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 Essay - july/aug 2006
Seeds: the ultimate delivery system
James C. Delouche
Professor Emeritus Mississippi State University
I can't remember when or where I first heard or read a reference to seeds as a delivery system but I do recall beginning to emphasize their role as a carrier of various chemical products in the 1960s. The concept of seeds as a delivery system, however, is so much more exciting than referring to them as a carrier. The phrase delivery system implies the active even dynamic transport of multiple and important products or technologies for critical uses, while the phrase carrier implies the rather passive use of seeds as convenient vehicles for transport of various materials. I readily adopted the dynamic delivery system concept and have since vigorously promoted it in word and script.
The concept and use of seeds as a delivery system is widely accepted, understood and appreciated in these times of stacked genetic traits, seed coatings, high seed prices, technology fees, and purchase agreements. But, seeds didn't just begin service as a delivery system in the present era of biotechnology. They have been delivering things of the gravest important to farmers and those who depend on farmers since farming began.
Delivering the Future
Seeds, first of all, deliver the future, the hope for a tomorrow. In the primitive rural settings where farming was first practiced and civilization began, seeds represented tomorrow's food supply, and, of course, they still do even in our times of grand scale urbanization, high technology and maturing civilizations. The early and recurring human aspirations for better places and times led people to explore and migrate to lands beyond the horizon always carrying with them seeds for the foods they would need tomorrow in the new land.
The authors of the article on "The Seed" in the last issue of SEED News related how their grandparents brought seeds from Europe, the old world, with them when they migrated to Brazil, the new world, as a sort of survival insurance. During the great age of exploration and migration of populations from the 14th to 20th centuries crop seeds were introduced, multiplied, and exchanged in and among the various regions.
The introduction of new crops, especially, had enormous and usually favorable impacts on population growth and living standards. Only infrequently did an introduced new crop precipitate a tragedy as the potato did in the Irish famine. Without seeds, there is no future, no tomorrow. I have probably related in these essays, perhaps more than once, the words of an elder in an African village during the great Sahelian drought that for me represent the most profound act of human desperation, "We had to eat our seeds." In former times this act would probably have ended unnoticed in famine and death of most of the villagers, but, fortunately, most such desperate circumstances of the human condition no longer go unnoticed, food and seeds were provided and the most dire of the age-old consequences of eating one's seeds was averted.
Delivering Creativity, Inventiveness and Visions
Seeds deliver the creativity, natural inventiveness, and labors of those exceptional persons that are always present in human populations. The individual(s) who first recognized and understood the generative function of seeds were visionaries. Seeds were the means of fulfilling their vision of replacing a very risky, nomadic, hunting and gathering existence with a settled, stable life style in a place of their choice.
During the Sung Dynasty in China (circa 1000 B.C.) an observant person discovered (or developed?) a rice variety that permitted two crops per year from well irrigated land and one fair crop in hilly, rainfed areas. The impact of this discovery and its wide adoption on food supply spawned two centuries of economic growth that, perhaps for the first time in the pre-modern world, advanced significantly more rapidly than population growth.
There are many great and relatively recent examples of human creativity and vision incorporated into crop varieties and delivered by seeds around the world for the benefit of all of us. Hybrid varieties of maize, sorghum, millet and many vegetables and the improvement and widespread cultivation of the soybean have improved the quantity and quality of our foods and the economy of the rural sector. In my judgment, however, the most significant human inventiveness, creative labor and vision incorporated into crops for delivery by seeds during the past 50 years of so was that of the "architects" of the "green revolution" varieties. Famine had been forecast by many "experts" for the late 1970s, especially for the huge populations in Asia and the rapidly increasing populations in Africa. Researchers had begun to genetically revise the architecture and physiology of rice and wheat, the two most important food crops, to permit greater use of production inputs and increase yields. There was a critical race not widely publicized or understood between population growth and food supply that was won just in time in a much bigger way than anticipated by the researchers and visionaries of a green revolution.
I was in India during the time when some of the large shipments of seeds of the "Mexican wheats" were received and witnessed unforgettably the hope and vision of a better fed future the seeds represented and were delivering to agricultural scientists, officials and peasant farmers. The development of high yielding hybrid varieties of rice in China and their spread to other areas even the U.S. was a great follow-up contribution of creative and inventive persons.
Delivering Improved Performance
In the early 1980s one of the U. S. seed trade magazines carried two advertisements for seeds that validated the concept of the seed delivery system deeply and indelibly in my psyche. One company was offering tall fescue (Festuca arundinacea) seed for pastures that was guaranteed endophyte free, while another company was offering tall fescue seeds for cool season lawns guaranteed to have endophyte present. The endophyte, a fungus living symbiotically in the tissues of tall fescue, had been identified a few years earlier as the probable cause of the well known toxic effects of tall fescue on some grazing animals. Thus, farmers purchasing fescue seed for cool season pasture wanted a guarantee that seeds were free of the fungus. On the other hand, since there was good evidence that for lawns and turf fescue with the endophyte did better and resisted insects, people purchasing fescue seed for use on recreational areas wanted a guarantee that the endophyte was present.
It is not surprising that this situation caused a lot of problems for seed analysts and seed control officials. First, analysts had to develop relatively simple and rapid methods for determining whether the fungus was present or absent from seedlings produced by the seeds being tested. Then, seed control officials had to develop regulations pertaining to the labeling of tall fescue for endophyte and use, i.e., pasture or turf. There were, of course, problems for the breeders of tall fescue, seed producers and farmers who had well established fescue pastures with the endophyte and wanted to get rid of it. Eventually, ways were devised to resolve all of these problems more-or-less satisfactorily.
Seeds have long been used to deliver materials that enhance or improve the performance of the seeds, the crop, or both. Seed treatment chemicals are perhaps the most familiar example. Seed applied protectant fungicides and insecticides protect the seeds against seed rotting fungi and seed destroying insects. Seed applied and delivered systemic fungicides and insecticides protect the seedlings and growing plants from certain diseases and insects. Applying the element molybdenum to soybean seeds delivered better nodulation and performance under very acidic conditions. Seed applied gibberellin delivers improved germination of lettuce seeds under warm conditions, more rapid emergence of centipede grass seed and better emergence of some semi-dwarf rice varieties. Microorganisms such as selected strains of Bacillus subtilis and Trichoderma spp. applied to and delivered by seeds enhance the performance of peanuts, cotton, and other crops, probably by occupying ecological niches along the root system that could otherwise be occupied by less benign microorganisms. The use of seed coatings to deliver a program for seed and crop performance also needs to be mentioned here, as well as some seed treatments of a physiological nature that alter the seeds in ways that enhance performance of the seed and crop. These beneficial effects are in a sense delivered by the seeds as physiological changes e.g., priming or osmoconditioning treatments to improve the uniformity and performance of seeds under stress conditions, or moisturization (increasing seed moisture content) of bean and pea seeds to reduce imbibitional injury.
I'm sure that by this point it has been noticed that the most powerful and revolutionary use of the seed delivery system has hardly been mentioned. Modern biotechnology has dramatically and irrevocably expanded the uses of the seed system to deliver enhanced traits, often from foreign and exotic sources, to improve and protect crops, improve the quality and nutritional value of products, and produce all sorts of specific chemicals. The biology and economics of such multiple uses of the seed's delivery system can and do place an enormous strain on its performance capabilities for if the seed doesn't perform its primal function of propagation nothing is delivered. Biotechnology and more conventional technologies, however, provide both means and opportunities to significantly improve the seed as a delivery vehicle that, unfortunately, have not received adequate attention. Some of the most potentially useful improvements will be considered in the next essay.
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