natural sciences and science educationacademic groupnatural sciences and science educationacademic group

About the StoryThe story “To Nip or Not to Nip” is based on actual events – and the experiences of one of our group members – that took place in the 1970s in China as the Cultural Revolution drew to a close. The story revolves around the experiences of a young city girl, Pin Pin, as she adapts to life on the communal farm. One day, Pin Pin and her friends are introduced to the fields by an old farmer. She notices a field of plants with beautiful yellow flowers, like those found in kailan or báicài (Brassica rapa chinensis). The old farmer advises Pin Pin to remove the flowers, lest she live to regret it. Pin Pin does not yet realise that the plants are turnips, a cultivar of Brassica rapa (var. rapa). Failing to remove the flowers will lead to the allocation of food reserves from root to developing seeds, resulting in small turnips – and a long, hard, food scarce winter. In a second field, Pin Pin notices identical yellow flowers, but this time is sternly instructed not to remove the flowers. Again, Pin Pin is confused. This second field are rape flowers (“canola” or “you cai”), Brassica rapa oleifera. Clearly removing these flowers would be a bad idea – no flowers means no seeds, and subsequently no oil for harvest and subsequent sale. Pin Pin has a lot to learn about Brassica cultivars.

Plant Physiology• Investigation: Photoassimilate partitioning among the

sinks affect the harvest index (Harvest index = usable plant material /total biomass)

• For undergraduate course - nipping flowers vs keeping flowers, measure harvest index

• For postgraduate course – nipping flowers vs keeping flowers, 14CO2 applied to one leaf of turnip plants with and without flowers, respectively, measure the amount of 14C-carbohydrates in each leaf, flower & modified root after feeding for a few hour, calculate the percentage of 14C for each harvested organ.

To Nip or Not to NipChia Tet Fatt, C.H. Diong, He Jie, Koh Chong Lek, Shirley Lim,

Shawn Lum, and Sam Choon Kook

Primary Science•Investigate: determine plant parts•Learn about plant cultivars: field trip to a wet market•Different plant parts have different uses: cook and eat!•Plant development: different Brassica cultivars•Manipulate plants: remove leaves, flowers, etc.

Animals aren’t left out…Neither were people•Key words: capon, gelding, farm animals, castrati, opera

www.gov.mb.ca/agriculture/crops/weeds/fab53s00.html

Rape flowersBrassica rapa flowers

Know Need to Know

• The Cultural Revolution was from 1966-76

• Brassica rapa has many cultivars

• Plants divert resources to where they are needed

• Humans can manipulate growth forms of plants

• How were people sent to the countryside?

• Which are grown in China? How were they selected?

• What controls resource allocation in plants?

• What happens at molecular and physiological levels?

Applications of the Case…

Some resourcesWeb: en.wikipedia.org/wiki/Turnip; 5e.plantphys.net/index.php;Also: Zamski, E., Schaffer, A. A.: Photoassimilate distribution in plants and crops: source-sink relationships. Marcel Dekker Inc. Publ., New York – Basel – Hong Kong 1996