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ŠUMARSKI LIST 7-8/2021 str. 56     <-- 56 -->        PDF

beginning of cotyledon emergence on the soil surface by total number of sown seeds and then multiplying the amount by 100. The following formula (Ahmadloo et al., 2014) was used to determining GP,
                GP = Sn/N ´ 100    (4)
Where n is number of seeds that were germinated and N is total number of sown seeds
The data were evaluated in the SPSS Statistical Package Programs. Since the GP did not show normal distribution, the arcsine square root Conversion (√P) was applied to the data (Compton, 1994). The Two-Way Variance Analysis (Two Way ANOVA) was used to determine whether there were differences and interactions between storage temperatures and pretreatment for GP. The Duncan Test was used to determine the differences between the groups.
Seed Characteristics – Značajke sjemena
The moisture content, 1000 seed weights and fill rates of the seeds used in the study were determined to be 9.03%, 201g and 55%, respectively. It was determined that the thinnest parts of the seed coat thickness ranged between 0.10 and 3.98 mm (0.90 mm); and between 2.01 and 4.14 mm (2.96 mm) in the thickest part.
Storage Temperatures – Temperature čuvanja
The results show that the effect of storage temperature is important on the GP (p<0.05). Although Bewley et al. (2013) reported that similar germination rates were achieved after storing seeds at room temperature for a few months in species that needed to be exposed to high summer temperatures in natural conditions for germination, in this study, higher germination rate (20.95%) was achieved in seeds that were stored at 15°C (Table 2).
Storage temperature can also ensure that the water permeability of the seed coatis increased (Gupta and Singh, 1990; Bewley et al., 2013; Baskin and Baskin, 2014). The storage temperature of 15ºC might have increased the permeability of the seed coats of azarole. However, Ahmadloo et al. (2017) reported that storage temperatures did not affect the rate of water absorption in the seed coats of hawthorn.
It is already known that the increases detected in the germination rates of dry-stored seeds are caused by the ripening of the embryos of the seeds in the storing process (Bewley et al., 2013). In addition, the effects of the inhibitory substances preventing the germination in the seed coat or embryo during storage are also eliminated (Bell, 1999). For this reason, higher germination rates can be achieved with long storage durations compared to short storage times (Ahmadloo et al., 2015).
It is recommended that orthodox seeds are stored in temperatures below zero, most preferably at -18°C for longer durations without losing their vitality (Hong et al., 1996). In this study, achieving higher GP in seeds stored at 15°C compared to seeds stored at -5°C might be associated with the storage durations. Although the storage temperature of 15°C had positive effects on the seeds stored for 10 months, this might vary in longer storage durations.
Pretreatments – Predsjetvene pripreme
As a result of the evaluations made without considering the differences in storage temperatures, it was determined that the effect of pretreatments was significant on the GP of the seeds (P<0.05). The highest GP was achieved as 33.31% in the seeds that underwent 6 s SA + 2d AS pretreatment (Table 3).
Higher germination results were achieved from the SA pretreatment than from the AS pretreatment. The effect of sulfuric acid on the seed coat was in the form of corroding and thinning the seed coat (Göktürk et al., 2017), and the effect of the ash solution was in the form of removing the inhibitory substances in the seed coat and providing water permeability since it has an alkaline characteristic (Hou and Simpson, 1994). Although not at statistically significant difference percentages, the combination of these two pretreatments compared to the SA process ensuring high GP can be explained by thinning of the coat. However, the fact that high GP were achieved from SA pretreatment compared to the AS pretreatment, and that the GP achieved from seeds that underwent AS did not differ significantly from the GP achieved from the control seeds shows that the germination barrier of azarole seeds is related to the coat thickness.
Scarification in sulfuric acid is the recommended pretreatment to be applied in combination with cold stratification in the elimination of germination barriers (Hartmann et al., 2002). The results obtained in this study show that the optimal scarification time for azarole seeds are 3 hours. The fact that the GP achieved with scarification in sulfuric acid and ash solution combinations did not differ only from the