Agro-Climatological Studies on C3-Plants and C4-Plants

Abstract

Crops can be divided into C3-crops and C4-crops by the difference in the pathways of CO2 fixation. We examined the distribution of C3-and C4-crops in the World and India. The results are as follows:1) C3-crops are cultivated in about 70% of cultivated area in the world and C4-crops are about 30%. In Europe and Oceania, C3-crops are mainly cultivated. In Latin America and Africa, C4-crops are.2) C3-crops are mainly cultivated in cool regions (Europe, Canada, etc.), high dry regions with high temperature (Arab countries), and high precipitation regions with high temperature (South-east Asia, Equator Africa, etc.). Barley and wheat are mainly cultivated in cool regions, and high dry regions with high temperature. Rice and cassava are in high precipitation regions with high temperature.3) C4-crops are mainly cultivated in dry regions with high temperature (coastal countries of the Caribbean Sea, Southern Africa, and Northern Africa of south of the Sahara Desert).4) The regions where C4-crops are cultivated over 50% of cultivated area are 17-18°C of mean annual air temperature with annual total precipitation from 200 to 1500mm. The regions where C3-crops are cultivated over 80% of cultivated area are under 19-20°C, over 19-20°C with under 200mm, or over 19-20°C with over 1500mm.5) In India, C3-crops are mainly cultivated in high precipitation regions. C4-crops are in dry regions.6) It is considered to be necessary to clarify the characters and the historical distribution of crops as well as the climate and environment of cultivated areas of C3-and C4-crops.