Iron (Fe) is a vital element for plants and other organisms, involving in several physiological processes including respiration, chlorophyll biosynthesis, and photosynthesis. Unfortunately, how Fe accumulation regulates in response to light quality has not been well established in plants. Therefore, the aim of the study was to explore the mechanism of Fe homeostasis by light quality. In this study, we found morpho-physiological attributes were significantly improved in response to blue (λmax: 450) compared to white (λ max: 500) and red (λmax: 660) light. The root-shoot length, plant biomass, photosynthesis efficiency (Fv/Fm) and leafgreen (SPAD) significantly declined in response to white and red light. However, these parameters were improved and iron deficiency was substantially alleviated by blue light exposure in alfalfa seedlings. This study might be useful to the forage breeders and farmers for improving alfalfa yield and nutritional benefits.

Ⅰ. INTRODUCTION
Ⅱ. MATERIALS AND METHODS
    1. Alfalfa growth in response to LED light
    2. Determination of photosynthesis, chlorophyll contentand morphological parameters
    3. Gene expression analysis
    4. Statistical analysis
Ⅲ. RESULTS AND DISCUSSION
    1. Fe deficiency caused phenotypic and physiologicalchanges in alfalfa
    2. Fe deficiency declined alfalfa growth and biomassyield
    3. Blue light enhanced Fe, Zn and S-transportergenes, which overcomed Fe-deficiency in alfalfa
Ⅳ. CONCLUSIONS
Ⅴ. ACKNOWLEDGEMENTS

• Ki-Won Lee(Grassland and Forage Division, National Institute of Animal Science, RDA, Cheonan 31000, Republic of Korea)
• Sang-Hoon Lee(Grassland and Forage Division, National Institute of Animal Science, RDA, Cheonan 31000, Republic of Korea)
• Yowook Song(Grassland and Forage Division, National Institute of Animal Science, RDA, Cheonan 31000, Republic of Korea)
• Md Atikur Rahman(Grassland and Forage Division, National Institute of Animal Science, RDA, Cheonan 31000, Republic of Korea) Corresponding author
• Bo Ram Choi(Grassland and Forage Division, National Institute of Animal Science, RDA, Cheonan 31000, Republic of Korea)
• Jae Hoon Woo(Grassland and Forage Division, National Institute of Animal Science, RDA, Cheonan 31000, Republic of Korea)
• Hyung Soo Park(Grassland and Forage Division, National Institute of Animal Science, RDA, Cheonan 31000, Republic of Korea)