Iranian Journal of Seed Research

Salinity is one of the most extensive environmental stresses and is a limiting factor for the growth and development of crops, such as rice. Then, an experiment based upon completely randomized design with four low levels (0, 7.5, 15, 22.5) and four high of salinity (75, 150, 225 and 300 mM) with control as the first factor and nine cultivars of rice (dollars, Hasan Saraii, Mousa Tarom, Kamfiruz, Lenjan Askari, Gharib, Domsiah Mamassani, 304, Champa Yasouj) as the second factor with three replications was conducted in 2012 in the Yasouj University. Results showed that Hasan Saraii had salinity tolerance with the most germination percentage, germination rate and shoot length at high salinity levels (more than 75 mM), and Domsiah Mamassani with the minimum of that traits had not any salinity tolerance. But in the low salinity (less than 22.5 mM), Hasan Saraii, Lenjan and Mousa Tarom had the highest percentage of germination. The maximum germination rate was due to Mousa Tarom and the maximum shoot length observed in Gharib variety. So it seems, if we would only consider the germination percentage, Hasan Saraii is the best variety and if the maximum germination percentage and rate are considered, the variety that would be considered is Mousa Tarom. Therefore, high salinity we should not just rely on the germination but the germination rate should also be noted and in lower salinity due to different cultivars germination percentage, germination rate and dry weight of root should be paid much more attention.

Salinity is one of the environmental stresses limiting rice cultivation. Evaluation of the tolerance and sensitivity of offsprings of segregated generations under salinity condition is one way of finding tolerant cultivars. In order to study the effects of salinity (80 mM NaCl) stress on the second generation offspring of crosses of three rice varieties (Dollars and Gharib with 304) and to compare them with their parents and their classification in terms of salinity stress, the first experiment was conducted, adopting a Completely Randomized Design with four replications (i.e., crossing parents with Yasouj and Kamfirooz varieties). In the second experiment, check cultivars and the second generation progeny were evaluated, using an augment with a completely randomized design. At the germination stage, the Dollar cultivar was sensitive to salinity stress because it had the lowest ratio of all traits except germination percentage. However, Gharib and Kamfirooz Cultivars were salt tolerant. In both crosses, second-generation offsprings showed genetic variations in terms of the traits measured. Broad-sense heritability values for Dollars×304 and Gharib×304 crosses for shoot height (5.98% and 96%), root length (8.90% and 86%) and shoot fresh weight (8.95% and 7.92%), were relatively high, indicating that we can select these traits based on their phenotypes. General irritability for the shoot and root length traits in the second generation offsprings of Dollar and 304 crosses was higher than that of the second generation progeny of 304 and Gharib crosses. Based on these results, we concluded that for the purpose of improving salt tolerance at germination stage, 304 and Dollars crosses are more useful in rice breeding programs.

