ABSTRACT
I. INTRODUCTION French bean (Phaseolus vulgaris) is known by several names, such as common bean, kidney bean, navy bean, pinto bean, field bean, haricot bean, China bean, marrow bean, frijole, snap or string bean, wax bean, black bean, or white bean. Over 14,000 cultivars of common bean are known to exist, and the International Center for Tropical Agriculture in Colombia is the main repository for the germplasm (59). The common bean (genus Phaseolus) includes 150-200 species of plants, many of which are cultivated as food or garden ornamentals. The common bean is therefore a highly polymorphic and perhaps the most widely cultivated of all beans in temperate and semi-tropical regions. Kaplan (60) suggests that the common bean is native to the New World, with origin(s) in Mexico, Central America, and northern areas of South America (60), and has been cultivated for at least 7000 years in Mexico. These beans are used as a green vegetable, green shelled, or dry as pulses according to the stage of harvest. In temperate regions, green mature pods are cooked and eaten as a vegetable (1). Immature pods are marketed as fresh, frozen, or canned, whole or French cut. Mature dry beans called navy beans, white beans, northern beans, or pea beans are widely consumed. The total world production of the French bean as a vegetable (green beans) in 1995 was 3,119,000 metric tons (MT), of which Asia accounted for 1,597,000 MT (51.2% of the total world production). China (560,000 MT), Turkey (440,000 MT), Spain (228,000 MT), Italy (158,000 MT), Indonesia (155,000 MT), the United States (122,000 MT), Egypt (108,000 MT), and France (103,000 MT) were the leading producers of French bean in 1995 (58). The name snap beans is applied to beans in the tender young stage when the pods are eaten. Snap beans are one of the most valuable vegetable crops grown by home and market gardeners and truck farmers for shipment and canning. Green shell beans are
shelled and used just before the seeds become ripe and hard. Dry or field beans are produced in the fully matured and dried stage and usually classed as field crop. In addition to classification according to use, beans may be divided into dwarf or bush and pole or climbing groups, each including green pods and wax pods, which in turn may be flat, round, or intermediate in cross section (2).
