Dr. Borlaug, "Norm" to his friends, is called the Father of the Green Revolution. (This is a really good piece that will help you answer my questions.) How did he earn that title?
"Norman Borlaug using selective breeding techniques to improve wheat production in Mexico. He produced plants which had large seed heads and hence a good yield. However the plants were too tall and were prone to falling over (lodging). A mutant dwarf form of wheat was discovered in post-war Japan. Borlaug crossed this strain with the high yield variety and produced a strong, high yielding wheat. This was subsequently grown throughout the world, and has reduced the levels of hunger on several continents. The innovation was called the 'Green revolution'. The cost issues related to growing this wheat are mentioned briefly and the question of sustainability is raised.
Borlaug's cross Illustrates the importance of selective breeding, with discussion of the features which were selected and the resultant cross. We could then look at other crop plants which have been selectively bred and discuss selected phenotypes. The material is also a stimulus for the discussion of how science can contribute to human well-being. Discussing the risks associated with the growing of monocultures, excessive use of fertilizer, the costs of using chemicals on foods is something you and I can help the public understand.
"The presence of certain versions of wheat genes has been important for crop yields. Apart from mutant versions of genes selected in antiquity during domestication, there has been more recent deliberate selection of alleles that affect growth characteristics. Genes for the 'dwarfing' trait, first used by Japanese wheat breeders to produce short-stalked wheat, have had a huge effect on wheat yields world-wide, and were major factors in the success of the Green Revolution in Mexico and Asia. Dwarfing genes enable the carbon that is fixed in the plant during photosynthesis to be diverted towards seed production, and they also help prevent the problem of lodging. 'Lodging' occurs when an ear stalk falls over in the wind and rots on the ground, and heavy nitrogenous fertilization of wheat makes the grass grow taller and become more susceptible to this problem. By 1997, 81% of the developing world's wheat area was planted to semi-dwarf wheats, giving both increased yields and better response to nitrogenous fertilizer.
Wild grasses in the genus Triticum and related genera, and grasses such as rye have been a source of many disease-resistance traits for cultivated wheat breeding since the 1930s.[26]
Heterosis, or hybrid vigor (as in the familiar F1 hybrids of maize), occurs in common (hexaploid) wheat, but it is difficult to produce seed of hybrid cultivars on a commercial scale (as is done with maize) because wheat flowers are perfect and normally self-pollinate. Commercial hybrid wheat seed has been produced using chemical hybridizing agents; these chemicals selectively interfere with pollen development, or naturally occurring cytoplasmic male sterility systems.
Hybrid wheat has been a limited commercial success in Europe (particularly France), the USA and South Africa.[27] F1 hybrid wheat cultivars should not be confused with the standard method of breeding inbred wheat cultivars by crossing two lines using hand emasculation, then selfing or inbreeding the progeny many (ten or more) generations before release selections are identified to be released as a variety or cultivar."
So, I ask my readers, do you plant or consume hybrid wheat or a "selfed propagated variety?"
Is Dr. Borlaug really the Father of the Green Revolution?
Ed Winkle
After generations of selection, don't these hybrids become stable and can be self-propagated?
ReplyDeleteBy the way, I read recently about "wide cross" hybrids, do you know anything about them?
The process involves irradiation, and seems way more potentially dangerous than modern genetic engineering where at least we know what gene is inserted, and usually, where too.
I read that the current "heirloom" tomatoes grown mostly by organic gardeners are such wide cross hybrids, but with no link to validate that. Are wide cross hybrids responsible for the bland vegetables in the store? ;)
To my knowledge, there is no true hybrid wheat being used much in wheat or cereal grain around the world. Most wheat being used has been "selfed" and takes 13 years or so to get the first cross into farmers hands! That has been sped up some using methods like Dr. Borlaug did, which are in themselves somewhat controversial. It often leads to less pure seed because there is not enough time to take all of the out crossing plants out of the seed lot.
ReplyDeleteHybrid corn is a whole different ballgame because the corn lends itself to true hybridization better than probably any plant on earth. My old but popular post on corn hybridization shows a direct correlation from increase of corn yield to increase in world population the last 80 years since it was first done in the late 1920's and quickly adapted in the 1930's.
I will need some help to discuss wide cross hybrids as they are not well understood unless you are a geneticist in plants!
Ed
Chimel, after a little reading, the Triticale plant might be a wide cross hybrid, introducing two parents of the same specie but far apart in genus?
ReplyDeleteDr. Norman Borlaug?
http://lifeofplant.blogspot.com/2011/03/hybridization.html