Showing papers by "International Maize and Wheat Improvement Center published in 1974"

The Development of Triticale

Abstract: Publisher Summary This chapter presents a historical overview of the development of triticale, which is an artificially created derivative of a cross between wheat and rye and possesses the chromosome complements of both parental species. It discusses two main groups of triticale: the octoploid triticales, which are amphiploids of hybrids between hexaploid wheats and rye; and hexaploid triticales, which are amphiploids of hybrids between tetraploid wheat and rye. The chapter discusses breeding and research of triticale in Eastern Europe, Western Europe, and North America. The triticale improvement at International Maize and Wheat Improvement Center (CIMMYT) is also discussed. CIMMYT initiated an international triticale testing program in 1969, which made it possible to estimate the productivity of triticale strains relative to wheat, from year to year over a wide range of environments. Triticale appears to have a competitive advantage under cool growth conditions at intermediate to low elevations and can serve as a substitute crop for rye on sandy soils.

Growth and yield of highland maize in Mexico

Abstract: SUMMARY The growth and yield of five highland varieties of tropical maize were studied. Grain yields were between 4·7 and 8·8 t/ha. Crop growth rates (C) increased to a maximum of between 25 and 35 g/m2/day at silking and then declined. Grain growth rates (maximum 21 g/m2/day) exceeded current C during most of the grain-filling period. After silking, when C exceeded grain growth rate, dry matter accumulated in the stem and husk, resulting in an increase of from 200 to 600 g/m2. Later, as grain growth rate increased and exceeded current C, some of this accumulated material was incorporated into the grain, and stem weight decreased. A comparison of the dry weight changes after flowering in these varieties with those reported for a hybrid that yielded 12 t grain/ha indicates that the smaller yield of the Mexican varieties was associated with smaller grain growth rates and the incorporation into the grain of a smaller fraction of the dry weight produced after flowering. These results suggest that the capacity of the grain ‘sink’ to utilize assimilates limited yields in the tropical varieties.

Cereal Grains: Future Directions for Technological Change

Abstract: The recent changes in agriculture in the developing countries have occurred largely as a result of the introduction of new technologies in rice and wheat and, to a lesser degree, in maize. The importance of these crops as a source of nutrition and as a source of income readily explains the emphasis given to them. Moreover, as they are widely cultivated in the developing countries, they represent an avenue for encouraging change and development.