Extended Abstract
Introduction: Salinity stress is one of the most important factors in decreasing crop yield. Crossing between cultivars and wild relatives is one of the methods to creating salinity tolerant plants that has led to the creation of new Tritipyrum cereals. Investigation of the effect of salinity stress at the germination stage is a reliable test in assessing salinity tolerance of many species; it reduces percentage and rate germination as well as decreases of root and shoots growth. This research aims to investigate the effects of different levels of salinity stress on germination of promising non-Iranian Tritipyrum lines and two wheat cultivars, Alvand (salinity tolerant) and Ghods (salinity sensitive).
Materials and Methods: The experiment was conducted in factorial based on the completely randomized design at the Faculty of Agriculture, Yasouj University. The first factor consisted of 13 Tritipyrum lines and two wheat cultivars and the second factor consisted of different salinity levels (240, 160, 80, 0 mM NaCl). After surface disinfection and seed culture in a petri dish, germination-related traits were measured until the 14^th day.
Results: The results showed that by increasing salinity level, germination rate and percentage, root length, shoot length, dry and fresh root weight, and shoot dry weight decreased. The highest percentage (79.79%) and rate (75.74 seed per day) of germination in stress and non-stress conditions were related to the Az/b line. The germination percentage of the Alvand tolerant cultivar (55.59%) was higher than 5 Tritipyrum lines but less than the other 7 lines, its germination rate (53.69 seed per day) was higher than 10 Tritipyrum lines. The percentage and germination rate of sensitive cultivar Ghods (40.98 and 36.87 seed per day, respectively) were lower than all Tritipyrum lines. Under salinity stress, the La/b line had the highest root length (7.77 cm) which was even longer than the root length of the Alvand tolerant cultivar (4.9 cm). The highest root dry weight (0.027 g) under stress conditions was related to the Ka/b line and the lowest root dry weight (0.013 cm) was related to the Ghods cultivar. Among germination traits, the highest and the lowest heritability were related to shoot length under stress and non-stress conditions and root fresh weight (under non-stress conditions) and root length (under stress conditions), respectively. Genetic variance of shoot length and germination percentage in non-stress conditions was higher than stress conditions and selection under non-stress conditions had a higher yield than stress conditions. Clustering of genotypes by cluster analysis divided the genotypes into four groups under normal and salinity conditions. Under salinity stress, the salt-tolerant cultivar was placed alone in the fourth cluster. The salinity-sensitive cultivar was also in the third cluster with the St/b line. The rest of the Tritipyrum lines were clustered in the first and second clusters, with (Ka/b)(Cr/b)F₆ hybrid line in the first cluster. Salt stress condition seems to have separated Qods from all Tritipyrum lines (except St/b), but under normal conditions, it did not indicate clustering accuracy of the studied genotypes.
Conclusion: The results of this study demonstrated salinity tolerance in the most simple and hybrid lines of this plant at the germination stage, among them (St/b)(Cr/b)F₃, (Ka/b)(Cr/b)F_6, and (Ka/b)(Cr/b)F₃ and La(4B/4D)×(b) and the simple lines La/b, Az/b and St/b were better than others. Therefore, these selected lines can be considered in further complementary studies.
 

Highlights:
1. The studied plant is new and needs to be examined at the germination level before introducing.
2. Simple lines with the hybrid lines of this new plant have been studied that can show the effect of crosses.
3. Grouping of lines for tolerance or susceptibility is done solely based on germination traits.

Extended abstract
Introduction: In agricultural systems, several environmental stresses can remarkably alter the growth, physiological, and biochemical responses of plants under stress. One of these factors is the biochemical reactions between plants along with the production of secondary compounds. Allelochemicals mainly have defence and cell wall ligninization roles in plants and do not directly play a role in the growth processes of plants. Thus, an experiment was carried out to evaluate the effect of allelopathic stress of Hypericum perforatum on the germination, physiological, biochemical, and antioxidant activity characteristics of green pea, the benchmark plant sensitive to allelochemicals.
Materials and methods: The treatments included different concentrations of H. perforatum at 11 levels (i.e., 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100% of the aqueous extract). This research was carried out as a completely randomized design with three replications at the weed science laboratory of Gonbad Kavous University in 2023.
Results: The results of this study showed that one of the factors influencing the physiological, and biochemical characteristics of green pea is the concentration of the H. perforatum extract. In most cases, the percentage and rate of green pea germination, radicle and plumule length, and dry weight of radicle and plumule decreased with increased concentration of aqueous extract compared to the control, so that the greatest reduction in these characteristics was observed in 100% of H. perforatum extract. In contrast, the content of compatible osmolytes such as proline and soluble sugars, phenolic and flavonoid compounds, and antioxidant activity of green pea roots and plumules increased significantly in all studied treatments, with the highest increase in these characteristics observed at the concentration of 100% of H. perforatum aqueous extract. In general, the decrease in the dry weight of green pea seedlings due to the increase in the concentration of the aqueous extract of H. perforatum, despite the relative increase in the content of physiological and biochemical traits, indicates the high intensity of allelopathic stress of H. perforatum extract and their insufficiency, which leads to cytotoxicity against oxidative stress.
Conclusion: Considering the heterotoxicity effect of H. perforatum on green pea sensitive to allelochemicals and its distribution in gardens, barren lands, and wheat and corn fields, the possible effect of their residues in the next planting and even in case of presence in mixed cultivation should be considered.

Highlights:

1. Aqueous extract obtained from the H. perforatum drastically reduces the germination and seedling growth of green peas.
2. The difference in the effect of the aqueous extract of H. perforatum on green pea, the benchmark plant sensitive to allelochemicals, depends on their concentration threshold.
3. The high intensity of allelopathic stress of H. perforatum extract and insufficient non-enzymatic antioxidants lead to oxidative stress.