botany

1. natural sciences and science education
academic group
About the Story
The 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 Nip
Chia 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
Plant Diversity
• Artifical vs Natural Selection
• Simulation:Creating
cultivars
• Market trip: Brassica hunt
• Phylogeny: create Brassica
family tree with DNA data
Plant Development
• Learn: homeotic genes
• Do: isolate leafy and other
genes
• Apply: study different
cultivars
www.gov.mb.ca/agriculture/crops/weed
s/fab53s00.html
Rape flowers
Brassica 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 resources
Web: 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