Mehmet Demir KAYA, Süleyman AVCI, Onur İLERİ

Sorgum Çeşitleri Arasında Tohum Gücü, Tuz ve Kuraklık Stresi Bakımından Genotipik Varyasyonun Belirlenmesi

Bu çalışma aynı ekolojik koşullarda yetiştirilen sorgum çeşitleri arasında tohum gücü, tuz (NaCl) ve kuraklık stresi bakımından genetik farklılıkların belirlenmesi amacıyla yürütülmüştür. Ayrıca sorgum çeşitleri arasında kuraklık stresine toleransın belirlenmesi amacıyla saksı denemesi olarak fide canlılık testi yapılmıştır. İncelenen 7 sorgum çeşidinde tohum gücü, elektriksel iletkenlik ve hızlı yaşlandırma testleriyle belirlenmiştir. PEG 6000 ve NaCl kullanarak su tutma gücü 0.0 (saf su), -1.8, -3.6, -7.2 ve -10.8 bar olarak ayarlanan solüsyonlarda çeşitlerin çimlenme ve fide gelişimi incelenmiştir. Araştırma sonuçlarına göre, aynı ekolojik koşullarda yetiştirilen sorgum çeşitlerinin tohum güçleri arasında önemli farklılıkların olduğu belirlenmiştir. Akdarı çeşidi diğer çeşitlere göre daha güçlü tohum üretmiştir. Tohum güç testlerinden hızlı yaşlandırma ile laboratuvar çıkışı arasında (r= 0.967**) ve elektriksel iletkenlik ile çimlenme arasında (r= -0.873**) önemli ilişkilerin olduğu belirlenmiştir. Sorgum çeşitlerinin çimlenme potansiyelini belirlemede elektriksel iletkenlik testi, çıkış performansının belirlenmesinde ise hızlı yaşlandırma testi uygun bulunmuştur. Artan NaCl ve PEG konsantrasyonları çimlenme ve fide gelişimini engellemiştir. NaCl ile karşılaştırıldığında, PEG solüsyonlarında çimlenme, kök ve sürgün uzunluğu daha yüksek, ortalama çimlenme süresi daha kısa bulunmuştur. Tuz, kuraklık ve fide canlılık testlerinde, Aldarı çeşidinin diğer çeşitlerden daha yüksek performans göstermiştir. Sonuç olarak, tohum güç testlerinin tuz ve kuraklık stresinde çimlenme performansı için güvenilebilir olmadığı ve genetik farklılıkların stres toleransında önemli rol oynadığı söylenebilir.

Determination of Genotypic Variation among Sorghum Cultivars for Seed Vigor, Salt and Drought Stresses

This study was conducted to determine genotypic variation among sorghum cultivars grown under similar ecological conditions for seed vigor, salt (NaCl) and drought stresses. A seedling survival test was also performed in a pod experiment to investigate genotypic differences in terms of sorghum drought tolerance. In seven sorghum cultivars, seed vigor was determined using electrical conductivity and accelerated ageing tests. Also, germination rate and seedling growth of these cultivars were evaluated under salt and drought stress induced by PEG 6000 at water potentials of 0.0 (distilled water), -1.8, -3.6, -7.2 and -10.8 bar. The results showed that there was a significant difference in seed vigor of sorghum cultivars grown at same ecological conditions. Akdarı produced more vigorous seeds than the other cultivars. The significant relationship between accelerated ageing and laboratory emergence (r= 0.967**), and between electrical conductivity and germination percentage (r= -0.873**) were determined. The suitable tests for germination and emergence potential in sorghum were electrical conductivity and accelerated ageing, respectively. Increasing NaCl and PEG levels inhibited germination and seedling growth. Germination, root length and shoot length were higher, whereas mean germination time was lower, in NaCl solution compared to in PEG solution at the same water potential. In salt, drought and seedling survival tests, Aldarı showed the better performance than the others. It could be concluded that seed vigor is not a reliable indicator of germination performance under salt and drought stress conditions and that genetic differences may play an important role in stress tolerance.

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