Abstract
The root systems of four field grown cereals were observed at heading. Foxtail millet (Setaria italica Beauv.) and common millet (Panicum miliaceum L.) are small-sized, while pearl millet (Pennisetum typhoideum Rich.) and corn (Zea mays L.) are large-sized. We compared foxtail millet with common millet, and pearl millet with corn. Root length in every 0.17 mm diameter class was determined by means of a personal computer assisted measuring system. Root length density (m root length/m3 soil volume) in deep soil layer was higher and the difference of root length density between under row and under inter-row was smaller in common millet than in foxtail millet, and in corn than in pearl millet. Thus common millet and corn are considered to have relatively uniform and desirable root distribution pattern in the soil. While root length per m2 soil surface varied from 5.5 to 11.1 km/m2 in four cereals, root length per stem was similar among foxtail millet, common millet and pearl millet (90-111 m), except in corn which had no tillers. This suggests close relationship between root length and number of stems in the field. Common millet and corn had more thick roots (>0.17 mm in diameter) than foxtail millet and pearl millet.
