A Purdue University study shows that lowering temperatures for two hours
each day reduces the height of corn without affecting its seed yield. Cary
Mitchell, horticulture professor at Purdue said the technique could be
useful for growing transgenic crops to produce high-value medicinal products
for the budding plant-derived industrial and pharmaceutical compounds
industry. According to him, corn is a good candidate crop because of the
plant's bounty of seeds and well-characterized genome.

But corn needs bright light and heat, and growing the crop in a controlled
environment presented a challenge to Mitchell and then-postdoctoral
researchers, Yang Yang and Gioia Massa. To reduce the crop height, they
borrowed a trick used to dwarf Christmas poinsettias and used a growth
chamber where they dropped the temperature to 60 degrees Fahrenheit for the
first two hours of each photoperiod, the time when corn receives light. The
temperature was restored to 80 degrees for 14 hours and then lowered to 65
degrees for eight hours of darkness. The dips in temperature dwarfed stalk
height by 9 to 10 percent and reduced stalk diameter by 8 to 9 percent
without significantly affecting the number and weight of the seeds.

Mitchell said, "This is a technique you could easily do in a mine or cave.
It is an affordable, non-chemical means of taking genetically modified crops
to harvest maturity without getting any kind of pollen or seed into the
ecosystem."

[www.sciencedirect.com]