ABSTRACT
The growth and development of a crop, which is an aggregation of individual plants of the same species, can be regarded as a system with the following components: the characteristics of the plant species, the functioning of the plant during its development and the plant environment. Since modern crop varieties have a great degree of genetic similarity among individual plants, the characteristics and the functioning of the single plant usually give a good indication of the characteristics of monoculture crops. In multiple cropping, the interaction between the components of the crop between plants of different species - is very important. Crop-environment interaction remains as important as in monocultures, and consequently, understanding the interrelationships between the physiological activities and the environment of a multi-species crop is more difficult than for a monoculture crop. Crops and varieties can be screened for their suitability for growth in associations and, of course, crops specially suited to multiple cropping can be selected and bred.
