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Hossein Sadeghi, Mohammad Delaviz, Hadi Pirasteh-Anosheh, Gholamhassan Ranjbar,
Volume 3, Issue 1 ((Spring and Summer) 2016)
Abstract

Germination is the first and the most stages for sainfoin (Onobrychis viciifolia) growth; which it has especially sensitivity to environmental stresses such as alkalinity. The current study was conducted to evaluate the effectiveness of seed pre-treatment methods on improving sainfoin tolerance to alkali stress in germination, early growth and its recovery as a factorial experiment based on a completely randomized design in College of Agriculture, Shiraz University in 2013. The first factor was four seed pre-treatment methods (seed with the pod, seed without the pod, pre-chilling of seed without pod and hydro-priming of seed without pod) and the second factor was five alkali stress levels (pH= 6.7, 7.9, 8.9, 9.8 and 10.7). Alkali stress levels were prepared using two neutral salts (Na₂SO4 and NaCl) and two alkaline salts (NaHCO3 and Na2CO3). The results showed that germination percentage was decreased as alkalinity (pH) levels were enhanced; so that, there were no germinated seeds in 9.8 and 10.7 treatments. Alkali stress reduced initial germination percentage (51.9%), final germination percentage (51.8%), plumule length (55.7%) and radicle length (72.2%). Under all alkalinity conditions, the lowest seed germination and seedling growth were observed in with pod seed, followed by pre-chilling treatments; while their highest were achieved in without pod seeds and hydro-priming treatments. The highest recovery was observed in without the pod, followed by hydro-primed seeds. Recovery was observed in Pre-chilled and with pod speeds up to 7.9 and in hydro-primed and without pod speeds up to 8.9.


Gholamhassan Ranjbar, Hossein Ghadiri,
Volume 3, Issue 2 ((Autumn & Winter) 2017)
Abstract

A controlled experiment was run to quantify emergence of Kochia indica under different temperature, salinity and seeding depth levels at Yazd National Salinity Research Center in 2013. Treatments were five day/night temperature regimes: 20/10, 25/15, 30/20, 35/25 and 40/30 °C, five salinity levels: 2, 6, 10, 14 and 18 dS m-1, and seeding depth on the surface (0 mm), 5, 10 and 15 mm. Final emergence percentage, emergence rate index and elapsed time (days) to reach 50% of the maximum emergence were measured. The results showed that the highest and lowest final emergence percentages were observed at 25/15°C and 40/30°C day/night, respectively. Final emergence percentages at salinity levels of 6, 10, 14 and 18 dS m-1were, respectively, 9, 22, 36 and 57% lower than 2 dS m-1. Final emergence percentages for 5, 10 and 15 mm seeding depths were, respectively, 30, 44 and 72% lower, as compared with the placement of seeds on the soil surface. Regression analysis showed that final emergence percentage linearly decreased with increase in salinity and seeding depth levels. However, elapsed time (days) to reach 50% of the maximum emergence (T50), increased as salinity and seeding depth increased, so that the highest T50 was obtained for 18 dS m-1 and seeding depth of 15 mm. Increase in salinity and seeding depth was associated with a significant decrease in emergence rate index. In addition, using a logistic regression equation, emergence rate of K. indica was quantified on each day after sowing for each temperature-salinity combination to predict the distribution range of the plant in these situations.
 


Hadi Pirasteh-Anosheh,
Volume 7, Issue 1 ((Spring and Summer) 2020)
Abstract



Extended abstract
Introduction: Camelthorn (Alhagi maurorum) has a high tolerance to salt and water stresses, and its forage quality is greater than cereal straw and is equal to alfalfa. Seeds of camelthorn do not germinate easily due to the hard seed coat. Therefore, camelthorn cultivation as an agricultural crop needs more research, especially on breaking seed dormancy and increasing germination. Despite numerous studies about camelthorn as a weed, there are few studies on evaluating agronomic factors of camelthorn as a field crop. Hence, in this study, some aspects of germination and salinity tolerance of camelthorn were examined.
Materials and Methods: In this research, different aspects of camelthorn germination were examined at the National Salinity Research Center in 2018. In the first experiment, different pretreatments including control, sandpaper, hydro-priming, hot water, and sulphuric acid were assessed. With the selection of sulphuric acid as the best treatment, varying durations (0, 5, 10, 15, 20, and 25 min) and concentrations (98% and 75%) of sulphuric acid priming were compared in the second and third experiments. In the fourth experiment, the seeds collected in 2018 were compared with the seeds collected in 2017 and 2016. The effect of different salt stress levels (0, 6, 12, 18, 24, 30, and 36 dS m-1) was evaluated on camelthorn germination and early growth in the fifth experiment. In the sixth experiment, lighting regimes including continuous dark, continuous light, and an alternative period of dark- light were examined and in the seventh experiment sibling factors (together and individual seeds) were evaluated. Seed germination and seedling length were calculated and salinity tolerance threshold levels and 50% reduction threshold were estimated.
Results: The results of the first experiment showed that the highest germination percentage was obtained in sulphuric acid priming (56.6%), which was six folds greater than the control. In the second experiment, it was shown that the highest germination percentage (81.1%) and seedling growth (5.7 cm) was observed in sulphuric acid priming 98% for 25 min. Important note was that these results were related to domestically produced sulphuric acid, and the highest germination and seedling growth were observed in 75% concentration for the imported sulphuric acid. In the fourth experiment, it was found that at least 3 years of seed longevity had no significant effect on seed germination. Considerable losses in germination and growth were observed from 30 dS m-1 salinity level; however, germination did not completely stop even at 36 dS m-1 salinity. In the sixth and the seventh experiments, it was found that there were no significant differences between seeds germination in the continuous dark, continuous light, and an alternative period of dark- light as well as between individual and together seeds. So, camelthorn seed is not photoblastic and had no negative sibling factor.
Conclusions: Generally, it was concluded that the best method for improving germination is priming with sulphuric acid 98% (internal) or 75% (imported) for 25 min. According to achievement of high germination in sulphuric acid pre-treatments (chemical scarification), it seems that seed dormancy in camelthorn is presumably physical. Furthermore, although the salinity tolerance threshold of this plant is estimated 14.2 dS m-1, it can germinate minimally even in very higher salinity. Light salt stress not only decreases the germination of this plant but also is necessary for growth promoting. Based on the high salinity tolerance of camelthorn in the germination stage, its cultivation in haloculture systems is recommended for more investigation.

Highlights:
1- Sulphuric acid 98% priming for 25 min led to breaking seed dormancy and acceptable camelthorn germination.
2- In moderate salinity, germination was not significantly changed and seedling growth was promoted compared with the non-stress conditions.
3- Salinity tolerance threshold level of camelthorn was estimated 14.2 dS m-1.


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