Proline-mediated responses of lettuce to alternating fresh and saline water irrigation: impacts on soil salinity, evapotranspiration and yield

Abstract

This study investigated the effects of alternating applications of freshwater and saline irrigation waters combined with exogenous proline treatments on soil salinity dynamics, evapotranspiration (ET), water use efficiency (WUE), and yield performance of lettuce (Lactuca sativa L.). The experiment was conducted under greenhouse conditions in Hatay, Türkiye. Lettuce plants were initially irrigated with freshwater until the 8-10 leaf stage and subsequently irrigated with saline water at salinity levels of 2, 4, and 6 dS m⁻¹ until harvest, while foliar proline was applied at doses of 0, 5, and 10 mM. The results indicated that increasing irrigation water salinity progressively limited soil salinity accumulation (ECe) and plant water consumption, with more pronounced effects under higher salinity levels. Proline applications, particularly at the 5 mM dose, reduced soil salt accumulation and contributed to the maintenance of ET under high salinity conditions. The optimal seasonal ET range for lettuce was determined to be approximately 9.1-9.5 L, whereas water consumption below or above this range negatively affected commercial head weight and marketability. Low to moderate salinity treatments (EC2-EC4) did not completely suppress yield and quality, whereas at 6 dS m⁻¹, losses in commercial quality became dominant. Overall, the findings suggest that appropriate irrigation management combined with careful selection of proline dose can effectively mitigate the adverse effects of salinity stress in lettuce cultivation.

Keywords

• Lettuce
• Proline
• Salinity stres
• Cyclic irrigation
• Evapotranspirasyon

Ethical Statement

This article does not require ethical approval as there are no experiments with human or animal subjects.

Thanks

The authors would like to thank Halid ZERZURİ for his assistance during the field studies.

Marulun dönüşümlü tatlı ve tuzlu su sulamasına prolin uygulamalarının tepkileri: toprak tuzluluğu, evapotranspirasyon ve verim üzerindeki etkileri

Abstract

Bu çalışma, tatlı ve tuzlu sulama sularının dönüşümlü uygulanmasının ve eksojen prolin uygulamalarının marulda (Lactuca sativa L.) toprak tuzluluğu dinamikleri, evapotranspirasyon (ET), su kullanım etkinliği (WUE) ve verim performansı üzerine etkilerini incelemiştir. Deneme, Hatay koşullarında sera ortamında yürütülmüş; marul bitkileri 8-10 yapraklı döneme kadar tatlı suyla, ardından hasada kadar 2, 4 ve 6 dS m⁻¹ tuzluluk düzeylerindeki sulama suları ile sulanmış ve 0, 5 ve 10 mM prolin dozları yapraktan uygulanmıştır. Bulgular, artan sulama suyu tuzluluğunun toprak tuzluluğunu (ECe) ve bitki su tüketimini sınırladığını, bu etkinin özellikle yüksek tuzluluk düzeylerinde belirginleştiğini göstermiştir. Prolin uygulamaları, özellikle 5 mM dozunda, toprakta tuz birikimini sınırlandırmış ve yüksek tuzluluk koşullarında ET’nin korunmasına katkı sağlamıştır. Marulda optimum ET aralığının yaklaşık 9.1-9.5 L olduğu, bu aralığın dışındaki su tüketimlerinin ticari baş ağırlığı ve pazarlanabilirliği olumsuz etkilediği belirlenmiştir. Düşük ve orta düzey tuzluluk uygulamaları (EC2-EC4) verim ve kaliteyi tamamen baskılamazken, 6 dS m⁻¹ düzeyinde ticari kalite kayıpları ön plana çıkmıştır. Sonuçlar, marul yetiştiriciliğinde uygun sulama yönetimi ve dikkatli prolin dozu seçiminin, tuzluluk stresinin olumsuz etkilerini azaltmada etkili olabileceğini göstermektedir.

Keywords

• Marul
• Prolin
• Salinity stres
• Cyclic irrigation
• Evapotranspirasyon

Ethical Statement

Bu makale, insan veya hayvan deneklerle yapılan deneyler içermediğinden etik onay gerektirmez.

Thanks

Yazarlar arazi çalışması sırasında yardımlarından dolayı Halid ZERZURİ'ye teşekkür ederler.

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