Sylvan H. Wittwer

Growth of bean and tomato plants as affected by root absorbed growth substances and atmospheric carbon dioxide

SummaryBean and tomato plants were grown in solution culture root media containing pre-determined concentrations of gibberellin A3 (GA), 1-naphthaleneacetic acid (NAA), N6-benzyladenine (BA), (2-chloroethyl)trimethylammonium chloride (CCC), and at atmospheric levels of 300 and 1000 ppm of CO2. Net assimilation rates (NAR), relative growth rates (RGR), leaf area ratios (LAR), root to top dry weight ratios (R/T) and changes in dry weight, size, and form of each organ were recorded.Gibberellin had no effect on RGR of either plant species but increased the NAR of tomatoes at 1000 ppm CO2. Total dry weight was only slightly affected by GA but root growth and R/T were markedly depressed. CCC had no effect on NAR, but decreased RCR and LAR. Root growth of beans and R/T in both plants were promoted by CCC. NAR and RGR were strongly inhibited by BA and NAA. Inhibition of stem and leaf growth by CCC and NAA was greater than that for roots; thus, R/T ratios were increased. Root branching was promoted by NAA.High (1000 ppm), compared to the low (300 ppm), atmospheric levels of CO2 generally promoted root growth and produced an increase in the R/T, both in the absence and presence of chemical treatment. The multiplicity of effects of the rootabsorbed chemical growth substances and CO2 on growth and photosynthesis is discussed.

Carbon dioxide levels in the biosphere: Effects on plant productivity

Human society is now inadvertently conducting a great biological and environmental experiment, the outcome of which is not known. Atmospheric carbon dioxide (CO2) is increasing at the rate of 1.5 parts per million (ppm) per year. It has risen from 315 ppm to 340 ppm in the past 25 years — a 9% increase. Because CO2 is among the factors which can limit the growth of plants, the increase may be beneficial. An increase in plant growth due to “fertilization”; of extra CO2 has not been measured, but a 5 to 10% increase may already have occurred. Current data indicate that plants growing at higher than normal CO2 levels are more tolerant of water, temperature, light, and atmospheric pollutant stresses. There are effects on carbon metabolism, plant growth and development, microbial activity, and terrestrial and aquatic plant communities. The current rising level of atmospheric CO2 represents ,a dramatic change in a resource base and can affect the total biological productivity of the earth. A global change in a ...

Future Technological Advances in Agriculture and Their Impact on the Regulatory Environment

world has never known. The ingredients of that system consist of labor-saving technologies, generally stable production at high levels, progressively largerscale operations, and massive inputs of capital, management, and resources. The focus is on single crop or livestock systems. Our food production technologies have had an important impact abroad as well as at home. World food supplies heretofore have kept ahead of population. There is now more food per person, on a global scale, than at any time in recent history. However, food production alone is not enough. There must be distribution, delivery, and income-getting the food where the people are and providing them with the purchasing power to buy it. Only poor people go hungry. It is time for reassessment of our tech-

The fruit-setting factor from the ethanol extracts of immature corn kernels.

Abstract The fruit-setting factor of the ethanol extract of immature kernels of sweet corn ( Zea Mays rugosa , var. Golden Cross ) has been identified as the ethyl ester of 3-indole acetic acid. This ester is approximately 100 times more effective than is 3-indole acetic acid in inducing parthenocarpy in the tomato.

Foliar uptake and translocation of rubidium in bean plants as affected by root absorbed growth regulators

SummaryThe absorption and subsequent transport of foliar applied Rb86 labeled Rb Cl (10 mM) was studied on bean plants (Phaseolus vulgaris, L. cv. Black Seeded Blue Lake) exposed to physiologically tolerable levels of certain plant growth substances in the solution culture root media. Gibberellin A3 (10-5 M) increased Rb uptake but did not affect total translocation from the treated leaf. Translocation was directed to the upper vegetative parts and markedly reduced to the roots. Foliar influx of Rb and transport to the roots were greatly enhanced by 1-naphthaleneacetic acid (10-6 M) but mobilization of Rb into the leaves and upper stem was reduced. 2-Chloroethyltrimethylammonium chloride (10-3 M) and N,N-dimethylaminosuccinamic acid (3×10-4 M) decreased the mobility of Rb to the upper stem, increased it to the roots, and had no effect on initial uptake. Rb absorption was depressed by 2,4-dichlorobenzyltributylphosphonium chloride (10-5 M) with no effect on subsequent translocation. Both uptake and mobility were strikingly inhibited by N6-benzyladenine (10-6 M).These results suggest that absorption and the subsequent transport of foliar absorbed Rb are independent processes and that the distribution or mobilization of Rb in the various plant organs was not always a function of the chemically modified growth rate of the corresponding organ.

