SEED RESEARCH (JOURNAL OF SEED SCIENCE AND TECHNOLOGY)
Year:2013 | Volume:2 | Issue:4|Papers Count:8

To survey the effect of salinity on germination and salinity tolerance index of seedling of some wheat cultivars, a factorial experiment was conducted based on a completely randomized design with three replications at Bu-Ali Sina University, Hamedan Iran. Combination of five wheat cultivars (Alvand, Tous, Sayson, Navid and Bezostaya) and five levels of salinity (0, 50, 100, 150 and 200 mM sodium chloride) were used in this study. Results showed that salinity increase resulted in a decrease in germination percentage, plumule length, radicle length and seedling dry weight as well as an increase in mean germination time. There was a significant difference in the studied traits among the cultivars. Interaction between the cultivar and salinity was significant in all traits, with the exception of germination percentage. As salinity increased, Alvand and Navid cultivars showed higher seedling salinity tolerance index in the case of plumule length, radicle length and seedling dry weight compared to the other cultivars. In the case of seedling dry weight, Bezostaya cultivar showed a great tolerance to salinity up to 50 mM sodium chloride, however, seedling dry weight decreased severely beyond this point. Sayson cultivar, in the case of seedling traits, showed the lowest tolerance to stress as, compared to the control group, this cultivar showed significant decrease in plumule length (86.6%), radicle length (82.4%) and seedling dry weight (61.7%), at the highest salinity. Tous showed a mean tolerance to salinity compared to the other wheat cultivars, in the case of seedling traits.

Heavy metals contamination is considered as one of the most important environmental stresses, which leads to plant normal growth suppression. Accumulation of these metals in agricultural soils could threaten crop production. However, many investigations revealed that inoculation of some microorganism could mitigate the heavy metals toxicity. Accordingly, this experiment aimed to investigate the effects of Trichoderma virens (TRI) fungi with Azospirillum brasilense (AZB) and Azotobacter chroococcum (AZC) on germination characteristics and seedling growth improvement of dill (Aniethum graveolens) using factorial experiment with three replicates during 2012. Treatments were combination four levels of copper nitrate (0, 40, 80 and 120 mg L-1) and four levels of biopriming [control (noninoculated), inoculation of TRI, AZB+AZC and TRI+AZB+AZC). Results indicated that germination characteristics responded differently to copper nitrate, in which root, shoot and seedling length showed a linear decreasing trend (slope of -0.005, -0.017 and -0.122, respectively) while fresh and dry weights of shoot and seedling responded as a quadratic equation. Trend of all parameters, with exception of daily germination rate, was increasing at the low levels of stress, whereas it was decreasing at the higher copper levels. Maximum value of these parameters was recorded at medium levels of copper nitrate. However, the effect of biopriming treatment and biopriming´copper interaction was not significant. In conclusion, it seems that repeat of similar experiments at other growth stages and growing medium could prepare comprehensive information about biopriming effect under heavy metal concentration.

In order to investigate the effects of different treatments to break Acroptilon repens seed dormancy, an experiment was conducted at Agriculture laboratory of Islamic Azad University of Bojnourd in 2009. The experiment design was factorial based on a completely randomized design with 3 replications. The experimental factors were seed type (rain-fed or irrigation), concentrated sulfuric acid (98%) over 0, 15 and 30 min and gibberellic acid (500 ppm) over 0, 1 and 3 h. Results showed that sulfuric acid, gibberellic acid and seed type had a significant effect on germination percentage, and that sulfuric acid, gibberellic acid had significant effects on germination uniformity; however, only sulfuric acid had a significant effect on D10. These factors had no effects on germination rate and D90. However, interaction effects of sulfuric acid, gibberellic acid were significant on the germination percentage and germination uniformity, at 1% probability level, and interaction effects of gibberellic acid and seed type were significant at 5% probability level.

The aim of this study was to assess the seed quality of 4 wheat cultivars (Zarin, Alvand, Shahryar and Sardari) at different harvesting time. The experiment performed in 2008-2009 as a factorial design based on completely randomized blocks with 4 replications. The seeds were harvested at ten different times with form 20th to 83rd day after flowering (with 7-day intervals) and 1000-grain weight, germination rate and percent, seedling dry weight and electrical conductivity (EC) were recorded. Results showed that the effect of cultivar and harvesting time on all traits was significant. Interaction effect between cultivar and harvesting time only was significant on the seedling dry weight and germination percent. Among the cultivars, Sardari had the highest 1000-grain weight and germination rate and the lowest germination rate and EC. There was a small variation among the germination percentage of different cultivars to harvesting times, indicating that germination test was not capable to express initial quality of seeds among the cultivars. Response curve of change in time and germination rate, 1000-grain weight and EC at the different harvesting times was quadratic and optimum time for seed harvesting was calculated to be 51-55 d after flowering at which EC and germination rate were 7.50ms/cm.gr and 16.29 (1/h). However, regression analysis showed that the most seedling dry weight obtained in 41-43 d after flowering. In conclusion, the best time for harvesting seems to be 51-53 d after flowering because, at this time range, the highest seed vigor was observed and can be considered as physiological maturity time.

