By Shardé Thomas

2004-2005

Effect of Light on Tuberization of Multiple

Potato VarietiesQuickTime™ and a

TIFF (LZW) decompressorare needed to see this picture.

White Tubers

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Photograph taken by Shardé Thomas

Purple Tubers

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Photograph taken by Shardé Thomas

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.

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

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.

Methods: Tissue Culturing

• Hood• Moist, autoclaved

paper towels• Test tubes filled with

solid media• Scalpel• Parafilm

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

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

Methods: Autoclave

•20 minutes for media

•30 minutes for

decontamination

•Wood and metal trays

Methods: Grafting

Table 1: Grafted Plants

Scion Rootstock

Norland Desirée

Desirée Norland

Norland Norland

Desirée Desirée

•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

Figure 1: Effect of Darkness on Potato Tuberization

0

0.5

1

1.5

2

2.5

Norland

Red Norland

Dark Red Norland

DesiréeBisonDazoc

Early OhioKerr's PinkRed Pontiac

Sangre

Variety of Potato Plant

Number of Tubers

6/29/04

7/7/04

Figure 2: Effect of blue Light (440 nm) on Potato Tuberization

0

0.5

1

1.5

2

2.5

3

3.5

Norland

Red Norland

Dark Red Norland

DesiréeBisonDazoc

Early OhioKerr's PinkRed Pontiac

Sangre

Variety of Potato Plant

Number of Tubers

6/29/04

7/7/04

Figure 3: Tuber Growth of Grafted Plants

0

0.5

1

1.5

2

2.5

Desirée-Norland Norland-Desirée Norland-Norland Desirée-Desirée

Graft

Number of Tubers

Tubers

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

Table 2: p-ValuesLight 0.0000

Plant Variety 0.0000

Plant Variety and type of light

0.0185

Light with experiment number

0.7900

Light, variety, and experiment number

0.5597

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

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

Acknowledgements

• Cindy Tong• Katie Goeden• Harpatap Mann• Ms. Fruen• Team Research

By Shardé Thomas

2004-2005

Effect of Light on Tuberization of Multiple

Potato VarietiesQuickTime™ and a

TIFF (LZW) decompressorare needed to see this picture.