Solar energy and agriculture

Agriculture stands pre-eminent as the world’s first and largest industry. It is our most basic enterprise, and its products are renewable as a result of ‘farming the sun’. Through the production of green plants, agriculture is the only major industry that ‘processes’ solar energy. The greatest unexploited resource that strikes the earth is sunlight and the green plants are biological sun traps. Each day they store on earth 17 times as much energy as is presently consumed world-wide. The goal of agriculture is to adjust species and cultivars to locations, planting designs, cropping systems and cultural practices to maximize the biological harvest of sunlight by green plants to produce useful products for mankind. Many products of agriculture may be alternatively used as food, feed, fiber or energy. Conflicts over the agricultural use of land and water resources for food, feed or fuel production will arise as resource constraints tighten.

MEETING FUTURE FOOD NEEDS: THE CHALLENGE TO AGRICULTURE*

The world’s greatest challenge is to provide adequate food for an expanding population. Jean Mayer’s projection of a year ago is appropriate: “We will have to find in the next 25 years food for as many people again as we have been able to develop in the whole history of man ’ti1 now.” The immediate solution to meeting world food needs lies in all-out agricultural production, improved nutrition, and in education. There are now significant technological, financial, and organizational opportunities for effective action. For the first time in history we have the capability to relieve mankind from the scourge of malnutrition and hunger. The reality of a rapidly growing world population with rising international affluency and demand discourages a policy of no action. Never before has a nation produced so much food. Never before has it been done on so few hectares. Never before has any nation exported so much food abroad. And never before has any nation exercised such a monopoly on the world’s surplus. Assuring our food supply, however, is more than production technology. It involves removal of a host of socio-politico-economic and institutional constraints, and effectively dealing with food policy issues. It involves research in post-harvest handling, processing, storage, transportation, and consumer acceptance. Food is truly a high technology export. That people today are malnourished or starving is a question of food distribution, resources and economics, not agricultural production limitations. Enough food is now produced to feed the world’s hungry. We are producing more food per capita than 20 years ago. The problem is delivery. It’s putting the food where the people are, and providing an income so they can buy it. Only poor people have a problem in meeting their food needs. Only scientists develop new technologies. Only farmers produce food. Motivation and incentives are important both for scientific discovery and food production. The time between a basic research discovery and its first application averages 13 years. The time from introduction of a new technology iintil its adoption reaches the expected ceiling is 35 years. It now takes 6-10 years to train scientists to do research. We must forcc the pace 6f agricultural development. New technologies must be tailored to each local condition. This can best be done by scientists who also know how to farm-a commodity that is becoming rare, indeed. There have been many recent assessments of technologies that are available or that can be developed for increasing plant and animal resources for human

Future challenges and opportunities for agricultural and forestry research

—The products of agriculture and forestry are our most important renewable resources. Photosynthesis is the key biochemical process. Through the utilization of solar energy, the leaves of plants provide a net increase to the resources of the earth. This is manifested as food, feed, fiber, and organic raw products for industrial materials. Increased biological productivity holds the key to future availability of renewable resources, and the ease by which the inevitable transition will occur from the non-renewable to the renewable. Some of the many research options available for enhancement of primary productivity are enumerated. For the first time in history, we have both the opportunity and technological capability of providing sufficient food for all people, and to greatly improve the output of our forest resources. The potential capacity for global crop and food animal production is enormous. Attention should be directed toward mission oriented basic research with economically important crops and commodities, and to the application of the results of basic research to the resolution of problems relating to the productivity of renewable resources.

Agricultural productivity and biological nitrogen fixation--an international view.

Biological nitrogen fixation is second only to photosynthesis as the most important biochemical process on earth. Many questions have been raised during this Conference by scientists and members of the press as to economics, hazards, pay-off, benefits, effects on our food supply, food prices, resource inputs, when results can be expected -- all related to research with biological nitrogen fixation.

Agricultural Production--Research Imperatives for the Future

Many studies have assessed the potential contributions of research for the enhancement of food production and of other renewable resources. An equal number have inventoried the earth’s resources of land, water, minerals, climate, etc. for absolute production capability. Recent emphasis on the “Politics of Food” suggests a strong third determinant for agricultural production potential. The tripartitions of productivity—new technologies, resource inputs, and economic incentives—must be constantly reviewed.