To investigate the effect of different salt stress levels on germination characteristics and seedling growth of four cultivars of Basil (Osmium basilicum L.), a factorial experiment based on completely randomized design with 4 replications was conducted at horticultural department of Ferdowsi University of Mashhad, 2013. One factor was salinity at eight levels (0, 50, 75, 100, 150, 200, 250, 300mM), induced by NaCl, and the other factor was Basil cultivars (Keshkeni Luvelo, Comin Hoja, Rubi, Genoes). Characteristics such as germination percentage (GP), germination rate (GR), mean germination time, germination index, energy of germination, seed vigor index (SVI), seedling length, seedling fresh weight and seedling dry weight were measured. Results showed that all studied characteristics decreased considerably, along with increase in salt level, and that germination was completely stopped at 200mM and higher salinity, in all cultivars. Mean germination percentage of different cultivars was 51% up to 150mM salt concentration, however, decreased dramatically at 200mM (2.23%) salinity. GP, GR and SVI in Genoes and Comin Hoja cultivars were significantly higher than compared to the other cultivars. Overall, in all studied cultivars, at least 50% of seedlings remained normal up to 75 mM salt concentration, however, increase in salt concentration beyond this point was not tolerable for the seedlings.

In order to investigate the allelopathic effect of aqueous extract of Eucalyptus globules L. on germination of Portulaca oleracea L., a factorial experiment was conducted as completely randomized design. In this experiment, the aqueous extract was prepared from leaf at the concentrations of 0, 1.25, 2.5, 5, 10 and 15 g/L and their effects were investigated on the germination of P. oleracea L. seeds. Results showed that the aqueous extract of E. globules L. leaf let to a significant difference in P. oleracea L. seed germination. Germination, germination rate, seed vigor, root and shoot length of seedlings decreased by increase in extract concentration. The highest inhibition was observed at 10 and 15 g/L leaf extract. Different E. globules L. extract treatments have different inhibitory effect on germination characteristics of P. oleracea L., but all decrease the characteristics, overall. 15 g/L aqueous extract treatment stopped the plant growth more than the other treatments, as the number of germinated seeds and shoot length was significantly different compared to control group. There are a positive relationship between the number of normal seedlings and E. globules L. concentration.

In order to evaluate the effect of salt priming on chickpea germination, a factorial experiment based on completely randomized design was performed under greenhouse condition, with three replications. Factors were three chickpea cultivars (Hashem, Azad and ICL480), three seed pretreatment levels (0, 4 and 8 dS/m NaCl solution) and two different medium solutions (distilled water and 6 dS/m NaCl; induced after priming). Results indicated that salinity decreased root length and vigor index of chickpea. Cultivar and salinity interaction significantly affected germination rate and germination percentage. Seed pretreatment with 8 dS/m salinity improved the germination percentage in ICL480 cultivar. It is also resulted that all examined cultivars had significant difference in root and shoot length, shoot dry weight, germination percentage, and germination percentage and vigor index. Among the cultivars, Hashem was the most tolerable one as ICL480 was the most susceptible cultivar to salinity.

Today, seed priming technique has been known as a factor to improve germination and seedling emergence under different environmental stresses. The objective of this research was to evaluate the effect of seed priming with gibberellic, salicylic acid and water on seed germination of maize seeds under drought stress. Treatments were combinations of 4 levels of drought stress (0, -3, -6 and -9 bar) and 4 levels of seed priming (25 ppm salicylic acid, 25 ppm gibberellic acid, distilled water and control with no priming) with 3 replications. Results indicated that with increase in drought stress, germination characteristics such as germination percentage, germination index, normal seedling percentage decreased as mean germination time increased. However, the primed seeds showed better performance compared to non-primed ones. The highest germination percentage (89.3%) was observed in the seeds primed by gibberellic acid. The highest germination index (32.54), normal seedling percentage (85%) and the lowest mean germination time (2.13) were also observed in the seeds primed by gibberellic acid, under control (non-stressed) conditions. Also, seed priming resulted in an increase in catalase and ascorbic peroxidase activity compared to the control seeds. It is concluded that priming results in improvement in germination characteristics of maize under drought stress conditions and increases the resistance of maize to drought stress in germination phase.