Effect of Potassium Levels on Antioxidant Enzymes and Malondialdehyde Content under Drought Stress in Sunflower (Helianthus annuus L.)

Abstract

Problem statement: Drought stress as a major adverse factor can lower leaf water potential, leading to reduced turgor and some other responses and ultimately lower crop productivity in arid and semi arid zones. Sunflower is one of the main oil seed crops in Iran, where drought stress is the most limiting factor. Drought stress tolerance requires the activation of complex metabolic activities including antioxidative pathways, especially Activated Oxygen Species (AOS) and scavenging systems within the cells which can contribute to continued growth under drought stress. Approach: To evaluate the effect of limited irrigation systems and potassium fertilizer on grain yield, antioxidant enzymes and lipid peroxidation biomarker (MDA), the crop was sown in the Research Farm of College of Agriculture, Islamic Azad University, Karaj Branch in 2009. The experimental treatments were arranged as split plots based on a Randomized Complete Block Design with three replications. The main plots were allocated to three different irrigation regimes. The irrigation regimes comprised of: Full Irrigation (IR 1 ), Moderate drought stress (IR 5 ) and Severe drought stress (IR 2 ). The subplots were allocated to four potassium chemical fertilizer (Potassium nitrate) consisting of K 1 = 25, K 2 = 50, K 3 = 75 and K 4 = 100% recommended. Results: Plants under drought stress and potassium levels showed a significant increase and decrease, respectively, in SOD, CAT and GPX activity and MDA in compared to control plants. In this context, plants with higher levels of potassium showed higher resistance to drought stress conditions and higher yield and dry matter allocation to grain filling process i.e. harvest index. Results of this study suggested that drought stress leads to production of oxygen radicals, which results in increased lipid peroxidation (MDA biomarker) and oxidative stress in the plant. Conclusion: The scavenging of AOS by the scavenging system especially by SOD, CAT and GPX was done well and damage to membranes or MDA was controlled at higher levels of potassium.

Potassium application mitigates salt stress differentially at different growth stages in tolerant and sensitive maize hybrids

“…However, addition of potassium further enhanced the activities SOD, POD and CAT in both maize hybrids under saline condition. These finding also parallel to the argument that antioxidant activities in plants under salinity stress are improved by potassium application (Zheng et al 2008;Soleimanzadeh et al 2010;Abbasi et al 2014).…”

“…Increasing evidence suggests that improvement of potassium (K ? ) nutritional status of plants can greatly lower the ROS production (Cakmak 2005;Abbasi et al 2014) and increased the activities of antioxidant enzymes in wheat (Zheng et al 2008) and sunflower (Soleimanzadeh et al 2010) under stress condition.…”

Respostas fisiológicas de cultivares de soja à adubação potássica sob diferentes regimes hídricos

“…Geralmente, plantas submetidas ao estresse hídrico severo apresentam recuperação de apenas 40-60% da taxa fotossintética máxima no dia seguinte. No presente trabalho, esses valores só foram alcançados nas plantas que foram suplementadas com K. A resposta da recuperação das plantas em razão da adubação potássica pode estar relacionada à influência deste nutriente na reparação de danos oxidativos das células, em condições de estresse hídrico (Soleimanzadeh et al, 2010). Essa maior retomada das taxas fotossintéticas das plantas suplementadas com K, após a reidratação, poderia oferecer uma maior recuperação do crescimento das plantas, o que minimizaria as perdas de produtividade.…”

Supplemental exogenous NPK application alters biochemical processes to improve yield and drought tolerance in wheat (Triticum aestivum L.)

“…Reports indicated significant effect of N nutrition on enzymatic activity of Catharanthus roseus (Misra and Gupta 2006) and Zea mays (Lü et al 2012). Likewise, Soleimanzadeh et al (2010) observed marked increase in CAT, POX, and SOD activity in sunflower plants applied with K under water-deficit conditions. The increased antioxidant activity might be attributed to the spontaneous dismutation of O 2− into H 2 O 2 (Cartes et al 2010) or the direct quenching of O 2− and OH − (Xu and Hu 2004) by NPK c .…”