The researches on the physiology of turkish hazelnut (Corylus colurna L.) seeds

Turkish hazelnut (Corylus colurna L.) has many isolated populations in the Black Sea, Marmara, Aegean, and Central Anatolia regions of Turkey. Many of the small populations in our country are endangered. In this study, the physiological characteristics of Turkish hazelnut seeds were investigated according to 10 populations. In addition, morphological, chemical, and germination characteristics were examined, and desiccation sensitivity and storage features were investigated. Populations differed significantly in terms of morphological characteristics. The overall average 1000-seed weight of the populations was 1438.8 g (1243.7-1658.8) and the kernel ratio was 35.0% (31.3%-37.9%). As a result of the chemical analysis in 7 populations, it was determined that the average fat content, protein, starch and ash were 64.1%, 15.9%, 1.02% (10.2 g/kg) and 2.5%, respectively. In order to break the physiological dormancy of the seeds, cold stratification was applied to the seeds at intervals of four weeks for up to 28 weeks and germinated at 20 °C after stratification. At the end of the physiological dormancy test, it was determined that the germination percentage was 30.8% on average. The presence and depth of morphological and morphophysiological dormancy were tested, and the average germination percentage was 12.2% at 20 °C after 4 weeks of warm stratification + 18 weeks of cold stratification according to three different populations. In the embryo and cracked seed germination test performed to determine the role of seed coat in dormancy (the presence of physical and mechanical dormancy). Respectively, the germination percentage was found 62.2% and 85.6% for result of mechanical and physical dormancy test on average at 20 °C after 20 weeks of cold stratification in three populations. The germination percentage increased with the cracked or even removal of the seed coat, but the fact. However, the absence of germination in both cracked seed and embryo until 8 weeks of cold stratification confirmed that Turkish hazelnut had combinational dormancy (physical + physiological). In order to determine the effect of germination temperature on germination parameters, germination tests were carried out in three populations at 10 °C, 15 °C and 20 °C. After 20 weeks of cold stratification, the average germination percentage was found 30% at 10 °C, 32.6% at 15 °C and 19.3% at 20 °C. According to the three populations, it can be concluded that the germination temperature of 15 °C is more suitable for Turkish hazelnuts. Furthermore, in order to determine desiccation sensitivity and storage features, the moisture content of the seeds was reduced to 3.5%, 5%, 6.5% and stored at +4 °C and -18 °C for 6 months. The highest vitality was achieved at +4 °C temperature with 3.5% moisture content (81.48%).