The other way in which humans increase food production, and does not necessarily involve an increase in gross productivity, is by genetic selection for an increase in the food-to-fiber ratio or harvest ratio. For example, a wild rice plant may put 20% of its net production into seeds (enough to ensure its survival), whereas a cultivated rice plant is bred to put as much as possible (50% or more) into seeds, the edible part. This grain-to-straw dry weight ratio has been increasing significantly in most crops. Consequently, the engineered plant does not have much energy available to produce antiherbivore chemicals (in order to defend itself); so more pesticides have to be used in the cultivation of highly bred varieties.
What has been termed the 'green revolution' involves the genetic selection for engineered crop varieties with high harvest ratios that are adapted to respond to massive energy, irrigation, and nutrient subsidies. Those who think that developed countries can upgrade the agricultural production of less-developed countries by supplying seeds and agricultural recommendations do not realize that the less-developed countries cannot afford the necessary energy subsidies. So far the green revolution has benefited the economically rich countries more than the economically poor countries.
In the 1960s, plant geneticists developed new varieties of wheat and rice that gave yields 2-3 times those of traditional varieties. Norman Borlaug received the Nobel Prize in 1970 for his leadership in the development of these new varieties. This advance in crop breeding was heralded as the beginning of the green revolution. It was poorly understood at the time that the need for an increased use of subsidies (such as optimal fertilization and irrigation) that had to accompany these new varieties would negate many of their benefits. This is one of several examples where discoveries judged worthy of Nobel Prizes resulted in unanticipated environmental consequences at a later date. So what appears to be a breakthrough discovery at one point in time may result in major ecological consequences at a later point in time.
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