OSMOTİK STRES ALTINDAKİ PAMUK (GOSSYPIUM HIRSUTUM L.) BİTKİSİNDE EKSOJEN PROLİN VE GLİSİN BETAİN UYGULAMALARININ FİZYOLOJİK VE BİYOKİMYASAL TEPKİLER ÜZERİNE ETKİLERİ

Öz

Bu çalışma, topraksız ortamda (Perlit) osmotik stres altında yetiştirilmiş pamuk bitkisine dışarıdan verilen sulama suyuna prolin ve glisin betain (GB) osmoliti ekleyerek, stres zararını nasıl iyileştirebileceğini görmek amacıyla yapılmıştır. Farklı PEG (polietilen glikol) konsantrasyonlarıyla (%0, %10 ve %20 (v/w)) oluşturulan osmotik stresinin, osmolitsiz ve osmolitli gruplar arasında gövde ve kök boyu, yaş ve kuru ağırlıklar, bağıl su içeriği (RWC), malondialdehit (MDA), Toplam fenol, antosiyanin ve flavonid miktarı, prolin seviyeleri gibi çeşitli büyüme ve stres göstergelerine olan etkisi değerlendirilmiştir. PEG 6000 ile oluşturulan su potansiyeli sırasıyla 0, -0.52 MPa ve -0.77 MPa su potansiyeline karşılık gelmektedir. Osmotik stresin olumsuz etkilerini iyileştirmek amacıyla eksojen olarak besin solüsyonuna prolin (PRO) ve glisin betain (GB) 2 mM konsantrasyonlarında eklenmiştir. Her PEG düzeyine 0 mM (kontrol) ve 2 osmolit grubu (prolin ve glisin betain) uygulanmıştır. Veriler SPSS 22.0 ile analiz edilmiş, anlamlılık düzeyi %5 olarak belirlenmiştir. Bulgular, osmolit uygulamaları, PEG kaynaklı osmotik stresin pamuk bitkisi üzerindeki olumsuz etkilerini hafifletmiştir. Özellikle kök gelişimi ve su tutma kapasitesinde anlamlı artışlar sağlarken, gövde yaş ve kuru ağırlıklarında azalmalar meydana gelmiştir. Osmolit uygulamaları olan prolin ve glisin betain gruplarının analiz sonuçları RWC, MDA ve prolin düzeylerini olumlu yönde etkileyerek benzer fizyolojik tepkiler oluşturmuştur. Ayrıca, osmolit uygulamaları antosiyanin, fenolik ve flavonoid bileşiklerin sentezini teşvik ederek bitkinin osmotik strese karşı sekonder savunma mekanizmalarını aktive etmiştir. Elde edilen bulgular, topraksız yetiştirme ortamında pamuk bitkisinin kuraklık stresine karşı dayanıklılığının artırılmasında prolin ve glisin betain gibi osmolitlerin etkili bir adaptif strateji olarak değerlendirilebileceğini ortaya koymaktadır.

Anahtar Kelimeler

• Peg 6000
• prolin
• pamuk
• osmolit
• glisin betain
• perlit

Destekleyen Kurum

Harran Üniversitesi HÜBAK

Proje Numarası

18162

Etik Beyan

Bu çalışma, sorumlu yazarın doktora tez çalışmasından elde edilmiştir. Yazarlar arasında çıkar çatışması yoktur.

Teşekkür

Proje Harran Üniversitesinin Bilimsel Araştırmalar Proje Koordinatörlüğünce 18162 nolu proje ile desteklenmiştir.

EFFECTS OF EXOGENOUS PROLINE AND GLYCINE BETAINE APPLICATIONS ON PHYSIOLOGICAL AND BIOCHEMICAL RESPONSES IN COTTON (Gossypium Hirsutum L.) PLANTS UNDER OSMOTIC STRESS

Öz

Drought-induced osmotic stress severely limits cotton productivity by disrupting water balance, membrane stability, and metabolic functions. This study investigated the effects of exogenous proline (PRO) and glycine betaine (GB) supplied via the nutrient solution on the physiological and biochemical responses of cotton (Gossypium hirsutum L.) under polyethylene glycol (PEG)-induced osmotic stress. A completely randomized factorial design was established with three PEG levels (0, 10%, and 20%) and three osmolyte treatments (0 mM, 2 mM PRO, and 2 mM GB). Growth parameters (shoot fresh and dry weight, root fresh weight), relative water content (RWC), malondialdehyde (MDA), and proline accumulation were evaluated. Increasing PEG concentration significantly reduced biomass and RWC while enhancing MDA accumulation, indicating oxidative damage. Both PRO and GB mitigated these adverse effects by improving plant water status and reducing lipid peroxidation. Under severe stress (20% PEG), osmolyte-treated plants exhibited higher RWC and lower MDA compared to untreated stressed plants. Proline application was particularly effective in preserving shoot fresh weight, whereas glycine betaine showed stronger suppression of MDA accumulation. Additionally, osmolyte treatments supported endogenous proline accumulation under stress conditions. Overall, supplementation of PRO or GB in the nutrient solution enhanced osmotic stress tolerance in cotton by stabilizing cellular water relations and alleviating oxidative damage. These findings suggest that osmolyte enrichment in soilless production systems may serve as a practical strategy for improving cotton resilience under transient water-deficit conditions.

Anahtar Kelimeler

• Peg 6000
• proline
• cotton
• osmolyte
• glycine betaine
• perlite

Destekleyen Kurum

Harran University HÜBAK

Proje Numarası

18162

Etik Beyan

This study is derived from the corresponding author's doctoral thesis. There is no conflict of interest between the authors.

Teşekkür

The project was supported by Harran University's Scientific Research Project Coordination Office under project number 18162.

Kaynakça

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