Crop physiology has been called “the retrospective science” by one plant breeder because we physiologists elucidate what the breeders have already achieved. Indeed, such explanations occupy the first part of this chapter, the whence of greater crop production. We shall also peer ahead, the whither in my title. But physiologists have learned that past increases in crop productivity have often come from unexpected and initially unrecognized directions, in many cases driven by developments in agronomy, mechanization, and demand. The integrating power of empirical selection for yield potential has, so far, proved more effective than ideological selection for specific physiological characteristics, presumably because yield is the integrated end result of a great variety of processes that must act in a balanced and coordinated way. Crop production can be increased in several ways, such as by extending the arable area, by increasing yield per hectare per crop or the number of crops per hectare per year (called intensification), by displacement of lower by higher yielding crops, and by reducing postharvest losses. Until the 1960s the major contribution for the world as a whole came from increases in the area of arable land and in the proportion of it under crop. Since then, however, the limited increases in arable area, in South America and Africa mostly, have largely been matched —though not in land quality —by losses to urbanization, transport, and degradation. The proportion of rainfed arable land under crop continues to increase slowly, currently being about three quarters for the developing countries as a whole. The intensification of arable land use is most important in warmer and wetter climates, particularly under irrigation. Double cropping of rice has been prominent in China since Sung times. Cropping intensity in the Punjab now approaches 200%, and FAO projects that 13% of the increase in crop production in developing countries by A.D. 2010 will come from intensification, compared with 21% from extension of the arable (Alexandratos, 1995). Further intensification will depend heavily on extension of the irrigated area, but much can also be achieved by the breeding of earlier maturing varieties coupled with improvements in fertilizer use and minimum tillage procedures.
Agrarian sector of Ukraine in the global world