This proposal requests funds to permit Drs. Susan U. Wallace and Ulysses S. Jones, Department of Agronomy and Soils, Clemson University, to pursue with Dr. Henry P. Samonte, Institute of Plant Breeding, University of the Philippines at Los Ba~os (UPLB), for a period of 24 months, a program of research on the tolerance of selected maize genotypes to nutritional problems related to soil acidity. The maize genotypes will be selected from the field screening program at UPLB where they will be evaluated for growth, yield, and nutritional status on three diverse acid soils of the Philippines. Nutritional factors related to plant adaptation will be identified, and the differential ability of the maize genotypes to modify root zone acidity will be determined. It has been estimated that nearly one half of the world's nonirrigated arable land area consists of acid soils. In strongly acid soils, plant growth may be limited by one or more of several mineral stresses, including deficiencies of phosphorus, calcium, and magnesium, and excesses of hydrogen ions, manganese, and aluminum. One approach to overcoming acid soil infertility is chemical treatment with such antacids as lime and supplementation of minerals. Another approach, more suitable in the less affluent countries, is to identify plant genotypes which adapt to soil acidity. In this project, the collaborators will identify such maize genotypes as well as plant traits associated with adaptation to one or more of these acid soils. Germ plasm containing these adaptive traits will be used by physiologists and geneticists for further study. The U.S. and Philippine collaborators are highly respected scientists who have successfully collaborated in the past. This project is relevant to the objectives of the Science in Developing Countries Program which seeks to increase the level of cooperation between U.S. scientists and engineers and their counterparts in developing countries through the exchange of scientific information, ideas, skills, and techniques and through collaboration on problems of mutual benefit.
