1. By Shardé Thomas 2004-2005 Effect of Light on Tuberization of Multiple Potato Varieties

2. White Tubers Photograph taken by Shardé Thomas

3. Purple Tubers Photograph taken by Shardé Thomas

4. Introduction Studies by researchers have shown that light has one of the greatest effects on potato tuberization. A study by Tong et al. found that Norland plants do not tuberize under blue light, but Desirée plants do. A study by Liscum et al. showed that photomorphogenesis in plants is induced by blue (400-500 nm), red (600-700 nm), and far-red (700-800 nm) signals through cryptochromes, phototropins, and phytochromes.

5. Goals To determine if blue light at 440 nm inhibits potato tuberization To determine if plants produce the same color tubers under each light condition (blue light at 440 nm, white light with fluence rate with of 198.98 mmolms, darkness) To graft Desirée and Norland plants and find if they tuberize under blue light at 440 nm To find which part of a grafted plant controls tuberization To determine if varieties require short days for tuberization

6. Hypotheses The best light conditions for tuberization would be under blue light. Desirée scion/Norland rootstock grafted plants would produce tubers under blue light, but the Norland scion/Desirée rootstock grafted plants would not. The potato plants would produce the same color tubers under blue light as they did under white light and darkness.

7. Methods: Tissue Culturing Hood Moist, autoclaved paper towels Test tubes filled with solid media Scalpel Parafilm

8. Methods: Preparation of Solid Media 30 g of sucrose 4.3 g of basal salts 1 mL of heated nitch and Nitch vitamins 1000mL deionized water pH between 5.6 and 5.7 with 2.0 M or 4.0 M HCl or 1.0 M KOH 2 g of phytagel Autoclaved 20 minutes

9. Methods: Preparation of Liquid Media 60 g of sucrose 4.3 g of basal salts 1 mL of heated nitch and Nitch vitamins 25 mL of kinetin 1000mL deionized water pH between 5.6 and 5.7 with 2.0 M or 4.0 M HCl or 1.0 M KOH Autoclaved 20 minutes

10. Methods: Autoclave 20 minutes for media 30 minutes for decontamination Wood and metal trays

11. Methods: Grafting Table 1: Grafted Plants ScionRootstock Norland Desir é e Norland Desir é e Conducted in hood Moist paper towels Scalpel, tongs Agar Short test tubes filled with solid media Grow for 2 weeks If successful, moved to magenta boxes with liquid media

15. Conclusion All varieties except Norland tuberized under blue light, positive effect Seven of ten varieties tuberized under long- day white light, did not need short days Four of ten varieties tuberized under darkness. Two of four Desirée scion-Norland rootstock grafts tuberized, top of plant controls tuberization

16. Table 2: p-Values Light0.0000 Plant Variety0.0000 Plant Variety and type of light 0.0185 Light with experiment number 0.7900 Light, variety, and experiment number 0.5597

17. Further Study To find which light conditions produce the optimal tuber color, oval shape, and largest size To make more grafts of Norland and Desirée plants to find if the grafted plants tuberize again and produce the same color tubers when placed under blue light

18. Practical Application Potato growers can use the data to maximize crop growth Potato farmers can obtain the highest yield out of their crops by knowing optimal light conditions for growth

19. Acknowledgements Cindy Tong Katie Goeden Harpatap Mann Ms. Fruen Team Research

20. By Shardé Thomas 2004-2005 Effect of Light on Tuberization of Multiple Potato Varieties