Yoncada (Medicago sativa L.) Tuzluluk Toleransı Farklı İki Çeşitte Fizyolojik ve Biyokimyasal Mekanizmalar

Abstract

Tuz stresi, tarımsal verimliliği azaltan abiyotik bir stres faktörü olarak kabul edilmektedir. Yapılan araştırmalar, tuz stresinin bitkilerde büyüme, gelişme ve verim üzerinde olumsuz etkiler yarattığını, aynı zamanda kalite kayıplarına yol açtığını ortaya koymaktadır. Özellikle yem bitkileri arasında yüksek besin değerine sahip olan yaygın yonca, tuz stresine karşı hassasiyet gösteren türlerden biridir. Bu nedenle, yaygın yoncanın tuz stresine karşı fizyolojik ve biyokimyasal tepkilerini anlamak, stres toleransını artırmak için gerekli olan programların ortaya konması adına büyük önem taşımaktadır. Bu çalışmada, tuz stresine farklı duyarlılık gösteren yaygın yonca çeşitlerinin tuz stresine maruz kaldığında gösterdiği fizyolojik ve biyokimyasal mekanizmaların ortaya konulması amaçlanmıştır. Araştırma öncesinde yapılan petri deneyleri, her iki çeşidin tuz stresine karşı farklı hassasiyet gösterdiğini ve 'Diane' çeşidinin 'Bilensoy-80' çeşidine kıyasla daha dayanıklı olduğunu ortaya koymuştur. Çalışmada, farklı tuzluluk seviyelerinin (0, 50, 100, 150, 200 mM NaCl) yaygın yonca çeşitlerinde büyüme parametreleri, fizyolojik ve biyokimyasal mekanizmaya etkileri analiz edilmiştir. Çalışma sonuçları 'Diane' çeşidinin tuz stresi altında 150 ve 200 mM NaCl uygulamaları dışında kontrol grubuna kıyasla kök gelişimini, fizyolojik ve biyokimyasal durumunu koruduğunu göstermiştir. Buna karşılık, 'Bilensoy-80' çeşidinde tuz stresi kontrol grubuna kıyasla, büyüme parametrelerinde belirgin bir azalmaya, fizyolojik ve biyokimyasal özelliklerde ise ciddi bozulmalara yol açmıştır. Elde edilen sonuçlar, 'Diane' çeşidinin yüksek tuz toleransının, serbest prolin ve toplam fenolik içeriğindeki artışın yanı sıra APX, CAT ve GR enzimlerinin artan biyosentezini içeren antioksidatif savunma mekanizmasına bağlı olabileceğini göstermektedir. Araştırma bulguları, tuz stresine dayanıklı yaygın yonca bitkisi geliştirmeyi hedefleyen ıslah programlarında kullanılabilir. Ayrıca, tuz stresine daha toleranslı olduğu belirlenen 'Diane' çeşidinin, tuzlu koşullarda verim ve adaptasyon kapasitesinin değerlendirilmesi amacıyla tarla denemeleriyle test edilmesi önerilmektedir.

Keywords

• Yem
• NaCl stresi
• Osmotik stres
• Antioksidan aktivite
• Yem bitkisi

Physiological and Biochemical Mechanisms in Two Alfalfa (Medicago sativa L.) Cultivars with Contrasting Salinity Tolerance

Abstract

Salinity stress has been accepted as an abiotic stress factor that decreases agricultural productivity. Earlier studies have showed that salinity stress has a negative impact on plant growth, development, and yield, while also leading to quality losses. Among forage crops, alfalfa is one of the species that exhibits sensitivity to salinity stress. Thus, gaining insights into the physiological and biochemical mechanisms of alfalfa under salinity stress is essential for formulating effective strategies to improve its tolerance. This study aimed to reveal the physiological and biochemical mechanisms of two alfalfa cultivars showing different sensitivity to salinity stress when exposed to salt stress. Preliminary petri dish experiments conducted before the study revealed that the two alfalfa cultivars exhibited different sensitivities to salinity stress, with the 'Diane' being more tolerant compared to 'Bilensoy-80'. In the study, the effects of varying salinity levels (0, 50, 100, 150, 200 mM NaCl) were tested in alfalfa cultivars by performing growth parameters, physiological and biochemical status. The results indicated that the cultivar 'Diane' showed maintained root development, physiological and biochemical status, compared to control under salinity stress, except for 150 and 200 mM NaCl. In contrast, salinity stress in the 'Bilensoy-80' caused a significant reduction in growth parameters and severe impairments in physiological and biochemical traits, compared to control. The results collectively revealed that higher salinity tolerance in 'Diane' could be attributed to its increased free proline content and antioxidative defense mechanism, including total phenolic content, APX, CAT and GR enzyme biosynthesis. The findings of this study can be used in breeding strategies that aimed to develop salt-tolerant alfalfa plants. Additionally, it is recommended that the 'Diane' cultivar, which has been identified as more tolerant to salinity stress, be tested through field trials to evaluate its yield and adaptation capacity under saline conditions.

Keywords

• Forage
• NaCl stress
• Osmotic stress
• Antioxidant activity
• Fodder crop

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