely randomized design with five treatments including nitrogen fertilizer 0, 30, 60, 90 and 120 kg/ha in four replications and field experiment was carried out as randomized complete block design in three replications in 2013- 2014 growing season at Dryland Agricultural Research Institute (DARI) in Iran. All traits including viable seed percentage, electrical conductivity, germination rate and root, shoot and seedling dry weight, but viable seeds were significantly affected by different nitrogen fertilizer rates in wheat parent plants. Seedling emergence rate and seedling emergence percentage affected significantly by different nitrogen fertilizer rates in parent plants at 1 and %5 levels, respectively. Seedling emergence percentage and rate in 60, 90 and 120 kg/ha, were located at the same group. Therefore, application of 60 kg/ha nitrogen fertilizer in parent plants of wheat cv. Azar2 are recommended for production of vigorous seed and seedling establishment in the field.

Using of lichens antimicrobial potential can be one of the safe, green, environment friendly methods for plant diseases management. In this study, antimicrobial activity of acetone, methanol, chloroform extracts of Ramalina capitaat, Xanthoparmelia stenophylla, Umbilicaria cylindrical, Rhizoplaca crysoleuca and Anamylopsora pulcherrima collected from Meshgin shahr and Jolfa mountains were evaluated against two potato rot agents vic. Fusarium oxysporum and Ralstonia solanacearum in laboratory using disc diffusion and minimum inhibitory and bactericide concentration methods and simulated storage conditions. Dimethyl sulfoxide solvent on paper disc was used as negative control. Positive controls were considered as %0.2 benomyl and gentamicin antibiogram discs for fungus and bacterium, respectively. There were no effect of lichens extract on above-mentioned fungus. Chlorophorm extract of R. capitata had remarkable antibacterial activity on R. solanacearum. Extracts of R. crysoleuca and R. capitata were more bacteriostatic and bactericide than others against the bacterium. The study with selected extracts in storage condition showed preventive effect of 80% of extracts on bacterium. The most protective effect was observed in methanol extract of R. chrysoleuca. Therefore, the lichen extracts would be promising biological product as a potential replacement instead of chemicals.