Selenium Supplementation Affects Physiological and Biochemical Processes to Improve Fodder Yield and Quality of Maize (Zea mays L.) under Water Deficit Conditions.

Fahim Nawaz,Muhammad N Tahir,Bilal Zulfiqar,Muhammad Y Ashraf,Muhammad Naeem,Muhammad Salahuddin,Muhammad Aslam,Rana N Shabbir

doi:10.3389/fpls.2016.01438

Abstract

Climate change is one of the most complex challenges that pose serious threats to livelihoods of poor people who rely heavily on agriculture and livestock particularly in climate-sensitive developing countries of the world. The negative effects of water scarcity, due to climate change, are not limited to productivity food crops but have far-reaching consequences on livestock feed production systems. Selenium (Se) is considered essential for animal health and has also been reported to counteract various abiotic stresses in plants, however, understanding of Se regulated mechanisms for improving nutritional status of fodder crops remains elusive. We report the effects of exogenous selenium supply on physiological and biochemical processes that may influence green fodder yield and quality of maize (Zea mays L.) under drought stress conditions. The plants were grown in lysimeter tanks under natural conditions and were subjected to normal (100% field capacity) and water stress (60% field capacity) conditions. Foliar spray of Se was carried out before the start of tasseling stage (65 days after sowing) and was repeated after 1 week, whereas, water spray was used as a control. Drought stress markedly reduced the water status, pigments and green fodder yield and resulted in low forage quality in water stressed maize plants. Nevertheless, exogenous Se application at 40 mg L-1 resulted in less negative leaf water potential (41%) and enhanced relative water contents (30%), total chlorophyll (53%), carotenoid contents (60%), accumulation of total free amino acids (40%) and activities of superoxide dismutase (53%), catalase (30%), peroxidase (27%), and ascorbate peroxidase (27%) with respect to control under water deficit conditions. Consequently, Se regulated processes improved fodder yield (15%) and increased crude protein (47%), fiber (10%), nitrogen free extract (10%) and Se content (36%) but did not affect crude ash content in water stressed maize plants. We propose that Se foliar spray (40 mg L-1) is a handy, feasible and cost-effective approach to improve maize fodder yield and quality in arid and semi-arid regions of the world facing acute shortage of water.

Highlights

Livestock is a major livelihood for poor people in developing countries fulfilling their social, economic and risk management functions
The plants supplemented with Se exhibited non-significant difference for Ψw under normal conditions (100% field capacity (FC)), Se foliar spray markedly enhanced Ψw by 41% with respect to no Se supply under drought stress conditions (Figure 1A)
Similar trend was noted for leaf relative water contents (RWCs) and excised leaf water loss (ELWL) as Se supplementation increased RWC by 30% (Figure 1B), whereas, it reduced ELWL by 44% (Figure 1C) in water stressed maize plants

Summary

Introduction

Livestock is a major livelihood for poor people in developing countries fulfilling their social, economic and risk management functions. Climate change has increased the vulnerability of livestock systems, which may trigger a loss of livelihoods of poor communities in arid and semi-arid regions of the world. Identification of an effective stress ameliorant for improving yield and quality of fodder crops under water deficit conditions is essential in today’s changing climates. Se mediated enhancement in plant resistance/tolerance to environmental stresses is attributed to its positive role in several physiological and biochemical mechanisms such as maintenance of water status (Djanaguiraman et al, 2005), enhancement in pigments (Malik et al, 2012), regulation of photosynthetic machinery (Balal et al, 2016), accumulation of osmoprotectants (Akbulut and Çakir, 2010) and activation of antioxidant enzymes (Hasanuzzaman et al, 2012; Ahmad et al, 2016). The understanding of physiological and biochemical mechanisms that underlie the positive effects of Se in improving yield and quality of fodders under water deficit conditions remains elusive

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Conclusion